A Quest for New Materials: Superhard Metals Conducting Polymers and Graphene

this program is presented by university of california television like what you learn visit our website or follow us on Facebook and Twitter to keep up with the latest UC TV programs funding for this program was provided by the UCLA office of instructional development [Music] it's my pleasure to participate in UCLA's 115 faculty research lecture by introducing our colleague professor richard Bikaner distinguished professor of chemistry and biochemistry and material science and engineering as you see professor caner received his PhD in organic chemistry from the University of Pennsylvania in 1984 and conducted his postdoctoral research at UC Berkeley before joining UCLA's faculty in 1987 he is the recipient of numerous awards including the UCL a gold shield faculty prize the luqman distinguished Teaching Award the American Chemical Society buck Whitney research award the National Science Foundation presidential Young Investigator the American Chemical Society Tolman medal and chemistry of materials award the Guggenheim Sloan and Packard fellowships and some room for him to talk you could see I could go on and on professor canners work has resulted in over 275 research papers and he now holds 14 US patents with twenty more patents pending throughout his career professor caner eric has been known for the access inclusiveness and mentorship he provides for both undergraduate and graduate students he has inspired generations of students to use knowledge and discovery to change the world by changing people's lives just as he has his research has been described as encompassing the intriguing elements of power strength and flexibility in a way that will impact the future today's lecture is entitled the quest for new materials super hard metals conducting polymers and graphene please join me in welcoming our 115 faculty research lecturer the distinguished colleague professor Richard B Cana thank you it's a great honor and pleasure to be here and when you look at the list of previous winners it's a rather humbling experience today I want to tell you about some of our work on new materials and it's this I look at as an opportunity to thank my students and my colleagues and some of my predecessors for making this possible and what I want to do is start with a slideshow and let's try this again so my journey began as an undergraduate at Brown University when I was bored in freshman chemistry talked to the chair and found out that I actually probably shouldn't be in freshman chemistry so then I said well I'd like to do research so right at the beginning of my first semesters of freshman I walked into this person's office professor unwalled and I said I'm interested in during research he said well I have a project for you so he said I need you to grow some crystals six weeks later I ran into him and he said any luck I said yeah and he came and looked and he was so impressed that he hired me and I spent four years working in his lab I found out later that he had given the same project to a graduate student and who didn't actually succeed so in their own worlds lab I learned the art of solid-state chemistry I also had the pleasure a year and a half of go about being invited back to Brown University and although he's retired he came to my lecture it was it was great fun well I learned about how to make materials at high temperature using solid state reactions and I had this idea when I came here that we developed low temperature reaction so I'm going to show you one of our low temperature reactions it's called a metathesis reaction where we take a B and C D and recombine them so you can judge for yourself if this is actually a room-temperature reaction this is in a vessel under helium and what we're doing is we're taking the lumen pentachloride and sodium sulfide and you'll see this again and we just mix them together and we wait about 30 seconds and I'm showing you after the 30 seconds and you can see the reaction takes off this reaction which makes lutein disulfide which is actually the world's best lubricant you see this appeared on the cover of nature and this isn't our dry box under helium so this is technically a room-temperature reaction it just happens to get to 1,400 degrees within a fraction of a second we've gone on to make over 100 materials by this process and you can see here we're making us the ceramic zirconium nitride and this is a few frames taken 1/2 second apart we can also make materials under high pressure and if you look here we're making tantalum nitride and we borrowed a press from my colleague mal Nichol and we ran this reaction at 45,000 atmospheres of pressure and we just set it off and we were able to make this phase that had only been made before under high pressure so one of the things I like about UCLA is the excellent colleagues and one day I got a call and it was from Jack Gilman and Jack said you probably don't know me but I'm a professor of in material science I do theory and I was reading one of your papers on making high-temperature borides and I was wondering if you ever thought about making super hard materials and I said well I've actually worked on some new forms of diamond and he said great we need to talk and he showed me this chart that showed that osmium was the most incompressible transition metal as almost as incompressible as carbon in the diamond form and so it became obvious that if we could combine osmium boron we could make a very incompressible material well here's incompressibility known as bulk modulus and when we made osmond i boride using metathesis reactions we found out that it's oh it's one of the most incompressible materials that have been made here's diamond here's the next cubic boron nitride here's all sorts of very hard materials now hardness is you must have something that's incompressible but it's not a sufficient condition so the idea was we're gonna put in short covalent bonds to get this to work when we do this if you look this is a hardness vs. applied load and it's quite a hard material in fact it scratches sapphire this is scratch as we put in a sapphire window sapphires 9 on the Mohs hardness scale so we realize we're on to something very interesting of course nobody really cares if you can scratch sapphire but the question is could you make this harder and could you scratch diamond and we did that by switching to rhenium and we did this here's a scratch put in diamond by rhenium die boride and you can see just how hard this is after we did this and I should point out that this is work with my colleagues Abbi Kavner from Earth and Space Sciences Jim and yang from material science in Sarah Tolbert who I've been working with for years she's an expert in measuring compressibility and after we did this I got a letter back a couple months later from somebody who didn't believe that we could actually have scratched a diamond and they challenged us to show the gouge put in a diamond well of course the student who had done this had had gone and I asked another student who came back a couple hours later said well this doesn't seem to work so I said well just take two diamonds and scratch one diamond against the other and came back an hour later said well that doesn't seem to work either so we discussed it and we figured out that it has an angular dependence and if you get the right angle you can take our rhenium die Boyd income multiple scratches in diamond so we put another scratch in diamond and we sent it back and reviewers decided this was really interesting so here's another paper that appeared in science and this is the diamond surface as measured using atomic force microscopy and you can see the gouge and here's the profile you can see we put a nice scratch in the diamond and then we analyze the surface to make sure that it was all carbon and you can see the pixels for carbon and you can see there's no pixels for rhenium so we really did put a scratch in in diamond well they sent it to reviewers and they got a chance to change what their comment before it was published and so they said well we didn't believe you could scratch diamond but it doesn't matter because rhenium too expensive to be of any practical value of course we got to change our answer and we said well you told us that we couldn't scratch diamond but we did here's the proof of it and in fact you know it's a science project so it doesn't really matter but in fact it does matter I mean I really when I'm looking at making new materials I want something that will actually be useful and so this was a real problem and so what we decided to do is find a metal that was less expensive and we came up with tungsten tetraborate and what I want to show you here is this is electric discharge machining you may ask why would you want a hard metal and the reason you want a hard metal is unlike diamond which can only be cut with other diamonds is you can cut it with an electric wire this is an electric wire underwater and you can slice through a metal like butter so you could make a really hard metal you could cut it and then you could use it to cut and polish other materials and so if we look at this next slide this is an ingot of tungsten tetraborate and tungsten is not a particularly expensive metal and so this is how we make the materials and then we took a slice through this using an electric discharge machining you can see we cut this out and we make cutting tools and this is what we're doing now and we're hoping that this will actually one day be practical in fact my student Chris Turner did this he made up an ingot here cut it out and then on a lathe simply turned a piece of aluminum which is not an easy thing to do and so the goal is that we can make a material that is much harder than currently used cutting materials and use it for cutting polishing and protective coatings okay I'm going to change gears to my next subject which is conducting polymers and this is something that I learned in graduate school from this gentleman professor Allan McDermott and I went to the University of Pennsylvania because a friend of mine told me that they had just made this great discovery and I needed to get myself there and what they had discovered is the first conducting plastic and here it is sis polyacetylene and here's the transform and here's aluminum foil and you can see you know either we're bad at taking pictures of this material looks metallic well it's not actually metallic in order for something to be metallic you have to have conditions one is you have to have a pathway for electrons or charge carriers to move and the other thing is you need those charge carriers so here's the structure of polyacetylene you can see alternating double and single bonds and that conjugated system provides the pathway however you have to dope it to provide the electrons of the holes and in this case this is iodine in the form of i3 - it pulls an electron away and there's holes that run along these chains and this is the first first conducting polymer in it yet led a number of years later 20 years later to the Nobel Prize for Ellen McDermott and I was invited back to the University of Pennsylvania for a Nobel Prize symposium and I said at the time we had a joke that he had probably never heard a joke from graduate school the joke is what is the only true application for polyacetylene now you have to understand this materials they're sensitive so everything was done in the absence of air and the answer to the joke is to produce PhDs but I said on this occasion we now know it's a dual-use material so PhDs and Nobel Prizes okay so we don't work on that almost no one in the world does what we work on these days is something called polyaniline and aniline is a very inexpensive material in fact if you're wearing any blue green or black clothing they're aniline dyes and they go back 150 years and then one day one of my colleagues invited Bruce Wyler from Aerospace Corporation to give a lecture aerospace corporations near LAX it's basically a National Lab has 1400 PhD scientists and they work on airforce projects and in their spare time they can do what they want so Bruce came and he will put up this picture of a shuttle going up and he said that one of the things the Air Force wants to know is what happens to these plumes and the reason they want to know is people keep living closer and closer to launch sites and so we talked about the cheapest sensor as a resistive type sensor and he said you know the plumes there's ammonium perchlorate that that is burned and one of the byproducts is HCl hydrochloric acid so if you could detect hydrochloric acid you have a really good detection system well I told them we have this conjugated polymer and it's in the insulator ten to minus ten Siemens per centimeter but if it's seeds hydrochloric acid it has over ten orders of magnitude change in Conda tivity which is just absolutely huge so he's like great send me some so I sent him some and three weeks later he called me and said well I got good news and bad news I said well start with the good news he said well the good news is it works I said well then what's the bad news he said well it's slow so I met with my research group and one of my graduate students said don't worry I'll make some nano form of the material and we can speed up this reaction and so what we did is we did an inter facial polymerization this is you can make nylon by this method but basically we took aniline this cheap starting material that comes from coal we put it in organic solvent we took oxidizing agent acid put it here and 30 seconds later at the interface you can see the conducting polymer form it why is why can you see it because it's conjugated and therefore it absorbs visible light so as soon as you see it it's forming now this is a minute two minutes and three minutes you'll notice that as it forms it goes into the water phase and that's because it forms in the doped salt form and so it disperses in water and we particularly chose a more dense organic phase so that gravity has nothing to do with it and we looked under microscopes and we have some really good microscopes in our nano Institute what we see is by transmission electron microscope that nano fibers that are about a micron in length and 30 nanometers in diameter and if we change the acid HCl is 30 nanometers camphor sulphonic acid about 50 nanometer diameter fibers in hydrochloric acid about 120 nanometer fibers we then looked at what how everybody else had been making polyaniline and what they did is they put in one drop of acid into aniline and when we repeated this experiment what we did with a stop flow reactor we found the first drop actually produces Nano fibers and it's the next thing that produces agglomerates and eventually get this agglomerated formula polymer that doesn't disperse and isn't useful in fact one of the things that I learned in graduate school is the only reason that conducting polymers haven't been used for very much is unlike conventional polymers they don't melt and they don't dissolve however after we did this we realized that we could make our nano fibers dispersed in water and in fact I'll even show you we now know how to meltem we discovered that process too but it led to this much simpler process and the idea is if we take oxygen and aniline and throw them together in a stoichiometric amount at room temperature we use up all the aniline form nano fibers they can agglomerate and so this process makes nano fibers in as large amount as you want and I can say that because we worked with Korean nylon known as Coulomb and they scaled up our reaction with our help to a hundred liter pilot plant reaction and so you can do this and you can make as much of this material as you want now we've also looked at coding technologies and one of my students julio darcy invented a coating material that if you think of making salad dressing you take oil in vinegar or oil and water and put it together and shake it of course they tries to separate and it forms a catenoid and so what we did is we took our nano fibers of a conducting polymer we put it in that oil water mixture and as the catenoid breaks up it sends a film growing up the side the wall of a tube and if you put a glass slide in you can make all different colors so here's poly thiophene in red and dope polyethylene and green and dido pollyanna in blue so we can make coding technologies in fact he earned the silver medal for in the national invented collegiate inventor Hall of Fame competition for this discovery okay getting back to sensors so Bruce and I looked at the sensor activity and here's the change in resistance on a log scale versus time here's the conventional material it sees an acid and the resistance drops here's the nano material it drops six orders of magnitude greater and so we saw we thought we had a really interesting sensor type material and the reason it does this can be seen if you look here's a conventional material and when the acid comes in of course it dopes the surface but in order for the conductivity to get through you have to diffuse the dopant and it's got to send the signal on the other hand here's our nano material on an electrode surface of course in this case there's no diffusion barrier so the gas can come in and as long as soon as it hits one of these surfaces it sends an electrical signal and we get a very instantaneous response and you can see this you can do it with acid in the dido form or take the dough form and bring up base here we're bringing up ammonia we turn it on the resistance goes up we turn it off and it's reversible and this would do in less than one part per million of ammonia now you know your nose is very sensitive to ammonia but even the best nose cuts out at about 25 parts per million in air so this is you could not smell this so one of my students said well I can just go over to RadioShack and you know for a couple dollars I can build a neat little sensor and we can do a demonstration okay so here is what we did and for $1 we got an LED and a comparator circuit and then arrow says provided this interdigitated gold electrode but then we didn't pay for it so thank you Bruce okay here's jjwong this is one part per million of ammonia watch the LED it takes about two seconds and you'll see it detects that he's gonna pull it out and it will reverse itself and then he's gonna do it one more time and of course if you put your nose in this you'd smell nothing because it's just a one part per million of ammonia but the detector is very sensitive so we can go on and we can do detection now one of the things I like is we can actually do this in a very interesting way and so we decided that this is such a straightforward experiment that we could teach our graduate students to do this so we introduced this in chem 285 a graduate student course and this is from the chemical engineering trade magazine there's one of our graduate students looking at an oscilloscope in fact we wrote this up for the journal of chemical education and we started teaching this to high school teachers and so Sarah Tolbert runs this program in the california nanosystems Institute in which 25 high school teachers come in on a Saturday and we do this every few every couple months and so I go over and I'll give the lecture and then the students will work with the teachers and show them how to sense things and then we give them kits and they go back to their high school classrooms and so hundreds of students across la high schools have now done this experiment where they take these poly any nano fibers and they expose them to things like lemon juice and vinegar any any households asses and bases and it's a it's a really wonderful experiment ok these nano fibers we can do many other things here's going grow old particles on them you can see 10 nanometers so these are about one nanometer gold particles and once you put on gold you can do all sorts of other things so we build memory devices this is work with yang Yang and Fraser Stoddard and you can see our crossbar memory devices here you can see this article about all different types of memory we can also put palladium nanoparticles and I was asked to do this by my colleague Paul ADEA kinesio and she's an expert in catalysis and what she was interested in doing is a coupling reaction called suzuki coupling suzuki won the Nobel Prize in Chemistry in 2010 and he shared it with Richard Hecht who was an undergrad and grad student in in our department he's come back since and these coupling reactions are simply taking things like boronic acid and Aero chloride and putting them together well it turns out that that polyaniline nano fibers are great platform for the Palladium which can run these reactions under very mild conditions now I promise that we could actually melt this polymer and here's how we do it we took the polymer and we expose it to a camera flash at close range and it melts and this is a very interesting phenomenon so it absorbs the light converts with the heat and it happened so fast that it melts you can't melt the polymer by heating and it's simply cross-links but you can do patterning with this so this is a copper transmission electron microscope grid and this is the dope form of the polymer doesn't matter if it's doped or D doped but we like this cuz of color contrast so we hit this with a flash of light and we remove the grid where the grid protected it's still green and nano where the grid didn't protect it it actually melted and you can see the huge contrast these are real colors now you can do real pattern in with this and so here's a patterning done with a laser scribe device just taking a 780 nanometer laser it's a $25.00 device and I'll tell you more about this later and we can write on CDs we can write in digitated electrodes we can make sensors we can write UCLA I had the opportunity to spend a sabbatical in Australia with Gordon Wallace on a Fulbright fellowship and what we did is we took this material and we simply melted the top surface so this is looking at a cross-section so you can see here's the nano part here's the melted part and we use this for an actuator so we dip this in acid the nano part absorbs the acid expands the melted part cannot expand so if you think of your hand as an actuator and you were to dip it in acid it will curl up in this thing in 20 seconds we'll do two full rotations we stick it in base and uncurl so you can make the motion of a human hand or an actuator now I said this was in Australia I want to prove that so here's a picture we took in Australia this is my family who are here this is a few years ago and by the way that koala and the eucalyptus leave that's in his mouth not my mouth and if you want to hear more about this this is one of our pieces of polyaniline that's been hit with a laser and it's very hard to tell the difference between the welded side and the non welded side unless you look under a high-powered microscope but here's the microscope images this is false coloured and here's another article in advanced materials in which we describe the Nano fibers I'll point out that we actually wanted to understand the basics of these long polymer chains and to do that we looked at the tetramer which is a smallest repeat unit and in this work we made some very nice structures and we looked at the conductivity and the way we did this we went to my colleague Dongfeng Duan and he has the ability to put these between two gold electrodes here's a little tiny nano wire and we measured in its metallic and so this four unit long segment has a conductivity almost as good as the bulk material which is one to ten it's over 1 and so this is remarkable and it means that the electrons in this material can hop very nicely from one place to the other if you align it perfectly in fact this material is so well aligned we did this with chris regan in in physics we were able to get single crystals of this and i just want to show you one single crystal and so jessica weighing last year entered this in Materials Research Society sciences art contest and this is a single crystal of polyaniline well it's actually multiple single crystals the only thing that's false coloured we colored this violet and we called this tetra aniline in full bloom and she won first prize in this all right let me turn turn to my my third in subject here so the third thing and I for this I want to thank my postdoctoral advisor from the institution to the north and Neil Bartlett when I went to work in his lab we worked on on graphite and my postdoctoral project was develop new forms of graphite in if he talked about a dream that he had with graphite and the dream was someday to make a material that had a high surface area he called it wholly graphite so if you think of all the batteries you use one of the electrodes and sometimes both or graphite based electrodes and graphite is a it's a very cheap material you can mine it it's highly conductive but it has one drawback has a low surface area and so he had this dream of making wholly graphite spelled hol ey and I'll get to that in a little bit this is one of my favorite pictures of graphite this is called highly oriented pyrolytic graphite and what we're doing here is hitting with a laser a normal material when here with a laser gets hot in three dimensions but graphite is not a normal material it's a two-dimensional material and heat or thermal conductivity follows two pathways it follows the chemical bonds known as the phonon modes which are in this direction because it's all the bondings that way and it follows the conduction electrons and again the PI star orbitals overlap and they overlap in that direction so all the heat transfers in two dimensions so if you touch here you burn yourself if you touch here it's cold and this is the only picture I've ever seen of a property atomic scale property in in three dimensions okay well enter the world of graphing graphene is a very interesting material it was discovered in 2004 novoselov and gaim who discovered it by peeling that stuff with scotch tape won the Nobel Prize in 2010 and you can think of graphene a single layer of graphite is a building block for all of the forms of carbon so for example if you put 12 five membered rings in you get something called fullerenes named after Buckminster Fuller who invented the geodesic dome you can roll up a sheet of graphene and get something called carbon nanotubes or you can stack it up and get grabbed fight but of course these forms were discovered much earlier these two basically in the last 25 years now our work in carbon dates from the earliest time I was at UCLA and this is work with my former colleagues Francois Diedrich and Rob wedyn and what they did is they came up with a large amount of carbon 60 and Bell Labs had just discovered conductivity and superconductivity in it but they had a very small volume fraction at about one percent we made the first pure samples and got the structure and the structure is here and you can see that it's here's carbon 60 and here's potassium and they sit on all octahedral and tetrahedral sites and this you know it's I have a nice model in in my office made out of soccer balls in fact I can probably tell you this story I walked in in order to make this model you need 14 soccer balls so I was in Toys R Us and I had my cart filled with 14 soccer balls and the guy being in front of me kept turning around and he said can I ask you a question unlike sure he said are you the coach of a little league soccer team and I said no I'm actually doing a science project what I didn't tell him is that as a professor at UCLA and that I was using taxpayer money to buy soccer balls but anyway so we looked at this we then went on and here's how the boss live and guy won the Nobel Prize by taking scotch tape and peeling it and they kept peeling until they got down to a single layer which is just quite remarkable but there's other ways of making graphene one is by chemical vapor deposition on copper and number of people have done that and then if graphene is ever going to be useful you need a method that you can scale up and so we're interested in doing solution processing methods in fact one of the things I really like about UCLA as I said is we have wonderful colleagues so in the year 2000 this is four years before graphene was discovered Tom Hahn knocked up my door Tom Hansa professor in mechanical engineering and he said I understand that you're a resident expert in carbon and I said well I've been working on carbon for a long time he said good I need you to make me a single layer of carbon can you do it and I said well probably but why would you want it he said well I did the following calculations in a single air carbon be the best reinforcement for polymers and then he's like well how would you do it I said well Graphite's a layered compound it's been known for many years that if you heat it in the presence of potassium it forms what's called the first-stage intercalation compound between every layer carbon you get a layer of potassium plus and it's a nice gold colored compound and I said we'd then take the compound we'd hit with water alcohol and blow the layers apart just like that's great you got to do this so we did this and then we sonicated it and interestingly enough these things scroll up and so here's a carbon nano scroll this is a lacy carbon grid behind it but you can see this nice scroll and here's a more tightly round scroll and here's a whole lot of scrolls now what's interesting is this is a paper we published in science in 2003 so this is one year before graphene was discovered but our goal was to make graphene and so I actually took out a patent in 2002 on graphene and so the patent hasn't been licensed but I'm very hopeful that graphene will be useful in this patent will someday be be recognized okay after the loss of a guy did their work we realized that the only problem with our method is it not only makes one layer as people have subsequently shown but it can make 230 all different numbers of layers so we switched our research a little and we started looking at a graphite oxide which is you if you oxidize graphite you in water you can divide it into individual layers that are oxidized and then you have to get them back to graphene and from this graphite oxide we've made everything from graphene paper to electronic devices we've worked with King Wang in electrical engineering we've built sensors we've done foam we've done LightScribe in super capacitors and I'll show you this because super capacitors are really interesting and you know if you could solve the energy storage problem that would that would be very helpful and this this may be part of a solution ok first just a word about graphite oxide so here's a layer of graphite that's been oxidized disperses in water and this chemistry goes back over 150 years well when we picked it up we looked anew at graphite oxide and we find that when you reduce it with hydrazine a good reducing agent it forms a dispersion and water I say it's a dispersion because if you look at the laser light going through if it's a solution the light goes through but if it's a dispersion of nano particles the light bounces off so we have all these little particles these little sheets of graphing and they stay apart because every sheet is negatively charged they don't like each other now it's called a charge stabilized colloid because if we add salt the sole neutralizes the charge and they all flocculate out you can see that here and if you look by atomic force microscope here's individual sheets of graphene and if you run a probe along you can see this going over it's about one nanometer step height and you can show that it's graphene well this is an article that we did for nature nanotechnology with my collaborator Gordon Wallace and last year the editor-in-chief sent me an email telling us we had the most highly cited paper in the history of their journal and so today it has over 2,800 citations okay we can scale this up we make as much as you want so we take this reduced graphite oxide this chemically produced graphene and we run it through filter paper and we just peel it off plastic filter paper and so this is graphene paper and it's a little bit different than graphite graphite SEBI stack this is just random stacks of many sheets of graphene and you can see it's very highly reflective we even tried reducing this in pure hydrazine to make an even better colloid in a better material and this is work done with yangyang in material science and when we did this at the time we produce the largest sheets of graphene that had been made and this is a standing electron microscope picture of a very large sheet of graphene and here's a Tomic force microscope picture and I think if you stare at these for a moment you'll agree that these are the same picture so about 20 by 30 microns and I was getting support at the time from the Defense Advanced project Research agency and wherever you're meeting at UCLA we had about 25 people and the program manager looked at this slide he said well Rick this is nice but there's a problem and like what's the problem he's like something's missing I'm like what's missing he said Florida it's missing yes so we decided that program managers actually have a sense of humor too so we ran a comic force microscope probe across white red and blue and what you'll see is the step height is about point six nanometers and by doing this we could demonstrate that this really was a single layer of carbon okay well what can you do with a single layer of carbon well with yangyang the best transparent conductor is known as Indian tin oxide so all your cell phones and your flat-screen TVs all have a coating of indium tin oxide but it's not very flexible how do we know that well we took in ancient oxide on plastic which is polyethylene terephthalate like Coke but like this kind of plastic and we took our graphene and we mixed it with carbon nanotubes and we made a material that's equally conductive then we bent in each 10 times well the Indian tin oxide is a nice crystalline inorganic solid and Eve ended 10 times the conductivity drops by a factor of a thousand when you bend our carbon nanotubes and our graphene nothing happens and so you can actually make flexible electronics out of this and many companies are now looking at at thin sheets of carbon for electronics and and you'll start seeing flexible cell phones other flexible electronic devices you can also make sensors and this is working with with Bruce Wyler again and we looked at the detection of two four dye nitro toluene at 52 parts per billion now you may say why do I care about that well the cousin this of dinette wrote on Ewing is trinitrotoluene our TNT and so this is the volatile component it has a vapor pressure above 700 parts per billion and so if you can detect this you can use graphing to the to detect explosives okay another thing you can do with this material this is freeze-dried graphite oxide and I'm just gonna light this on fire and to see what happens oh here we go and I'm sure many of you played with snakes on the 4th of July it doesn't but what's interesting is it looks like it's burning but it's all still there so what it's doing is it's getting hot it's giving off co2 but most of its most of the carbons still there now what we're gonna do is hit it with a flash of light this is graphite oxide paper okay so what's it doing again it's absorbing the light converting to heat and blowing off carbon dioxide completely uncontrolled reaction but imagine controlling this reaction so to do that we again use LightScribe and light scribes this $25 device and we hit it with a 780 nanometer laser we can draw whatever pattern we want so we paid an artist for this picture of a person with a computer for a brain and we just told the computer to raster that image and we reproduce that in graphene and so where you see the light part that's graphite oxide it's an insulator the dark part has been converted with the laser to graphene and the things in between are partially converted and we can show that we go from an insulating graphite oxide to a conducting graphene okay now this gets really interesting one of my students my hello Katie came to me and he started looking at the electrochemistry of this and he came to me and he said I measured you know the cyclic voltammetry of a iron three iron two couple and it has a peak separation of 0.05 nine volts I realized that that doesn't mean much to most of you but it meant something to me I said well I study electrochemistry probably thirty years ago and I don't think you can get that because the theoretical limit according to the Nernst equation is 0.05 nine volts and he came back to me and he said no you're not quite right he said actually the Nernst equation is 0.0591 six volts and I measured point oh five nine five volts so it's actually a JIT a legitimate measurement but it says that electron transfer on a single sheet of graphene is extremely fast and in fact when he did the calculations moving charge on graphene is at the rate of 10 to minus 2 centimeters per second and it's a hundred times faster than graphite so at that point we realize we had a really good electrode material and we needed to start making use of it and so we use laser scribe and instead of drawing a pretty picture we just told it to darken the whole thing and so here's laser scribe graphene versus the graphite oxide and you can see the graphite oxide is this beautiful layered material we hit it with the laser it absorbs the light converts it to heat in is off co2 and as the co2 leaves it leaves pockets behind and so here is a material it has a fractal geometry in which it's highly conductive but what we've really done is made a three dimensional coordinated cardboard Network so we have a high surface area and high conductivity that's exactly what you want for electrodes in fact I wish Neil Bartley were still alive today because this is the wholly graphite that he talked about back in the 1980s and so it was obvious to us that we should start building electrochemical devices and so my hair started building super capacitors and here's what it looks like it looks like a battery two electrodes in a separate and electrolyte but now we're gonna charge one positive and one negative and there's no real movement of ions they just jump on the surface and jump off and so you can charge and discharge these devices millions of times literally and they can store their very high power they're not quite as high energy as batteries but they can they can be used for a lot of things and this is called a cyclic voltammetry and in theory if you get a rectangular wave that would be a perfect result and this is as close as you'll probably ever seen a rectangular wave when we compare this to commercial devices based on activated carbon as you drive an activated carbon device faster and faster it falls off our material still keeps performing and this is up at 4,000 milliamps per cubic centimeter very high current we can even bend our material this is the cycle voltammogram is a function of bending angle and you'll see every one of these are on top of each other so you can now start thinking about flexible charge storage devices and then you may say well you know if I look at my computer battery it doesn't run on one volt or three volts but it runs at fourteen point four volts so how am I gonna get there well you can combine these devices in series so here's a 1 volt aqueous cell we put four of them together in series you get out four volts here's two in series we double the voltage and two in parallel we double the area under the curve and so you can stack these together very nicely and you can actually run real-world devices with this and here's what a row goney plot looks like this is power density versus energy density and these are what are called commercial super capacitors so super capacitors bridge of capacitors which are high-powered devices but they don't store much energy and batteries which are relatively low-powered of devices but they store a lot of energy so the goal is to make higher better super capacitors and then we could have electric vehicles in all sorts of other good things well here's our aqueous cells here's our organic cells and here's some ionic liquid cells so our materials actually show they have power comparable to capacitors and they have energy density now comparable to lead acid batteries and we have plans on how to make them eventually comparable to lithium ion batteries okay with that what I want to show you now is a movie that will describe this and it was made for the Sundance Film Festival a lot of times experiments in science or discoveries look like accidents but there are only accidents in the sense that we were trying to find something else and then we realize that what we had was better for a different application [Music] graphene is a single eric cartman it's one of the strongest materials ever known and it's completely flexible the discoverers of graphene won the Nobel Prize in 2010 however the method they use to make it which was taking graphite in peeling it with scotch tape is not practical so we set out to find a better method we start with graphite oxide which is a water dispersible material we then coat it on two sheets of plastic we hit it with a light from a laser the oxygenates it turns it into graphene so it's pretty exciting because we made all organic graphene in a very simple process using consumer grade DVD drive that you can find everywhere but the real discovery was yet to come I think the Eureka moment that you're looking for was not exactly that the real exciting discovery came when ma hare dragged me into the lab and he said take a look at this and he just took a light bulb and he just turned it on with this little piece of graphene but the amazing thing is it doesn't stop working after charging for 2 or 3 seconds he ran this light for over five minutes I thought we have something very important I thought the world changed okay let's talk about the future batteries have a bad reputation but what we're working on are super capacitors and super capacitors you can think of as a charge storage device like a battery except it charges and discharges one hundred to a thousand times faster a battery it stores a fair amount of charge but it charges and discharges slowly a capacitor puts out a high output but it doesn't store much charge so like the flash to a camera a super capacitor is one which combines the best attributes of both if you think about all the electronic devices you have right now every time you need one you realize oh I forgot to charge it up but imagine if you could take that same device plug it in the wall for 30 seconds for a minute and be ready to go life would be very different and eventually we'll get to things like electric vehicles now you pull into a gas station well you'd pull into a charging station within a minute it would charge up your car if you think the batteries batteries all composed of a lot of metals often they're toxic metals and so in fact you're not allowed to throw a battery away but if you had something that's carbon-based it wouldn't matter carbon-based you can put in your compost bin and use it to grow vegetables when I was a kid I wanted to be a scientist and so my goal has always been to develop something that will change people's lives so this film was made by a professional videographer for a contest for the Sundance Film Festival last year and when he made the top 20 finalists he told me that we should get ready to go to Sundance but unfortunately we didn't win however when the movie was released to the Internet it went viral it's probably one of the most watched science of videos over 2 million people downloaded it and with that let me thank all the people who made this possible which is very hard to do but the first thing I want to do is think the wonderful colleagues I've had at UCLA and I sat down and I looked at how many my colleagues have I've written papers with and there are actually 36 colleagues and you can see them all here and by the way if your name's not on this list and you'd like to be just see me after the seminar I also want to think we have some very generous supporters and I want to especially mention two because they have been great supporters for the Department of Chemistry and biochemistry as well as my own lab and that's ray and Dorothy Wilson and George and Jerry Gregory and then there's all the funding agencies we just put there they're symbols here but they've been an integral part of our ability to get things done but the real thing is I get the pleasure of standing up here and talking but the people who go in every day and actually do the experiments and make those discoveries those are my graduate students postdocs and undergraduates and visiting professors and so I would especially like to thank them I have one more thank you and that is UCLA has been a wonderful place to do research as I think we all know and one of the crown jewels here is the California nanosystems Institute and it has the high-powered microscopes it has the professional staff that enable us to see things on the nano scale and to do you know great deal of what I talked about today has been making new materials and they work because of Nano and so I'm very grateful for them for the support for this institute and with that I want to thank you for coming I want to thank you for your attention and I'm very happy to answer questions [Applause] sorry there are people in the audience who will be able to hand you a microphone if you have questions so if you raise your hand we will have somebody with the microphone come to you so you can ask the question or if you want to volunteer to be one of the co-authors with the professor yes hi I was just wondering about the the super hard material the the tungsten tetrachloride is that considered a what do you call it diamond does synthetic diamond material so tungsten tetra board is a material that is hard enough to scratch diamond but it's not a you know synthetic diamond is usually some form of carbon that's made artificially in the lab so in fact about 10% of the diamond in the world is actually made in the laboratory okay but most of the diamond that's used is actually made in the laboratory although gemstones are more often made our mind but the material that we're making it's clearly a synthetic material it's not particularly expensive and it's extremely hard but what we do is we're working on the fracture toughness of the material this is true of all very hard materials they can be somewhat brittle and so if you use tungsten carbide which is really probably our real competition that's all your drill bits and all your your cutting tools all have tungsten carbide in them and what they do is they put another agent in they reduce the hardness a little but they increase the fracture toughness so that's what we're doing to make improvement and so I'm hopeful those experiments are going well you saw we already have a have been able to make a cutting tool and so I'm hoping someday that that these materials start replacing some of the current materials cuz a lot of the materials like tyson carbide wear out very quickly others like diamond are just very expensive to make and the same with with cubic boron nitride which is a diamond replacement what are the current challenges and prospects for moving super capacitors into applications that we currently use batteries for so that's a really good question so super capacitors I actually didn't I have a whole series of slides on what they can be used for but let me give you some of the highlights so currently carbon based super capacitors are used for electric buses in China and the idea is if you don't have a lot of infrastructure don't want to put it in you just make a charging station the bus stop every 5 or 10 miles and as people get on and off the bus the bus gets charged so you can do that within a minute to two minutes so there's a promise for using them that way the real question is could you stick them into your cell phone and could you charge your cell phone in 30 seconds or less and that is a problem that we're actually working on in the lab in order to do that we have the power to do that in other words we can charge them fast enough the question is can we provide enough energy and in that we have to combine graphene with some other materials and that's what we're working on however I could today build an external charger that charger could be charged in 10 seconds you can put your cell phone in it you could stick it in your pocket and it'll trickle charge your cell phone with with that charge so that's that's a possibility there's many other applications my favorite is there's a revolving door at a train station in Amsterdam that's connected to a super capacitor so as people go through the revolving door it runs the restaurant next door at least the lights yes so we could we can all be involved with super capacitors but there's great promise for portable electronics for even stoic storing solar energy and sometimes I joke you know if the worst problem you have is that if you're driving from Southern California Northern California in your electric Tesla and you have to stop for lunch for two hours well we could probably solve that problem too so there's there's a lot of commercial promise with these materials they just need to be scaled and improved a bit the experiment that you showed where some form of graphene or graphite admitted carbon dioxide yes is there anything reversible about that so that you could absorb carbon dioxide from the atmosphere yes that's a very good question it would be very nice to get rid of carbon dioxide which is a greenhouse gas but no this is a very irreversible process it's a we're using the carbon dioxide to make the expanded lattice in fact I can tell you that the service area graphene is 2630 meter squared per gram and when we do this experiment we've measured above 1500 meter squared per gram which means we've measured beyond what you'd get if you put two sheets together because that would reduce it by half so we really have individual sheets separated by these pillars and so we really have what what I like to think of is wholly graphite and so that's why we can make such good charge storage devices however capturing co2 is not one of the things that these are good for so there are many other ways to do that that other people are working on but it's it's it's a good thought just these materials aren't meant for that oh very good if you google super super capacitor yes it's a film by Brian Golden Davis and it's very easy to find in fact if you're interested ke CET our local public radio station did an interview with me a few months ago and it turned out to be the most popular interview that they did all year it was number one on the KCET website I don't know I haven't seen it myself but they send me a thing if you just go to KCET I don't know didn't put put in my last name and it will it should probably pop up yeah we were actually with that video we were my students tell me we were on the top of the reddit web site for a week which apparently tracks videos and that I don't know what that means but they said that's that's that's a good thing and there's a site that has the most popular videos or short videos of 2013 and we were like number three and you know if you look at the top ten they're all about famous people or you know singers or people doing crazy things and there's a science video so it's kind of it's interesting and I should tell you that a lot of people have gotten interest to this the first few high school students that emailed me and say professor caner I'm you know I want to do this for my science project and I said I don't think you want to do this for your science project because yes graphite oxides cheap but we make it in the lab and if you buy commercially it's expensive and you know there's gonna be all these problems and then finally a high school student wrote to me and said well it worked so here it is and three weeks ago I had a home school Network email me and they said we want to do this for our great school project or something and I'm like and and then they say you know I gave him some advice and then they emailed me back and he said they did the laser scribe and they put the electrodes together but they can't get any output current and I wrote back and I said did you put in an electrolyte and they said what's that and I said we'll just take some acid and I told them which one and put it in and they wrote back and I said it works and they could light something so I don't understand it but apparently this is easy enough that that high school students or even grade school with some assistance can actually go and do this so this LightScribe device many of us who are older have never heard about LightScribe but if you have kids and you ask your kids they know all about it it's a $25 device that you can buy on the internet and they use the Gillette razor model Gillette razor model is give away the razors sell the blades so they give away the device with all the very sophisticated software that can raster any digital image and then what they do is they charge for the light scribed enable disc but what we do is we take their disc and we put a piece of plastic on top we coat it with graphite oxide we here the laser converted to graphing we peel off that and use that and then we put a new piece on and so we're we're kind of cheap and I assume that some of the high school students who are doing this to do the same thing but it's it's actually possible it's been very popular on on some of these websites people and people start I was getting several emails a day and and I just I told I just referred them to our papers because I just couldn't answer all the all the emails coming in if not first I would like to all to give a hand to Professor [Applause] [Music] you video copies of this program are available for purchase from the UCLA instructional media library call toll-free 1-800 additional information about the people places and ideas discussed in this program is available at our website

Channel: University of California Television (UCTV)

Views: 35,638

Rating: 4.818697 out of 5

Keywords: material science, high-temperature materials, chemistry

Id: du6H990Z9yA

Length: 55min 53sec (3353 seconds)

Published: Tue Jun 03 2014