讲座时间：2026年1月9日（星期五）15:30-16:30
讲座地点：北京大学深圳研究生院 C303
主持人：陈召龙 林德武 新材料学院助理教授
主讲人：Rodney S. Ruoff
Center for Multidimensional Carbon Materials (CMCM), Institute for Basic Science (IBS) (Republic of Korea)
Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST) (Republic of Korea)
讲座摘要
During this presentation, l will highlight how this versatile chemistry can be successfully applied to address important challenges in the field of energy(hydrogen production, heat transfer, fuel cells/batteries..), environment (capture of pollutants, CO2 reduction...)and health (wound healing, cancer...).
On Earth circa 2025 significantly more natural graphite (G) than diamond (D) is mined/processed, and significantly more synthetic G than D is made. In metric tons: ~1,500,000 to ~24 (G to D, natural) and ~3,500,000 to ~3,100 (G to D, synthetic).
D&G are almost isoenergetic at 273K and 1 atm and the same is true for hexagonal boron nitride (hBN) and cubic boron nitride (cBN). E.g., ΔHf of D at STP is about the same as ΔHvap of liquid neon at its boiling point of 27K, and about 1/10 the enthalpy of an H-bond in liquid water. (Graphite is the standard state at STP.). ΔGf and ΔHf at STP of cBN are even smaller (with it currently being perceived that hBN is just barely more stable than cBN.). And we will chat a bit about what Prof. Gibbs reminds us of in terms of phase equilibria.
My perspective: Kinetic control and not thermodynamic control dictates why it has been simpler to synthesize G than D at 1 atm pressure. And: (I suggest) that it is also kinetic control and not thermodynamic control that favors synthesis of D vs G in high temperature-high pressure (HTHP) synthesis in metal flux (pressure in the range 5 – 10 GPa; typically, but not always, a seed crystal is used). Almost invariably the explanation for each case (e.g., in textbooks, the published literature, etc.) has been based on thermodynamics (“It is hard to obtain diamond because graphite is SO MUCH MORE STABLE.”): This is “simply wrong” (as outlined above).
I discuss possibilities to synthesize D (please see/read [1]) in new ways. The parameter space for the elemental compositions of metal fluxes that might dissolve the needed amount of C (or for cBN the needed amount(s) of B and/or N) at ~1 atm pressure is very large per combinatorics and the relevant elements in the Periodic Table.
Fortunately (for basic science frontier research, as well as technology) there is a great deal that is “not studied at all” about dissolution of carbon, phase equilibria, and other interesting issues, for almost all choices of metal fluxes (aka “liquid metal alloys”).
And from some recent modeling results, we can open the question of liquid metals behaving as a new type of solvent for chemical synthesis. I’ll explain this during the talk.
With retrosynthesis (terms such as inverse design and/or inverse optimization are also used and perhaps apt) and achieving kinetic control in mind, I foresee a new—and very promising— horizon for synthesis of diamond and cubic boron nitride and new approaches to the use of metal fluxes and/or other liquid media (molten salts, etc.) for crystal growth in general.
I will also discuss an entirely different topic: The macroscale tensile loading mechanics of monolayer single crystal graphene (SCG) is presented. We have measured the Young’s modulus, strain at failure, and tensile strength, as a function of crystallographic orientation. SCG is grown on either single crystal Cu(111) or on Ni(111) foils, and ‘dog bone’ samples with gauge length of 10 mm and width 2 mm have been found to have remarkably high tensile strength values, which we suggest bodes well for applications, particularly for ‘lightweighting’ in space and aerospace, among others. An earlier version of this study (in progress) has been archived, please see [2]. Supported by the Institute for Basic Science (IBS-R019D1).
References
[1] Yan Gong, Da Luo, Myeonggi Choe, Won Kyung Seong, Pavel Bakharev, Meihui Wang, Seulyi Lee, Tae Joo Shin Zonghoon Lee, Rodney Ruoff. Growth of diamond in liquid metal at 1 atmosphere pressure. Nature. 2023, 629, 348-354.
[2] https://arxiv.org/abs/2411.01440v1
主讲人介绍
Rodney S. Ruoff, UNIST Distinguished Professor (The Departments of Chemistry and Materials Science, and The School of Energy Science and Chemical Engineering), directs the Center for Multidimensional Carbon Materials (CMCM), an Institute for Basic Science Center (IBS Center) located at the Ulsan National Institute of Science and Technology (UNIST) campus. Prior to joining UNIST in 2014, he was the Cockrell Family Regents Endowed Chair Professor at the University of Texas at Austin from September, 2007. He earned his Ph.D. in Chemical Physics from the University of Illinois-Urbana in 1988, and was a Fulbright Fellow in 1988-89 at the Max Planck Institute für Strömungsforschung in Göttingen, Germany. He was at Northwestern University from January 2000 to August 2007, where he was the John Evans Professor of Nanoengineering and director of NU’s Biologically Inspired Materials Institute, and did research at the Molecular Physical Laboratory, SRI International for 6 years after being a postdoctoral fellow at IBM TJ Watson Research Center.
Further information about Rod is at http://cmcm.ibs.re.kr/ and https://en.wikipedia.org/wiki/Rodney_S._Ruoff
