Our primary focus on the materials side are nanostructured inorganic systems and their interfaces: Their structure, stability, electronic properties, etc. Up to date publication information can be found on our group's publications page.
Current work in the group addresses new semiconductor materials and their properties.
Several distinct avenues of research on new, crystalline organic-inorganic hybrid materials funded by NSF and also, as of Fall 2018, through DoE's Energy Frontier Research Center "CHOISE", which is led at the National Renewable Energy Laboratory.
- Chi Liu, William Huhn, Ke-Zhao Du, Alvaro Vazquez-Mayagoitia, David Dirkes, Wei You, Yosuke Kanai, David B. Mitzi, and Volker Blum
Tunable Semiconductors: Control over Carrier States and Excitations in Layered Hybrid Organic-Inorganic Perovskites
Physical Review Letters 121, 146401 (2018).
Preprint including full supplemental information: arXiv:1803.07230 [cond-mat.mtrl-sci]
New multinary chalocgenides for light harvesting applications (e.g., photovoltaics or photo-electrochemistry) in a recent, joint NSF project with the group of David Mitzi at Duke University:
- Garrett C. Wessler, Tong Zhu, Jon-Paul Sun, Alexis Harrell, William P. Huhn, Volker Blum, and David B. Mitzi,
Band gap tailoring and structure-composition relationship within the alloyed semiconductor Cu2BaGe1-xSnxSe4
Chemistry of Materials 30, 6566 (2018). DOI: 10.1021/acs.chemmater.8b03380
- Tong Zhu, William P. Huhn, Garrett C. Wessler, Donghyeop Shin, Bayrammurad Saparov, David B. Mitzi, and Volker Blum
I2-II-IV-VI4 (I = Cu, Ag; II = Sr, Ba; IV = Ge, Sn; VI = S, Se): Chalcogenides for Thin Film Photovoltaics
Chemistry of Materials 29, 7868-7879 (2017) DOI: 10.1021/acs.chemmater.7b02638
- Donghyeop Shin, Tong Zhu, Xuan Huang, Oki Gunawan, Volker Blum and David B. Mitzi, Earth-Abundant Chalcogenide Photovoltaic Devices with over 5% Efficiency Based on a Cu2BaSn(S,Se)4 Absorber, Advanced Materials, 1606945 (2017)
- Donghyeop Shin, Bayrammurad Saparov, Tong Zhu, William Huhn, Volker Blum, and David Mitzi, BaCu2Sn(S,Se)4 - Earth-Abundant Chalcogenides for Thin-Film Photovoltaics , Chemistry of Materials 28, 4771-4780 (2016).
Further recent work has focused on materials and their interfaces for electronic, photo- or electrocatalyic applications, including:
Graphene and related nanostructures on SiC surfaces. On SiC, high-quality mono- and bilayer graphene films can be grown directly by the controlled sublimation of Si, creating what may be the most promising platform for graphene based applications grown directly on a semiconducting substrate. Recent publications include:
- Lydia Nemec, Florian Lazarevic, Patrick Rinke, Matthias Scheffler, and Volker Blum
Why graphene growth is very different on the C face than on the Si face of SiC: Insights from surface equilibria and the (3x3)-3C-SiC(-1 -1 -1) reconstruction
Physical Review B 91, 161408(R) (March 27, 2015).
- J. Sforzini, L. Nemec, T. Denig, B. Stadtmüller, T.-L. Lee, C. Kumpf, S. Soubatch, U. Starke, P. Rinke, V. Blum, F.C. Bocquet and F.S. Tautz
Approaching truly freestanding graphene: The structure of hydrogen-intercalated graphene on 6H-SiC(0001)
Physical Review Letters 114, 106804 (2015).
- L. Nemec, V. Blum, P. Rinke and M. Scheffler,
Thermodynamic Equilibrium Conditions of Graphene Films on SiC (open access link)
Physical Review Letters 111,065502 (2013). (Supplemental material: pdf)
- T. Schumann, M. Dubslaff, M.H. Oliveira Jr, M. Hanke, F. Fromm,T. Seyller, L. Nemec, V. Blum, M. Scheffler, J.M. J Lopes, H. Riechert,
Structural investigation of nanocrystalline graphene grown on (6√3×6√3) R30°-reconstructed SiC surfaces by molecular beam epitaxy.
New Journal of Physics 15, 123034 (2013).
Ongoing work includes the definitive identification of the critical, so far unresolved pre-graphitic surface structures of C-face SiC, the mechanical properties of 2D materials as a means to achieve subsurface structural resolution in experiment.
Together with the group of Bettina Lotsch in Germany and visiting student Tiago Botari from Brazil, work in the group also addresses the mechanisms behind the photocatalytic activity of graphitic carbon nitride materials:
- Tiago Botari, William Paul Huhn, Vincent Wing-hei Lau, Bettina V. Lotsch, and Volker Blum
Thermodynamic Equilibria in Carbon Nitride Photocatalyst Materials and Conditions for the Existence of Graphitic Carbon Nitride g-C3N4
Chemistry of Materials 29, 4445-4453 (2017). DOI:10.1021/acs.chemmater.7b00965 .
- Vincent Wing-hei Lau, Victor Wen-zhe Yu, Florian Ehrat, Tiago Botari, Igor Moudrakovski, Thomas Simon, Viola Duppel, Elise Medina, Jacek Stolarczyk, Jochen Feldmann, Volker Blum, and Bettina V. Lotsch, Urea-modified Carbon Nitrides: Enhancing Photocatalytic Hydrogen Evolution by Rational Defect Engineering, Advanced Energy Materials 2017, 1602251.
- Vincent Lau, Igor Moudrakovski, Tiago Botari, Simon Weinberger, Maria Mesch, Viola Duppel, Jürgen Senker, Volker Blum, and Bettina Lotsch, Towards rational design of carbon nitride photocatalysts: Identification of cyanamide "defects" as catalytically relevant sites, Nature Communications 7, 12165 (2016).
- Vincent Lau, Maria Mesch, Viola Duppel, Volker Blum, Jürgen Senker and Bettina Lotsch
Low molecular-weight carbon nitrides for solar hydrogen evolution
Journal of the American Chemical Society 137, 1064-1072 (2015).
Earlier work covered the reconstructed surfaces of Au, Pt, catalytically relevant surface properties, and many other aspects of surface science. In addition, Volker has some significant background in creating first-principles multiscale models for specific materials, e.g.,
- V. Blum, G.L.W. Hart, M.J. Walorski, and A. Zunger,
Using Genetic Algorithms to Map First-Principles Results to Model Hamiltonians: Application to the Generalized Ising Model for Alloys
Physical Review B 72, 165113 (2005).
- G.L.W. Hart, V. Blum, M. Walorski, and A. Zunger,
Genetic determination of first-principles Hamiltonians
Nature Materials 4, 391-394 (2005).
[see also Axel van de Walle's News and Views article in the same issue, Nature Materials 4, 362-363 (2005).]
and in surface crystallography (low-energy electron diffraction), e.g.,
- V. Blum and K. Heinz,
Fast LEED intensity calculations for surface crystallography using Tensor LEED
Computer Physics Communications 134, 392-425 (2001).