Material Surfaces with Tuned Properties
Solid-state surface properties are of utmost importance for many applications including catalysis, chemical synthesis, crystal growth, energy
conversion, and electrochemistry. Most of my research projects rely on tuning surface properties and involve a thorough study of
the surface chemistry and electronic properties at the surface. Surface termination and functional surface groups are key enablers for the
growth of high quality growth of thin films, as described in more detail on my research focus page
thin-film syntehsis at the atomic scale. Another key surface property for the efficient
conversion of heat into electricity is the work function. This electronic property determines how much energy is required to extract and
electron from the surface of a materials. More details on the development of next-generation low work function materials for thermionic
energy conversion are described in the materials for renewable energy applications and
AI-driven material discovery sections of my research page.
Apart from the main research topics mentioned above, tuning surface properties play a key role in a few other projects that I worked on with collaborators. Understanding of the precursor – substrate surface interaction is crucial when it comes to studying the nucleation phase of film growth during atomic layer deposition (ALD). Nucleation is strongly controlled by the surface termination and interfacial interaction between the precursor and the substrate. This limits the minimum thickness for films requiring complete coverage for many ALD chemistries. In Nature Catalysis we report a new technique that uses carbon monoxide as a passivation gas during ALD to modify the surface energy of already deposited Pt nanoparticles to assist direct deposition onto a carbon catalyst support. This new approach to synthesizing nanoparticulate Pt/C catalysts achieved high Pt mass activities for the oxygen reduction reaction. The growth of Pt using conventional ALD and passivation-gas-incorporated ALD is illustrated below on the left and right, respectively.
In another collaboration, we have developed an ab-initio photoemission model that accurately describes the photoemission process for the most diverse range of photocathode materials to date. Our model directly includes the full electronic structure of the material, photoexcitation probabilities for all direct optical transitions, and an improved surface-vacuum barrier transmission probability. For materials with a short skin-depth (typically metals) it is important to include electronic surface states in the photoemission model to accurately predict the emittance, as shown in the plot below for Cupper (100).
- E. R. Antoniuk, Y. Yue, Y. Zhou, P. Schindler, W. A. Schroeder, B. Dunham, P. Pianetta, T. Vecchione, and E. J. Reed, Generalizable density functional theory based photoemission model for the accelerated development of photocathodes and other photoemissive devices, Phys. Rev. B, 101 (2020) 235447 10.1103/PhysRevB.101.235447
- P. Schindler*, D. C. Riley*, I. Bargatin, K. Sahasrabuddhe, J. W. Schwede, S. Sun, P. Pianetta, Z.-X. Shen, R. T. Howe, and N. A. Melosh, Surface Photovoltage-Induced Ultralow Work Function Material for Thermionic Energy Converters, ACS Energy Letters, 4 (2019) 2436–2443 10.1021/acsenergylett.9b01214
- H. J. K. Kim, K. E. Kaplan, P. Schindler, S. Xu, M. M. Winterkorn, D. B. Heinz, T. S. English, J Provine, F. B. Prinz, and T. W. Kenny, Electrical Properties of Ultrathin Platinum films by Plasma Enhanced Atomic Layer Deposition, ACS Appl. Mater. Inter., 11, 9 (2019) 9594–9599 10.1021/acsami.8b21054
- S. Xu, Y. Kim, J. Park, D. Higgins, S.-J. Shen, P. Schindler, D. Thian, J Provine, J. Torgersen, T. Graf, T. Schladt, M. Orazov, B. Liu, T. Jaramillo, and F. B. Prinz, Extending the Limits of Pt/C Catalysts with Passivation-Gas-Incorporated Atomic Layer Deposition, Nature Catalysis, 1 (2018) 624–630 10.1038/s41929-018-0118-1
- D. Thian*, Y. T. Yemane*, M. Logar, S. Xu, P. Schindler, M. M. Winterkorn, J Provine, and F. B. Prinz, Atomically Flat Silicon Oxide Monolayer Generated by Remote Plasma, J. Phys. Chem. C, 120, 15 (2016) 8148–8156 10.1021/acs.jpcc.6b00768
- A. L. Dadlani, P. Schindler, M. Logar, S. P. Walch, and F. B. Prinz, Energy States of Ligand Capped Ag Nanoparticles: Relating Surface Plasmon Resonance to Work Function, J. Phys. Chem. C, 118, 43 (2014) 24827–24832 10.1021/jp5073044
* contributed equally