Topic #1: Development of electrocatalytic and photocatalytic materials
Left image: Cross-sectional TEM image of a SiOx-coated Pt nanoparticle deposited on a Si photocathode for H2 evolution.[ref. 3] Right image: Schematic of an oxide-encapsulated metal film that is capable of selective transport of electroactive species to the buried interface between the oxide overlayer and active metal electrocatalyst.[ref. 1,2]
Central to the operation of PEC, electrolyzer, fuel cell, and PV electrolysis devices are electrocatalysts and photocatalysts, materials that must efficiently facilitate charge transfer processes across solid/solid and solid/electrolyte interfaces. Developing new electrocatalytic and photoelectrochemical materials architectures with improved activity, stability, and selectivity in (photo)electrochemical processes is a major focus of our lab’s activities. We are especially interested in electrocatalysts and photocatalysts where the electrochemical reaction occurs at the buried interface between a very thin (1-10 nm thick) permeable oxide overlayer and an impermeable metallic electrocatalyst. The figure above shows an oxide-encapsulated nanoparticle co-catalyst for a p-Si photoelectrode (left image), as well as a well-defined oxide-encapsulated thin film. The oxide overlayers have several potential advantages over conventional electrocatalysts that are directly exposed to the bulk electrolyte, such as the ability to stabilize nanoparticles by mitigating degradation by coalescence, detachment, or dissolution. Additionally, thin oxide overlayers can be engineered to alter the energetics and reaction pathways that occur at the buried oxide/metal interface. In recent work, our lab has used ultrathin silicon oxide (SiOx) layers that behave as “nanomembranes” capable of controlling reaction pathways through selective transport of reactants or products between the electrolyte and catalyst. Many open questions remain about the structure of these thin overlayers and the catalytic properties of the buried interface.
- D.V. Esposito, “Membrane Coated Electrocatalysts—an Alternative Approach to Achieving Stable and Tunable Electrocatalysis“, ACS Catalysis, vol. 8, pp 457–465, 2018. Download here.
- N. Y. Labrador, E. L. Songcuan, C. De Silva, Han Chen, Sophia Kurdziel, Ranjith K. Ramachandran, Christophe Detavernier, D.V. Esposito, “Hydrogen Evolution at the Buried Interface between Pt Thin Films and Silicon Oxide Nanomembranes”. ACS Catalysis, vol. 8, pp 1767–1778, 2018. Download here.
- N. Y. Labrador, X. Li, Y. Liu, J. T. Koberstein, R. Wang, H. Tan, T. P. Moffat, and D. V. Esposito, “Enhanced Performance of Si MIS Photocathodes Containing Oxide-Coated Nanoparticle Electrocatalysts”, Nano Letters, vol. 16, 6452-6459, 2016. Download here.
- D.V. Esposito, Y. Lee, N.Y. Labrador, H. Yoon, P. Haney, A.A. Talin, V. Szalai, T.P. Moffat, “Deconvoluting the Influences of 3-D Structure on the Performance of Photoelectrodes for Solar-Driven Water Splitting”. Sustainable Energy & Fuels, 2017, DOI: 10.1039/C6SE00073H. Available for download here.
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