Computational and Experimental Investigations of the Au and NiOOH Interface in the Oxygen Evolution Reaction

The transition to renewable energy sources is crucial for combating climate change, and hydrogen (H 2 ) is a promising clean fuel. Electrolysis of water, specifically the oxygen evolution reaction (OER), is a key process for producing H 2 . Prior experimental results have shown that gold (Au) could improve the apparent activities of the OER electrocatalysts such as nickel hydroxide (Ni(OH) 2 ) in alkaline electrolytes. 1-3 However, the detailed interfacial atomic structure and mechanisms of the increased catalytic activity remain poorly understood. To understand the interfacial effect between Au and Ni(OH) 2 in the OER process, our research uses the model system of Au nanoparticles (NPs) and nickel oxyhydroxide (NiOOH), which is the active phase of Ni(OH) 2 layers in the OER, to investigate their interfacial interactions with both experimental and computational approaches. We hypothesize that the Au NPs on NiOOH enhances the OER activity by promoting electron transfer at the interface. Our studies involve computational analysis using Density Functional Theory (DFT) calculations to obtain the local density of states (LDOS), which can help us better visualize and compare the local electronic structure of NiOOH in the presence and in the absence of AuNPs. Two architectures of the Au and NiOOH interface will be investigated: Au NPs on a NiOOH film and NiOOH NPs on a Au film.Additionally, Bader analysis is employed to determine the Bader charge, offering a more detailed understanding of how electrons are distributed across the AuNPs/NiOOH interface. Furthermore, the catalytic efficacy of AuNPs on NiOOH is assessed through electrodepositions followed by cyclic voltammetry(CV) measurements. The experimental and computational results will be directly compared, and this research is expected to contribute to the insights of substrate and catalyst interactions for design of more efficient electrocatalysts. References: (1) Yeo, B. S.; Bell, A. T. Enhanced Activity of Gold-Supported Cobalt Oxide for the Electrochemical Evolution of Oxygen. J. Am. Chem. Soc. 2011 , 133 (14), 5587–5593. (2) Strickler, A. L.; Escudero-Escribano, M.; Jaramillo, T. F. Core-Shell Au@Metal-Oxide Nanoparticle Electrocatalysts for Enhanced Oxygen Evolution. Nano Lett. 2017 , 17 (10), 6040-6046. (3) Chakthranont, P.; Kibsgaard, J.; Gallo, A.; Park, J.; Mitani, M.; Sokaras, D.; Kroll, T.; Sinclair, R.; Mogensen, M. B.; Jaramillo, T. F. Effects of Gold Substrates on the Intrinsic and Extrinsic Activity of High-Loading Nickel-Based Oxyhydroxide Oxygen Evolution Catalysts. ACS Catal. 2017 , 7 (8), 5399– 5409.