(15b) Modeling Hydrogen Evolution Reaction at the Interface of Silica Coated Transition Metal Electro-Catalysts from First Principles

Current technology for water electrolysis requires highly purified water, which increases the overall energy requirements and thereby cost. Recently, it was found that a thin semi-permeable silica (SiO₂) coating on the surface of Pt electrocatalysts ^[1] can prevent the contamination from cations and can increase the stability of the electro-catalyst in complex solutions with little impact on the catalytic performance. Using first-principles calculations, we have previously shown that the interaction of silica membranes with Pt surfaces is environment-dependent and changes with the pH value of the electrolyte and the electrode potential ^[2].

Here, we discuss the impact of silica membrane coatings on the mechanism of the hydrogen evolution reaction (HER) on different transition-metal surfaces (SiO₂/TM, e.g., TM = Pt, Cu, Au). Stable configurations of the buried SiO₂/TM interface during HER were determined using density-functional theory (DFT) calculations. Extending our previous work ^[2], computational interface Pourbiax diagrams were calculated, showing the pH and potential dependence of different intermediates and of the hydrogen coverage on the metal surface. Activation energies for different reaction mechanisms at the buried interface were obtained from Nudged Elastic Band (NEB) simulations.

Our modeling results indicate that the HER mechanism at buried SiO₂/TM interfaces involves the silica membrane. In addition to the protective quality of silica membranes, this hints also at the possibility of designing synergistic membrane-coated electrocatalysts that surpass in catalytic performance (activity and/or selectivity) the bare surfaces of earth-abundant transition metals.

1. Labrador, N. Y.; Songcuan, E. L.; De Silva, C.; Chen, H.; Kurdziel, S. J.; Ramachandran, R. K.; Detavernier, C.; Esposito, D. V. ACS Catal. 2018, 8 (3), 1767–1778. https://doi.org/10.1021/acscatal.7b02668.

2. Qu, J.; Urban, A. Potential and PH Dependence of the Buried Interface of Membrane-Coated Electrocatalysts. ACS Appl. Mater. Interfaces 2020, 12 (46), 52125–52135. https://doi.org/10.1021/acsami.0c14435.