(145f) Trends in Hydrogen Evolution Reaction Activity Among Metal Modified Carbide Thin Films and Powders

Water electrolysis, coupled with renewable energy sources, is an important technology for producing CO₂-free hydrogen gas that can be used for energy storage or CO₂ conversion. One of the major barriers to widespread electrolyzer use is the high cost of platinum-group metals required to catalyze the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) at the electrolyzer cathode and anode, respectively. In the current study, metal-modified transition metal carbides were investigated as inexpensive replacements for bulk Pt for the HER. Transition metal carbides were synthesized as thin film electrocatalysts and modified with monolayer coverage of precious and non-precious metals. The HER activities of these catalysts were measured electrochemically in both acidic and basic electrolyte, and activity trends were established based on density functional theory (DFT) calculated hydrogen binding energy (HBE). Pt-modified niobium carbide showed promise as a low-cost alternative to bulk Pt for the HER, and it also showed impurity tolerance in the presence of common tap water ions. Thin film results were then extended to industrially relevant high surface area molybdenum carbides (Mo₂C) with dispersed metal nanoparticles. Pt-Mo_2­C demonstrated a high mass activity with low Pt loading. Future work should focus on controlled synthesis techniques for well-defined high surface area catalysts in order to facilitate the use of DFT to help screen for active HER catalysts.