Non-equilibrium plasma activated durable molybdenum oxycarbide electrocatalysts for acidic hydrogen evolution up to 10 A cm-2

Abstract

Electrocatalytic hydrogen evolution in acidic media at industrial-level current densities is limited by high overpotential, performance degradation, and consequently low throughput. To address these challenges, we develop nanoedge-enriched molybdenum oxycarbide (MoOxCy) electrocatalysts with a uniform phase by non-equilibrium plasma-enhanced chemical vapor deposition. The vertically standing MoOxCy exhibits a low overpotential of 415 mV and stable long-term operation (~ 0.11% performance degradation over 1000 h) at high current densities up to 10 A cm-2, corresponding to a high hydrogen throughput of 4,477.4 L cm-2, which exceeds the Department of Energy targets. Molybdenum oxycarbide catalysts are competitive with state-of-the-art transition-metal and even noble-metal catalysts in terms of throughput and lifetime throughput. The key mechanism involves carbon incorporation into MoO2 lattices, which lowers the Mo valence and weakens Mo-H binding energy, thereby improving hydrogen evolution performance. Density functional theory results suggest that carbon atoms in MoOxCy increase the binding energy between Mo and the adjacent atoms, enhancing MoOxCy structural stability. This study establishes a pathway toward practical and efficient transition-metal catalysts for hydrogen evolution.