Hydrogen Spillover Mechanism at the Metal–Metal Interface in Electrocatalytic Hydrogenation

Abstract Hydrogen spillover in metal‐supported catalysts can largely enhance electrocatalytic hydrogenation performance and reduce energy consumption. However, its fundamental mechanism, especially at the metal–metal interface, remains further explored, impeding relevant catalyst design. Here, we theoretically profile that a large free energy difference in hydrogen adsorption on two different metals (|ΔG H‐metal(i) −ΔG H‐metal(ii) |) induces a high kinetic barrier to hydrogen spillover between the metals. Minimizing the difference in their d‐band centers (Δϵ d ) should reduce |ΔG H‐metal(i) −ΔG H‐metal(ii) |, lowering the kinetic barrier to hydrogen spillover for improved electrocatalytic hydrogenation. We demonstrated this concept using copper‐supported ruthenium–platinum alloys with the smallest Δϵ d , which delivered record high electrocatalytic nitrate hydrogenation performance, with ammonia production rate of 3.45±0.12 mmol h −1 cm −2 and Faraday efficiency of 99.8±0.2 %, at low energy consumption of 21.4 kWh kg amm −1 . Using these catalysts, we further achieve continuous ammonia and formic acid production with a record high‐profit space.