Hydrogen Spillover Mechanism at the Metal-Metal Interface in Electrocatalytic Hydrogenation.

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.