A fundamental viewpoint on the hydrogen spillover phenomenon of electrocatalytic hydrogen evolution

Hydrogen spillover phenomenon of metal-supported electrocatalysts can significantly impact their activity in hydrogen evolution reaction (HER). However, design of active electrocatalysts faces grand challenges due to the insufficient understandings on how to overcome this thermodynamically and kinetically adverse process. Here we theoretically profile that the interfacial charge accumulation induces by the large work function difference between metal and support (Phi) and sequentially strong interfacial proton adsorption construct a high energy barrier for hydrogen transfer. Theoretical simulations and control experiments rationalize that small Phi induces interfacial charge dilution and relocation, thereby weakening interfacial proton adsorption and enabling efficient hydrogen spillover for HER. Experimentally, a series of Pt alloys-CoP catalysts with tailorable Phi show a strong Phi -dependent HER activity, in which PtIr/CoP with the smallest Phi =0.02eV delivers the best HER performance. These findings have conclusively identified Phi as the criterion in guiding the design of hydrogen spillover-based binary HER electrocatalysts. Despite the significance of hydrogen spillover on metal-supported electrocatalysts for hydrogen evolution, fundamental understandings on such a process are insufficient. Here the authors show that small work function difference between metal and support facilitates hydrogen spillover and enhances activity.

Automated summary

The work function difference between metal and support has been identified as a key factor influencing hydrogen spillover and activity in hydrogen evolution reaction. A small work function difference facilitates hydrogen spillover and enhances activity, providing important insights for the design of hydrogen spillover-based electrocatalysts.