Unique ethylene glycol ligand environments are utilized to overcome the HER kinetic limitation of CoP modified by a low Pt loading via local proton concentration and subsequent hydrogen spillover.

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 (∆Φ) and sequentially strong interfacial proton adsorption construct a high energy barrier for hydrogen transfer. Theoretical simulations and control experiments rationalize that small ∆Φ 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 ∆Φ show a strong ∆Φ-dependent HER activity, in which PtIr/CoP with the smallest ∆Φ = 0.02 eV delivers the best HER performance. These findings have conclusively identified ∆Φ as the criterion in guiding the design of hydrogen spillover-based binary HER electrocatalysts.

Pristine Ru generally shows unsatisfying activity for the electrocatalytic hydrogen evolution reaction (HER). How to activate its HER activity through facile methodologies is very challenging. Recently, metal-supported electrocatalysts integrating metals with efficient hydrogen adsorption and supports with facile hydrogen desorption delivered a high HER performance through a metal-to-support hydrogen spillover process, where the small metal–support work function difference (ΔΦ) was identified as the criterion for the successful interfacial hydrogen spillover. Herein, we demonstrate that a hydrogen spillover strategy significantly boosts the HER activity of Ru by depositing a Ru1Fe1 alloy on CoP (Ru1Fe1/CoP) with a small ΔΦ of 0.05 eV. Experimentally, Ru1Fe1/CoP (0.7 wt % Ru loading) delivered a high Ru utilization activity of 139.8 A/mgRu and a long-term durability in acid. Mechanism investigations authenticated that the small ΔΦ guaranteed the interfacial hydrogen spillover from Ru1Fe1 with efficient hydrogen adsorption to CoP with facile hydrogen desorption and thereafter boosted the HER activity of Ru.