H-buffer effects boosting H-spillover for efficient hydrogen evolution reaction

The hydrogen (H) spillover effect on metal/support electrocatalysts plays a significant role in facilitating the hydrogen evolution reaction (HER). However, the gradual accumulated hydrogen migration barrier during H-spillover processes leads to sluggish H-migration kinetics. Therefore, building an effective hydrogen transport channel to impede the interface H accumulation is highly expected for H-spillover. Herein, we design a multi-shell H-buffer chain by exploiting the oxygen diversity of confined polyoxometalates (POMs) to accelerate H-spillover on Pt in the HER. A series of dual-confinement systems (Pt1@POMs@PC) are built by confining single Pt atoms within POMs that are restricted by sub-1-nm pores of porous carbon (PC), and they achieve superior HER activities (eta 10 = 3.8-8.3 mV) and long-term durability properties. Experiments and calculations co-reveal a typical H-spillover pathway from Pt to the support via the H-buffer chains (Pt -> Obr -> O3H -> Mo/W -> Oc -> PCsub-1-nm), which strikingly mitigate the H-migration barriers. We believe the H-buffer chain introduced by this work provides operative guidance for the rational design of metal/support catalysts in various H-spillover-related reactions. A H-buffer chain by exploiting the oxygen diversity of confined polyoxometalates to accelerate H-spillover on Pt in HER is designed. A typical H-spillover pathway (Pt -> Obr -> O3H -> Mo/W -> Oc -> PCsub-1-nm) is revealed, which can buffer the H-migration barriers.