In Situ Insertion of Silicon Nanowires into Hollow Porous Co/NC Polyhedra Enabling Large‐Current‐Density Hydrogen Evolution Electrocatalysis

Abstract N‐doped carbon (NC)‐encapsulated transition metal (TM) nanocomposites are considered as alternatives to Pt‐based hydrogen evolution reaction (HER) electrocatalysts; however, their poor electron transfer and mass diffusion capability at high current densities hinder their practical application. Herein, an oriented coupling strategy for the in situ grafting of ultrafine Co nanoparticle‐embedded hollow porous C polyhedra onto Si nanowires (Co/NC‐HP@Si‐NWs) is proposed to address this concern. Experimental investigations reveal that the intimate coupling between the Si‐NW and Co/NC nanocage forms a multithreaded conductive network, lowering the energy barrier for internal electron transfer. When functionalized as an HER electrocatalyst in 0.5 m H₂SO₄, Co/NC‐HP@Si‐NWs deliver overpotentials as low as 57 and 440 mV at 10 and 500 mA cm⁻², respectively, which are much better than those of the pristine Co/NC‐HP. Moreover, Co/NC‐HP@Si‐NWs show an outstanding cycle durability of 24 h at 10 and 500 mA cm⁻². The findings of this study are expected to inspire revolutionary work on the development of Si‐mediated TM‐based electrocatalysts for the HER.