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

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. An oriented coupling strategy that in situ inserting hollow porous Co/NC nanocage by Si nanowires is developed for the acidic hydrogen evolution reaction, which delivers remarkable activity and stability. Furthermore, the presence of Si nanowire toward Co/NC polyhedra not only facilitates the charge transfer during catalysis, but also optimizes the hydrogen adsorption and desorption.image