Seamlessly Conductive Co(OH)2 Tailored Atomically Dispersed Pt Electrocatalyst in Hierarchical Nanostructure for Efficient Hydrogen Evolution Reaction

Single-atom catalysts (SACs) have exhibited extraordinary catalytic performance due to the utmost atom utilization efficiency and unique electronic states by metal-support interaction. Rationally designing SACs at the atomic level by structural engineering is desirable for efficient hydrogen evolution reaction (HER). Herein, single-atom Pt was anchored on two-dimensional (2D) Co(OH)2 nanosheets growing on Ag nanowires (PtSA-Co(OH)2@Ag NWs) to construct a seamlessly conductive network hybrid catalyst via electrochemical phase transformation from metallic Co@Ag NWs. The Ag NWs network provides a continuous electron transport pathway through metal active sites, contributing to an extremely lower charge transfer resistance (Rct, 0.7 Ω), and the hierarchical nanostructure owns a large electrochemical surface area for high atom utilization efficiency and rich mass transport pathways for hydrogen generation and release. Moreover, Co(OH)2 tailored Pt sites induce a local tip-enhancement electric field region around the Pt site and more d contribution for boosting H adsorption and H2O adsorption. Thus, the synthesized PtSA-Co(OH)2@Ag NWs catalyst shows an outstanding HER activity with only 29 mV overpotential in 1.0 M KOH at 10 mA cm-2 and 22.5-folds higher in mass activity than commercial Pt/C catalyst.