Seamlessly conductive Co(OH)2 tailored atomically dispersed Pt electrocatalyst with a hierarchical nanostructure for an efficient hydrogen evolution reaction

Abstract

Single-atom catalysts (SACs) have exhibited extraordinary catalytic performance due to the utmost atom utilization efficiency and unique electronic states via metal–support interactions. Rationally designing SACs at the atomic level by structural engineering is desirable for an efficient hydrogen evolution reaction (HER). Herein, single-atom Pt was anchored on two-dimensional (2D) Co(OH)₂ nanosheets growing on Ag nanowires (Pt_SA–Co(OH)₂@Ag NW) to construct a seamlessly conductive network hybrid catalyst via electrochemical phase transformation from metallic Co@Ag NW. The Ag NW network provides a continuous electron transport pathway through metal active sites, contributing to an extremely low charge transfer resistance (R_ct, 0.7 Ω), and the hierarchical nanostructure has 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 Pt_SA–Co(OH)₂@Ag NW catalyst shows outstanding HER activity with only 29 mV overpotential in 1.0 M KOH at 10 mA cm⁻² and 22.5-fold higher mass activity than the commercial Pt/C catalyst.