Preparation and characterization of self–supporting Co5P3Y@Co2P heterojunction as efficient hydrogen evolution catalyst

In this study, the impact of Y doping on the microstructure evolution and catalytic performance of Co–P@Cu immiscible alloys were systematically investigated. By the doping of Y element, novel bird’s nest–like structure consisting of Co₅P₃Y@Co₂P heterojunction rods interwoven with each other were successfully synthesized, in which porous Co₅P₃Y was found to serve as the core and wrapped by Co₂P precipitations. According to the electrochemical measurements, it was found that the overpotential of dealloyed CCY₂P containing 2 wt% Y exhibited preeminent electrocatalytic activity with a low overpotential of 140 mV@10 mA cm⁻² and Tafel slopes as 90 mV dec^–1 in 1 M KOH aqueous solution. Moreover, in the long–term stability test of HER performance of dealloyed CCY₂P for 20 h, no significant fluctuations in the LSV curve were observed. It was confirmed by XPS analysis that the charge distribution of CoP was effectively adjusted by the addition of Y element. In addition, Co₅P₃Y@Co₂P porous heterojunctions with unique bird’s nest-like structure was also found to have a remarkable promotion on the catalytic activity with excellent stability, which could provide more active sites and fast ion channels for HER process.