Co Single Atoms Anchored in N and P Co-doped Porous Carbon Fibers for Efficient Water Splitting

Single atom catalysts (SACs) show potential application for highly efficient water splitting. Herein, we designed Co single atoms (SAs) dispersed on N and P co-doped porous carbon nanofibers as electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The configuration of Co SAs is proved to coordinate with 4 N/O atoms. The long-range interactions between doped P atoms and Co-N-4(O) sites could modulate the electronic structures of M-N-4(O) sites, which greatly reduce the adsorption energies of HER and OER intermediates at metal sites. Density Functional Theory calculations reveal that Co-SA/CNFs exhibits optimized HER and OER kinetics when P coordinates with two N atoms. The atomically dispersed Co electrocatalyst exhibits the low overpotentials of 61, 89 and 390 mV for acidic HER, alkaline HER and OER at 10 mA cm(-2) current density, along with the Tafel slope of 54, 143 and 74 mV dec(-1), respectively. This work demonstrates the prospect of utilizing di-heteroatom-doping transition metal SACs, and provides a novel and general strategy for the preparation of SACs.