Electronic modulation optimizes OH* intermediate adsorption on Co-Nx-C sites via coupling CoNi alloy in hollow carbon nanopolyhedron toward efficient reversible oxygen electrocatalysis

Optimizing the electronic structure of the electrocatalyst to adjust the adsorption energies of oxygen intermediates to approach the equilibrium potential (U0RHE = 1.23 V) is of paramount importance to inhibit the sluggish reaction kinetics of the oxygen reduction/oxygen evolution reaction (ORR/OER), yet remains a huge challenge. Herein, a hierarchical 1D/3D hollow carbon nanopolyhedron with strong electron coupling between the encapsulated CoNi alloy and Co-Nx sites in N-CNTs was designed by a silicon protection-Ni infiltration strategy. Impressively, the optimized CoNi/Co-N@HNC catalyst exhibits high oxygen catalytic activity with a small potential gap of 0.73 V and superior ZABs durability over 350 h. DFT simulation results revealed that coupling with CoNi nanoclusters can effectively downshift the Ed energy levels of the Co adsorption site in CoN4, dramatically decreased the energy barrier of the rate-determining step (OH* to OH- in ORR; OH* to O* in OER), thereby promote the overall oxygen catalysis reaction kinetics.