The Synergistic Activation of Ce-Doping and CoP/Ni3P Hybrid Interaction for Efficient Water Splitting at Large-Current-Density

The high intermediate (H*, OH*) energy barriers and slow mass/charge transfer increase the overpotential of alkaline water electrolysis at large-current-density. Engineering the electronic structure with the morphology of the catalyst to reduce energy barriers and improve mass/charge transportation is effective but remains challenging. Herein, a Ce-doped CoP nanosheet is hybrid with Ni3P@NF (Ni foam) support to enhance mass/charge transfer, tune energy barriers, and improve water-splitting kinetics through a synergistic activation. The engineered Ce-0.2-CoP/Ni3P@NF cathode exhibits an ultralow overpotential (eta(500), eta(1000)) of -185, and -225 mV at -500 and -1000 mA cm(-2) in 1.0 m KOH, along with an excellent pH-universality. Impressively, an electrolyzer using the Ce-0.2-CoP/Ni3P@NF cathode can afford 500 mA cm(-2) at a cell voltage of only 1.775 V and maintain stable electrolysis for 200 h in 25 wt% KOH (50 degrees C). Characterization and density functional theory calculation further reveal the Ce-doping and CoP/Ni3P hybrid interaction synergistically downshift d-band centers (epsilon(d) = -2.0 eV) of Ce-0.2-CoP/Ni3P to the Fermi level, thereby activate local electronic structure for accelerating H2O dissociation and optimizing Gibbs free energy of hydrogen adsorption ( increment G(H*)).