Active sites and intermediates adsorption regulation of Ni₅P₄ porous nanosheets arrays through Ce doping toward efficient electrocatalytic overall water splitting

The development of non-noble metal-based bifunctional electrocatalysts toward overall water splitting is urgent recently. However, their catalytic activity is still limited by the insufficient active sites and unsatisfactory adsorption toward reaction intermediates. Here, a self-supported rare earth Ce-doped Ni5P4 porous nanosheets array is designed as an efficient bifunctional electrocatalyst, which requires a competitive overall water splitting potential of 1.56 V to drive the current density of 10 mA/cm(2) under alkaline condition. It is shown that the introduction of Ce can greatly reduce the charge transfer resistance and increase the active sites of Ni5P4, which promotes fast charge transfer and facilitates the kinetics to maintain high catalytic activity. Especially, systematic DFT theoretical calculation is further conducted to study the electrocatalytic process, and it is shown that Ce doping can regulate the center of the d band and adsorption of reaction intermediates, thus reducing the overall speed-decisive step of water splitting reaction. This work demonstrates an efficient strategy for enhancing the overall water splitting properties of bifunctional electrocatalysts through rare earth Ce doping, which also has guiding significance for the study of electrocatalytic mechanism in atomic scale.