Balancing electron transfer and intermediate adsorption ability of metallic Ni-Fe-RE-P bifunctional catalysts via 4f-2p-3d electron interaction for enhanced water splitting

Balancing electron transfer and intermediate adsorption ability of bifunctional catalysts via tailoring electronic structures is crucial for green hydrogen production, while it still remains challenging due to lacking efficient strategies. Herein, one efficient and universal strategy is developed to greatly regulate electronic structures of the metallic Ni-Fe-P catalysts via in-situ introducing the rare earth (RE) atoms (Ni-Fe-RE-P, RE = La, Ce, Pr, and Nd). Accordingly, the as-prepared optimal Ni-Fe-Ce-P/CC self-supported bifunctional electrodes exhibited superior electrocatalytic activity and excellent stability with the low overpotentials of 247 and 331 mV at 100 mA cm−2 for HER and OER, respectively. In the assembled electrolyzer, the Ni-Fe-Ce-P/CC as bifunctional electrodes displayed low operation potential of 1.49 V to achieve a current density of 10 mA cm−2, and the catalytic performance can be maintained for 100 h. Experimental results combined with density functional theory (DFT) calculation reveal that Ce doping leads to electron decentralization and crystal structure distortion, which can tailor the band structures and d-band center of Ni-Fe-P, further increasing conductivity and optimizing intermediate adsorption energy. Our work not only proposes a valuable strategy to regulate the electron transfer and intermediate adsorption of electrocatalysts via RE atoms doping, but also provides a deep understanding of regulation mechanism of metallic electrocatalysts for enhanced water splitting.