Porous heterojunction of Ni2P/Ni7S6 with high crystalline phase and superior conductivity for industrial anion exchange membrane water electrolysis

Abstract

Limited by sluggish mass and charge transfer in anion exchange membrane (AEM) water electrolysis, designing high crystalline phase and superior conductivity electrocatalysts for oxygen evolution is crucial in promoting application of hydrogen. Herein, maple leaf-shaped porous heterojunction (Ni2P/Ni7S6) is fabricated by one-step molten salt method. Benefited from rich porosity and high crystal structure, the target catalyst with abundant active sites and great mechanical strength only requires the overpotentials of 330 mV to reach 1000 mA cm−2, and can sustain at 500 mA cm−2 for 700 h. Besides, characterizations and theoretical calculations reveal that strong interaction between Ni2P and Ni7S6 leads to a depleted electron density in Ni sites and optimizes the adsorption energy of *OOH and H2O, achieving favorable kinetics and superior conductivity. Meanwhile, assembled AEM water electrolyzer delivers 1000 mA cm−2 at a cell voltage of 1.88 V, operating at the average energy efficiency of 72 % for 140 h.