Heterostructure engineering of iridium species on nickel/molybdenum nitride for highly-efficient anion exchange membrane water electrolyzer

Abstract

Developing highly active electrocatalysts is a pivotal issue for anion-exchange membrane water electrolyzers (AEMWE). However, realizing the continuous hydrogen generation at a large current density remains challenging. Herein, a novel kind of hybrid electrode is successfully developed by introducing trace iridium (Ir) species onto a hierarchical Ni/Mo5N6 heterostructure on Ni foam (Ir-Ni/Mo5N6/NF). The synergistic advantages of high conductivity, abundant active sites, and strong electronic interaction endow superior reaction kinetics, presenting a highly-active bifunctional electrocatalyst. Remarkably, the Ir-Ni/Mo5N6/NF exhibit extremely low overpotentials of 52 mV and 250 mV at 100 mA cm−2 for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). By exploiting the Ir-Ni/Mo5N6 as both anode/cathode, the constructed AEMWE device delivers superior performance. The current density reaches 2.1 A cm−2 at a voltage of 2.0 V and 250 mA cm−2 at 1.8 V in alkaline/neutral media. This work put forward a facile and effective strategy to synthesize advanced bifunctional electrocatalysts for water electrolysis.