Molybdate-Leaching-Induced Bimetallic Catalyst for Efficient Anion Exchange Membrane Water Electrolysis

Abstract

Anion exchange membrane water electrolysis (AEMWE) offers a promising route for green hydrogen production avoiding noble metal catalysts. The sluggish oxygen evolution reaction (OER) kinetics constrained by the intrinsic activity and limited abundance of active sites however remains a significant barrier to the advancement of AEMWE. In this study, heteroatom doping is combined with a molybdate-leaching strategy to enhance both the intrinsic activity and active site abundance in a single catalyst. Iron is doped into nickel molybdate through a microwave-assisted method, followed by molybdenum leaching, formed molybdate-derived Fe-doped nickel hydroxide (MD-FeNi). The synergistic effects of the bimetallic composition and the expanded active surface area facilitate the transformation of Ni(OH)₂ in MD-FeNi to NiOOH, significantly enhancing OER activity. When integrated into an AEMWE system, the catalyst achieves an impressive current density of 7.48 A cm⁻² at 2 V, which is ≈2.2 and 2.0 times higher than that of molybdate derived Ni(OH)₂ (3.35 A cm⁻²) and traditional Fe doped Ni(OH)₂ (3.75 A cm⁻²). Furthermore, this binary high-activity system strategy has demonstrated broad applicability across various catalytic systems, molybdate-derived Ag-doped copper hydroxide for high-efficient CO electroreduction and molybdate-derived Fe-doped cobalt hydroxide for NaBH₄ hydrolysis reaction, indicating its potential for diverse applications.