Dual Cocatalytic Sites Synergize NiFe Layered Double Hydroxide to Boost Oxygen Evolution Reaction in Anion Exchange Membrane Water Electrolyzer

Abstract

Nickel-iron layered double hydroxide (LDH) is a promising cost-efficient catalyst to replace noble metals for alkaline oxygen evolution reaction (OER), yet its intrinsic activity under high current density conditions is not satisfactory, which greatly constrains the industrial application of NiFe LDH catalysts. Herein, a new class of integrated Co and W co-doped NiFe LDH catalysts is reported with dual cocatalytic sites for alkaline OER catalysis. The optimized Co_2.8, W_3.8-NiFe LDH integrated catalyst has superior alkaline OER activity (255 mV@1000 mA cm⁻²) and excellent catalytic stability (200 h@500 mA cm⁻²). The turnover frequency value of Co_2.8, W_3.8-NiFe LDH can reach 4.02 s⁻¹ at 1.49 V versus RHE, which is 9.6 times higher than that of NiFe LDH and superior to the noble metal catalysts. Moreover, it can achieve 1.0 A cm⁻² at 1.86 V and maintain 300-h stable operation in anion exchange membrane water electrolyzer. Theoretical and experimental studies indicate that W sites promote the *OH adsorption and Co sites favor protons desorption of OH*. These dual cocatalytic sites jointly promote *O coverage, effectively accelerating alkaline OER kinetic.