Ag on NiCo Layered Double Hydroxide as Oxygen Evolution Electrocatalyst for Anion Exchange Membrane Water Electrolyzer Under Large Current Densities.

Abstract

A facile and universal strategy is employed to synthesize Ag decorated NiCo layered double hydroxide (LDH) heterogeneous structure for the oxygen evolution reaction (OER). The Ag nanoparticles are deposited on NiCo LDH nanosheets via a spontaneous redox reaction. The synthesized Ag/NiCo LDH achieves an overpotential of 460 mV at a current density of 1 A cm^-2 _geo, surpassing that of NiCo LDH (722 mV). In an anion exchange membrane water electrolyzer (AEMWE) with Ag/NiCo LDH as the anode and Pt/C as the cathode, the cell can deliver an ultrahigh current density of 5 A cm^-2 at a low voltage of 2.10 V. This superior current density is nearly four times larger than that of AEMWEs with other non-precious anode electrocatalysts reported in literature under the same effective area. Furthermore, it exhibits desired durability with no performance decay for over 300 h at 1 A cm^-2, which is almost six times longer than that of electrolyzer with an IrO₂ anode. Operando electrochemical impedance spectroscopy results reveal that Ag decoration facilitates active site formation and reduces the OER onset potential compared to NiCo LDH. This study showcases a practical approach to designing highly effective and durable OER electrocatalysts in industrial hydrogen production.