Ag Nanocluster-Triggered Lattice Oxygen Activation in Amorphous Sulfide Matrices for Superior Oxygen Evolution

Polymetallic sulfides have emerged as promising electrocatalysts for the oxygen evolution reaction (OER) due to their exceptional compositional tunability and excellent catalytic activity. However, stability is a huge challenge for large-scale alkaline water electrolysis. In this work, we introduce highly electronegative Ag species together with an amorphous CoWFeNiAgS_x (Ag/CWFNAS_x) to substantially enhance both the activity and durability of sulfide-based catalysts. The integration of Ag induces favorable electron redistribution among adjacent Co, Fe, and Ni centers, downshifting the d-band center and weakening M─O bonds to trigger a mechanistic transition from AEM to the LOM, thereby lowering the OER barriers. When implemented as the anode in an anion exchange membrane water electrolyzer (AEMWE) device, the catalyst delivers an ultralow cell voltage of 1.87 V at 1 A/cm² and exhibits exceptional operational stability with a voltage decay of 0.21 mV/h over 600 h at 60°C. The stability arises from the synergy between the amorphous framework and Ag doping. The framework buffers strain via bond reconfiguration, and Ag doping prevents over-oxidation and dissolution of the active site. This study highlights a synergistic electronic and structural engineering strategy for achieving highly active and durable sulfide-based anodes for practical alkaline electrolysis.