Constructing AgO/Ag₂O Electrocatalysts with Highly Exposed and Tightly Contacted Active Facets for Efficient Oxygen Evolution

The development of efficient electrocatalysts for the oxygen evolution reaction (OER) and the elucidation of their underlying mechanisms are crucial for overcoming the low efficiency of hydrogen production through the electrolysis of water. Utilizing the electrochemical anodic oxidation method, a series of silver-based electrocatalysts (Ag-x, where x signifies the applied direct current (DC) voltage, x=0, 5, 10, 15) were prepared employing metallic silver wire as the anode under DC voltages. The resulting silver-based electrodes have been oxidized and reconstructed, yielding AgO/Ag₂O composite on the surface. Notably, the Ag-10 electrode exhibited the lowest overpotential (399 mV at 50 mA cm^-2 and 456 mV at 100 mA cm^-2), along with good stability. The superior OER performance of Ag-10 is not only attributed to the high exposure and tight interface of the AgO (-111) and Ag₂O (111) crystal phases, as well as the higher prevalence of Ag-O-O-Ag species on its surface, but also its larger electrochemical active surface area (ECSA). This work provides insight for the synthesis of metal oxide-based electrocatalysts and understanding the electrocatalytic mechanism.