Evaluating the water splitting promotion effects of birnessite Mn3+/4+ platelets of α-Mn3O4 coated with Ag@Ag2WO4 nanosphericals

Developing an accessible and durable catalyst with minimal overpotentials to split water to produce both H2 and O2 is challenging. The hydrothermal-deposition precipitation route was adopted to synthesize α-Ag2WO4 (20–80%) supported on α-Mn3O4 (AgW/Mn). The 60%AgW/Mn catalyst, which is structurally made up of Mn platelets decorated with AgW nanoparticles, confirmed the existence of the MnO2 (200) active sites, surpassing the Ag nanoparticles (54.3%), and the proportion of the birnessite Mn3+/4+ moieties. In comparison to other catalysts, it presented more selectivity for OER in 1.0 M KOH with a low overpotential (0.28 V) at 10 mA cm−2, a Tafel slope of 50.7 mV dec−1, an O2-equivelent amount of 221.5 mmolg−1, and a TOF of 1.17 s−1. Similarly, it produced HER at an overpotential of 0.089 V at η10, a Tafel slope of 73.35 mV dec−1, an H2-generated amount of 429.4 mmol g−1, and a TOF of 1.59 s−1.