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 H 2 and O 2 is challenging. The hydrothermal-deposition precipitation route was adopted to synthesize α-Ag 2 WO 4 (20–80%) supported on α-Mn 3 O 4 (AgW/Mn). The 60%AgW/Mn catalyst, which is structurally made up of Mn platelets decorated with AgW nanoparticles, confirmed the existence of the MnO 2 (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 O 2 -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 H 2 -generated amount of 429.4 mmol g−1, and a TOF of 1.59 s−1. [Display omitted] • α-Ag 2 WO 4 (20–80%) supported on α-Mn 3 O 4 was synthesized by deposition precipitation. • Mn platelets including Mn3+, Mn4+, and Mn2+ decorated by Ag@α-Ag 2 WO 4 nanoparticles. • 60%AgW/Mn catalyst is an efficient water splitting electrocatalyst. • The overall splitting of the 60% catalyst indicates a potential of 1.54 V at η10. • The highest activity was based on the birnessite and Mn2+ ratio and Ag nanoparticles. [ABSTRACT FROM AUTHOR]