A study of coral reef-like tetragonal Mn3O4 nanostructure photoelectrode for photoelectrochemical water splitting under visible irradiation

Abstract

For obtaining superior photoelectrochemical activity under light illumination, the interface interaction among the semiconducting photoelectrode and aqueous electrolytes is very important. In this facet, the impact of anions and cations exits in the aqueous electrolyte play a vital role during its interaction on the photoelectrode, which significantly determines the electron-hole generation and transportation. Herein, the coral reef-like Mn3O4 nanostructures were prepared for photoelectrochemical water splitting applications. The crystalline structure, morphology, optical properties, and chemical state were investigated by various analytical techniques. Further, it demonstrated the electrolyte effect on the developed photoelectrodes of Mn3O4 nanostructures. Structural and chemical analyses confirm that the Mn3O4 synthesized for this study exhibits a tetragonal crystalline structure with an Mn3+-oxidation state and an optical band gap of 2.67 eV. An enhanced photocurrent density of 0.43 mAcm−2 vs. Ag/AgCl was achieved in 0.1 M Na2SO3 electrolyte solution under visible light illumination, observed maximum photocurrent density compared to other electrolytes. The enhanced photocurrent density of the photoelectrodes can be ascribed to better light absorption, enhanced separation of photo-induced electron-hole pairs, and reduced recombination rates of photoinduced charge carriers, low charge transfer resistance, and hole scavenging activity.