Oxygen vacancy mediated TiO2-x-MoS2/FTO heterostructure as an efficient photoanode for photoelectrochemical water splitting

Abstract

To achieve a complete water splitting cycle, solar-assisted oxidation plays a crucial role. Discovering efficient photoanodes capable of absorbing visible light is essential to enable cost-effective solar energy conversion. This study devised an efficient hydrothermal method to synthesize a TiO2-MoS2 heterostructure with an oxygen vacancy on FTO (fluorine-doped tin oxide). The structure, morphology, optical properties, and photoelectrocatalytic behavior of the TiO2-x-MoS2 heterostructure using various techniques. The oxygen vacancy state can create a new sublevel state below the conduction band of TiO2, which narrows the band gap to a lower level and thus extends the absorption edge into the visible region. The strategy of oxygen vacancy resulted in a photocurrent density of 0.6 mA cm-2, which is 3 times higher than pure TiO2. Also, the TiO2-x-MoS2 heterostructure exhibits a photocurrent density of 2.6 mA cm−2 and higher O2 evolution than pure TiO2 in a 1.0 M KOH solution under UV–Vis irradiation. Compared to unmodified TiO2 nanorods, TiO2-x-MoS2 electrodes exhibit an increase of 13 times in photoelectrochemical activity and have a low overpotential. This is due to accelerated electron transfer kinetics at the TiO2-x-MoS2 interface, an enhanced density of charge carriers, a reduced rate of charge recombination, and a highly wettable surface.