Boosting visible-light photoelectrochemical water splitting response of WO3–MoS2 nanocomposites by transition metal doping: Experimental and first-principles studies

Abstract

The current study employs both theoretical and experimental methods to investigate the effect of Ti and Co doping on the WO3 nanocomposite with MoS2 photoanode's photoelectrochemical (PEC) water-splitting reaction. A simple hydrothermal and sol-gel method was adopted for the preparation of samples. The Ti-doped WO3–MoS2 (1.96 at %) sample showed the maximum optical absorption with a photocurrent density of 1.15 mA/cm2 at 1.6 V vs Ag/AgCl. The improvement in photocurrent density may be ascribed to the upward shifting of the conduction band edge towards the H+/H2 redox potential as well as the presence of a large number of active sites in MoS2. A high value of flat band potential of −0.3 V vs Ag/AgCl was achieved in Ti-doped WO3–MoS2, which was confirmed by Mott-Schottky measurements with the corresponding lowest charge transfer resistance at the semiconducting electrode/electrolyte interface. Furthermore, density functional theory calculations have also indicated that on doping WO3 with Ti and Co, there is a slight upward shift in the conduction band minimum, without any significant change in the valence band maximum, with respect to the Fermi level. This study provides new insight into the impact of transition metal doping and nanocomposite of chalcogenide materials for WO3-based PEC electrodes.