Tailoring the deposition of MoSe₂ on TiO₂ nanorods arrays via radiofrequency magnetron sputtering for enhanced photoelectrochemical water splitting

MoSe₂/1 D TiO2 nanorods (NRs) heterojunction assembly was systematically fabricated, and its photoelectrocatalytic properties were investigated. The fabrication process involves the growth of 1D TiO₂ NRs arrays on FTO substrates using hydrothermal synthesis followed by the deposition of MoSe₂ nanosheets on the TiO₂ NRs using radiofrequency magnetron sputtering (RF magnetron sputtering). The photoelectrochemical properties of the heterojunction were explored and optimized as a function of the thickness of the MoSe₂ layer, which was controlled by the sputtering time. The MoSe₂ grows perpendicularly on TiO₂ NRs in a 2D layered structure, maximizing the exposed active edges, an essential aspect that permits maximum exploitation of deposited MoSe₂. Compared to pure TiO₂ NRs, the heterojunction nanostructured assembly displayed excellent spectral and photoelectrochemical properties, including more surface oxygen vacancies, enhanced visible-light absorption, higher photocurrent response, and decreased charge transfer resistance. In particular, the sample synthesized by sputtering of MoSe₂ for 90 s, i.e., MoSe₂@TiO₂-90 s, depicted the highest current density (1.86 mA cm⁻² at 0.5 V vs. Ag/AgCl) compared to other samples. The excellent photoelectrochemical activity of the heterojunction stemmed from the synergy between tailored loading of MoSe₂ nanosheets and the 1D structure of TiO₂ NRs, which afford a high surface/volume ratio, effective charge separation, fast electron transfer, and easy accessibility to the MoSe₂ active edges. These factors boost the catalytic activity.