MoS2 thin film decorated TiO2 nanotube arrays on flexible Ti foil for solar water splitting application

Abstract

MoS _2 /TiO _2 nanostructure provides a lot of advantages in photoelectrochemical (PEC) applications due to the absorption of the wide spectrum solar radiation, more catalytically active sites, proper band alignment, and better separation of photogenerated charge carriers. Here we report PEC water splitting studies of MoS _2 thin film grown by chemical vapor deposition on TiO _2 nanotubes fabricated on flexible thin Ti foil. Raman and x-ray diffraction analysis confirmed the polycrystalline growth of a few layers MoS _2 on TiO _2 /Ti through their characteristic peaks. Field emission scanning electron microscopy revealed the nanotube surface morphology of TiO _2 having a diameter in the range of 200–300 nm. The chemical and electronic composition of MoS _2 and TiO _2 were investigated by x-ray photoelectron spectroscopy. PEC measurements performed in 0.5 M Na _2 SO _4 aqueous electrolyte solution under 100 mW cm ^−2 (AM 1.5G) simulated sunlight revealed 2-fold improved photocurrent density for MoS _2 /TiO _2 heterostructure (∼135.7 μ A cm ^−2 ) compared to that of bare TiO _2 (∼70 μ A cm ^−2 ). This is attributed to extended light absorption and more catalytically active surface area resulting from MoS _2 functionalization of the TiO _2 nanotubes, which results in better PEC activity. This study provides a new insight to explore the performance of thin metal foil-based photoelectrode in PEC applications that can be beneficial to develop roll-to-roll device fabrication to advance futuristic flexible electronics.

Keywords

• solar water splitting
• TiO2 nanotube
• MoS2 thin film
• x-ray photoemission spectroscopy
• chemical vapor deposition
• Raman spectroscopy