Nanostructured SrTiO3 thin films sensitized by Cu2O for photoelectrochemical hydrogen generation

•Heterojunction thin films were prepared by using two different deposition techniques.•Variation of Cu2O film thickness played a significant role in PEC response.•Improved charge separation & enhanced PEC response was achieved in heterojunction.•Heterojunction with overall film thickness (454 nm) exhibited the best PEC response.

We prepared nanostructured thin films of pristine SrTiO3, Cu2O and SrTiO3/Cu2O heterojunction with varying the thickness of Cu2O. SrTiO3 and Cu2O thin films were deposited on ITO (Sn:In2O3) glass substrate using sol–gel spin-coating technique and spray pyrolysis method respectively. Samples were characterized using XRD (X-ray diffractometry), SEM (Scanning electron microscopy), and UV–Visible absorption spectroscopy. Nanostructured thin films of pristine SrTiO3, Cu2O and SrTiO3/Cu2O heterojunction systems were used as photoelectrode in the Photoelectrochemical (PEC) cell for water splitting reaction. Maximum photocurrent density value of 2.44 mA cm−2 at 0.95 V/SCE were observed for SrTiO3/Cu2O heterojunction photoelectrode with 454 nm thickness, which was approximately 34 times higher than pristine SrTiO3 thin film. Increased photocurrent density observed for the heterojunction can be attributed to the improved conductivity and better separation of the photogenerated charge carriers at the SrTiO3/Cu2O interface.