Improved Photoelectrochemical Water Splitting Performance of Cu2O/SrTiO3 Heterojunction Photoelectrode

Abstract

Nanostructured thin films of Cu2O modified by overlayering SrTiO3 with varying thickness have been studied for the first time as photoelectrode in photoelectrochemical (PEC) water splitting. Effective mass calculations for electrons and holes in bulk SrTiO3 and Cu2O using DFT first-principles have also been attempted to explain the enhanced charge separation at Cu2O/SrTiO3 interface. All samples were characterized using XRD, SEM, and UV–vis spectrometry. The influence of surface modification of Cu2O with varying thickness of SrTiO3 on PEC performance has been investigated. Photocurrent density for Cu2O/SrTiO3 heterojunction with overall thickness of 343 nm at 0.8 V/SCE was found to be 2.52 mA cm–2 which is 25 times higher than that of pristine Cu2O (0.10 mA cm–2 at 0.8 V/SCE). Theoretical studies showed that the electrons in SrTiO3 had large effective masses as compared to electrons in Cu2O at conduction band minima indicating weak mobility of photogenerated electrons in SrTiO3 and strong mobility in Cu2O leading to improved separation of charge carriers resulting in the enhancement of photocurrent densities at the Cu2O/SrTiO3 heterojunction.