P-type Cu2O has long been regarded as an advantageous material in photoelectrochemistry, owing to the suitable band gap structure and cost-effective production. However, such promising material is suffering from corrosion in aqueous electrolytes. To address this issue and attain a high photoelectrochemical performance, protective oxide layers and expensive catalysts have to be adopted. The complicacy of such additional procedures, however, limits the further applications. Instead of utilizing surface protecting oxide layers and expensive catalysts, herein, we report that the surface treatment of Cu2O photocathodes using trisodium citrate (TSC) could also greatly enhance the photoelectrochemical performance. In comparison with the electrode without TSC, the photocathode of FTO/Au/Cu2O/TSC/TiO2/Pt presents a pronounced increment in photocurrent with a factor of about 2. Therefore, this paper provides a novel but convenient methodology to optimize the performance of solar energy conversion systems employing p-type Cu2O by modifying the surface with functional molecules. (C) 2016 Elsevier B.V. All rights reserved.