Facile and green synthesis of Cu/Cu2O composite for photocatalytic H2 generation

Cu/Cu2O composites as photocatalysts were successfully synthesized by a sustainable and eco-friendly method employing microwave-assisted heating. In addition, Citrus aurantium L. has been used as a green reducing agent to replace conventional toxic reducing agents. The crystalline phases, morphology, and absorption properties of the samples were characterized by XRD, HR-SEM, TEM, and UV–Vis DRS respectively. The Cu and Cu2O phases were found in the synthesized composite powders, which show a hollow spherical morphology after the microwave reaction synthesis at a relatively low temperature (80 °C). The Cu phase content in those composites increases with the reaction time of microwave heating, which inhibits the Cu2O phase growth. Furthermore, a higher Cu phase content also enhances the absorption in the visible light region, which is important for photocatalytic hydrogen production. Finally, Cu/Cu2O composites were proven as photocatalysts and showed a 141 μmol/g H2 production rate under ambient conditions and visible light. This study confirms an alternative for designing rapid and low-cost photocatalysts for H2 production. [Display omitted] •A rapid and low-cost synthesis method to produce Cu/Cu2O composites was proposed.•Cu/Cu2O composites produced H2 from water splitting under visible light.•Citrus aurantium L. was recycled to synthesize the Cu/Cu2O composites.•Increasing the Cu content inhibits the growth of the Cu2O phase crystallites.•Higher Cu phase content enhances the absorption in the visible light region.