High-efficient n-type TiO2/p-type Cu2O nanodiode photocatalyst to detoxify hexavalent chromium under visible light irradiation

n -Type TiO 2 / p -type Cu 2 O nanodiode photocatalyst with different Cu 2 O contents had been successfully synthesized. The nanocomposite also had been well characterized and tested for its photocatalytic activity toward reduction of 10 ppm K 2 Cr 2 O 7 aqueous solution under visible light illumination. It was found that 30 % Cu 2 O loading in the nanocomposite had the best photocatalytic activity in detoxifying Cr(VI) without any hole scavenger agents and the solution pH adjustment. As a result, water was simultaneously oxidized by photogenerated holes to evolve oxygen. The 20 mg as-prepared TiO 2 /Cu 2 O nanocomposites could reduce almost 100 % of 10 ppm K 2 Cr 2 O 7 aqueous solution in 90 min under 150 W halogen lamp illumination. From the results, it was concluded that the photocatalytic activities of p – n heterojunction of TiO 2 /Cu 2 O nanodiodes had proven to be an efficient photocatalyst under visible light illumination. The photocatalytic performances of TiO 2 /Cu 2 O nanocomposites and its photoreaction mechanism were proposed and discussed in this work.