Efficient photocatalytic hydrogen production by Zn(1−2x)CuxIn2S(4−1.5x) co-doped with Cu and excess in under visible light irradiation

Abstract

Herein, in order to achieve visible light responsive ability and efficient photogenerated electron–hole pairs separation Zn(1−2x)CuxIn2S(4−1.5x) photocatalysts were fabricated through a simple one-step solvothermal method. The effects of the Cu/Zn molar ratios on the crystal structure, morphology, optical property, as well as photocatalytic activity have been investigated in detail. In addition, the stability of the photocatalysts and apparent quantum yield were measured. The band gap became wider due to the decrease in Cu doping and Zn. The band gap of Zn(1−2x)CuxIn2S(4−1.5x) (x = 0 ~ 0.20) decreased from 2.67 to 1.76 eV with the increase in x value. When Pt was used as a co-catalyst, H2 evolution rates up to 2400 μmol g−1 h−1 were achieved over Zn0.74Cu0.13In2S3.805. Furthermore, when PdS was used as a co-catalyst, the hydrogen generation rates were improved with up to 3600 μmol g−1 h−1 by optimizing the Zn(1−2x)CuxIn2S(4−1.5x). The apparent quantum yield achieved 16% at 420 nm, 9.4% at 500 nm and 9.1% at 600 nm when x = 0.20. The improved visible light photocatalytic performance is considered to be due to the manipulation of the band structure and efficient photogenerated charge separation due to the effects of Cu doping and composition ratio.