Synthesis of (CuIn) xCd 2(1− x) S 2 photocatalysts for H 2 evolution under visible light by using a low-temperature hydrothermal method

Abstract

A new series visible-light driven photocatalysts (CuIn) x Cd 2(1 − x) S 2 was successfully synthesized by a simple and facile, low-temperature hydrothermal method. The synthesized materials were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET) surface area measurement, X-ray photoelectron spectroscopy (XPS) and ultraviolet-visible spectroscopy (UV–Vis DRS). The results show that the morphology of the photocatalysts changes with the increase of x from 0.01 to 0.3 and their band gap can be correspondingly tuned from 2.37 eV to 2.30 eV. The (CuIn) x Cd 2(1− x) S 2 nanocomposite show highly photocatalytic activities for H 2 evolution from aqueous solutions containing sacrificial reagents, SO 3 2− and S 2− under visible light. Substantially, (CuIn) 0.05Cd 1.9S 2 with the band gap of 2.36 eV exhibits the highest photocatalytic activity even without a Pt cocatalyst (649.9 μmol/(g h)). Theoretical calculations about electronic property of the (CuIn) x Cd 2(1− x) S 2 indicate that Cu 3 d and In 5 s5 p states should be responsible for the photocatalytic activity. Moreover, the deposition of Pt on the doping sample results in a substantial improvement in H 2 evolution than the Pt-loaded pure CdS and the amount of H 2 produced (2456 μmol/(g h)) in the Pt-loaded doping system is much higher than that of the latter (40.2 μmol/(g h)). The (CuIn) 0.05Cd 1.9S 2 nanocomposite can keep the activity for a long time due to its stability in the photocatalytic process. Therefore, the doping of CuInS 2 not only facilitates the photocatalytic activity of CdS for H 2 evolution, but also improves its stability in photocatalytic process.