Synthesis of (CuIn)xCd2(1-x)S2 photocatalysts for H2 evolution under visible light by using a low-temperature hydrothermal method

A new series visible-light driven photocatalysts (CuIn)(x)Cd2(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)Cd2(1-x)S-2 nanocomposite show highly photocatalytic activities for H-2 evolution from aqueous solutions containing sacrificial reagents, SO32- and S2- under visible light. Substantially, (CuIn)(0.05)Cd1.9S2 with the band gap of 2.36 eV exhibits the highest photocatalytic activity even without a Pt cocatalyst (649.9 mu mol/(g h)). Theoretical calculations about electronic property of the (CuIn)(x)Cd2(1-x)S-2 indicate that Cu 3d and In 5s5p 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 mu mol/(g h)) in the Pt-loaded doping system is much higher than that of the latter (40.2 mu mol/(g h)). The (CuIn)(0.05)Cd1.9S2 nanocomposite can keep the activity for a long time due to its stability in the photocatalytic process. Therefore, the doping of CuInS2 not only facilitates the photocatalytic activity of CdS for H-2 evolution, but also improves its stability in photocatalytic process. (C) 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.