Photocatalytic hydrogen evolution from aqueous solutions of Na2S/Na2SO3 under visible light irradiation on CuS/Cd0.3Zn0.7S and NizCd0.3Zn0.7S1+z

Noble-metal-free photocatalysts CuS/Cd0.3Zn0.7S and NizCd0.3Zn0.7S1+z were prepared by a two-step technique. The photocatalysts were characterized by a wide range of experimental techniques: X-ray diffraction, high-resolution transmission electron microscopy, low-temperature N-2 adsorption/ desorption, X-ray photoelectron spectroscopy, and UV vis spectroscopy. The photocatalytic activity was tested in a batch reactor in the hydrogen evolution from aqueous solutions of Na2S/Na2SO3 under visible light irradiation (lambda > 420 nm). The activity of CuS/Cd0.3Zn0.7S photocatalysts was shown to exceed that of NizCd0.3Zn0.7S1+z photocatalysts likely because of the hetero-junctions between CuS and Cd0.3Zn0.7S nanoparticles. The highest photocatalytic activity (3520 mu mol g(-1) h(-1)) was possessed by 1 mol% CuS/ Cd0.3Zn0.7S. A model of the photocatalytic hydrogen production from aqueous solutions of Na2S/Na2SO3 was proposed on the basis of the Langmuir Hinshelwood mechanism. (C) 2014 Elsevier B.V. All rights reserved.