Efficient and stable photocatalytic hydrogen production from water splitting over ZnxCd1–xS solid solutions under visible light irradiation

• Published in: International journal of hydrogen energy 2014-01, Vol.39 (4), p.1630-1639
• Main Authors: Chan, Chih-Chieh, Chang, Chung-Chieh, Hsu, Chia-Hao, Weng, Yu-Ching, Chen, Kew-Yu, Lin, Hsiao-Han, Huang, Wen-Chih, Cheng, Sheng-Fa
• Format: Article
• Language: English
• Subjects: Alternative fuels. Production and utilization; Applied sciences; Energy; Exact sciences and technology; Fuels; Hydrogen; Photocatalyst; Visible light; Water splitting; ZnxCd1−xS
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2013.11.059

A simple co-precipitation method was employed to synthesize a series of cubic zinc-blende phase of ZnxCd1−xS photocatalysts using Na2S as the S source. Structural, morphological and optical properties of the samples have been investigated by XRD, SEM, EDS, XRF, ICP, N2 physisorption and UV–vis diffuse reflectance techniques. The ZnxCd1−xS solid solution is not a simple compound mixture of ZnS and CdS, its XRD patterns show new structural peaks instead of mixture of original peaks. The lattice parameter a measured from the XRD patterns of the ZnxCd1−xS samples exhibits a slightly nonlinear relationship with the Zn mole fraction, which is slightly inconsistent with Vegard's law, thus suggesting that a nonhomogeneous alloy structure exists in ZnxCd1−xS solid solution. The photocatalytic H2 evolution from water splitting in the sacrificial reagents of 0.25 M Na2S/0.35 M K2SO3 under visible light at 30 °C and 55 °C were also examined in the study. It is found that ZnxCd1−xS solid solution with composition x = 0.4–0.5 shows the highest photocatalytic H2 production performance. The studied ZnxCd1−xS exhibits at least 50 h stable photocatalytic activity under outdoor sunlight irradiation. •Cubic phased ZnxCd1−xS photocatalysts were synthesized by co-precipitation method.•ZnxCd1−xS photocatalysts are solid solutions, not physical mixture of ZnS and CdS.•The lattice constant of the studied solid solution does not comply with Vegard's law.•The positions of conduction and valence band are estimated by Butler–Ginley approach.•The highest H2 production obtained from ZnxCd1−xS is in the range of x = 0.4–0.5.