International Journal of Hydrogen Energy, Vol.44, No.37, 20805-20814, 2019
Efficient photocatalytic hydrogen production by doped ZnS grown on Ni foam as porous immobilized photocatalysts
Ni-doped ZnS nanomaterials were decorated on the surfaces of porous Ni foam as immobilized photocatalysts for H-2 production by a solvothermal process. Effects of the Ni dopant content on the photocatalytic hydrogen production activity, morphology, optical property, crystalline properties, surface wetting, and photocurrent were studied by scanning electron microscopy (SEM), X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS), photoluminescence (PL), photocurrent response, and contact angle meter. The surface changed from hydrophobic to superhydrophilic by decorating Ni-doped ZnS on the NiO/Ni foam substrate. A mechanism is proposed to elucidate the band positions of ZnS and NiO, together with the transfer of photoinduced electrons among ZnS, NiO, and Ni foam. The Ni-doped ZnS/NiO/Ni foam photocatalyst NZ5 showed much higher photocatalytic activity because of the matched band structure and the high conductivity of Ni foam. Meanwhile, the porous texture and superhydrophilic nature of the photocatalyst favor the light trapping, effective mass transfer of reactant molecules, and provide large contact area. Ni doping leads to a decreased band gap. The highest photocatalytic H-2 generation activity reached 2500 mu mol/g(-1) h(-1). After being operated for 3 cycles, the activity of the third run was 85% of that obtained at the first run. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.