Template synthesis of ZnIn2S4 for enhanced photocatalytic H2 evolution using triethanolamine as electron donor

A series of ZIS-x [ZIS and x represent the ZnIn2S4 and the addition amount of TEOA (mmol) in the synthesis process, respectively] were synthesized via a hydrothermal method using triethanolamine (TEOA) as a template. The as-synthesized photocatalysts were characterized by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), Ultraviolet-visible (UV-vis) diffuse reflection spectroscopy and Brunauer-Emmett-Teller (BET) surface area measurement. The effects of TEOA on the crystal structures, morphologies and optical properties of ZIS-x products were investigated. The photocatalytic activity was tested in the reaction of H-2 evolution from aqueous TEOA solution under visible light irradiation (lambda >= 420nm). It was found that the activity of ZIS-x synthesized in TEOA solution was higher than that of ZIS-0 synthesized in pure water. This can be attributed to the facts that ZIS-x is composed of single ZnIn2S4 and more TEOA can be adsorbed on ZIS-x surface, which improves the separation of an electron-hole pair. When TEOA was used as an electron donor, it can enhance notably photocatalytic H-2 evolution with its simultaneous degradation. The effect of TEOA concentration on the H-2 evolution rate is consistent with a Langmuir-Hinshelwood kinetic model. The optimal amount of Pt loaded on the photocatalyst is 0.50 wt%, and the optimal pH for photocatalytic H-2 evolution is 13. On the optimal condition, the rate of hydrogen evolution over ZIS-2.0 is 2 times as high as that of ZIS-0 during 20 h irradiation. (C) 2016 Elsevier B.V. All rights reserved.