The effects of amount of La on the photocatalytic performance of ZnIn_2S_4 for hydrogen generation under visible light

摘要

A series of La modified ZnIn_2S_4 photocatalysts (x wt% La-ZnIn_2S_4, x = 0, 0.02, 0.1, 0.5, 1.0, 2.0, 5.0,10.0) were prepared using the hydrothermal method and characterized by various analysis techniques, such as UV-Vis, XRD, SEM, EDX, TEM, BET and PL. The results indicated that the La element existed as the oxide La_2O_3 which was located on the surface of ZnIn_2S_4 petals. The increase in La amount can reduce ZnIn_2S_4 crystallite size, inhibit ZnIn_2S_4 grain growth, promote ZnIn_2S_4 crystallite self-organization into a micro-sphere with flower-like morphology, increase ZnIn_2S_4 surface area and total pore volume, and bring rich defects to ZnIn_2S_4, indicating that the properties of these photocatalysts greatly depended on the amount of La added. The photocatalytic activities of La-ZnIn_2S_4 were evaluated based on photocatalytic hydrogen production from water under visible-light irradiation and the hydrogen production efficiency increased by 60.6%, 110.8%, 129.8%, 141.6%, 103.7%, 79.3% and 83.2% after adding 0.02 wt%, 0.1 wt%, 0.5 wt%, 1.0 wt%, 2.0 wt%, 5.0 wt% and 10.0 wt% of La, respectively. On the basis of the characterization of the catalysts, the effect of the amount of La added as a modifier on the photocatalytic activity of La-ZnIn_2S_4 was studied.