Efficient and stable photocatalytic hydrogen evolution from alkaline formaldehyde solution over Cd0.5Zn0.5S solid solution under visible light irradiation

Cd0.5Zn0.5S photocatalyst was prepared by a hydrothermal method and characterized by x-ray diffraction and UV-Vis absorption spectroscope techniques. Using the pollutant formaldehyde as an electron donor, the photocatalytic H-2 evolution from water splitting under visible light (lambda >= 420 nm) irradiation was examined. It was found that formaldehyde can notably enhance photocatalytic H-2 evolution with its simultaneous degradation. An alkaline condition also was beneficial to the photocatalytic H-2 evolution. The effect of formaldehyde concentration on the H-2 evolution rate was consistent with a Langmuir-Hinshelwood kinetic model. The stability test indicated that the catalyst was rather stable during 20-h irradiation and the average apparent quantum yield amounted to 3.1% under visible light irradiation (lambda >= 420 nm) and 25.7% at 420 nm even without any cocatalysts. The possible mechanism was discussed. (C) 2017 Society of Photo-Optical Instrumentation Engineers (SPIE)