Recently, with the problems of energy environment and global warming, the use of hydrogen as energy in the future has been attracting attention. Also, waste water containing dyes causes environmental pollution and gives a harm for the health of living organisms [1].
Previously, we reported ZnO/ZnS composites for the photocatalytic hydrogen production. The photocatalyst ZnS/ZnO with CuS as a cocatalyst can simultaneously treat H2 production and dye decolorization. The hydrogen production was 2,110 µmol/g・h with CuS/ZnO0.5S0.5 (molar ratio ZnO/ZnS = 5/5). Furthermore, methyl orange solution of up to 80 ppm could be decolorized with about 90% efficiency.
In the present study, ZnOS was prepared via a solvothermal method [2]. Firstly, ZnS was prepared by hydrothermal synthesis.Typically, Zn(Ac)2・2H2O of 10 mmol and thiourea of 30 mmol were dissolved in 15 mL of pure water for stirring for 30 min at room temperature. Fourty mL of ethylenediamine were then added into the above aqueous solution. After the stirring for 30 min, the solution was added into 15 mL pure water, and was stirred for more 30 min. Next, autoclave treatment was perfprmed at 160 ℃ under autogenous pressure for 4 h. After cooling to room temperature, the products were washed with pure water and ethanol, and were dried at 60 ℃ in vacuum overnight. The ZnS photocatalyst was sintering at 600 ℃ for 2 hours convert to obtain ZnO. ZnO was dissolved in 50 mL of pure water. Next, Na2S was added to the aqueous solution during magnetic stirring. A nanocomposite of ZnO core and ZnS shell could be prepared. Sintering was performed in an air atmosphere using an electric furnace to obtain ZnOS.
The amount of hydrogen production using ZnOS with CuS as a cocatalyst was 2230 µmol / g・h.
References
[1] K. Chu, L. Ye, W. Wang, D. Wu, D. Chan, C. Zeng, H. Yip, J. C. Yu, P. Wong, Chemosphere
2017, 183, 219.
[2]P. Li, T. He, Appl. Catal. B : Environ.
2018, 238, 518