Band structure-controlled solid solution of photocatalyst for hydrogen production by water splitting

A series of Cd 1 - x Zn x S ( x = 0 –0.92) photocatalysts were prepared by coprecipitation method and were calcined at 723 K under N 2 atmosphere. X-ray diffraction patterns results showed that the solid solution of Cd 1 - x Zn x S were formed between ZnS and CdS. UV–Vis spectra indicated that the absorption edges of Cd 1 - x Zn x S were red-shifted as the value of x decreased. The band gaps of the photocatalysts were estimated to be between 2.20–3.12 eV ( x = 0 –0.92) from the onsets of the absorption edges and almost showed linear variation with x increasing. The position of conduction band for solid solution is shifted towards more negative potential as compared to that of CdS. The hydrogen productions of Cd 1 - x Zn x S ( x = 0 –0.92) by splitting water photocatalytically under ultraviolet and visible light irradiation were carried out in an inner-irradiation type reactor. The results indicated that the photocatalyst of Cd 0.62 Zn 0.16 S has the highest rate of hydrogen evolution with the quantum efficiency of 2.17% and 0.60% under ultraviolet and visible light irradiation, respectively. It has been considered that the crystallite size, (1 0 1) plane and band gap for the Cd 1 - x Zn x S solid solutions have a strong influence on the efficiency of hydrogen production capability for water splitting.