Visible Light Active Metal Sulfides Photocatalyst For Hydrogen Evolution In Aqueous Solution

• Main Author: Melody, Kimi
• Format: Monograph
• Language: English
• Published: Universiti Teknologi Malaysia 2012
• Subjects: QD Chemistry
• Online Access: http://ir.unimas.my/id/eprint/7026/1/visible%20light%20active%20metal%20sulfides%20photo%20catalyst%20for%20hydrogen%20evolution%20in%20aqueous%20solution%20%2824pgs%29.pdf; http://ir.unimas.my/id/eprint/7026/; http://www.sps.utm.my/sps-ir/id/eprint/1645

This research focuses on the development of multicomponent sulfides based- ZnS material i.e., M(x)-doped Cd0.1Zn0.9S, In(0.1),M(x)-ZnS and Ga(0.1),M(x)-ZnS (M = Sn, Cu, or Ag, x = 0.01, 0.03, 0.05) for photocatalytic hydrogen production under visible light irradiation. The role of dopant or co-dopants on the physical chemical properties of the photocatalyst and the effects on photocatalytic activity were investigated. The comparison studies on the effects of preparation methods, namely co-precipitation and hydrothermal method, on the physical chemical properties of the photocatalyst were investigated. High crystallinity which is beneficial for photocatalytic hydrogen production was obtained on the samples prepared by hydrothermal route. Cd0.1Zn0.9S solid solution combining both benefits of CdS and ZnS was further enhanced with the addition of dopants Sn, Cu or Ag in optimum amount. Cu and Ag improved the crystallinity and visible light absorption of Cd0.1Zn0.9S with Cu(0.03)-doped Cd0.1Zn0.9S hydrogen production rate at 3.86 mmol/h and Ag(0.01)-doped Cd0.1Zn0.9S at 3.91 mmol/h. Sn(0.01)-doped Cd0.1Zn0.9S produced hydrogen at 3.52 mmol/h which benefited from higher conduction band level. When Cd was replaced by In, the photocatalytic activity of In(0.1)-ZnS was small due to the low absorption in the visible region. The absorption was enhanced with doping of Sn, Cu or Ag. These photocatalysts benefited from the small crystallite size and the improved visible light absorption. For Ga co-doped with Sn, Cu or Ag, only Ga and Cu co-doped ZnS showed efficient photocatalytic activity with hydrogen production rate of 114 μmol/h. This is due to the synergistic effect of Ga and Cu. The photocatalytic activity of Ga(0.1),Cu(0.01)-ZnS was improved greatly with the addition of 0.5 wt% Ru with hydrogen production rate at 744 μmol/h. From this study, development of multi component sulfides successfully provides a route for the development of visible light active photocatalyst with high photocatalytic activity when suitable dopants at optimum amount are added.