Photocatalytic Hydrogen Production on Cd_1−xZn_xS Solid Solutions under Visible Light: Influence of Thermal Treatment

Abstract

Cd 1-x Zn x S solid solutions have been prepared by employing different thermal treatments (He flow from 773 to 1073 K and static vacuum at 1073 K). The photocatalysts were characterized by inductively coupled plasma atomic emission spectroscopy (ICP-AES), N 2 adsorption isotherms, X-ray diffraction (XRD), UV-vis absorption spectra, and X-ray photoelectron spectroscopy (XPS) techniques and tested in the production of hydrogen from aqueous solutions containing S 2-/SO 3 2as sacrificial agents under visible light irradiation. Structure, morphology, composition, and visible light absorption capacity of the Cd 1-x Zn x S solid solutions were found to be strongly dependent on the postsynthesis thermal treatments. The samples treated under He flow presented Cd loss with the temperature rise that implies formation of defects in the crystalline structure of the solid solutions. The increase in the extent of the structural defects of the Cd 1-x Zn x S solid solutions with the annealing temperature rise is related with a progressive decrease in their capacity to produce hydrogen. A significant improvement of the photoactivity was obtained for the solid solution derived from the treatment under static vacuum. The improvement in activity is related to the formation of Cd 1-x Zn x S solid solutions with higher crystallinity and less thermal Cd sublimation that inhibits the formation of structural defects and thus improves the effective utilization of the e -/hole energy carriers.

Novel-CdS-nanorod with stacking fault structures: Preparation and properties of visible-light-driven photocatalytic hydrogen production from water

“…Because of the type-II staggered band alignment in twin CdZnS photocatalysts, the separation rate of photo-induced electrons and holes was remarkably promoted, resulting in greatly improving photocatalytic hydrogen production activity. This material showed the highest photocatalytic activity for non-noble metal loaded photocatalysts which had been reported in the literatures [32][33][34][35][36].…”

Facile synthesis of uniform ZnxCd1−xS alloyed hollow nanospheres for improved photocatalytic activities

“…The Zn x Cd 1-x S alloyed nanostructures received intense interests because it is a typical solid solution of semiconductor occupied some advantages including the stability over pure semiconductor. Solid solution of Zn x Cd 1-x S allows one to control the potentials of the conduction and valence bands; which would make the photogenerated electrons and holes move in the continuous valence and conduction bands [37]. In addition, Zn x Cd 1-x S has good and tunable absorption properties in the visible region of the solar spectrum and excellent electrical conductivity [38].…”

Enhanced Visible‐Light Photocatalytic H2 Production by ZnxCd1−xS Modified with Earth‐Abundant Nickel‐Based Cocatalysts

“…[13,14] However, the H 2 -production activity observed for Zn x Cd 1Àx S is far from the fundamental requirement of practical application and a precious Pt co-catalyst is still required to achieve a high quantum yield. To improve the photocatalytic performance of Zn x Cd 1Àx S solid solution, many modification approaches have been developed, such as new synthesis methods, [15,16] doping transitional [17,18] or alkaline earth metal ions, [19] and nanostructure engineering. [13,14] However, only a few studies have focused on the integration of Zn x Cd 1Àx S with an earthabundant and inexpensive co-catalyst as a substitute for a Pt co-catalyst to achieve highly efficient photocatalytic H 2 production.…”