Abstract
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•Active CdS-based photo-catalysts were prepared via dispersion of Au ions using KI.•Photocatalytic H2 production from water-ethanol mixture is evaluated under visible light.•Highest H2 production rate is obtained for ethanol–water electrolyte-Au/CdS system.•A significant growth of Au particles was observed during the photocatalytic process, without affecting the reaction rate.•A reaction mechanism involving both organic and inorganic agents is proposed.
Photo-catalytic hydrogen production has been studied on Au supported CdS catalysts under visible light irradiation in order to understand the effect of Au particle size as well as the reaction medium properties. Au nanoparticles of size about 2–5nm were deposited over hexagonal CdS particles using a new simple method involving reduction of Au3+ ions with iodide ions. Within the investigated range of Au (between 1 and 5wt.%) fresh particles with mean size of 4nm and XPS Au4f/Cd3d surface ratio of 0.07 showed the highest performance (ca. 1 molecule of H2/Auatoms−1) under visible light irradiation (>420nm and a flux of 35mW/cm2). The highest hydrogen production rate was obtained from water (92%)-ethanol (8%) in an electrolyte medium (Na2S–Na2SO3). TEM studies of fresh and used catalysts showed that Au particle size increases (almost 5 fold) with increasing photo-irradiation time due to photo-agglomeration effect yet no sign of deactivation was observed. A mechanism for hydrogen production from ethanol–water electrolyte mixture is presented and discussed.