Photochemical preparation of Cd/CdS photocatalysts and their efficient photocatalytic hydrogen production under visible light irradiation

Metal Cd can serve as an analogue of cocatalysts loaded on CdS to separate electrons and holes to significantly enhance the efficiency of CdS photocatalytic hydrogen production. A series of Cd/CdS photocatalysts were synthesized at various molar ratios of CdSO4 and Na2S2O3 center dot 5H(2)O in the presence of simulated solar irradiation. Superior photocatalytic activities relative to that of pure CdS were observed on the Cd/CdS photocatalysts. When the optimal molar ratio R of Na2S2O3 center dot 5H(2)O to cadmium salt is 7, it results in a high average H-2-production rate of 1753 mu mol h(-1). Possible mechanisms for both the formation and the enhanced photocatalytic activity of Cd/CdS were proposed on the basis of theoretical speculation and experimental observations. Most of all, this work highlights that (i) Cd/CdS leads to an improvement in the photocatalytic activity for H-2 generation; and (ii) adding Na2S2O3 center dot 5H(2)O into the solution containing cadmium ions to prepare Cd/CdS can effectively remove cadmium ions.