Photocatalytic reduction of Cr(VI) by using stacked ZnS layers of ZnS(en)x complex

Abstract

We investigated the photoreduction of hexavalent chromium in the absence or presence of citric acid using ZnS(en)x complex photocatalyst of different intercalated layers of ZnS and of different morphology; wires, sheets and flakes. The hybrid semiconductors were prepared by precipitation method with a mixture of ethylenediamine-H2O solution varying the zinc precursor and the sulfur source. The flake-like of ZnS(en)x hybrid with low layer-by-layers structure prepared from zinc acetate and carbon sulfide provides of enhanced photocatalytic properties that allows an efficient electron transfer process in the photoreduction of Cr(VI) in the presence of citric acid in acid media. The highest photoactivity of the flake hybrid was considered in function of the number of layers of ZnS stacked and of its high degree of protonation. The possible mechanism of photoreduction of chromic acid (HCrO4−) species absorbed on protonated surface was discussed.