Fabrication of ZnO quantum dots and In2O3 nanofiber composite photocatalysts for selective Cr(Ⅵ) detection and
Yinli Duan1, Juanqin Xue2, Yubo Ma3
1Department of Chemical Engineering, Chongqing Chemical Industry Vocational College, Chongqing, 401228, PR China; Department of Chemical Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, PR China.
Abstract:
Hexavalent chromium (Cr(VI)) as one of the most highly toxic heavy metal ion in the water environment, thus its detection and treatment play a cardinal role in environmental assessment and treatment. In this study, ZnO quantum dots (ZnO-QDs) were successfully synthesized via the sol-gel method, with a narrow size distribution between 2 and 9 nm (average size of approximately 4.96 nm). The ZnO-QDs showed high sensitivity and selectivity for Cr(VI) detection with a low detection limit of 1.69 μM in water realized by dynamic fluorescence burst effect of the ZnO-QDs. Meanwhile, the as-prepared ZnO-QDs were composited with In2O3 nanofibers for the photocatalytic reduction of Cr(VI).The results showed that the built-in electric field of the Z-scheme heterojunction formed between ZnO and In2O3 drives the transfer of photogenerated electrons to the interface, achieving an outstanding Cr(VI) reduction efficiency of 92 %. Density Functional Theory (DFT) calculations revealed that the Cr preferentially adsorb on the In2O3 surface for subsequent reduction reactions.This study provides an advanced technical investigation for treating and detecting the Cr(VI)-containing wastewater.
