Electrostatic Self-assembly Aided Synthesis of CdS/Cs3PW12O40 Hybrids for Photocatalytic Reduction of Cr(VI)

Abstract

Photocatalytic reduction is a promising approach to detoxifying carcinogenic Cr(VI) in water. Herein, CdS-sensitized Cs3PW12O40 composites were fabricated by electrostatic self-assembly followed by hydrothermal post-treatment strategy. The composite with 28.6 wt% CdS loading (CdS/CsPW) was characterized by XRD, FT-IR, SEM/TEM, EDX, UV-vis DRS, XPS, potentiometric titration, and N2 adsorption. The catalytic activity was evaluated by reducing Cr(VI) in the presence of EDTA under UV and visible light irradiation. The results revealed that CdS/CsPW had good photocatalytic reduction performance for Cr(VI) degradation under both UV and visible light illumination. After four-time repetitive use, ~ 93% of catalytic activity still remained. The photocatalytic reduction of Cr(VI) under visible light irradiation followed pseudo-first-order kinetics; the decreasing solution pH and initial Cr(VI) concentration, and increasing catalyst dosage and EDTA concentration were beneficial to Cr(VI) photoreduction. XPS analyses further indicated that the Cr(VI) adsorbed on surface of the catalyst was also reduced to Cr(III), and CdS and Cs3PW12O40 existed strong interaction. Meanwhile, the photoelectrons in CdS could migrate to Cs3PW12O40. Further, PL results verified CdS/CsPW heterostructure effectively suppressed the photogenerated electron-hole recombination. Based on experimental results, the mechanisms for Cr(VI) photoreduction by the prepared catalyst were proposed. This work may provide an attractive avenue to construct the efficient photocatalyst using polyoxometalates for environmental remediation.