An excellent multifunctional photocatalyst with a polyoxometalate–viologen framework for CEES oxidation, Cr(vi) reduction and dye decolorization under different light regimes

Abstract

Photocatalytic detoxification of highly toxic agents is a promising approach to protect the ecological environment and human health, and the key problem lies in the development of novel efficient photocatalysts. Herein, we report a 2D versatile photocatalyst [Co^II(bcbpy)₂(θ-Mo₈O₂₆)_0.5]·5H₂O (BHU-1, bcbpy = 1-(4-carboxybenzyl)-4,4′-bipyridinium) by incorporating isopolymolybdate into a cobalt–viologen framework using a structural design strategy. The photocatalytic performance of BHU-1 was evaluated by 2-chloroethyl ethyl sulfide (CEES) oxidation, Cr(VI) reduction and RhB decolorization. BHU-1 exhibits an effective photogenerated electron–hole separation rate. Under visible light irradiation as a representative condition, the photooxidation conversion of CEES is 98% with 97% selectivity to CEESO within only 5 min; the photoreduction rate of Cr(VI) to Cr(III) reached 95% within 30 min; the photocatalytic decolorization rate of RhB is 100% within 90 min. Additionally, the photocatalytic effects of BHU-1 under full spectrum and NIR light irradiation were also studied. Electron paramagnetic resonance (EPR) spectra and the bandgap energy further demonstrate the accuracy of the electron transport. Furthermore, the photocatalytic reaction kinetics and the mechanisms of the above three photocatalytic processes were studied in detail.