Organic Moiety-Regulated Photocatalytic Performance Of Phosphomolybdate Hybrids For Hexavalent Chromium Reduction

Visible-light-driven photocatalytic Cr(VI) reduction is a promising pathway to moderate environmental pollution, in which the development of photocatalysts is pivotal. Herein, three hourglass-type phosphomolybdate-based hybrids with the formula of: (H(2)bpe)(3)[Zn(H2PO4)][Zn(bpe)(H2O)(2)]H{Zn[P4Mo6O31H6](2)} . 6H(2)O (1) Na-6[H(2)bz](2)[ZnNa4(H2O)(5)]{Zn [P4Mo6O31H3](2)} . 2H(2)O (2) and (H(2)mbpy) {[Zn(mbpy)(H2O)](2)[Zn(H2O)](2)}{Zn[P4Mo6O31H6](2)} . 10H(2)O (3) (bpe=trans-1,2-bi(4-pyridyl)-ethylene; bz=4,4 '-diaminobiphenyl; mbpy=4,4'-dimethyl-2,2'bipyridine) were synthesized under the guidance of the functional organic moiety modification strategy. Structural analysis showed that hybrids 1-3 have similar 2D layer-like spatial arrangements constructed by {Zn[P4Mo6](2)} clusters and organic components with different conjugated degree. With excellent redox properties and wide visible-light absorption capacities, hybrids 1-3 display favourable photocatalytic activity for Cr(VI) reduction with 79%, 70% and 64% reduction rates, which are superior to that of only inorganic {Zn[P4Mo6](2)} itself (21%). The investigation of organic components on photocatalytic performance of hybrids 1-3 suggested that the organic counter cations (bpe, bz and mbpy) can effectively affect the visible-light absorption, as well as the recombination of photogenerated carriers stemmed from {Zn[P4Mo6](2)} clusters, further promoting their photocatalytic performances towards Cr(VI) reduction. This work provides an experimental basis for the design of functionalized photocatalysts via the modification of organic species.