Organic Moiety‐Regulated Photocatalytic Performance of Phosphomolybdate Hybrids for Hexavalent Chromium Reduction

Abstract 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(H 2 PO 4 )][Zn(bpe)(H 2 O) 2 ]H{Zn[P 4 Mo 6 O 31 H 6 ] 2 } ⋅ 6H 2 O ( 1 ) Na 6 [H 2 bz] 2 [ZnNa 4 (H 2 O) 5 ]{Zn [P 4 Mo 6 O 31 H 3 ] 2 } ⋅ 2H 2 O ( 2 ) and (H 2 mbpy) {[Zn(mbpy)(H 2 O)] 2 [Zn(H 2 O)] 2 }{Zn[P 4 Mo 6 O 31 H 6 ] 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[P 4 Mo 6 ] 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[P 4 Mo 6 ] 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[P 4 Mo 6 ] 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.