Reduced phosphomolybdate as photoassisted electrochemical crystalline sensor for trace Cr(VI) detection
Hao Song, Meng-Si Guo, Jiefei Wang, Yuqing Liu, Hao‐Xue Bi, Jing Du, Wenting An, Yuan‐Yuan Ma, Zhangang Han
Abstract
Sensitive and efficient detection technology for trace toxic hexavalent chromium (Cr(VI)) in water is urgent. Herein, an hourglass-type phosphomolybdate-based metal-organic network was hydrothermally synthesized with formula of [Na<sub>0.5</sub>Cu<sub>5.5</sub>(H<sub>2</sub>O)<sub>2</sub>(btmbp)<sub>4</sub>][Mn(H<sub>2</sub>O)<sub>3</sub>]<sub>2</sub>{Mn[H<sub>6</sub>P<sub>4</sub>Mo<sub>6</sub>O<sub>31</sub>]<sub>2</sub>}·10H<sub>2</sub>O (<strong>1</strong>, btmbp= 4,4′-bis((1H-1,2,4-triazol-1-yl)methyl)biphenyl). Crystal network consists of ladder-like two-dimensional layer-like structure constructed by the vertical connections of 1-D [Na<sub>0.5</sub>Cu<sub>5.5</sub>(H<sub>2</sub>O)<sub>2</sub>(btmbp)<sub>4</sub>]<sup>6+</sup> metal-organic chains and 1-D inorganic polyanionic chains. Compound <strong>1</strong> exhibits good excellent electrochemical property and wide light absorption that can absorb visible light to accelerate the electron transfer in redox process. When serving as a photo-assisted electrochemical (PAEC) sensor for trace Cr(VI) detection, compound <strong>1</strong> exhibits high sensitivity of 330.5 μA·μM<sup>-1</sup> and low detection limit of 0.95 nM (98.79 ppt) along with high anti-interference ability and excellent PAEC detection stability. These results are superior to most reported POM-based sensors, and even comparable to noble-metal sensors, far satisfying WHO standards for Cr(VI) concentration in drinking water. This work provides a new promising photoelectrochemical sensor material for actual environmental pollutant monitoring.