A bifunctional 3D inorganic–organic hybrid framework constructed by [β-Mo8O26]n4n- chains and [Cu(dap)2]2+ cations for efficient electrochemical sensing and photocatalytic reduction of Cr(VI)

Abstract

Under hydrothermal conditions, a new 3D inorganic–organic hybrid polyoxometalate(POM), {[Cu(dap)2]2[β-Mo8O26]}·H2O (1, dap = 1,2-diaminopropane) was synthesized and characterized. Structural analysis displays that 1 represents an interesting 3D POM-based framework constructed from the 1D infinite inorganic chains [β-Mo8O26]n4n- and [Cu(dap)2]2+ cations. 1 exhibits good electrochemical performance and acts as electrochemical sensor for the detection of Cr(VI) with low limit of detection (LOD) of 0.291 µM, high sensitivity of 0.483 μA μM−1 and good anti-interference. The LOD of Cr(VI) for 1 is lower than the maximum content of Cr(VI) in groundwater required by the World Health Organization (WHO). Interestingly, 1 also displays excellent photocatalytic activity for Cr(VI) reduction. The reduction rate of Cr(VI) by 1 can reach 96% within 80 min under the original pH condition. Furthermore, the photocatalytic process obeys the pseudo-first-order reaction kinetic with the half-life of 16.35 min.