A bifunctional 3D inorganic-organic hybrid framework constructed by [beta-Mo8O26](n)(4n-) chains and [Cu(dap)(2)](2+) cations for efficient electrochemical sensing and photocatalytic reduction of Cr(VI)

Under hydrothermal conditions, a new 3D inorganic-organic hybrid polyoxometalate(POM), {[Cu(dap)(2)](2)[beta-Mo8O26]}center dot 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 [beta-Mo8O26](n)(4n-) and [Cu(dap)(2)](2+) cations. 1 exhibits good electrochemical performance and acts as electro-chemical sensor for the detection of Cr(VI) with low limit of detection (LOD) of 0.291 mu M, high sensitivity of 0.483 mu A mu M-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.