Multifunctional photoelectric sensors and catalysts for CO2RR and Cr(vi) solution based on a series of POM-based materials

Abstract

Five new Keggin-based compounds, namely [Cu^I(dm4bt)₂]₄[GeW₁₂O₄₀] (1), [M^II₄(dm4bt)₈(GeW₁₂O₄₀)₂(H₂O)₂]·4H₂O (M = Ni for 2 and Co for 3), [Co^II₄(dm4bt)₈(SiW₁₂O₄₀)₂(H₂O)₂]·6H₂O (4) and [Cu^II₂(H₂bdpm)(HBW₁₂O₄₀)(H₂O)₂]·H₂O (5) (dm4bt = 2,2′-dimethyl-4,4′-bithiazole, H₂bdpm = 1,1′-bis(3,5-dimethyl-1H-pyrazolate)methane), were synthesized through traditional hydrothermal methods. Compounds 1–5 can be used as photoelectric multifunctional sensors to detect various ions. As electrochemical sensors, n-CPEs have a good sensitivity and wide concentration range for nitrite. As fluorescent sensors, the title compounds have remarkable fluorescence detection performance for Cr₂O₇²⁻. Furthermore, we modified the compounds as catalysts to investigate their catalytic activities for CO₂ reduced to CO and the reduction of Cr(VI) to Cr(III). The results show that these compounds have high catalytic activities.