Polyoxometalate-based crown ether supramolecular hybrid electrocatalyst for the hydrogen evolution reaction and robust nitrite reduction

The novel crown ether–polyoxometalate assembly, [Na(H24C12O6)(CH3CN)(H2O)]2[Na(H24C12O6)(CH3CN)2][PW12O40] (PW12@Crown), based on Keggin-type phosphotungstic acid, was successfully synthesized in acetonitrile solution, and characterized by single-crystal/powder X-ray diffraction and a wide range of analytical methods, including FT-IR, Raman spectroscopies, thermogravimetric analysis. This POM-based supramolecular structure is the first example of a Keggin-type POM linked to three [18]-crown-6 ether components forming unique supramolecular host-guest structures by hydrogen bonding and other intermolecular forces. In addition, the hydrogen evolution reaction (HER) and the reduction of sodium nitrite (NaNO2) activity were studied by cyclic voltammetry to verify the catalytic performance of the compound.