Single ion sandwich-type polyoxomolybdates based on Strandberg anions and their electrocatalytic properties

Abstract Two new single ion sandwich-type polyoxometalate compounds built on Strandberg-type anions and divalent transition metal cations, (NH 4 ) 10 [Cu(H 2 O) 4 (P 2 Mo 5 O 23 ) 2 ]·6H 2 O ( 1 ) and (NH 4 ) 10 [Mn(H 2 O) 4 (P 2 Mo 5 O 23 ) 2 ]·6H 2 O ( 2 ) were synthesized and structurally characterized by single crystal X-ray crystallography. To the best of our knowledge, these compounds represent the first case of pure inorganic sandwich-type phosphomolybdate based on the coordination between copper(II)/manganese(II) cation and terminal oxygen atoms from Strandberg-type anions {P 2 Mo 5 O 23 } 6− . UV–Vis spectrum and surface photovoltage spectra clearly indicate that the two compounds exhibit semiconducting behavior. Significantly, cyclic voltammetry of compounds 1 and 2 show five redox peaks, and electrocatalytic experiments show that compounds 1 and 2 possess excellent electrocatalytic activity for nitrite and hydrogen peroxide reduction.