Synthesis, characterization and electrocatalytic properties of two new open Wells-Dawson-type tungstosilicates

Two new open Wells-Dawson-type polyoxometalates (POMs), K7H2[K(Co(H2O)4)2Co(H2O)2(Si2W18O66)]·22H2O and K7H2[{C(NH2)3} (Co(H2O)4)2Co(H2O)2(Si2W18O66)]·20H2O (abbreviated as K-Co3Si2W18 and C(NH2)3-Co3Si2W18), were synthesized by conventional synthesis and characterized by X-ray single crystal and powder diffraction (XRSCD and XRPD), IR and UV-vis absorption spectra. XRSCD analysis reveals that two tungstosilicates have similar anionic structures with an open Wells-Dawson anion [Si2W18O66]16− and three Co2+ ions. The electrocatalytic activities of both compounds toward the reduction of H2O2 and NaNO2 were studied. Also their electrocatalytic water oxidation performance was evaluated at neutral pH.