POLYOXOMETALATES AS PHOTOELECTROCHEMICAL MODELS FOR QUANTUM-SIZED COLLOIDAL SEMICONDUCTING OXIDES

A comparative analysis is made of the photoredox, electrochemical and electron storage properties of polyoxotungstate and polyoxomolybdate c lusters in comparison with those of colloidal WO3 particles. Both spec ies can harvest light and act as photocatalysts, but polyoxotungstates present a smaller size, wider gap, lower reduction potentials and gre ater tunability. Furthermore, WO3 colloids are structurally ill-charac terized and tend to coagulate whereas polyoxometalate structures are w ell characterized, controllable and stable in solution. These characte ristics and the confinement of injected electrons in a zero-dimensiona l nanometre-sized polynuclear molecule make of polyoxometalates remark able models for colloidal quantum-sized semiconducting oxides.