Polyoxometalates: Tailoring metal oxides in molecular dimension toward energy applications

Polyoxometalates could be viewed as the molecular counterpart of the metal oxides, which are essential ingredients for various energy conversion and storage applications. In this manuscript, we review the progress of engineering functional polyoxometalates toward energy applications, focusing on, but not limited to, polyoxotitanate, polyoxotungstate, and polyoxomolybdate. These polyoxometalates are considered to be promising candidates for dye-sensitized solar cell, perovskite solar cell, lithium-ion battery, lithium-sulfur battery, supercapacitor, and water-splitting system. We believe advanced energy devices with better performance could be derived from further engineering the polyoxometalates owing to their molecular design flexibility.