(Invited) Computational Modelling of Super-Reduced Polyoxometalates for Energy Storage

Abstract

It is well know that polyoxometalates can be reduced at relatively potentials and can act as reservoir of electrons. Very recently, it has been reported that polyoxometalates clusters like Li6[P2W18O62] can achieve very high proton–electron storage capacities in aqueous solution. DFT calculations in combination with classical MD and CPMD simulations were able to substantiate that the physical properties of classical polyoxotungstates, like those of the prototypical Dawson anion [P2W18O62]6-, strongly depend on the presence of collective forces associated to POM concentration, pH and countercation nature. At low POM concentration and neutral pH only four electrons are reversibly incorporated to the POM. However, in acidic media, the POM framework begins to protonate after the third electron reduction. The salt concentration is also very relevant, since it favours the POM aggregation, which induces an additional stabilization of molecular orbitals. These and another features of reduced polyoxometales will be discussed in the present communication.