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Redox Potentials of Polyoxometalates from Implicit Solvent Model and QM/MM Molecular Dynamics

Lookup NU author(s): Emanuele Falbo, Professor Thomas Penfold



This is the authors' accepted manuscript of an article that has been published in its final definitive form by American Chemical Society, 2020.

For re-use rights please refer to the publisher's terms and conditions.


The ability to electrochemically store energy is crucial for the integration of intermittent renewable energy sources such as wind and solar power into modern energy grids. Amongst a wide variety of possible solutions, redox flow batteries (RFBs) are especially attractive as their energy content and power output can be scaled independently, offering a high degree of flexibility. For RFBs, polyoxometalates (POM) are very appealing as these transition metal-oxide nanoclusters exhibit the ability to store multiple electrons in a reversible manner. However, despite the interest in their properties, the link between POMs structure and redox properties remains unclear. In this contribu- tion, we study the redox potentials of [SiW12O40]4− (SiW12) and [PV14O42]9− (PV14) using a number of different theoretical methods. We first adopt the thermodynamic cycle approach combined with quantum chemistry and implicit solvation to estimate the redox potentials. Subsequently, we used molecular dynamics to facilitate an explicit description of the solvent environment. The implicit solvation model is semi-quantitative in some cases, but problems arise when strong solute-solvent interactions are present. Using two approaches, thermodynamic integration (TI) and fractional number of electrons (FNE) methods, we show that explicitly including the solvent environment can improve the calculated redox potentials for strong solute-solvent interactions, but also gives important insights into the interactions between the POM and its environment and how this changes upon reduction. Our results illustrate the performance of these approaches to simulate the redox potentials in POMs and provides the framework to develop a more detailed understanding and structure property relationship for the redox properties of POMs.

Publication metadata

Author(s): Falbo E, Penfold TJ

Publication type: Article

Publication status: Published

Journal: Journal of Physical Chemistry C

Year: 2020

Volume: 124

Issue: 28

Pages: 15045-15056

Print publication date: 16/07/2020

Online publication date: 18/06/2020

Acceptance date: 18/06/2020

Date deposited: 24/06/2020

ISSN (print): 1932-7447

ISSN (electronic): 1932-7455

Publisher: American Chemical Society


DOI: 10.1021/acs.jpcc.0c04169


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