Theoretical Study on the Electrochemical Properties of Ti-Modified Vanadium-Oxide Clusters

Density functional theory (DFT) calculations were employed to systematically investigate the electrochemical properties of a series of vanadium-oxide clusters, including Lindqvist-type polyoxovanadates (POVs), [V₆O₇(OCH₃)₁₂] (V₆), [TiV₅O₆(OCH₃)₁₃]^- (TiV₅), and [Ti₂V₄O₅(OCH₃)₁₄] (Ti₂V₄) as well as the cationic vanadium-oxide cluster [Ti₃V₃O₄(OCH₃)₁₅]⁺ (Ti₃V₃). Analysis on the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) reveals that Ti modification shifts the electron-gaining center to Ti atoms, while V atoms remain the electron-losing centers. DFT calculations demonstrate that Ti modification effectively modulates the redox potentials of vanadium-oxide clusters and significantly broadens their electrochemical windows. However, root-mean-square deviation (RMSD) values and recombination energy calculations indicate that Ti modification adversely affects the structural stability of vanadium-oxide clusters. Notably, Ti modification substantially enhances the diffusion coefficients, with Ti₂V₄ exhibiting the most pronounced improvement. Additionally, solvation energy calculations show that Ti modification alters the surface charge distribution of vanadium-oxide clusters, strengthening hydrogen bonding interactions between vanadium-oxide clusters and acetonitrile (CH₃CN), thereby significantly improving their solubility.