Transition-metal Substituted Polyoxometalates as Soluble RedOx Mediators in Electrocatalytic Biomass Conversion

Abstract

Polyoxometalates (POMs) are known for their unique redox properties, making them interesting candidates as redox mediators in electro-organic transformations. We investigated derivatives of H3[PMo12O40], a classical Keggin-type POM, as a potential redox mediator in the indirect electrolysis of biobased glyceraldehyde (GLAD), focusing on the effects of double substitution of the Mo framework metal by redox active transition metals (Mo replaced by V, Ni, Co, Mn). By combining electrochemical techniques with HPLC, UV-Vis spectroscopy, and 31P-NMR spectroscopy, a comprehensive overview of the reaction pathways, as well as the electronic and structural changes of the POM during the reaction were revealed. This work not only contributes to the fundamental understanding of POMs as redox mediators, but also paves the way for innovative development of sustainable and environmentally friendly electro-organic transformations.