Electro‐Assisted Reduction of CO₂ to CO and Formaldehyde by (TOA)₆[α‐SiW₁₁O₃₉Co(_)] Polyoxometalate

Abstract

We report here on the multiproton-multielectron electrochemical reduction of CO 2 in homogeneous solution by using (TOA) 6 [α-SiW 11 O 39 Co(_)] (TOA = tetraoctyl ammonium; _ = vacant position in the coordination sphere of Co) as an electrocatalyst. First, the electrochemical behavior of (TOA) 6 -[α-SiW 11 O 39 Co(_)] was analyzed in detail by cyclic voltammetry in dichloromethane, studying the influence of the pres- [a]3642 ence of protons and/or CO 2 . These preliminary results were further used to optimize the conditions of electrolysis in terms of reduction potentials. Analysis of the electrolysis products in the gas and liquid phases show the formation of CO and HCHO without formation of H 2 . Our results tend to show that the (TOA) 6 [α-SiW 11 O 39 Co(_)] polyoxometalate is a catalyst for CO 2 electroreduction, with unique selectivity.

Polydopamine and Barbituric Acid Co‐Modified Carbon Nitride Nanospheres for Highly Active and Selective Photocatalytic CO2 Reduction

“…Emission of carbon dioxide (CO 2 ) from consumption of fossil fuels has led to serious global climate issues, ocean acidification and other environmental concerns. International attention to those concerns have stimulated governmental regulations and extensive research efforts . Among various solutions, photochemical reduction of CO 2 into high‐value chemicals and fuels using solar energy is ultimately a sustainable solution to the problems .…”

Assessing the Electrocatalytic Properties of the {Cp*RhIII}2+‐Polyoxometalate Derivative [H2PW11O39{RhIIICp*(OH2)}]3– towards CO2 Reduction

“…Surprisingly, only a few reports of CO 2 reduction with POMs exists: while in 1990 Yamase proposed the photoreduction in water of CO 2 to CH 4 catalyzed by [PTi 2 W 10 O 40 ] 7– , Neumann published more recently that [RuSiW 11 O 39 ] 5– promotes the photoreduction of CO 2 to CO in toluene . Following Kozik's work,, we have reported that [CoSiW 11 O 39 ] 6– is an electrocatalyst in dichloromethane for the two electron reduction of carbon dioxide to CO, but also, in the presence of acid, to a very seldom observed four electron reduction product, formaldehyde . Besides being the catalytic species, another role for the POM as an electron/proton relay has also been recently proposed …”

“…Besides the necessity to work in a non‐coordinating apolar solvent such as dichloromethane, another drawback of [CoSiW 11 O 39 ] 6– as an electrocatalyst for CO 2 reduction is its low activity . To move forward, we aimed at investigating the association of the POM properties with those of a known catalyst, preferably in more “classical” solvents like acetonitrile or even water.…”

Future perspectives for formaldehyde: pathways for reductive synthesis and energy storage

“…Other electrochemical approaches gave Faradaic efficiencies between 0.08% and 25% for formaldehyde derived from CO2 using polyoxometalate as catalyst material. 64 Scheme 8. Electrocatalytic reduction with Boron doped-diamond electrode with highest efficiency for formaldehyde at -1.7V.…”