Elucidation of the Selectivity of Proton-Dependent Electrocatalytic CO₂ Reduction by fac-Re(bpy)(CO)₃Cl

Abstract

A complete mechanism for the proton-dependent electrocatalytic reduction of CO2 to CO by fac-Re(bpy)(CO)3Cl that is consistent with experimental observations has been developed using first principles quantum chemistry. Calculated one-electron reduction potentials, nonaqueous pKa's, reaction free energies, and reaction barrier heights provide deep insight into the complex mechanism for CO2 reduction as well as the origin of selectivity for this catalyst. Protonation and then reduction of a metastable Re-CO2 intermediate anion precedes Brønsted-acid-catalyzed C-O cleavage and then rapid release of CO at negative applied potentials. Conceptually understanding the mechanism of this rapid catalytic process provides a useful blueprint for future work in artificial photosynthesis.

Supramolecular Assembly Promotes the Electrocatalytic Reduction of Carbon Dioxide by Re(I) Bipyridine Catalysts at a Lower Overpotential

“…The influence of the methyl acetamidomethyl groups on the electrochemical behavior of complex 1 is evident by cyclic voltammetry under N 2 atmosphere, as four redox processes were observed in a potential range where the model compound 2 exhibits two features ( Figure 2A). 8,30,32 Starting from resting potential, an irreversible redox feature is observed at −1.77 V, a reversible one at −1.88 V, a quasi-reversible one at −2.14 V, and a final irreversible one at −2.34 V (versus Fc/Fc+). In comparison, complex 2 exhibits a reversible feature at −1.85 V and an irreversible one at −2.20 V (vs Fc/Fc+).…”

“…28−33 This electronic structure appears to lead to lower kinetic barriers for the binding and reduction of CO 2 /H + over H + . 32 A bimolecular mechanism has also previously been proposed for Re(bpy)-based complexes (Scheme 2). 34−36 Sullivan et al Scheme 1.…”

Ultraefficient homogeneous catalyst for the CO 2 -to-CO electrochemical conversion

“…solar fuels | CO 2 reduction | electrochemistry | catalysis | contemporary energy challenges T he reductive conversion of CO 2 to CO is an important issue of contemporary energy and environmental challenges (1)(2)(3)(4)(5)(6)(7)(8)(9)(10). Several low-oxidation-state transition metal complexes have been proposed to serve as homogeneous catalyst for this reaction in nonaqueous solvents such as N,N'-dimethylformamide (DMF) or acetonitrile (11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23).…”

Design of a Catalytic Active Site for Electrochemical CO2 Reduction with Mn(I)-Tricarbonyl Species

“…COOH is the rate-limiting step (i.e., C−O bond cleavage) and that [Re(N−N)(CO) 4 ] + is the CO generating species 48. Overpotentials (η), Current Densities (j), Relative Turnover Frequencies ((i cat /i p ) 2 ), and Peak Potentials in the Absence of a Substrate (E p ) for Selected Catalysts a…”