Electrons, Photons, Protons and Earth-Abundant Metal Complexes for Molecular Catalysis of CO₂ Reduction

Abstract

Electrochemical and photochemical reduction of CO2, or a smart combination of both, are appealing approaches for the storage of renewable, intermittent energies and may lead to the production of fuels and of value-added chemicals. By using only earth-abundant metal (Cu, Ni, Co, Mn, Fe) complexes, cheap electrodes and/or cheap sacrificial electron donors and visible light sensitizers, systems functioning with molecular catalysts have been recently designed, showing promising results, in particular, for the two-electron reduction of the carbon dioxide. By combining experimental and mechanistic studies, key parameters controlling the catalysis efficiency have been deciphered, opening the way to the design of future, more efficient and durable catalysts, as well as to the development of electrochemical or photoelectrochemical cells, all being key steps for the emergence of applied devices. The most recent advances related to these issues are discussed in this review.

A Bioinspired Nickel(bis-dithiolene) Complex as a Homogeneous Catalyst for Carbon Dioxide Electroreduction

“…In particular competition with proton reduction can also be controlled synthetically. 3 As a consequence, during the last 40 years a number of molecular complexes have been studied for their catalytic activity for CO 2 electroreduction into CO/HCOOH. 1,2 However, the best catalysts so far are based on expensive noble metals, such as rhenium, iridium, rhodium and ruthenium.…”

“…1,2,7 Surprisingly there is a very limited contribution of Ni complexes so far, the prototype being Ni(cyclam) 2+ , a catalyst with excellent activity in aqueous solutions and highly selective for CO production, developed in the 80's by Sauvage and collaborators and revisited by several groups recently. 8 , and Ni(terpy) 2 ] 2+ (bipy, phen, terpy = bipyridine, phenanthroline, and terpyridine respectively) which catalyze the selective conversion of CO 2 into CO, albeit with large overpotential requirements and low Faradaic yields; 1,15 (ii) Ni complexes supported by N-heterocyclic carbeneamine ligands and displaying high selectivity and activity for the electrocatalytic and photocatalytic conversion of CO 2 to CO; 16 (iii) very recently, a Ni complex bearing a S 2 N 2 -type tetradentate ligand which was found to selectively catalyze CO 2 reduction to CO in a visible-light-driven photocatalytic system. 17 In the quest for new Ni-based molecular catalysts for CO 2 electro-reduction, we were intrigued by the possibility to explore Ni complexes supported by bioinspired ligands, with a specific interest for those ligands providing a sulfur-rich environment to the metal ion.…”

1D/2D TiO2/MoS2 Hybrid Nanostructures for Enhanced Photocatalytic CO2 Reduction

“…[1][2][3][4][5][6][7] This approach can recycle CO 2 back to rene wable fuels by using solar energy which is green and inexhaustible. Photocatalytic CO 2 reduction over photocatalysts is a promising approach to overcome these two crises.…”

Recent Advances in Transition-Metal-Mediated Electrocatalytic CO2 Reduction: From Homogeneous to Heterogeneous Systems

“…The past decades have witnessed the appearance of many effective homogeneous CO2 reduction electrocatalysts [16]. In the following subsections, recently published seminal works employing these catalysts are summarized and classified into two major categories depending on the ligand type: (1) metal catalysts with macrocyclic ligands [17]; and (2) metal catalysts with polydentade ligands [18].…”