Julien Bonin

A one-pot two-step process combining electroreduction and organocatalysis to selectively transform CO into C _5–6 carbohydrates with formaldehyde as the key intermediate.

A Cu(In,Ga)S ₂ -based hybrid photocathode protected by a protective layer and functionalized by a Co molecular complexes reduces CO ₂ in water with high rate and selectivity.

Chalcogenide‐based thin‐film solar cell optimized for rear illumination and used for CO₂ reduction is presented. Central to this innovation is a thinner, Cu(In,Ga)S₂ chalcopyrite absorber coated with a robust metallic top layer, which potentially surpasses the performance of conventional front‐illuminated designs. Using cobalt quaterpyridine molecular catalyst, photocurrent densities for CO₂ reduction exceeding 10 mA/cm² at 0.0 V vs. RHE under 1 Sun illumination, and ca. 16 mA/cm² at −0.25 V vs. RHE were achieved in voltammetry experiments. Controlled potential electrolysis showed catalytic activity over 20 h with selectivity for CO ranging from >92 % (first 4 hours) to 86 % at the end of the experiment. This approach opens limitless possibilities for employing various reduction catalysts, extending far beyond CO₂ reduction. It imposes minimal constraints on absorption properties, immobilization methods, and catalyst nature, setting the stage for high‐performance, adaptable PEC devices.

Chalcogenide‐based thin‐film solar cell optimized for rear illumination and used for CO₂ reduction is presented. Central to this innovation is a thinner, Cu(In,Ga)S₂ chalcopyrite absorber coated with a robust metallic top layer, which potentially surpasses the performance of conventional front‐illuminated designs. Using cobalt quaterpyridine molecular catalyst, photocurrent densities for CO₂ reduction exceeding 10 mA/cm² at 0.0 V vs. RHE under 1 Sun illumination, and ca. 16 mA/cm² at −0.25 V vs. RHE were achieved in voltammetry experiments. Controlled potential electrolysis showed catalytic activity over 20 h with selectivity for CO ranging from >92 % (first 4 hours) to 86 % at the end of the experiment. This approach opens limitless possibilities for employing various reduction catalysts, extending far beyond CO₂ reduction. It imposes minimal constraints on absorption properties, immobilization methods, and catalyst nature, setting the stage for high‐performance, adaptable PEC devices.

Iron porphyrins are molecular catalysts recognized for their ability to electrochemically and photochemically reduce carbon dioxide (CO₂). The main reduction product is carbon monoxide (CO). CO holds significant industrial importance as it serves as a precursor for various valuable chemical products containing either a single carbon atom (C1), like methanol or methane, or multiple carbon atoms (Cn), such as ethanol or ethylene. Despite the long‐established efficiency of these catalysts, optimizing their catalytic activity and stability and comprehending the intricate reaction mechanisms remain a significant challenge. This article presents a comprehensive investigation of the mechanistic aspects of the selective electroreduction of CO₂ to CO using an iron porphyrin substituted with four trimethylammonium groups in the para position [(pTMA)Fe^III−Cl]⁴⁺. By employing infrared and UV/Visible spectroelectrochemistry, changes in the electronic structure and coordination environment of the iron center can be observed in real‐time as the electrochemical potential is adjusted, offering new insights into the reaction mechanisms. Catalytic species were identified, and evidence of a secondary reaction pathway was uncovered, potentially prompting a re‐evaluation of the nature of the catalytically active species.

Iron porphyrins are molecular catalysts recognized for their ability to electrochemically and photochemically reduce carbon dioxide (CO₂). The main reduction product is carbon monoxide (CO). CO holds significant industrial importance as it serves as a precursor for various valuable chemical products containing either a single carbon atom (C1), like methanol or methane, or multiple carbon atoms (Cn), such as ethanol or ethylene. Despite the long‐established efficiency of these catalysts, optimizing their catalytic activity and stability and comprehending the intricate reaction mechanisms remain a significant challenge. This article presents a comprehensive investigation of the mechanistic aspects of the selective electroreduction of CO₂ to CO using an iron porphyrin substituted with four trimethylammonium groups in the para position [(pTMA)Fe^III−Cl]⁴⁺. By employing infrared and UV/Visible spectroelectrochemistry, changes in the electronic structure and coordination environment of the iron center can be observed in real‐time as the electrochemical potential is adjusted, offering new insights into the reaction mechanisms. Catalytic species were identified, and evidence of a secondary reaction pathway was uncovered, potentially prompting a re‐evaluation of the nature of the catalytically active species.

A key challenge in green synthesis is the catalytic transformation of renewable substrates at high atom and energy efficiency, with minimal energy input (ΔG ≈ 0). Non-thermal pathways, i.e., electrochemical and photochemical, can be used to leverage renewable energy resources to drive chemical processes at well-defined energy input and efficiency. Within this context, photochemical benzene carbonylation to produce benzaldehyde is a particularly interesting, albeit challenging, process that combines unfavorable thermodynamics (ΔG° = 1.7 kcal mol⁻¹) and the breaking of strong C–H bonds (113.5 kcal mol⁻¹) with full atom efficiency and the use of renewable starting materials. Herein, we present a mechanistic study of photochemical benzene carbonylation catalyzed by a rhodium-based pincer complex that is capable of metal–ligand cooperation. The catalytic cycle, comprising both thermal and non-thermal steps, was probed by NMR spectroscopy, UV-visible spectroscopy and spectrophotochemistry, and density functional theory calculations. This investigation provided us with a detailed understanding of the reaction mechanism, allowing us to unlock the catalytic reactivity of the Rh–pincer complex, which represents the first example of a metal–ligand cooperative system for benzene carbonylation, exhibiting excellent selectivity.

The dynamic field of the CO₂ Reduction Reaction (CO₂RR) seeks to harness CO₂ as a sustainable carbon source or energy carrier. This review explores CO₂ reduction into formaldehyde (HCHO) or acetal-type compounds using various CO₂RR systems.

A key challenge in green synthesis is the catalytic transformation of renewable substrates at high atom and energy efficiency, with minimal exergonicity (ΔG≈0). Non-thermal pathways, i.e., electrochemical and photochemical, can be used to leverage renewable energy resources to drive chemical processes at well-defined energy input and efficiency. Within this context, photochemical benzene carbonylation to produce benzaldehyde is a particularly interesting, albeit challenging, process that combines unfavorable thermodynamics (DG° = 1.7 kcal/mol) and the breaking of strong C-H bonds (113.5 kcal/mol) with full atom efficiency and renewable starting materials. Nevertheless, little progress has been made since this transformation was first reported, in 1980s and ’90s. By following a mechanistic approach, applying spectrophotochemical and computational tools, we sought to gain a detailed understanding of the non-thermal C-H activation of benzene using metal-ligand cooperative (MLC) PNP rhodium complexes. This allowed us to unlock catalytic MLC benzene carbonylation promoted by irradiation in the near-visible UV region (390 nm) for the first time.

Inspired by natural enzymes, this study presents a nickel‐based molecular catalyst, [Ni^‖(N₂S₂)]Cl₂ (NiN₂S₂, N₂S₂=2,11‐dithia[3,3](2,6)pyridinophane), for the photochemical catalytic reduction of CO₂ under visible light. The catalyst was synthesized and characterized using various techniques, including liquid chromatography‐high resolution mass spectrometry (LC‐HRMS), UV‐Visible spectroscopy, and X‐ray crystallography. The crystallographic analysis revealed a slightly distorted octahedral coordination geometry with a mononuclear Ni²⁺ cation, two nitrogen atoms and two sulfur atoms. Photocatalytic CO₂ reduction experiments were performed in homogeneous conditions using the catalyst in combination with [Ru(bpy)₃]Cl₂ (bpy=2,2’‐bipyridine) as a photosensitizer and 1,3‐dimethyl‐2‐phenyl‐2,3‐dihydro‐1H‐benzo[d]imidazole (BIH) as a sacrificial electron donor. The catalyst achieved a high selectivity of 89 % towards CO and a remarkable turnover number (TON) of 7991 during 8 h of visible light irradiation under CO₂ in the presence of phenol as a co‐substrate. The turnover frequency (TOF) in the initial 6 h was 1079 h⁻¹, with an apparent quantum yield (AQY) of 1.08 %. Controlled experiments confirmed the dependency on the catalyst, light, and sacrificial electron donor for the CO₂ reduction process. These findings demonstrate this bioinspired nickel molecular catalyst could be effective for fast and efficient photochemical catalytic reduction of CO₂ to CO.