Cobalt phthalocyanine supported on multiwalled carbon nanotubes (CoPc/MWCNTs) represents a benchmark molecular electrocatalyst for the reduction of CO2 and CO. However, the exact nature of its redox states and their catalytic functions remains uncertain. In this work, we elucidate the successive electrochemical transformations of CoPc/MWCNTs under Ar, CO2, and CO atmospheres. Cyclic voltammetry combined with in situ spectroscopic measurements reveals several reduction steps that occur prior to substrate activation. The second reduction is ligand-based and pH-dependent, coinciding with the onset of hydrogen evolution and the formation of a cobalt-hydride intermediate─identified experimentally for the first time. Neither the singly nor doubly reduced CoPc species react with CO2 or CO, demonstrating that a 2e-/2H+ process does not suffice for CO2-to-CO conversion or subsequent CO activation at near-neutral pH. Additional overpotentials of approximately 40-90 mV and 350-400 mV are required for CO2-to-CO and CO-to-CH3OH conversion, respectively. Catalytic activity primarily arises from redox-active CoPc sites, whereas redox-inactive species contribute marginally.

Traditional synthesis of organonitrogen compounds often requires high temperatures and pressures, contributing to greenhouse gas emissions and relying on costly noble metal catalysts. Electrosynthesis powered by renewable energy presents an alternative for C-N coupling reactions, though challenges remain in selectivity and mechanistic understanding. Here, we demonstrate that a molecular cobalt phthalocyanine (CoPc) complex immobilized on multiwalled carbon nanotubes (MWCNTs) efficiently catalyzes the co-electroreduction of CO and nitrite (NO2 -) to produce C-N coupling products with high selectivity. Our study reveals that formaldehyde (HCHO), generated from CO reduction, reacts with in situ produced hydroxylamine (NH2OH) from nitrite reduction to form formaldoxime (CH2=NOH) and methylamine (CH3NH2), achieving a total Faradaic efficiency exceeding 50%. Operando spectroscopy confirmed NH2OH as a key intermediate driving selective C-N bond formation. Extending this approach, we synthesized oximes like acetaldoxime and cyclohexanone oxime with similar to 70% Faradaic efficiency. This work offers a promising route for synthesizing diverse nitrogen-containing compounds.

Abstract Formaldehyde (FA) electrolysis is attractive for paired production of value‑added chemicals. However, conventional electrolysis adopts alkaline electrolytes, which triggers FA self-disproportionation and severe feed loss. Here we introduce a sustainable and selective strategy for valorizing FA through electrochemically mediated disproportionation in acidic electrolytes. By leveraging a dual-electrode system consisting of a hydrophobic copper tetraminophthalocyanine layer (CuTAPc-layer) cathode and a Pt2Ru bimetallic anode, we efficiently convert FA into methanol and formic acid at high Faradaic efficiencies of 93.2% and 91.3%, respectively. Compared with alkaline FA oxidation, which can lose up to 76% FA and complicate downstream separation, the acidic system suppresses side reactions to ensure high product purity. Mechanism studies reveal that the hydrophobic microenvironment of CuTAPc-layer suppresses hydrogen evolution, while the stronger oxophilicity of Pt2Ru enhances FA activation and lowers the key deprotonation barrier for FA oxidation. The integrated device demonstrates application potential in polyoxymethylene upgrading, delivering 374.2 mA at 4 V with ~90% single-pass conversion, establishing a scalable and eco-friendly electrochemical pathway for chemical upcycling.

Iron porphyrin complexes constitute a well-established and versatile class of molecular electrocatalysts for the reduction of CO2 to CO. In both organic and aqueous media, the reaction mechanism is typically proposed to involve the interaction of CO2 with a formally defined [(porphyrin)Fe0] intermediate. In this work, we performed a mechanistic investigation of CO2 reduction using the water-soluble complex [(pTMA)FeIIICl]Cl4 under aqueous conditions. In situ scanning spectroelectrochemistry was employed, enabling the synchronized acquisition of UV-vis or IR spectra during cyclic voltammetry experiments. Our results provide strong evidence for CO2 binding to the electrogenerated [(pTMA)FeI]3+ species, followed by reductive C─O bond cleavage to yield a stable [(pTMA)(Cl)FeII-CO]3 + complex. This process corresponds to an overall two-electron reduction per iron center. This mechanism, which has not been previously considered for molecular iron porphyrins in CO2 reduction, is proposed to be facilitated by the charged porphyrin periphery and the hydrogen-bonding network of the aqueous medium. These features may open new avenues toward achieving CO2 reduction at lower overpotentials in water.

Developing novel molecular catalysts for electrochemical CO2 reduction can play an important role for the development of highly selective transformations towards valuable compounds such as CO, HCOOH and CH3OH. Iron...

While molecular electrocatalysis for CO2 reduction has advanced significantly, a key challenge persists in accurately defining the active site distribution, surface density, and structural organization of heterogenized catalysts at electrode interfaces. In this study, we address this gap by employing self-assembled monolayers of physisorbed metal porphyrins (Fe and Cu) on graphite electrodes as structurally well-defined model systems for the electrochemical CO2 reduction reaction (CO2RR). High-resolution scanning tunneling microscopy (STM) revealed crystalline monolayers with uniform active site distribution, offering periodicities of ∼1.5 nm. These monolayers exhibit moderate Faradaic efficiencies (FEs) for CO production, with Fe porphyrin outperforming its Cu analogue. Isotopic labeling experiments were employed to confirm that the product CO originates from added CO2. Bicomponent monolayers comprising Fe porphyrin and catalytically inactive free-base porphyrin were fabricated to investigate composition-activity relationships. STM imaging enabled direct, quantitative assessment of surface composition, and subsequent CO2RR measurements revealed a systematic decrease in FE with increasing coverage of the catalytically inactive component. These findings demonstrate the utility of molecularly ordered porphyrin monolayers as a powerful platform for probing structure-activity relationships in electrocatalytic CO2 reduction with exceptional spatial and compositional precision.

While molecular electrocatalysis for CO 2 reduction has advanced significantly, a key challenge persists in accurately defining the active site distribution, surface density, and structural organization of heterogenized catalysts at electrode interfaces. In this study, we address this gap by employing self‐assembled monolayers of physisorbed metal porphyrins (Fe and Cu) on graphite electrodes as structurally well‐defined model systems for the electrochemical CO 2 reduction reaction (CO 2 RR). High‐resolution scanning tunneling microscopy (STM) revealed crystalline monolayers with uniform active site distribution, offering periodicities of ∼1.5 nm. These monolayers exhibit moderate Faradaic efficiencies (FEs) for CO production, with Fe porphyrin outperforming its Cu analogue. Isotopic labeling experiments were employed to confirm that the product CO originates from added CO 2 . Bicomponent monolayers comprising Fe porphyrin and catalytically inactive free‐base porphyrin were fabricated to investigate composition–activity relationships. STM imaging enabled direct, quantitative assessment of surface composition, and subsequent CO 2 RR measurements revealed a systematic decrease in FE with increasing coverage of the catalytically inactive component. These findings demonstrate the utility of molecularly ordered porphyrin monolayers as a powerful platform for probing structure–activity relationships in electrocatalytic CO 2 reduction with exceptional spatial and compositional precision.

We report a Nickel CO2 reduction electrocatalyst based on a C 3-symmetric tris-(phosphino)-alkyl ligand, CNPPh3, which displays a metalated axial carbon atom. Catalyst Ni H Br selectively reduces CO2 to CO (FYCO = 94%) at -2.3 V vs Fc+/0 with a TO F max = 65 s-1 in DMF/[TBA]-PF6 with 3.5 M of added H2O. Cyclic voltammetry (CV) and an exhaustive computational study of the reaction mechanism show that our NiII complex undergoes two one-electron reduction events before the CO2 binding step. Afterward, the catalytic CO2 reduction takes place through a reduction-first pathway. The formation of a Ni-CO intermediate along the CO2 reduction pathway was inferred by CV, and the corresponding [NiII-CO]+ complex was isolated. FTIR spectroelectrochemistry (SEC) allowed for the detection of three different Ni-CO species: [Ni-CO]+, [Ni-CO]0, and [Ni-CO]-. This work provides critical insights into the electrocatalytic CO2 reduction, laying the foundation for efficient CO2 conversion strategies.

Electrocatalytic conversion of carbon dioxide (CO 2 ) into valuable carbon‐based fuels and chemicals represents a promising approach to closing the carbon cycle and setting a circular economy. Nevertheless, for current electrocatalytic CO 2 reduction reaction (ECO 2 RR) systems, realizing 100% CO 2 conversion with simultaneously high overall CO 2 conversion rate (i.e., single‐pass conversion) and high Faradaic efficiency (FE) remains a significant challenge. Enhancing CO 2 conversion rate often results in a decrease in FE, conversely, improving FE may limit the CO 2 conversion rate. Metal–CO 2 (M–CO 2 ) batteries with CO 2 conversion functions face similar challenges, particularly for reversible M–CO 2 batteries, which do not accomplish net CO 2 reduction because nearly all of CO 2 RR products are reoxidized to CO 2 during subsequent charging process. Such electrocatalytic CO 2 conversion system for carbon neutrality poses substantial challenges. This perspective provides an in‐depth analysis of state‐of‐the‐art ECO 2 RR systems and M–CO 2 batteries, alongside the main strategies employed to address their respective challenges. The critical importance of achieving both a high CO 2 conversion rate and high Faradaic efficiency is underscored for practical applications and to effectively close the carbon cycle. Furthermore, a strategic roadmap that outlines future research directions is presented, thereby facilitating the advancement of comprehensive CO 2 electroconversion technologies.

Electrochemical reduction of carbon dioxide (CO 2 ) can yield valuable chemicals, energy carriers, and renewable fuels that serve as storage forms of renewable energy. 1 This transformation can be achieved using molecular catalysts immobilized on conductive surfaces. 2 A prerequisite for achieving control over CO 2 reduction is a detailed understanding of proton-coupled electron transfer (PCET) mechanisms in such adsorbed systems. 3 With cobalt phthalocyanine (CoPc), we have demonstrated that CO 2 can undergo 2-, 4-, or 6-electron reductions to afford CO, 4–6 formaldehyde, 7,8 and methanol, 4,9,10 respectively, and we have elucidated the underlying mechanisms 7,10 . Building on these insights, polyoxygenated compounds such as sugars can be synthesized via a one-pot, two-step electro-organocatalytic strategy. 11 Our latest investigations in this direction will be presented. Figure 1. Schematic representation of CO 2 reduction catalyzed by CoPc immobilized on conductive surface, coupled with electro-organocatalytic sugar production from HCHO using CO. References 1 C. Costentin, M. Robert and J.-M. Savéant, Chem. Soc. Rev. , 2013, 42 , 2423–2436. 2 K. Elouarzaki, V. Kannan, V. Jose, H. S. Sabharwal and J.-M. Lee, Advanced Energy Materials , 2019, 9 , 1900090. 3 P. Hutchison, L. E. Smith, C. L. Rooney, H. Wang and S. Hammes-Schiffer, J. Am. Chem. Soc. , 2024, 146 , 20230–20240. 4 E. Boutin, M. Wang, J. C. Lin, M. Mesnage, D. Mendoza, B. Lassalle-Kaiser, C. Hahn, T. F. Jaramillo and M. Robert, Angew Chem Int Ed , 2019, 58 , 16172–16176. 5 S. Ren, D. Joulié, D. Salvatore, K. Torbensen, M. Wang, M. Robert and C. P. Berlinguette, Science , 2019, 365 , 367–369. 6 M. Wang, K. Torbensen, D. Salvatore, S. Ren, D. Joulié, F. Dumoulin, D. Mendoza, B. Lassalle-Kaiser, U. Işci, C. P. Berlinguette and M. Robert, Nat Commun , 2019, 10 , 3602. 7 A. Singh, A. Zamader, R. Khakpour, K. Laasonen, M. Busch and M. Robert, J. Am. Chem. Soc. , 2024, 146 , 22129–22133. 8 E. Boutin, A. Salamé, L. Merakeb, T. Chatterjee and M. Robert, Chem. Eur. J. , 2022, 28 , e202200697. 9 J. Su, C. B. Musgrave, Y. Song, L. Huang, Y. Liu, G. Li, Y. Xin, P. Xiong, M. M.-J. Li, H. Wu, M. Zhu, H. M. Chen, J. Zhang, H. Shen, B. Z. Tang, M. Robert, W. A. Goddard and R. Ye, Nat Catal , 2023, 6 , 1–11. 10 X. Ren, J. Zhao, X. Li, J. Shao, B. Pan, A. Salamé, E. Boutin, T. Groizard, S. Wang, J. Ding, X. Zhang, W.-Y. Huang, W.-J. Zeng, C. Liu, Y. Li, S.-F. Hung, Y. Huang, M. Robert and B. Liu, Nat Commun , 2023, 14 , 3401. 11 A. Singh, D. Martins-Bessa, J. Bonin, M. Robert and S. Bontemps, Chem. Sci. , 2025, 16 , 22996–23004. Figure 1

The conversion of C1 molecules (single-carbon species) into C n products (carbon chains) is a key challenge for developing sustainable chemical feedstocks to replace fossil resources. Carbohydrates, a vital class of complex polycarbon molecules, are mainly extracted from biomass, but de novo synthesis provides a complementary route to access rare and non-natural carbohydrates. Here, we report a fully integrated, one-pot two-step system converting carbon monoxide (CO) into carbohydrates. This process couples the electroreduction of CO to formaldehyde with the organocatalytic oligomerization of formaldehyde into C5-6 carbohydrates selectively. This work establishes a novel pathway to utilize CO as a building block for synthesizing complex carbon chains.

Vacancy‐ordered Cs 2 SnX 6 perovskites, with low‐toxicity and high stability, have emerged as promising photocatalysts for hydrogen evolution reaction (HER). However, most Cs 2 SnX 6 and derivatives have low catalytic activity mainly due to their insufficient light utilization efficiency. Herein, a simple in situ method is introduced to sensitize Cs 2 PtSnCl 6 with Eosin Y (EY), forming EY‐Cs 2 PtSnCl 6 for HER in aqueous solution. Various characterizations indicate that the EY is immobilized onto the Cs 2 PtSnCl 6 during the synthesis process. The EY‐Cs 2 PtSnCl 6 displayed extended light absorption range and efficient charge transfer from EY to Cs 2 PtSnCl 6 . The resulting EY‐Cs 2 PtSnCl 6 material exhibits high HER rate of 17.6 mmol g −1 h −1 , ≈1760 folds than that of the pristine Cs 2 PtSnCl 6 . This work demonstrates an effective method to construct dye‐sensitized perovskites and highlights the importance of interaction between dye and perovskite. It provides useful guidance for the design of new perovskite‐based photocatalysts and it will advance the development of perovskites for solar energy conversion into renewable fuels.

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.

The electrochemical reduction of CO2 to CO using renewable electricity offers a compelling pathway for greenhouse gas recycling. The two-electron, two-proton process is particularly attractive due to its operational simplicity and scalability, with copper- and silver-based nanomaterials being the most widely studied catalysts as the field approaches industrial maturity. However, achieving the necessary efficiency and stability for practical applications remains a significant challenge. Recently, molecular catalysts immobilized on conductive surfaces with carbon-based inks have emerged as highly tunable hybrid systems capable of remarkable selectivity. In this work, we report that a straightforward cobalt phthalocyanine complex, simply modified with a single trimethylammonium group, delivers outstanding CO2-to-CO conversion rates and selectivity, reaching a Faradaic efficiency of 93% at a total current density of 700 mA/cm2 (j CO = 650 mA/cm2) at neutral pH. Notably, CO selectivity above 90% was sustained for over 42 h at 150 mA/cm2, illustrating the potential of simply designed molecular catalysts for large-scale applications.

Hybrid photocathodes that integrate inorganic semiconductors with molecular catalysts offer a promising strategy for photoelectrochemical CO2 reduction into value-added products. In this work, we present the design and characterization of a high-performance photocathode based on copper indium gallium sulfide (CIGSu), functionalized with a cobalt quaterpyridine (CoQPy) molecular catalyst. The device features a thin (5 nm) TiO2 protective layer deposited by atomic layer deposition (ALD) on CIGSu/CdS, followed by a mesoporous TiO2 layer formed under mild conditions using UV curing and low-temperature annealing (150 degrees C). The mesoporous structure enables high CoQPy loading through chemisorption via phosphonic acid anchoring groups. Under simulated sunlight, the optimized photocathode delivers a photocurrent density of ca. 2 mA cm-2 with 95% CO selectivity in carbonate buffer, double the performance of systems using low-porosity TiO2. This work marks progress towards efficient, molecularly functionalized photocathodes for aqueous CO2 reduction.

Chalcogenide-based thin-film solar cell optimized for rear illumination and used for CO 2 reduction is presented. Central to this innovation is a thinner, Cu(In,Ga)S 2 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 CO 2 reduction exceeding 10 mA/cm 2 at 0.0 V vs. RHE under 1 Sun illumination, and ca. 16 mA/cm 2 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 CO 2 reduction. It imposes minimal constraints on absorption properties, immobilization methods, and catalyst nature, setting the stage for high-performance, adaptable PEC devices.