The discovery of new materials for electrochemical CO2 reduction can take inspiration from biology and geology. Indeed, in the context of the hydrothermal vent theory of the Emergence of Life, alkaline vents represent a system of significant interest. These vents involve an alkaline, H2 and HS− rich fluid that meets the carbonic acidulous primordial ocean, resulting in the precipitation of a mineral barrier composed of iron sulfides and oxyhydroxides. This inorganic membrane separates the two fluids, generating an electrochemical potential difference. This ΔE can be dissipated by coupling CO2 reduction (on the acidic side) with H2 or HS-oxidation (on the alkaline side), potentially leading to the generation of the very first organic molecules on Earth. In this study, mackinawite [FeSm] and violarite [Fe,Ni)3S4] were synthesized through homogeneous precipitation, their structures and electrochemical properties were characterized. Electrodes based on these materials were prepared and tested for CO2 reduction. It was found that FeSm can reduce CO2 to formic acid and methanol, while (Fe,Ni)3S4 preferentially generates formic acid and carbon monoxide at − 0.82 V vs RHE. The results also indicate that very low overpotential is required for HCOOH generation on mackinawite. The proof that CO2 reduction under these conditions occurs electrochemically, rather than purely chemically, is evidenced by the absence of CO2 reduction products without the application of an electrical bias. Although the efficiency of these materials is currently limited, the potential for CO2 reduction using earth-abundant elements such as iron, nickel, and sulfur is promising. Further engineering of these materials could lead to cost-effective technology.

Ligand systems used for electrochemical reductions commonly comprise single metal centres. This is opposed to complexes with two or more adjacent metals which are significantly less studied. In order to fill this gap a Fe dimer embedded into the 1,1′,5,5′,6,6′-hexamethyl-4,4′-bis(picolinimino)-2,2′-bibenzimidazole (Mebpbbi) ligand system is studied in the present work with focus on electrochemical properties in acetonitrile solution. A combination of cyclic voltammetry and density functional theory (DFT) reveals that the complex is present at least as an open, non-bridged, and a closed, (µ-Cl)2 bridged complex. Both forms possess very different redox properties and ligand exchange energetics. The presence of a stable reversible electron transfer couple for the non-bridged complex is promising for electrocatalytic reactions. Surprisingly, our calculations demonstrate that the iron ions essentially maintain their charge while the ligand accommodates the charges involved in the different redox steps.

To achieve a sustainable future, the electrification of the chemical manufacturing industry is crucial. The electrochemical CO2 reduction reaction (CO2RR) offers a promising pathway to produce value-added chemicals and fuels, including methanol─a key chemical building block and energy carrier. This approach presents a carbon-neutral alternative to conventional, fossil fuel-based methanol production. However, replacing well-established thermochemical processes and achieving cost-competitive production requires the development of highly efficient and selective catalysts for CO2-to-methanol conversion, as well as systematic device-level optimization. In this Perspective, we discuss the potential of methanol production via CO2RR and provide an overview of recent advances in catalyst development. We also propose experimental protocols for methanol quantification, emphasizing the critical need for rigorous evaluation of catalysts to ensure the validity and reproducibility of results, and demonstrating boron phosphide as an irreproducible case. We review seminal studies on CO2RR by cobalt phthalocyanine to make methanol, and current understanding of the reaction mechanistic details. Lastly, we discuss the challenges associated with its translation into practical devices and outline future research opportunities to advance electrochemical CO2RR for methanol production at scale.

P2-type layered oxides are attractive cathode active materials for sodium-ion batteries, however, these materials typically suffer from detrimental Na+/vacancy orderings. In this work, we investigate the origin as well as the influence of the transition metal ratio on Na+/vacancy orderings in P2-type cathode materials. A combination of X-ray diffraction (XRD), neutron diffraction, advanced electrochemical methods, operando XRD and DFT calculations is applied to study Na+/vacancy orderings in P2-NaxNi1/3Mn2/3O2 and P2-NaxMn3/4Ni1/4O2. In P2-NaxNi1/3Mn2/3O2, a honeycomb Ni/Mn superstructure leads to charge ordering within the transition metal slab and pronounced Na+/vacancy orderings, causing distinct voltage jumps at specific sodium contents (x = 2/3, 1/2 and 1/3). For P2-Na0.60Mn3/4Ni1/4O2, the Ni/Mn superstructure is disrupted, resulting in more complex charge orderings within the transition metal slab, partially suppressed Na+/vacancy orderings and an overall smoother potential profile. Based on our findings, guidelines to suppress Na+/vacancy orderings in P2-type cathode materials for sodium-ion batteries are postulated and discussed with respect to electrochemical measurements of various transition metal compositions. These guidelines can serve to predict the tendency towards Na+/vacancy orderings for a given cathode composition or to design new cathode compositions for enhanced cycle life based on the absence of Na+/vacancy orderings.

Chlorinated trityl radicals functionalized with electron-donating groups are promising red-emitting materials for optoelectronic and spintronic applications, overcoming the spin-statistical limit of conventional emitters. Donor functionalization induces charge transfer character, enhancing photoluminescence quantum yield, which depends on the donor strength and its orientation. However, donor-functionalized tris(trichlorophenyl)methyl radicals often show lower quantum yield than their perchlorinated derivatives, likely due to weaker donor-acceptor electronic coupling and enhanced non-radiative decay. A novel trityl derivative is presented with two additional chlorines that restrict the orientation of the donor to a nearly perpendicular arrangement toward the trityl plane, minimizing vibronic coupling and non-radiative losses. Spectroscopic and computational studies reveal that this steric constraint improves the photoluminescence quantum yield compared to the tris(trichlorophenyl)methyl analogs. These findings highlight the potential of donor-acceptor decoupling to enable efficient, redshifted emission, offering a design strategy for high-performance radical emitters.

Conversion of CO2 to hard carbon is an interesting technology for the removal of carbon dioxide from the atmosphere. Recently, it was shown that CeO2 can selectively catalyze this reaction, but we still lack information regarding the reaction mechanism. Using density functional theory modeling, we explore possible reaction mechanisms that allow for the polymerization of CO2. According to our computations, the reaction is initialized by the adsorption of CO2 in an oxygen vacancy. Owing to the rich defect chemistry of ceria, a large number of suitable sites are available at the surface. C–C bond formation is achieved through an aldol condensation-type mechanism which comprises the electrochemical elimination of water to form a carbene. This carbene then performs a nucleophilic attack on CO2. The reaction mechanism possesses significant similarities to the corresponding reactions in synthetic organic chemistry. Since the mechanism is completely generic, it allows for all relevant steps of the formation of hard carbon like chain growth, chain linkage, and the formation of side chains or aromatic rings. Surprisingly, ceria mainly serves as an anchor for CO2 in an oxygen vacancy, while all other subsequent reaction steps are almost completely independent from the catalyst. These insights are important for the development of novel catalysts for CO2 reduction and may also lead to new reactions for the electrosynthesis of organic molecules. 

Carbon dioxide reduction reaction (CO2RR) is a promising method for converting CO2 into value-added products. CO2RR over single-atom catalysts (SACs) is widely known to result in chemical compounds such as carbon monoxide and formic acid that contain only one carbon atom (C1). Indeed, at least two active sites are commonly believed to be required for C–C coupling to synthesize compounds, such as ethanol and propylene (C2+), from CO2. However, experimental evidence suggests that iron phthalocyanine (PcFe), which possesses only a single metal center, can produce a trace amount of C2+ products. To the best of our knowledge, the mechanism by which C2+ products are formed over a SAC such as PcFe is still unknown. Using density functional theory (DFT), we analyzed the mechanism of the CO2RR to C1 and C2+ products over PcFe. Due to the high concentration of bicarbonate at pH 7, CO2RR competes with HCO3– reduction. Our computations indicate that bicarbonate reduction is significantly more favorable. However, the rate of this reaction is influenced by the H3O+ concentration. For the formation of C2+ products, our computations reveal that C–C coupling proceeds through the reaction between in situ-formed CO and PcFe(“0”)–CH2 or PcFe(“-I”)–CH2 intermediates. This reaction step is highly exergonic and requires only low activation energies of 0.44 and 0.24 eV for PcFe(“0”)–CH2 and PcFe(“-I”)–CH2. The DFT results, in line with experimental evidence, suggest that C2+ compounds are produced over PcFe at low potentials whereas CH4 is still the main post-CO product. 

Formox, a highly energy-intensive process, currently serves as the primary source of formaldehyde (HCHO), for which there is a crucial and steadily growing chemical demand. The alternative electrochemical production of HCHO from C1 carbon sources such as CO2 and CO is still in its early stages, with even the few identified cases lacking mechanistic rationalization. In this study, we demonstrate that cobalt phthalocyanine (CoPc) immobilized on multiwalled carbon nanotubes (MW-CNTs) constitutes an excellent electrocatalytic system for producing HCHO with productivity through the direct reduction of CO, the two-electron reduction product of CO2. By carefully adjusting both the pH and the applied potential, we identified conditions that enable the production of HCHO with a partial current density of 0.64 mA cm–2 (17.5% Faradaic efficiency, FE) and a total FE of 61.2% for the liquid products (formaldehyde and methanol). A reduction mechanism is proposed.