Electrocatalytic CO₂ reduction

Oxide-derived copper materials display high catalytic activities for the electrochemical reduction of carbon dioxide, but the mechanisms surrounding this high performance are not fully understood. Here, the authors use time-resolved operando spectroscopy to probe the structural dynamics of copper oxide reduction and reformation, both in the bulk and on the surface of copper foam catalysts.

CO₂ electrolyzers with gas diffusion electrodes take advantage of improved mass transport of gaseous CO₂ to the catalyst surface to afford increased current densities, but the complex and coupled multi-phase processes occurring inside the electrolysis device are not fully understood. Here, the authors use a two-dimensional volume-averaged model of the cathode side of a microfluidic CO₂ to CO electrolysis device with a gas diffusion electrode and find that under high cathodic potential, the catalyst layer is prone to forming H₂ and CO bubbles, mirroring observed experimental electrode instability.

The electrolytic reduction of CO₂ in aqueous media promises a pathway for the utilization of the greenhouse gas by converting it to base chemicals, however, reactions at the electrodes and their proximity remain challenging to elucidate. Here, the authors use multinuclear in operando NMR to study CO₂ electrolysis in aqueous media and find that stable ion pairs in solution catalyze the bicarbonate dehydration reaction.

Co-electrolysis of nitrogen oxides and carbon oxides has been studied for over two decades but remains largely inefficient with numerous persisting knowledge voids. Here, the authors report a thermodynamic basis for modelling urea production via co-electrolysis using several exchange-correlation functionals, highlighting the importance of gas-phase error assessment in computational electrocatalysis.

Experimental methods to evaluate electrocatalytic performance typically only address one sample at a time. Here the authors show that scanning electrochemical microscopy can screen product selectivity and electrocatalytic activity of CO₂ reduction catalyst arrays.

Phosphate-derived nickel catalysts enable access to multicarbon products via CO₂ electroreduction, but it remains unclear how operating conditions influence product formation. Here, refined ¹H NMR spectroscopy protocols are introduced and combined with an automated NMR data processing routine, enabling quantification of carbon product formation as a function of various parameters.

Syngas is an industrially highly relevant gaseous mixture of carbon monoxide and hydrogen, but its production is energy-intense and relies on natural gas precursors and noble-metal catalysts. Here, the authors explore metal-organic chalcogenolate assemblies (MOCHAs) for tuneable syngas production via electrocatalytic CO₂ reduction.

Metal foam electrodes are promising for efficient CO₂ reduction, but detailed characterizations of the foams at the macro and nanoscale are lacking. Here, the authors combine physicochemical and microscopic techniques in conjunction with electrochemical analyses to relate the morphologies of silver foam electrodes to their CO₂ reduction performance.

Room-temperature ionic liquids are increasingly investigated as electrolytes for electrocatalytic CO₂ reduction thanks to their high intrinsic ionic conductivities, wide electrochemical potential windows, and high CO₂ absorption capacities and solubilities. Here, seven imidazolium-based ionic liquids are investigated as electrolytes for the electrochemical conversion of CO₂ to CO using a silver foil cathode, with their stability, co-catalytic effects, and varying selectivities elucidated.

Tuning the metal core and ligand environment of atomically precise nanoclusters enables the correlation of structural and electrocatalytic properties at an atomic level. Here, single-atom doping and ligand tuning of atomically precise copper clusters is shown to be an effective route to tuning CO₂ electroreduction activity and selectivity.

The simultaneous electroreduction of carbon dioxide and nitrate is a promising and environmentally benign route to urea production, but achieving high selectivity for urea electrosynthesis via this route remains challenging. Here, CuO_xZnO_y electrodes are shown to enable the efficient and selective production of urea under mild conditions, with the efficiency found to strongly depend on the metal ratio within the catalyst composition.

Electrochemical reduction of carbonyl groups is a promising sustainable route for converting biomass-based compounds into value-added products. Here, the authors investigate the electrochemical reduction of the model reactants formaldehyde, acetaldehyde, and acetone on single-site M–N–C catalysts (M = Fe, Co and Ni), gaining mechanistic insight into the role that the nature of the metal center plays on the selectivity of these carbonyl reduction reactions.

For economic viability, CO₂ electrolyzers must meet a range of criteria such as low cell voltage, high current density, high product selectivity and long-term stability—which continues to be a challenge. Here, the authors systematically screen which parameters of twenty commercially available gas diffusion layers affect cell performance the most.

To reach a net-zero energy economy by 2050, it is critical to develop negative emission technologies, such as CO₂ reduction electrolyzers, but these devices still suffer from various issues including low utilization of CO₂ because of its cross-over from the cathode to the anode. This comment highlights the recent innovative design of membrane electrode assembly, utilizing a bipolar membrane and catholyte layer that blocks CO₂ cross-over and enables high CO₂ single-pass utilization.