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Electrocatalytic CO₂ reduction is typically studied at laboratory scale under ambient conditions; however, temperature and pressure may have a profound impact on the mechanism of this reaction and on its relevance to industrial applications. This study uses a custom temperature- and pressure-adjustable cell to reveal a chain growth mechanism emerging on copper electrodes at elevated temperatures and pressures.

Adsorbed carbon monoxide typically acts to poison the oxidation of alcohols on heterogeneous catalysts and electrocatalysts. Here, it is shown that carbon monoxide that has been adsorbed irreversibly on a Au(111) surface can act as a promoter for this process by enhancing the scission of C–H bonds in the alcohol to yield the corresponding aldehyde.

Intramolecular proton relays are proposed to enhance oxygen evolution for heterogeneous (hydro)oxide electrocatalysts, but molecular-level evidence remains limited. Now it has been shown, using an aza-fused microporous polymer with Ni–Fe sites, that adjacent Ni³⁺–OH sites relay protons from Fe⁴⁺=O, accelerating the water nucleophilic attack pathway and achieving high turnover frequencies with pH-tunable kinetics.

The appropriate descriptors for a catalyst’s hydrogen evolution activity in alkaline electrolyte are debated. Combining simulations and single-crystal studies of metal-decorated Pt surfaces, McCrum and Koper show that activity exhibits a volcano-type relationship with the hydroxide binding strength of the catalyst, providing a target for catalyst design.

Iridium oxide is an active and stable catalyst for the oxygen evolution reaction, however Ir is very rare, making it unsuitable for large-scale application. Here the authors develop a class of Ir double perovskites containing less Ir than iridium oxide, but exhibiting 3-fold higher activity in acidic media.

The corrosion mechanism of metals at cathodic potentials is still poorly understood. Here the authors report the cathodic corrosion onset potential of platinum in concentrated sodium hydroxide, showing etching anisotropy, and present a framework to determine such characteristics for other metals/solutions.

Although gas bubble dynamics during electrochemical processes dramatically affect performance, the fundamental understanding and manipulation of such dynamics have been limited. Now, electrolyte composition is found to be a key factor in inducing a solutal Marangoni instability that impacts both H₂ gas detachment and coalescence between H₂ microbubbles.

Cathodic corrosion of platinum is investigated using operando high-resolution X-ray absorption spectroscopy matched with density functional calculations. Platinum hydrides are found to be reaction intermediates in conditions at which these species are expected to be unstable.

Despite its role in electrocatalysis and hydrogen generation, a complete understanding of the hydrogen evolution reaction on platinum remains elusive. Here, a detailed kinetic study of hydrogen adsorption and evolution on Pt(111) highlights the role of interfacial water reorganization in the hydrogen adsorption step.

The electrocatalytic activity of metal catalysts commonly exhibits a positive linear correlation with the presence of steps, but this dependency breaks down for Pt catalysts with high step densities. Now, using in situ electrochemical scanning tunnelling microscopy, it is shown that this is due to the bunching of closely spaced steps, forming double and triple steps.

Metal cations present in the electrolyte are known to influence the performance in CO₂ electroreduction, but their specific role remains under discussion. Now, it is shown that the reaction can only take place in the presence of such cations, which are required to stabilize negatively charged reaction intermediates.

The field of electroreduction of the oxidized forms of nitrogen (NO_x) to ammonia (NH₃) tends to focus on catalyst design, sometimes under impractical conditions. This Comment touches on the potential limitations of several popular approaches in NO_x-to-NH₃ research and explores opportunities for its translation into a more practical domain.

In homoepitaxial crystal growth, four established modes describe atom deposition on a single crystal surface. Here the authors present a model that shows that, for each adatom growth mode, there exists an analogous but inverse version for vacancy growth. This also applies to combined growth.

Stress release at stepped platinum surfaces is shown to influence the strain experienced by atoms near the steps, resulting in effects on the catalytic activity of the whole surface.

The conversion of carbon dioxide to useful products is a major challenge in energy research. Here, the authors report a cobalt protoporphyrin immobilized on graphite that is capable of the selective and efficient electrochemical reduction of carbon dioxide, primarily to carbon monoxide, in acidic media.

The deployment of fuel cells demands more efficient electrode–electrolyte interfaces to catalyse the oxygen reduction reaction (ORR). A kinetic ORR descriptor is put forward, which is related to the rate of the *O ↔ *OH transition and includes electrolyte effects via the role of non-specifically adsorbed anions.

The electrocatalytic reduction of carbonyl groups is gaining attention in the context of biorefinery. However, fundamental knowledge on such processes is still limited. Now, the selectivity for the electroreduction of acetone on platinum single crystals is studied, revealing a remarkable structural sensitivity.

Large scale CO₂ electrolysis to produce CO has mainly been performed in neutral and alkaline media. Here, we show that it can also be realized in acidic media, with faradaic efficiencies of 80–90%, and 30% better energy efficiency than obtained in neutral media.

The proper verification of the stability of metal oxide catalysts for water electrolysis in acid electrolyte remains unresolved. Here, the ‘stability number’ is introduced to evaluate the dissolution mechanisms of various iridium-based oxides and to facilitate benchmarking of catalysts independent of loading, surface area or involved active sites.

Understanding how palladium inhibits CO poisoning is important for rational design of enhanced catalysts. Here the authors show high formate coverage on the palladium-modified electrode inhibits poisoning during formic acid oxidation and the adsorption of CO precursor dictates the delayed poisoning during CO2 reduction.

Understanding the structural stability of platinum surfaces upon oxidation and reduction conditions has proved challenging. A correlation of surface site formation to nanoisland growth in the electrochemical roughening of Pt(111) is now identified.

Hydrogen–oxygen alkaline fuel cells are promising devices for the 'hydrogen economy' but their oxidation of hydrogen fuel is slow compared with that of acidic fuel cells. More efficient electrocatalysts have now been prepared in which the adsorption of hydroxyl groups onto the electrode surface is controlled through suitable promoters.

Understanding degradation of platinum catalysts during oxygen reduction is vital for improving proton-exchange membrane fuel cells. Here, the authors identify intermediate stages in the oxidation of Pt(111) and Pt(100) in perchloric acid using in situshell-isolated nanoparticle-enhanced Raman spectroscopy.

This Registered Report presents evidence from 87 countries and regions showing that brief emotion-regulation interventions consistently reduced negative emotions and increased positive emotions during the COVID-19 pandemic.

Understanding how oxygen-evolution reaction (OER) catalysts work is important for the development of efficient energy storage technologies. It has now been shown that lattice oxygen participates in O₂ generation during the OER on some highly active metal oxides and that this behaviour becomes more prevalent with greater metal–oxygen covalency.

Aqueous phase electrochemical reduction of CO₂requires an active electrocatalyst and efficient mass transport. Here, the authors report a hollow fibre copper electrode displaying compact 3D geometry, with a large area, three phase boundary for gas-liquid reactions, and subsequently enhanced performance.

Electrochemically-gated graphene field-effect transistors show promise for sensing of charged species in real time. Here, the authors leverage the interplay between electrical in-plane transport and electrochemical activity to explore the sensing performance of hydrogenated graphene.

Scaling relations between the adsorption energies of reaction intermediates facilitate the computational design of catalysts. However, these relations are restricted to low-index surfaces and how they differ from surface to surface cannot be predicted. Structural sensitivity has now been incorporated into scaling relations by elucidating how they are affected by the coordination number of an adsorption site.

The membrane separating anode from cathode in CO₂ electrolysers plays a key role in determining the performance, stability and material selection of the device. Here the authors argue that bipolar membranes could become the primary choice for scarce-metal-free, stable and efficient CO₂ electrolysers.

Electrochemical water splitting using renewable electricity is a promising method for the sustainable production of hydrogen. This Primer overviews considerations, techniques and methods for water electrolysis and describes methods to improve rigour and reproducibility when analysing electrochemical data.

Electrocatalytic reduction of CO₂ to fuels could be used as an approach to store renewable energy in the form of chemical energy. Here, Birdja et al. review current understanding of electrocatalytic systems and reaction pathways for these conversions.

What do a rock in a river, a red blood cell in our body and the electrodes inside a car battery have in common? Charged surfaces in contact with water. Although a unified approach to study such a variety of systems is not available yet, the current understanding — even with its limitations — paves the road to the development of new concepts and techniques.

Combining computational and experimental methods is a powerful approach, but these are not always directly comparable. This Perspective discusses the relationship between experimental measurements and theoretical calculations in electrocatalysis and aims to enhance the connections between the two.