Search

Heterolytic hydrogenations are a key reaction class that includes CO₂ reduction to formate and NADH regeneration, yet the mechanism remains unclear. Now it has been shown that this class of thermochemical reactions proceeds through an electrochemical mechanism, with polarization-driven, interfacial hydride transfer as the rate-determining step.

Interfacial polarization influences catalytic reactions occurring at solid–liquid interfaces, but its measurement was previously limited to conductive materials. Now redox-active molecules enable electrochemical potential measurements of metal catalysts, even on insulating supports.

The mechanism by which bimetallic catalysts can outperform their monometallic counterparts is often unexplained. Now nitrate hydrogenation on bimetallic catalysts is shown to proceed via the electrochemical coupling of hydrogen oxidation and nitrate reduction half-reactions, each of which occurs on one metal component.

Although interfacial proton-coupled electron transfers are critical reaction steps in chemical and biological processes, studies investigating these reactions are complicated by surface heterogeneity. Now, interfacial proton-coupled electron transfer kinetics are studied and modelled at isolated, well-defined active sites to provide a foundation for understanding complex reactions involved in energy conversion and catalysis.

Bipolar membranes are increasingly being applied in a variety of electrochemical devices, yet understanding of how they operate in complex electrolyte environments is still limited. Here the authors outline a mechanistic model to explain the behaviour of bipolar membranes in forward bias polarization in mixed electrolytes.

Forward-biased bipolar membranes (FB-BPMs), which recover potential from pH gradients through ion–ion recombination, show promise for application in sustainable devices. The authors use physics-based modeling to elucidate how ion-specific phenomena dictate performance, reveal how selective ion management can mitigate energy losses and provide insights into the rational design of next-generation FB-BPMs.

Charge transfer and chemical kinetics both contribute to the overall overpotential that is observed in a typical electrocatalytic experiment, but it remains difficult to resolve the individual contributions. Here a Pd membrane double cell is used to separate the charge transfer and chemical steps in the hydrogen evolution reaction to evaluate how experimental conditions affect the individual steps.

Although homogeneous hydride transfer reactivity is well understood, the heterogeneous counterpart at metal surfaces remains rather unexplored. This work introduces the electrocatalytic hydrogen reduction reaction, which in net reduces H₂ to reactive hydrides via the intermediacy of surface M−H species. The study reveals that hydride transfer from surface M−H species can be driven by electrical polarization.

There are numerous heterogeneous oxygen reduction reaction catalysts, although synthetic tunability is rare among these materials. Here, the authors report that a conductive metal-organic framework functions as a well-defined, tunable electrocatalyst for the oxygen reduction reaction in alkaline solution.

Heterogenized molecular catalysts are often assumed to operate via analogous mechanisms to their homogeneous counterparts. Here, the authors demonstrate that a tethered cobalt porphyrin exhibits either molecule-like or metal-like behaviour depending on the strength of adsorption between the molecule and the electrode surface.

The mechanism of heterogeneous aqueous-phase aerobic oxidations remains under debate. Now, it has been shown that the reaction can be described as two coupled electrochemical half-reactions for oxygen reduction and substrate oxidation, and the thermochemical rates can be derived from the electrochemical half-reactions via the application of mixed potential theory.

Iron- and nitrogen-doped carbon materials are effective catalysts for the oxygen reduction reaction whose active sites are poorly understood. Here, the authors establish a new pyridinic iron macrocycle complex as a more effective active site model relative to legacy pyrrolic model complexes.

Despite over a century of research to understand heterogeneous electrocatalysis, the precise mechanisms of action remain poorly understood. Now, it is proposed that the oxygen evolution reaction on IrO_x is driven by changes in the redox state of the Ir–O active sites, rather than by changes in the interfacial electric field.

To achieve net-zero carbon emissions, we must close the carbon cycle for industries that are difficult to electrify. Developing the needed science to provide carbon alternatives and non-fossil carbon will accelerate advances towards defossilization.