Volume 5 Issue 5, May 2022

Bioelectrochemical CO₂ fixation often suffers from a mismatch between the electrochemical and biological components. Now, a spatial decoupling strategy, where CO₂ electrolysis produces electrolyte-free acetic acid as the feed for engineered yeast fermentation, enables highly productive synthesis of glucose or fatty acids.

Molecular catalysts anchored on electrode surfaces are commonly assumed to behave similarly to their homogeneous counterparts. Under some conditions, however, they can behave like metallic electrodes. Now, the underlying phenomena behind this fresh paradigm in heterogeneous electrocatalysis are uncovered.

Nitrogenase reduces dinitrogen at one of its iron–sulfur cores to produce ammonia by a convoluted mechanism. Now, research highlights the importance of sulfur mobility on one of nitrogenase’s metallocofactors for nitrogen fixation.

Reliable testing of fuel cell and electrolyser catalysts is crucial for comparison between studies. This Perspective discusses the differences between rotating disk electrode (RDE) and membrane electrode assembly (MEA) testing of electrocatalysts, and identifies where RDE can be useful and when MEA is more appropriate to study activity and stability under realistic conditions.

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.

Integrated electro-biocatalytic systems based on immobilization have been limited by low maximum current density. Here, the authors present spatially separated electrocatalytic CO₂ fixation to acetic acid with high activity, as feedstock for fermentation by genetically engineered yeast to produce complex bioproducts including glucose and fatty acids.

The electrochemical generation of reactive hydrides has the potential to drive the electrification of chemical reactions. Now, a modified electron paramagnetic resonance set-up is put forward to demonstrate the role of Mo³⁺ hydride in amorphous MoS_x to catalyse both the hydrogen evolution reaction and electrochemical NADH regeneration.

Hybrid 2D/3D ring systems have emerged as important scaffolds in medicinal chemistry, but efficient protocols for their synthesis are scarce. Now, energy-transfer-mediated cascade dearomative [2 + 2] cycloaddition/rearrangement reactions are developed to provide facile access to pyridine-fused 2D/3D ring systems.

Molecularly well-defined single-site catalysts are very promising from an atom utilization perspective, as well as for a potential fine-tuning of the single-site environment. Now, high water oxidation performance is reported on a π-conjugated microporous polymer with single Co sites, which follows an intramolecular hydroxyl nucleophilic attack that promotes O–O formation.

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.

A recently proposed structure of an N₂-bound Mo-nitrogenase has sparked considerable attention, although the direct evidence for N₂ binding and sulfur mobilization during turnover has remained elusive. Now, additional spectroscopic and kinetic measurements further support this state and provide evidence that belt-sulfur displacement is an essential aspect of the nitrogenase mechanism.

The development of platinum group metal-free catalysts for the oxygen reduction reaction is central to the implementation of fuel cell technology. Here the authors introduce and analyse a dedicated protocol for platinum group metal-free oxygen reduction reaction catalysts to assess their activity and durability under relevant working conditions.