Volume 6 Issue 5, May 2023

Proton exchange membrane fuel cell catalyst layers (CLs) have complex structures that largely determine their performance and durability. Their three-dimensional morphology and component spatial distribution is still poorly understood. This comprehensive work reports one of the first cryogenic transmission electron tomography reconstructions of a full commercial CL section, including challenging-to-image ionomer distribution.

The issue of gas solubility has profound implications for studying the activity of oxygen reduction reaction electrocatalysts. Aqueous solutions endowed with permanent microporosity — termed microporous water — could be the answer.

The catalyst layer in proton-exchange membrane fuel cells involves the complex and crucial interplay between an ionomer network and metallic nanoparticles supported on carbons, but current methods are unable to describe it with high resolution. Now electron tomography at cryogenic temperatures and deep learning algorithms are used to provide quantitative three-dimensional imaging at nanometre resolution of a fuel cell catalyst layer structure.

The full potential of the well-known platinum oxygen reduction catalyst has not been realized in membrane electrode assembly for fuel cells due to the detrimental impacts of the required ionomer layer. Here the authors show how cyclohexanol can block the interaction between Pt and sulfonate groups of Nafion with benefits for reaction kinetics and mass transport.

Electrocatalytic nitrate reduction represents an opportunity to generate ammonia under ambient conditions, yet the efficiency has been limited by the large overpotential required. Here, a Ru–Co alloy demonstrates a three-step relay mechanism involving a spontaneous redox step that reduces the overpotential for the process.

Nitrogenases are of high interest due to their ability to form NH₄⁺ by reduction of atmospheric dinitrogen. However, the detailed architecture of the Fe-only isoform remained unknown. Now, a high-resolution crystal structure of Fe-nitrogenase is solved, deepening the understanding of nitrogenase catalysis.

Electrocatalytic processes involving gas molecules are generally limited by low solubility in aqueous solutions. Here water endowed with permanent microporosity by silicalite-1 nanocrystals is used to concentrate O₂, allowing the measurement of the intrinsic activity of a Pt/C catalyst in the oxygen reduction reaction.

Saccharomyces cerevisiae can be engineered to slowly use methanol; however, a co-carbon source is usually required to support its growth. Now, a Saccharomyces cerevisiae strain that can use methanol as the sole carbon source for growth, and produce value-added bioproducts, is developed.