Reviews & Analysis

The chlor-alkali industry is one of the largest global electricity consumers. In the 1970s, the discovery of dimensionally stable anodes (DSAs) allowed for drastic savings in electricity consumption. The fundamental reasons behind the effectiveness of DSAs, however, were only clarified decades later.

The d-band model was proposed by Bjørk Hammer and Jens Nørskov almost 30 years ago to explain trends in the interaction of adsorbates with transition-metal surfaces. It remains a cornerstone in heterogeneous catalysis research and has inspired a wealth of later models.

Scientific research on human insulin was a crucial development in medicine, and its discovery led to the treatment of diabetes, one of the most prevalent global chronic diseases. A seminal work published in 1979 describing recombinant DNA technology to produce human insulin through biocatalysis has resulted in this field’s establishment and routine industrial applications.

The conditions employed for alkane dehydrogenation reactions are usually detrimental for catalyst stability. Now, subnanometre Pt clusters stabilized by the Ge-enriched double four-membered-ring units in a UTL-type zeolite structure show exceptionally high stability for this important transformation.

Linear polyethylene and isotactic polypropylene, the two largest-volume polymers on the market, were invented in the 1950s thanks to diverse mixes of serendipity, intuition and talent. After 70 years, a thoughtful revisitation of those ground-breaking discoveries can still be revealing and inspirational.

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 discovery of the Tetrahymena group I intron’s self-splicing defined RNAs as capable catalysts. Now, cryogenic electron microscopy structures of this ribozyme have revealed large conformational changes and mechanistic details of its two-step mode of action.

In a standard electrochemistry experiment, the electrochemical signal reports on all electron transfer, chemical, and diffusion steps between the anode and cathode. Now, a membrane reactor decouples each of these steps to enable direct measurement of elementary reaction steps in ways that are otherwise not possible.

Electrochemical hydride (H^–) transfer has been an elusive process. Now, using well-designed model systems, the phenomenon has been isolated and further demonstrated as a practical synthetic method with H₂ gas as the hydrogen source.

Microporous zeolites have pores of molecular dimension that can stabilize desired chemical pathways but may also introduce mass-transfer limitations. Now, synthesis protocols allow for greater control of catalyst active-site location via elemental zoning, enabling an alternative strategy to reduce mass-transfer limitations and consequently improve catalyst performance for methanol-to-hydrocarbon reactions.

Electron transfer processes are almost ubiquitous, yet hard to understand thoroughly due to the variability of catalytic species involved. Now, a detailed mechanistic picture of the electron transfer associated with polypyridine nickel systems has been reported, offering an answer to the electron transfer puzzle of these complexes.

The ability to maximize electron utilization in electrosynthesis has been a long-standing goal, with research typically focusing on catalyst design or pairing disparate reactions. Now, electrocatalytic hydrogenation is performed with Faradaic efficiencies approaching 200% by producing hydrogen atoms from both the reduction and oxidation reactions simultaneously.

Computational chemistry has the potential to aid in the design of heterogeneous catalysts; however, there is currently a large gap between the complexity of real systems and what can be readily computed at scale. This Review discusses the ways in which machine learning can assist in closing this gap to facilitate rapid advances in catalyst discovery.

Retrobiosynthesis aims to create novel biosynthetic pathways for the beneficial production of molecules of interest. This Review outlines how machine learning can help to advance retrobiosynthesis by improving retrosynthesis planning, enzyme identification and selection, and the engineering of enzymes and pathways.

Reaction networks provide complete mechanistic understanding of catalytic processes, although they can be highly complex and thus very challenging to obtain. This Perspective discusses the use of machine learning for the exploration of reaction networks in heterogeneous catalysis.

Controlling the stereochemical outcomes of chemical reactions is essential in modern chemical synthesis and manufacturing. Now, a nickel-catalysed, stereoselective hydrometalation and enantioconvergent alkyl–alkyl coupling of alkenyl boronic esters and α-bromo carbonyl derivatives has been achieved to provide single stereoisomers.

High current densities during CO₂ reduction in gas diffusion electrode (GDE) flow cells are incompatible with present online product-profiling methods. With the adaptation of proton-transfer reaction time-of-flight mass spectrometry, operando mechanistic information on C₁–C₄ product formation at copper-based GDEs is now accessible.

Hydrogen oxidation reactions in hydroxide exchange membrane fuel cells have slow kinetics. Switching from platinum group metal (PGM) electrocatalysts to those that are PGM-free is a challenging task as the latter are prone to oxidation. Now, stable and active nickel–molybdenum–niobium catalysts are introduced for this type of fuel cell.

Photosynthetic semiconductor biohybrids represent a viable approach to solar-to-chemical production but it remains challenging to tap their full potential. Now, a microbe–quantum dot hybrid has been developed for simultaneous fixation of CO₂ and N₂ with internal quantum efficiencies approaching the theoretical limits.