Perspectives

Biomass is a renewable source of carbon that can be exploited to produce valuable chemicals and fuels. This Perspective discusses the electrochemical valorization of biomass, identifying specific chemical transformations in which the approach can excel.

Electrocatalytic NO_x reduction (NO_xR) to ammonia has recently become an increasingly popular alternative to the more challenging N₂ reduction. This Perspective critically assesses the possible ways NO_xR could contribute to the ammonia economy and clarifies the necessary steps for a rigorous experimental protocol.

Direct CO₂-to-C₂₊ and tandem CO₂-to-CO and CO-to-C₂₊ electrocatalytic systems have been proposed as strategies for sustainable fuel and chemical synthesis. This Perspective considers the role of acidic CO₂ gas on the cathodic microenvironment and local pH and draws connections between this and product selectivity in the electrochemical CO₂ reduction reaction and the electrochemical CO reduction reaction, focusing on the competition between two major pathways: ethylene/ethanol and acetate.

Thanks to a unique set of properties, liquid metal catalysts provide advantages compared to traditional solid systems, yet their potential in heterogeneous catalysis has not been fully explored. This Perspective identifies some of the key advances in the field of liquid metal catalysis, discussing areas where progress is expected through further fundamental understanding as well as reactor engineering.

Understanding the structure–performance relationships of heterogeneous catalysts is of fundamental importance for their deployment in industry. However, gaps exist between the conditions and catalytic materials commonly employed in laboratory studies and those encountered in practical reactors. This Perspective highlights the importance of recognizing such gaps, with the goal to inform the planning of academic research and maximize its impact.

Progress in the field of photocatalytic CO₂ reduction has been constrained by a lack of comparability between studies. This Perspective provides recommendations for best practices in the undertaking and reporting of experimental data in this promising research area.

Catalytic pyrolysis is a promising process for the valorization of biomass and plastic waste, although several aspects related to its practical utilization remain unexplored. This Perspective revisits the salient features of catalytic pyrolysis, identifying a roadmap to advance the application of this technology at commercial scale.

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.

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.

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.

Most applications of machine learning in catalysis use black-box models to predict physical properties, but extracting meaningful physical insights from them is challenging. This Perspective discusses machine learning approaches for heterogeneous catalysis and classifies them in terms of their interpretability.

Liquid fuels produced by electrocatalytic CO₂ reduction are costly to separate from liquid electrolytes in a conventional cell. This Perspective identifies the need for novel cell designs that can directly produce high-concentration and high-purity products and discusses the progress towards this goal using porous solid electrolytes.

The practical implementation of CO₂ electrocatalysis is premised on the availability of captured CO₂—a consideration that is often overlooked. This Perspective presents several concepts for integrating CO₂ capture with electrochemical CO₂ conversion for the enhancement of overall efficiency.

Electrochemical CO₂ reduction is a complex process with many competing products, yet nature has evolved ways to overcome these issues. This Perspective makes connections between the motifs observed in nature and strategies that can be employed in synthetic systems for the advancement of selectivity in CO₂ reduction.

Methanol is a leading candidate for storage of solar-energy-derived renewable electricity as energy-dense liquid fuel, yet there are different approaches to achieving this goal. This Perspective comparatively assesses indirect CO- and direct CO₂-based solar strategies and identifies the conditions under which the former becomes economically viable.

Synthetic chemical processes often do not operate at sustainable or mild conditions—in contrast with natural complex reaction networks. This Perspective provides a roadmap for bio-inspired integrated catalytic systems for chemical manufacturing, sketching a biologically based future of industrial catalysis.

Genetic incorporation of unnatural amino acids into proteins broadens the possibilities of enzyme design. This Perspective discusses the exciting opportunities for biocatalysis offered by this method — such as new-to-nature catalytic activities — and potential benefits over classical enzyme engineering.

Carbon monoxide can be electrochemically transformed to multi-carbon products selectively at high rates, raising the prospect of a two-step pathway to transform CO₂ into value-added chemical products. This Perspective highlights recent progress complemented by a techno-economic analysis of the two-step conversion process and cradle-to-gate lifecycle assessment.

The energies of the species in a given reaction network are linked by linear scaling relationships, limiting the design of catalysts with improved activity and selectivity. In this Perspective, López and Pérez-Ramírez discuss strategies to circumvent such scaling relationships.

While the oxidative addition of Pd to carbon–halide bonds is often regarded as being essentially irreversible, this is sometimes not the case. This Perspective looks at the conditions leading to reductive elimination of Pd from carbon–halide bonds, and the synthetic opportunities that this offers are discussed.