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Ammonia is not only an important raw material for industry and agriculture but also a carbon-free energy carrier with high energy density. Traditional ammonia synthesis relies on the Haber-Bosch process under extreme conditions, leading to substantial energy consumption and greenhouse gas emissions. Electrochemical reduction of nitrate (NO3−reduction reaction [RR]) to ammonia can simultaneously produce valuable ammonia and eliminate nitrate pollution from the environment and has therefore attracted global attention. In this paper, we summarize recent progress in the field of NO3−RR, including the reaction mechanism, electrocatalyst development, reactor designs, and practical applications. New coupling reactions for removing NO3−together with other contaminants are also introduced briefly. Finally, the future prospect of NO3−RR, particularly the critical requirement to enable practical application of the technique, is put forward. This paper provides a timely summary of the research progress and offers important guidance for researchers in the field of environmental remediation and clean energy.

The designability of a polymeric photocatalyst is the main factor that facilitates the modification of its physical properties, such as porosity, solubility, and processability, allowing the entry of a polymeric photocatalyst into a flow reactor. Here, we provide a quick overview of recent investigations into how polymeric photocatalysts have been utilized in flow systems through observations in structural engineering and polymerization techniques. We also show representative examples of how the design of a flow setup can lead to improvements in the performance of polymeric photocatalysts. This paper provides insights for choosing the best reactor options for polymeric photocatalysts, depending on the properties and synthetic protocols of the polymers.

Traditional thermochemical synthesis of N-containing compounds presents disadvantages in terms of high energy consumption and large pollution, motivating growing interest in the development of energy-saving, efficient, and green electrochemical alternatives. Due to their special structure and electronic properties, amorphous nanomaterials possess several advantages for applications in catalysis, which include electrochemical synthesis of N-containing compounds. This paper reviews recent research progress in the application of amorphous nanomaterials as electrocatalysts for efficient electrosynthesis of N-containing compounds from a variety of abundant N-containing small molecules (N2, NO, NO3−, etc.). It discusses the controllable synthesis and structural advantages of amorphous nanomaterials and their enhanced electrocatalytic properties for various N-containing systems with emphasis on the structure-function relationships between the catalysts and catalytic reactions, especially for the porbital regulated main group catalysts. Finally, it makes recommendations for future electrochemical synthesis of various N-containing compounds and describes current challenges as well as opportunities for new developments.

The use of visible-light photosensitizers to power [2 + 2] photocycloadditions that produce complex tetrasubstituted cyclobutanes is a true success of photochemistry, but the scope of this reaction has been limited to activated α,β-unsaturated carbonyls. This paper describes selective intermolecular homo- and hetero-[2 + 2] photocycloadditions of terminal and internal aryl-conjugated dienes—substrates historically unsuited for this reaction because of their multiple possible reaction pathways and product configurations—through triplet-triplet energy transfer from CdSe nanocrystal photocatalysts to generate valuable and elusive syn-transaryl vinylcyclobutanes. The negligible singlet-triplet splitting of nanocrystals' excited states allows them to drive the [2 + 2] pathway over the competing [4 + 2] photoredox pathway, a chemoselectivity not achievable with any known molecular photosensitizer. Reversible tethering of the cyclobutane product to the nanocrystal surface results in near-quantitative yield of the syn-transproduct. Flat colloidal CdSe nanoplatelets produce cyclobutanes coupled at the terminal alkenes of component dienes with up to 89% regioselectivity.

Efficient translation of renewable biomass into fine commodity chemicals and fuel is vital for a more sustainable economy and carbon-neutral society. Phenolics represent one of the most important intermediates in the transformation of lignin into bio-based bulk chemicals. Currently, (partial) hydrodeoxygenation is a promising strategy for upgrading phenolics to value-added products. Nevertheless, conventionally thermo-catalytic hydrodeoxygenation is generally accompanied by high reaction temperatures and external hydrogen supply, which to some extent leads to costly expenditure and operational complexity. In this paper, we focus on the recent advances in the synthesis of industrially relevant bulk chemicals from lignin-derived phenolics via three novel technologies of electrocatalytic hydrogenation, non-thermal plasma-assisted catalysis, and photocatalytic hydrogenation. Meanwhile, the reaction condition adopted, physicochemical properties, and reaction mechanisms of employed catalytic systems are presented and discussed. Last, some personal perspectives on the existing challenges and future research directions in this promising area are highlighted.

Photocatalytic membrane reactors (PMRs) are promising for various synthesis and environmental applications, particularly CO2capture and conversion. This paper provides a comprehensive review of the use of photocatalytic membranes (PMs) and reactors for CO2reduction. A brief introduction to different CO2reduction processes, including photocatalytic CO2reduction (PCR), together with their advantages and disadvantages, is first provided. Then the general concept, mechanism, selectivity, and photocatalyst used in PCR reactions are discussed. After the introduction of available configurations of PMRs and effective operational conditions, the applications and performance of various PMs in generating value-added products from PCR are presented. Finally, the recent advancements of the PCR process hybridized with other processes, primarily CO2capture and water splitting, are reviewed. Overall, the challenges that should be overcome before scaling PMRs up to industrial applications include the introduction of efficient solar-light-driven photocatalysts and selective and durable membranes under harsh conditions in long-term processes.