The design of electrochemical reactors that convert CO2 into valuable chemicals and fuels is made challenging by the lack of computational models that capture the complex physics and chemistry of these systems. Now, Adam Weber and colleagues have developed a comprehensive continuum model that links ion, water and gas transport with coupled ion–electron transfer kinetics to quantify rate-limiting phenomena and trade-offs in reactor design. The cover shows how this digital model complements CO2 reduction experiments to accelerate the development of improved reactors.

See Lees et al. and Elgazzar & Wang

The recovery of valuable metals from waste sources remains challenging. Now, Xiao Su and colleagues demonstrate an electrochemical liquid–liquid extraction process that utilizes selective single-site binding of metal ions to a redox-active ferrocene in a continuously operating platform. This process achieved substantial up-concentration for gold and platinum group metals from several practical waste feedstocks.

See Cotty et al. and Schuur

Benzyl acetate, a compound with a jasmine-like scent used in various products, is traditionally made through inefficient plant extraction or chemical methods. Now, Choi, Lee and colleagues have developed a more sustainable method using a metabolically engineered bacterium to produce benzyl acetate, achieving significant production levels in a fermentation process. The cover shows a 300-liter pilot-scale fermentor at KAIST, Korea.

See Choi et al. and Sokolova & Haslinger

The fast construction and on-the-fly reconfiguration of liquid-based devices have long been challenging. Now, Gu, Du and colleagues have developed a strategy to generate diverse liquid-based devices that can be designed and reconfigured on-demand within minutes simply by adding, connecting and removing liquid droplets in a pillared substrate. The cover shows a fluidic channel constructed using this method.

See Zeng et al. and Wang & Wang

Recalcitrant C–C bonds in lignin limit the monomer yield of current depolymerization strategies that target labile C–O bonds. Now, Emiel Hensen and colleagues present a process based on a bifunctional Pt/zeolite catalyst that selectively cleaves common C–C linkages in lignins, resulting in substantially increased fuel yields from common lignin sources.

See Luo et al. and Subbotina & Samec