Electrochemical carbon dioxide reduction to multicarbon products provides the storage of renewable energy in the form of chemical bonds, as well as a means to displace fossil sources of chemical feedstocks. However, the accompanying anodic oxygen evolution reaction (OER) reduces the energy efficiency of the process without providing a salable product. Replacing OER with alternative organic oxidation reactions (OORs) is an emerging strategy to reduce the full-cell potential and generate valuable products on both sides of the cell. We pursue carbon monoxide reduction that avoids carbonate formation and benefits from highly alkaline anode conditions favorable for OOR. This coelectrolysis strategy achieves a cathodic C2+ product stream (71% FE) and an anodic C3 product stream (75% FE) at 180 mA cm–2 with a full-cell potential of 1.34 V. The integrated system reduces the CO-to-C2H4 energy requirement by 55% (to ∼72 GJ/ton_C2H4), halving the projected energy cost of ethylene production from CO2.

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From physical property measurement to modelling pore-scale environments, the study of fluids at the microscale is key to understanding and optimizing fluids for large-scale energy applications. Silicon-glass microfluidics is now a proven technology for chemical effectiveness testing in the conventional oil and gas energy sector. We see potential to apply microfluidic fluid characterization technology to renewable sectors, such as geothermal and solar thermal energy recovery where fluid customization is central to performance. Key to unlocking performance gains in these renewable energy systems are phase change material slurries (PCSs)fluids that exhibit a high apparent specific heat capacity. However, testing PCS synthesis recipes is currently a slow and expensive process, given the challenges of dynamic testing at process-relevant temperatures and pressures. In this work, we develop and test a robust silicon microfluidic device and measure important PCS emulsion properties including (i) viscosity, (ii) shear stability, (iii) phase change temperature/hysteresis, and (iv) phase change stability under dynamic conditions where tests are performed quickly (<1 h) and require only minimal test fluid volumes.