Yurou Celine Xiao

Higher post-capture bicarbonate concentrations improve CO FE but must be balanced against viscosity and conductivity. Screening the performance of binary and commercial amine blends, we find a CO energy efficiency (EE) of 31% at 50 mA cm ⁻² .

Reactive capture integrates CO₂ capture and electrochemical conversion into CO - a key building block in the synthesis of industrial chemicals and fuels - avoiding costly regeneration steps and improving efficiency. Amino acid salt solutions, which offer rapid CO₂ capture, facile CO₂ release, O₂ tolerance, and low toxicity, are promising sorbents for reactive capture. However, we find that amino acids can adsorb to common CO-producing catalysts, covering the active sites and deactivating the catalyst, and that they bind less to nickel phthalocyanine (NiPc). Still, when tested for reactive capture systems - where CO₂ supply is inherently limited - NiPc's performance is constrained by its weak CO₂ adsorption and activation. Here we develop a nickel molecular catalyst supported on carbon nanotubes with a conjugated NiPc framework that resists amino acid adsorption and a coordinatively unsaturated Ni-N₃ structure that promotes CO₂ adsorption and enhances CO selectivity. As a result, we achieve 94% CO Faradaic efficiency at 100 mA cm^-2 with an energy efficiency of 42% and an energy cost of 25 GJ t_CO^-1.

Electrocatalysis offers a promising route to convert CO₂ into alcohols, which is most efficient in a two-step cascade reaction with CO₂-to-CO followed by CO-to-alcohol. However, current alcohol-producing CO₂/CO electrolyzers suffer from low selectivity or alcohol crossover, resulting in alcohol concentrations of less than 1%, which are further diluted in downstream cold-traps. As a result, electrocatalytic alcohol production has yet to be scaled beyond the lab (1-10 cm²). Here, we reverse the electroosmotic drag of water using a cation exchange membrane assembly, enabling the recovery of over 85% of alcohol products at a concentration of 6 wt.%. We develop a multi-step condenser strategy to separate the produced alcohols from the effluent gas stream without dilution. Scaling up this approach to an 800 cm² cell resulted in an output of 200 mL alcohol/day.

High-throughput evaluation of CO ₂ capture fluids accelerates the development of next-gen carbon capture technologies.

Reactive capture – the integration of CO₂ capture with electrochemical upgrade – offers the prospect of improving overall energy efficiency in captured-CO₂-to-fuels by eliminating the gas-phase CO₂ desorption step, and by further offering a CO₂-free gas product stream. Two related challenges limit the potential impact of electrified reactive capture today: its propensity to produce lower-value C₁ products (carbon products containing one carbon atom per molecule); and its failure to retain performance when fed dilute streams (e.g. ~1-10% CO₂). We posit that these could be addressed using catalysts that locally concentrate and activate in-situ generated CO₂: we integrate a redox-active polymeric network whose polymer fragments undergo reversible reduction during the electrochemical conversion process, enabling electron transfer to CO₂ molecules generated in-situ from carbonate capture liquid. We report as a result a 55 ± 5% C₂₊ (carbon products containing two or more carbon atoms per molecule) Faradaic efficiency (FE) at 300 mA/cm² in an electrochemical reactive capture system in which the electrolysis stage is fed with 1 M K₂CO₃. We obtain 56 ± 4 wt% C₂H₄ in the product gas stream. When we use a dilute stream consisting of 1% CO₂ in N₂ at the KOH capture stage, we retain the C₂₊ FE to within 85% (relative) of its value achieved in the case of pure CO₂.