Efficient amino-acid-based reactive capture of CO2 via nickel molecular catalyst

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 tCO–1.