Nutrient diffusion-inspired catalysts with self-reinforced concentration gradient for sustainable electroreduction of dilute CO<sub>2</sub>.

Chen, Jialei; Lu, Tiantian; Liao, Xuelong; Chen, Shan; Li, Youzeng; Wang, Yue; Lv, Runyu; Cui, Wenyue et al. · Nat Commun · 2025

basic_science · Level V

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Abstract

The electrocatalysis of flue gas into CO in membrane electrode assembly (MEA) provides a sustainable route for realizing practical CO<sub>2</sub> electrolysis technology but suffers from restricted CO<sub>2</sub> mass transport due to thick gas boundary layer (GBL) and weak concentration gradient. Inspired by nutrient diffusion mechanism in plant, we introduce the concept of self-reinforced CO<sub>2</sub> concentration gradient, which is realized via porous carbon nanosheets (PC) as soil for enriching CO<sub>2</sub> and single-atomic Ni-doped carbon nanotubes (Ni-CNTs) as rhizome for electro-catalyzing CO<sub>2</sub>. A combined experimental and simulation study reveals optimal length of Ni-CNTs on PC reduces the GBL thickness and spontaneously enhances CO<sub>2</sub> concentration gradient, synergistically breaking the limitation of CO<sub>2</sub> transport. Consequently, the CO Faradaic efficiency attains >90% with varying CO<sub>2</sub> concentration of 4-15 vol. % CO<sub>2</sub> in MEA. Further through incorporation of an O<sub>2</sub>-adsorption packed column before MEA, we realize the stable and selective conversion of O<sub>2</sub>-containing flue gas into CO.