Flexible Cuprous Triazolate Frameworks as Highly Stable and Efficient Electrocatalysts for CO 2 Reduction with Tunable C 2 H 4 /CH 4 Selectivity.

Cu-based metal-organic frameworks have attracted much attention for electrocatalytic CO ₂ reduction, but they are generally instable and difficult to control the product selectivity. We report flexible Cu(I) triazolate frameworks as efficient, stable, and tunable electrocatalysts for CO ₂ reduction to C ₂ H ₄ /CH ₄ . By changing the size of ligand side groups, the C ₂ H ₄ /CH ₄ selectivity ratio can be gradually tuned and inversed from 11.8 : 1 to 1 : 2.6, giving C ₂ H ₄ , CH ₄ , and hydrocarbon selectivities up to 51 %, 56 %, and 77 %, respectively. After long-term electrocatalysis, they can retain the structures/morphologies without formation of Cu-based inorganic species. Computational simulations showed that the coordination geometry of Cu(I) changed from triangular to tetrahedral to bind the reaction intermediates, and two adjacent Cu(I) cooperated for C-C coupling to form C ₂ H ₄ . Importantly, the ligand side groups controlled the catalyst flexibility by the steric hindrance mechanism, and the C ₂ H ₄ pathway is more sensitive than the CH ₄ one.
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