Hydrogen-Bonded Organic Framework Supporting Atomic Bi-N₂O₂ Sites for High-Efficiency Electrocatalytic CO₂ Reduction

Single atomic catalysts (SACs) offer a superior platform for studying the structure-activity relationships during electrocatalytic CO₂ reduction reaction (CO₂RR). Yet challenges still exist to obtain well-defined and novel site configuration owing to the uncertainty of functional framework-derived SACs through calcination. Herein, a novel Bi-N₂O₂ site supported on the (1 1 0) plane of hydrogen-bonded organic framework (HOF) is reported directly for CO₂RR. In flow cell, the target catalyst Bi1-HOF maintains a faradaic efficiency (FE) HCOOH of over 90 % at a wide potential window of 1.4 V. The corresponding partial current density ranges from 113.3 to 747.0 mA cm^-2. And, Bi1-HOF exhibits a long-term stability of over 30 h under a successive potential-step test with a current density of 100-400 mA cm^-2. Density function theory (DFT) calculations illustrate that the novel Bi-N₂O₂ site supported on the (1 1 0) plane of HOF effectively induces the oriented electron transfer from Bi center to CO₂ molecule, reaching an enhanced CO₂ activation and reduction. Besides, this study offers a versatile method to reach series of M-N₂O₂ sites with regulable metal centers via the same intercalation mechanism, broadening the platform for studying the structure-activity relationships during CO₂RR.