Reconstructed Bismuth‐Based Metal−Organic Framework Nanofibers for Selective CO2‐to‐Formate Conversion: Morphology Engineering

Abstract Electrochemical reduction of carbon dioxide (ERCO 2 ) is an attractive and sustainable approach to close the carbon loop. Formic acid is a high‐value and readily collectible liquid product. However, the current reaction selectivity remains unsatisfactory. In this study, the bismuth‐containing metal−organic framework CAU‐17, with morphological variants of hexagonal prisms (CAU‐17‐hp) and nanofibers (CAU‐17‐fiber), is prepared at room temperature through a wet‐chemical approach and employed as the electrocatalyst for highly selective CO 2 ‐to‐formate conversion. An H 3 BTC‐mediated morphology reconstruction is systematically investigated and further used to build a CAU‐17‐fiber hierarchical structure. The as‐prepared CAU‐17‐fiber_400 electrodes give the best electrocatalytic performance in selective and efficient formate production with FE HCOO− of 96.4 % and j COOH− of 20.4 mA cm −2 at −0.9 V RHE . This work provides a new mild approach for synthesis and morphology engineering of CAU‐17 and demonstrates the efficacy of morphology engineering in regulating the accessible surface area and promoting the activity of MOF‐based materials for ERCO 2 .