Nanocrystalline High-Dimensional Nb2O5 for Efficient Electroreductive Dicarboxylation of CO2 with Cycloalkane

The electrocarboxylation of C–C single bonds using CO₂ under ambient conditions is a promising strategy for synthesizing diacids, which have significant applications in polymer and biomedical sectors. In this study, we present the development of nanocrystalline Nb₂O₅ featuring a high-dimensional structure (Nb₂O₅–HD) that enables the efficient dicarboxylation of CO₂ with cycloalkanes under mild conditions. Utilizing commercially available, unactivated diethyl cyclopropane-1,2-dicarboxylate as a model substrate, we achieved an impressive average yield of approximately 94%, with an 88% yield demonstrated in a gram-scale experiment. Notably, Nb₂O₅–HD maintained its structure and performance after 100 h of continuous operation, highlighting its long-term stability. In situ mechanistic investigations elucidated the reaction pathway, revealing that the CO₂ radical anion (CO₂^•–) serves as an essential intermediate driving the reaction rather than cycloalkane adsorption onto the cathode. Besides, the high-dimensional structure and abundant crystal defects of Nb₂O₅–HD exhibit a greater number of acid sites, which is advantageous for the generation and stabilization of the CO₂^•–. These findings underscore the potential of Nb₂O₅–HD as a robust catalyst for CO₂ conversion, paving the way for advancements in organic electrosynthesis.