Fluorine-induced d-band center shift of the Nb site boosts anodic formamide electrosynthesis

Abstract

Anodic oxidative amidation (EOA) strategies offer a sustainable and potentially promising route for amide synthesis. However, the efficiency and activity of catalysts under oxidative conditions are highly dependent on noble metals. Herein, we present our experimental findings and fundamental understanding that fluorine-doped Nb2O5 nanosheet arrays on carbon fiber (F-Nb2O5/CP) serve as an efficient and robust non-noble catalyst for the electrochemical synthesis of formamide from ammonia and methanol under ambient conditions. In 0.5 M KHCO3 solution, this catalyst achieved a high Faradaic efficiency of 52.0%, with an N selectivity of 79.1% at 1.5 V versus Hg/HgO electrode. The catalyst exhibited remarkable stability, maintaining its performance over 120 h. By integrating in-situ spectroscopy studies with density functional theory calculations, we revealed that fluorine doping induces a shift in the d-band center of the Nb site. This shift alters the adsorption behavior of OH- and *NH2 intermediate on the F-Nb2O5 (100) surface, thereby effectively lowering the C-N coupling energy barrier, and boosting the production of formamide.