Porifera-like nickel nanodendrite for the efficient electrosynthesis of C–N compounds from carbon dioxide and nitrate anions

Abstract

Generating high-energy compounds with heteroatomic bonds via electrochemical reactions has attracted interest owing to the highly desired goal of achieving a net zero carbon state. In this dimension, herein, heteroatomic compounds, such as acetamide (CH₃CONH₂), were successfully produced together with the formation of ethylene glycol and other C₂₊ compounds by integrating CO₂RR with nitrate reduction reaction (NtRR). Highly porous nickel nanodendrites (p-Ni NDs) with a porifera architecture were constructed via the electrodeposition method and subsequent etching process. In 0.05 M KNO₃ and 0.5 M KHCO₃ electrolyte, p-Ni NDs generated acetamide and ethylene glycol at the yield rate of 657 μg h⁻¹ cm⁻² and 640 μg h⁻¹ cm⁻² with an FE of 23.2% and 18.0% under an applied voltage of −0.3 V vs. RHE, respectively. ¹H NMR spectroscopy was extensively used to detect and quantify the products. During the reaction, the surface of p-Ni NDs remained in the metallic state, which was confirmed by several X-ray spectroscopic techniques. Density functional theory (DFT) calculations revealed that *COHCOH_(a) is the crucial intermediate in the production of acetamide. Both the experimental and theoretical experiments substantiated the high activity of p-Ni NDs towards acetamide formation via C–N coupling.