Boosting Selective Nitrogen Oxidation to Nitric Acid by Synergizing Cobalt Phthalocyanine on Carbon Nitride Surface

Abstract

Abstract The Ostwald process, which is producing HNO 3 for commercial use, involves the catalytic oxidation of NH 3 and a series of chemical reactions conducted under severe operating conditions. Due to their energy‐intensive nature, these activities play a major role in greenhouse gas emissions and global energy consumption. In response to the urgent requirements of the global energy and environmental sectors, there is an increasingly critical need to develop novel, highly efficient, and environmentally sustainable methods. Herein, CoPc/C 3 N 4 electrocatalyst, integrating CoPc nanotubes with C 3 N 4 nanosheets, is shown. The CoPc/C 3 N 4 electrocatalyst demonstrates yield rate of 871.8 µmol h −1 g cat −1 at 2.2 V, with corresponding Faradaic efficiency (FE) of 46.4% at 2.1 V, which notably surpasses that of CoPc. Through a combination of experimental investigations and density functional theory (DFT) calculations, this study shows that CoPc anchored on C 3 N 4 effectively simplifies the adsorption and activation of chemically inactive nitrogen molecules. The improved catalytic activity for composite system may be the reason of re‐distribution of charges over the CoPc, tuning the valence orbital of Co center due to the presence of 2D layer of C 3 N 4 . This mechanism significantly lowers the energy barrier required for critical breaking of inert N 2 , ultimately leading to a significant improvement in N 2 oxidation efficiency.