Investigation on Cu₂O Surface Reconstruction and Catalytic Performance of NH₃‑SCO by Experimental and DFT Studies

Cubic cuprous oxide is applied in the selective catalytic oxidation of ammonia to nitrogen (NH₃-SCO) to investigate the effect of structure evolution on catalytic performance. Different structures (Cu₂O, Cu₂O–CuO, and CuO) that formed progressively during the reconstruction process with time are discovered by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and other characterization methods. The optimal CuO–Cu₂O exhibits the best catalytic performance, which has T_100% = 210 °C and above 80% N₂ selectivity. Combining the experimental method and the density functional theory (DFT), the oxygen molecule is adsorbed in the form of a stable molecular state on Cu₂O particles, while the dissociative adsorption of O₂ occurs over the mixed CuO–Cu₂O and pure CuO phases. It is found that O₂ is more likely to be dissociated and activated on CuO–Cu₂O with E_ads = −7.15 eV. There are three kinds of intermediate species (monodentate, bidentate, and bridging nitrate) observed. The formation of key bidentate nitrate species facilitates NH₃ conversion and N₂ formation, but the other intermediate species have a negative effect on NH₃ oxidation.