Modifying the Local Bonding Environment of Co3O4 Enhances Photothermal N2O Decomposition

Abstract

Photothermal catalysis offers a light-driven route for N2O abatement by coupling broadband light harvesting with catalytic surface reactions. Here, spinel Co3O4 catalysts were prepared by calcining at 400, 500, and 600 °C (denoted as Co3O4-400, Co3O4-500, and Co3O4-600, respectively). This temperature-controlled synthesis preserved the spinel framework while modulating the local bonding environment surrounding the Co centers. Among the three catalysts, Co3O4-500 exhibited a relatively less-coordinated octahedral Co–O–Co environment, accompanied by modest surface Co2+ enrichment. Light-assisted N2O temperature-programmed desorption showed that Co3O4-500 retained a larger population of thermally stable N2O-related species, while in situ infrared spectroscopy revealed more rapid attenuation of the bands assigned to N–N- and N–O-related vibrations under illumination. Temperature-matched controls further showed that its enhanced activity could not be explained by macroscopic catalyst-bed heating alone. Accordingly, Co3O4-500 achieved 93.5% single-pass N2O conversion and a decomposition rate of 40.82 mmol g–1 h–1 at 1.81 W cm–2 under broadband irradiation. These results associate the photothermal activity of Co3O4 with its local Co–O coordination environment and identify coordination regulation through controlled thermal treatment as a strategy for designing non-noble-metal catalysts for N2O abatement.