Local structures and catalytic N₂O decomposition properties of Ni_1-xCu_xCo₂O₄

This study focuses on the catalytic performance of Ni_1-xCu_xCo₂O₄ (x = 0.00-1.00) spinel oxides for the direct decomposition of nitrous oxide (N₂O), a potent greenhouse gas. Ni-Cu-Co spinels were synthesized via controlled precipitation and characterized using X-ray diffraction, Brunauer-Emmett-Teller analysis, X-ray photoelectron spectroscopy, and H₂ temperature-programmed reduction to elucidate the relationship between catalyst composition, catalyst structure, and catalytic activity. Catalytic tests were conducted under 200 ppm of N₂O, 10% O₂, and N₂ balance with and without water vapor. Results revealed that partial substitution of Ni by Cu significantly modifies redox properties and oxygen vacancy concentration, thereby enhancing N₂O conversion. Among the tested compositions, Ni_0.75Cu_0.25Co₂O₄ exhibits the highest activity, achieving nearly complete N₂O decomposition at ~ 400 °C. Mechanistic insights suggest that Co²⁺-oxygen-vacancy pairs are the primary active sites, whereas Ni and Cu modulate electronic structures and oxygen mobility.