Engineering Oxygen Vacancies in Non-Noble Cu x Fe 1 /ZrO 2 Catalysts for Synthesis of N , N ′-Diphenylurea from CO 2 and Aniline

In this study, a non-noble bimetallic-supported metal oxide catalyst, Cu x Fe 1 /ZrO 2 rich in oxygen vacancies, was synthesized via dry ball milling for the direct synthesis of N, N ′-diphenylurea (DPU) from CO 2 and aniline. The optimal Cu 5 Fe 1 /ZrO 2 catalyst achieved 12.7% aniline conversion with near-100% DPU selectivity (99.9%). Comprehensive characterizations revealed that abundant oxygen vacancies enhance metal–support interaction and serve as primary sites for CO 2 adsorption and activation. Combined temperature-programmed desorption of NH 3 and CO 2 (CO 2 /NH 3 -TPD) and in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) studies elucidated a synergistic acid–base catalytic mechanism. Lewis basic Cu/Fe sites activate CO 2, while Lewis acidic Zr 4+ sites adsorb and activate aniline, promoting the formation of the key C 6 H 5 NH–(CO) intermediate. The catalyst maintained high performance over five cycles, demonstrating excellent stability. This work offers an effective strategy for designing robust non-noble catalysts for CO 2 valorization into value-added chemicals.