Probing the Metal/Oxide Interface of IrCoCeO in N₂H₄·H₂O Decomposition: An Experimental and Computational Study

Understanding the structure of a functional catalyst is crucial to disclosing the complexity of heterogeneous processes and improving their efficiency. Herein, coprecipitated cobalt-ceria (CoCeO) oxides doped with Ir (IrCoCeO) were synthesized and used to assess the performances of metal/oxide interfaces in the N₂H₄·H₂O decomposition performed in aqueous NaOH. Kinetic experiments in batch showed that CoO is the active phase of CoCeO and that the copresence of Ir and Co (IrCoCeO) enhanced H₂ productivity. A comprehensive characterization (X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy, and in situ diffuse reflectance infrared Fourier transform spectroscopy) combined with robust computational modeling based on the density functional theory was employed to attribute the IrCoCeO performance enhancement to the Ir/CoO metal/oxide interface, the active site of the reaction. On these sites, the improved H₂ productivity in the presence of aqueous NaOH was studied operando through modulated excitation-attenuated total reflectance infrared coupled with phase sensitive detection. The formation of surface Co-hydroxyl and -imido groups at the Ir/CoO interface induced the preferential breakage of the N-H bond of N₂H₄·H₂O, favoring the production of H₂.