Probing the Metal/Oxide Interface of IrCoCeO_<i>x</i> 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_<i>x</i>) oxides doped with Ir (IrCoCeO_<i>x</i>) 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_<i>x</i> and that the copresence of Ir and Co (IrCoCeO_<i>x</i>) 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_<i>x</i> 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.