Shape-controlled pathways in the hydrogen production from ethanol steam reforming over ceria nanoparticles

VECCHIETTI, JULIA; PATRICIA PÉREZ BAILAC; PABLO LUSTEMBERG; ESTEBAN FORNERO; LAURA PASCUAL; MARTA BOSCO; ARTURO MARTÍNEZ-ARIAS; VERÓNICA GANDUGLIA-PIROVANO, M.; ADRIAN L. BONIVARDI

Zaragoza

Workshop; ZCAM-ASEVA METAL-OXIDE ULTRATHIN FILMS AND NANOSTRUCTURES; 2022

The ethanol surface reaction over CeO2 nanooctahedra (NO) and nanocubes (NC), whichmainly expose (111) and (100) surfaces, respectively, was studied by means of infraredspectroscopy (TPSR-IR), mass spectrometry (TPSR-MS) and density functional theory (DFT)calculations. TPSR-MS results show that the production of H2 is 2.4 times higher on CeO2-NC than on -NO, which is rationalized starting from the different types of adsorbed ethoxyspecies controlled by the shape of the ceria particles. Over the CeO2(111) surface,monodentate type I and II ethoxy species with the alkyl chain perpendicular or parallel tothe surface, respectively, were identified. Whereas on the CeO2(100) surface, bidentateand monodentate type III ethoxy species on the checkerboard O-terminated and on apyramid of the reconstructed (100) surface, respectively, are found. The more labilesurface ethoxy species on each ceria nanoshape, which are the monodentate type I or IIIethoxy on CeO2 -NO and -NC, respectively, react on the surface to give acetate species thatdecomposes to CO2 and CH4, while H2 is formed via the recombination of hydroxyl species.In addition, the more stable monodentate type II and bidentate ethoxy species on CeO2-NO and -NC, respectively, give an ethylenedioxy intermediate the binding of which is facetdependent. On the (111) facet, the less strongly bound ethylenedioxy desorbs as ethylene,whereas on the (100) facet, the more strongly bound intermediate also produces CO2 andH2 via formate species. Thus, on the (100) facet an additional pathway towards H2formation is found. ESR activity measurements show an enhanced H2 production on thenanocubes.