Albert Casanovas

Ambient Pressure Photoemission Spectroscopy Reveals the Mechanism of Carbon Soot Oxidation in Ceria-Based Catalysts

Removing soot is one of the most important challenges in minimizing the impact of combustion engines on the environment. Catalysts based on CeO2 have proved suitable to oxidize soot owing to their capacity to store and release oxygen easily while maintaining structural integrity, although their mode of operation in a complex environment involving two solid phases (catalyst and soot) and a gas phase (oxygen) is not yet fully understood. Herein, we provide a study of the surface/subsurface of ceria–soot and ceria–zirconia–soot mixtures under working conditions by means of near‐ambient‐pressure photoelectron spectroscopy. Soot abatement involves two cooperative routes: one occurring at the ceria–soot interface with formation of oxygen vacancies and CeIII and the other at the surface of soot, mediated by active superoxide species, which result from the reaction between gas‐phase O2 and oxygen vacancies. The two routes occur simultaneously and mutually reinforce each other.

Gold(I)-complex–titania hybrid photocatalyst for hydrogen production

The integration of TiO2 with a AuI complex containing a thiocoumarin moiety resulted in a very efficient photocatalyst for the generation of H2. The molecular structure of the complex was preserved under the photoreaction owing to the strong AuI−S bond. The AuI complex played a determinant role in the photogeneration of H2 by accepting the photoinduced electrons originated in TiO2 upon light exposure. This is the first example of a AuI complex semiconductor hybrid photocatalyst. The rate of H2 generation under dynamic conditions from water/ethanol is approximately one order of magnitude superior on a metal basis to that obtained over conventional TiO2 decorated with Au metal nanoparticles.