Incorporated Hydrogen into Mixed Oxides Provides A Novel and Versatile Concept to Promote Catalytic Oxidation Reactions

Abstract Hydrogen promotion of mixed oxides is a rather general approach to tune the oxidation performance in both thermal and electrocatalysis. We have exemplified this approach with the catalytic propane combustion, CO oxidation, HCl oxidation, and the oxygen evolution reaction (OER), the latter reaction representing the bottleneck in water electrolysis for the production of green hydrogen from renewable energy sources. For the incorporation of hydrogen into mixed oxides (hydrogen promotion), a specific design strategy is proposed: the mixed oxide (solid solution) consists of one metal oxide that is capable of activating H 2 dissociation and a second component that stabilizes the mixed oxide against chemical reduction upon exposure to H 2 at temperatures of 150–250 °C. To date this concept has been successfully demonstrated for solid solutions with rutile structure (Ru x Ti 1‐x O 2 and Ir x Ti 1‐x O 2 ). Hydrogen promotion of mixed oxides is expected to be useful in hydrogenation catalysis as well. Other mixed oxide systems in which hydrogen promotion is observed remain to be discovered. Hydrogenation of catalysts is so simple that it should be included in routine screening protocols of oxidation catalysts.