Electro-oxidation Reaction of Methanol over Reducible Ce1-x-y Ni x Sr y O2-δ: A Mechanistic Probe of Participation of Lattice Oxygen

Methanoloxidation reaction crucially depends on theformationof -OOH species over the catalyst's surface. Ni-basedcatalysts are by far the choice of materials, where the redox coupleof Ni2+/Ni3+ facilitates the formation of -OOHspecies by surface reconstructions. However, it is challenging tooxidize Ni2+ as it generates charge-transfer orbitals nearthe Fermi energy level. One possible solution is to substitute Ni2+ with a reducible oxide support, which will not only facilitatethe Ni2+ & RARR; Ni3+ oxidation but also adsorboxygenated species like -OOH at a lower potential owing toits oxophilicity. This work shows with the help of structural andsurface studies that the reducible CeO2 support in Ni andSr co-doped Ce1-x-y Ni x Sr y O2-& delta; solid solution can easily facilitateNi(2+) & RARR; Ni3+ oxidation as well as evolutionof lattice oxygen during the methanol oxidation reaction. While theNi(3+) species helped in formation of -OOH surfaceintermediates, the evolved lattice oxygen eased the CO oxidation processin order to bring out the better CO-tolerant methanol oxidation activityover Ce1-x-y Ni x Sr y O2-& delta;. The study shows the unique importance ofthe electronic interactions between the active site and support andinvolvement of lattice oxygen in the methanol oxidation reaction.