CuGaO2 delafossite as a high-surface area model catalyst for Cu+-activated reactions

Abstract

Copper is one of the goldilocks metals in catalysis. Deciphering the local atomic environment and oxidation state of active centers in supported copper catalysts, as well as the design of materials to control their stability under reaction conditions remains a great challenge today. We show here that a mixed-oxide of copper delafossite with gallium (CuGaO2, Cu1+ and Ga3+) in the form of porous nanoplates, mainly exposing (110) facets with Cu1+ and Ga3+ cations in well-defined surface positions is a promising material as a model catalyst to explore the activity and stability of Cu1+-activated reactions. It is shown that the delafossite structure is preserved after calcination or reduction pretreatments (in pure O2 or H2, respectively). Extensive reduction of the mixed-oxide leads to a stable catalyst with higher activity for CO oxidation, as a result of the formation of geminal dicarbonyl species on Cuδ+, with 0 < δ < 1, under reaction conditions.