Engineering the Metal/Oxide Interface of Pd Nanowire@CuOx Electrocatalysts for Efficient Alcohol Oxidation Reaction

Abstract

The development of new type electrocatalysts with promising activity and antipoisoning ability is of great importance for electrocatalysis on alcohol oxidation. In this work, Pd nanowire (PdNW)/CuO_x heterogeneous catalysts with different types of PdOCu interfaces (Pd/amorphous or crystalline CuO_x ) are prepared via a two-step hydrothermal strategy followed by an air plasma treatment. Their interface-dependent performance on methanol and ethanol oxidation reaction (MOR and EOR) is clearly observed. The as-prepared PdNW/crystalline CuO_x catalyst with 17.2 at% of Cu on the PdNW surface exhibits better MOR and EOR activity and stability, compared with that of PdNW/amorphous CuO_x and pristine PdNW catalysts. Significantly, both the cycling tests and the chronoamperometric measurements reveal that the PdNW/crystalline CuO_x catalyst yields excellent tolerance toward the possible intermediates including formaldehyde, formic acid, potassium carbonate, and carbon monoxide generated during the MOR process. The detailed analysis of their chemical state reveals that the enhanced activity and antipoison ability of the PdNW/crystalline CuO_x catalyst originates from the electron-deficient Pd^δ+ active sites which gradually turn into Pd₅ O₄ species during the MOR catalysis. The Pd₅ O₄ species can likely be stabilized by moderate crystalline CuO_x decorated on the surface of PdNW due to the strong PdOCu interaction.

Keywords: PdCu; direct alcohol fuel cells; ethanol oxidation; heterogeneous nanostructures; methanol oxidation.