Bimetallic PdAu Nanoparticles Supported on TiO₂ for the Selective Catalytic Reduction of NO_x in the Presence of Oxygen

A bimetallic PdAu/TiO 2 nanocatalyst has been fabricated by the hydrothermal method, and its catalytic performance for the selective catalytic reduction of NO x with H 2 (H 2 –SCR) has been investigated. PdAu/TiO 2 catalyst exhibited remarkably higher activity and N 2 selectivity than the Pd/TiO 2 catalyst, and the synthesis temperature significantly affects the H 2 –SCR activity of PdAu/TiO 2 by affecting the nanoparticle size of PdAu. The most active catalyst is PdAu/TiO 2 -160, obtained at a hydrothermal temperature of 160 °C, with a particle size of 1.35 nm. The introduction of Au led to the formation of metallic Pd and PdAu alloy, both of which play key roles for the enhanced catalytic performance. In situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS) reveals that more reactive NO x species and NH 3 intermediates are generated over bimetallic PdAu/TiO 2 than over a single Pd/TiO 2 catalyst. The inhibition of CO can be ascribed to the decreased NO x adsorption and the reduced activity of adsorbed NO x and NH 3 species. This investigation would provide guidelines for the rational design of a highly active H 2 –SCR nanocatalyst for the removal of NO x .