Structural and electronic effects in bimetallic PdPt nanoparticles on TiO2 for improved photocatalytic oxidation of CO in the presence of humidity

Abstract Bimetallic Pd x Pt 1− x /TiO 2 -P25 photocatalysts have been proven to maintain high activity for CO photocatalytic oxidation even under 50% relative humidity for 0.3  x 2 supported monometallic particles. The catalysts were characterized by XPS, TEM, HAADF-STEM, TPR, CO-TPD and FTIR-CO adsorption characterization. The results suggested a random distribution of Pd and Pt atoms within the bimetallic nanoparticles, and in particular at their surface. It was proposed that the synergy observed in bimetallic Pd x Pt 1− x /TiO 2 may be explained by their modified electronic structure, playing a key role in overcoming the negative effects of humidity on the photocatalytic CO conversion. The behavior of Pd x Pt 1− x /TiO 2 under humid air was assumed to result from a preferential oxygen and water adsorption on surface Pt sites, leaving Pd sites free for CO adsorption, Pd being more resistant to oxidation than Pt in Pt-rich PtPd particles.