Size-modulated photo-thermal catalytic CO2 hydrogenation performances over Pd nanoparticles.

Monodispersed Pd nanoparticles ranging from 2.8 to 8.0 nm with narrow size distribution are prepared and supported on TiO 2 for photo-thermal catalytic RWGS reaction. The catalytic activity presents volcano-type dependence over Pd sizes with 6.3 Pd/TiO 2 exhibiting the highest activity. [Display omitted] • A library of monodispersed Pd nanoparticles with successively increased sizes from 2.8, 3.4, 4.7, 5.3, 6.3 and 8.1 nm were prepared. • The photo-thermal catalytic activity towards RWGS reaction presents volcano-type dependence over Pd sizes with 6.3 Pd/TiO 2 giving the highest activity. • The size-modulated activity can be attributed to the tunable surface electronic properties including metal-support interaction and quantum size effect. Size of metal nanoparticles significantly influences their catalytic behaviors. However, it is still challenging to obtain monodispersed metal nanoparticles with successively tuned sizes to unveil their size-dependent catalytic performances, especially for photo-thermal catalytic reverse water–gas shift (RWGS) reaction. Herein, a library of Pd nanoparticles of 2.8, 3.4, 4.7, 5.3, 6.3 and 8.1 nm were synthesized and supported on TiO 2 for photo-thermal catalytic RWGS reaction. The catalytic activity presented volcano-like dependence on sizes of Pd nanoparticles with 6.3 Pd/TiO 2 exhibiting the highest catalytic efficiency. Based on the results of X-ray photoelectron spectroscopic analysis, photo-to-thermal conversion efficiency evaluation and density functional theory (DFT) calculations following the formate (*HCOO) pathway revealed by in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS) measurements, the volcano-type tendency in catalytic activity could be attributed to the superposition of size-governed surface electronic properties over Pd nanoparticles. [ABSTRACT FROM AUTHOR]