Solar Light Induced Photon-Assisted Synthesis of TiO2 Supported Highly Dispersed Ru Nanoparticle Catalysts

Joanna Wojciechowska (1) , Elisa Gitzhofer , Jacek Grams (2) , Agnieszka Ruppert (2) , Nicolas Keller (3)

1 ICPEES - Institut de chimie et procédés pour l'énergie, l'environnement et la santé
2 Łódź University of Technology
3 LMSPC - Laboratoire des Matériaux, Surfaces et Procédés pour la Catalyse

Ru/TiO2 are promising heterogeneous catalysts in different key-reactions taking place in the catalytic conversion of biomass towards fuel additives, biofuels or biochemicals. TiO2 supported highly dispersed nanometric-size metallic Ru catalysts were prepared at room temperature via a solar light induced photon-assisted one-step synthesis in liquid phase, far smaller Ru nanoparticles with sharper size distribution being synthesized when compared to the catalysts prepared by impregnation with thermal reduction in hydrogen. The underlying strategy is based on the redox photoactivity of the TiO2 semiconductor support under solar light for allowing the reduction of metal ions pre-adsorbed at the host surface by photogenerated electrons from the conduction band of the semiconductor in order to get a fine control in terms of size distribution and dispersion, with no need of chemical reductant, final thermal treatment or external hydrogen. Whether acetylacetonate or chloride was used as precursor, 0.6 nm sub-nanometric metallic Ru particles were synthesized on TiO2 with a sharp size distribution at a low loading of 0.5 wt.%. Using the chloride precursor was necessary for preparing Ru/TiO2 catalysts with a 0.8 nm sub-nanometric mean particle size at 5 wt.% loading, achieved in basic conditions for benefitting from the enhanced adsorption between the positively-charged chloro-complexes and the negatively-charged TiO2 surface. Remarkably, within the 0.5-5 wt.% range, the Ru content had only a slight influence on the sub-nanometric particle size distribution, thanks to the implementation of suitable photo-assisted synthesis conditions. We demonstrated further that a fine control of the metal Ru nanoparticle size on the TiO2 support was possible via a controlled nanocluster growth under irradiation, while the nanoparticles revealed a good resistance to thermal sintering.

Mots clés: Ru/TiO2 catalyst; catalyst preparation; sub-nanometric particle size distribution; highly dispersed Ru nanoparticle; reaction mechanism; photodeposition; photon-assisted synthesis

Domaines: Catalyse; Matériaux

Joanna Wojciechowska, Elisa Gitzhofer, Jacek Grams, Agnieszka Ruppert, Nicolas Keller. Solar Light Induced Photon-Assisted Synthesis of TiO2 Supported Highly Dispersed Ru Nanoparticle Catalysts. Materials, 2018, 11 (11), pp.2329. ⟨10.3390/ma11112329⟩. ⟨hal-02354985⟩