Photo-assisted deposition of noble metals : Investigation of a new route for metallic and bimetallic catalyst preparation

The photocatalytic deposition of noble metals on photosensitive supports is proposed to synthesize well dispersed metal catalysts in mild conditions of preparation. The effects of various parameters governing the kinetics of photodeposition (light flux, solution, concentration, temperature, nature of ions) have been studied. Noble metals, such as Pt, Pd, Ag, Rh, Au, Ir have been deposited on titania. Other photosensitive supports such as oXides (ZnO, Nb 2O5 ZrO2, ThO2, etc ⋯) or sulfides (CdS) have also been employed. Bimetalic, atalysts (Pt-Pd, Pd-Ag, Pt-Ir) on TiO2 have been prepared with a probable alloy formation according to STEM analysis. Although common insulating supports are theoretically unsuitable for photodeposition, a limited deposition of Pt was observed on alumina. A photodeposited 0.5 wt% Pt/TiO2 was used in two bifunctional photocatalytic reactions. It exhibited a higher activity than a well dispersed analogue obtained by impregnation and H? reduction, possibly because the support did not undergo a severe reduction treatment. © 1987 Elsevier Science Publishers B.V., Amsterdam - Printed in The Netherlands.