Ag-Pd Alloy Nanoparticle Photocatalysts: Reductive Coupling of Nitrobenzene with Visible Light
The Ag-Pd alloy nanoparticles (NPs) strongly absorb visible light and exhibit significantly higher photocatalytic activity compared to both pure Pd or Ag nanoparticles. Ag-Pd alloy NPs on photocatalytically inert support, ZrO2 and Al2O3 supports are developed for catalyze the nitoaromatic coupling to the corresponding azo compounds under visible light irradiation. Ag-Pd/ZrO2 exhibited the highest photocatalytic activity for nitrobenzene coupling to azobenzene (yield of ~80 % in 3 hours). The photocatalytic efficiency could be optimized by altering the Ag:Pd ratio of the alloy NPs, irradiation light intensity, temperature and wavelength. The rate of the reaction depends on the population and energy of the excited electrons, which can be improved by increasing the light intensity or by using a shorter wavelength. The knowledge developed in this study may inspire further studies of Ag based alloy photocatalysts for organic syntheses driven by visible light irradiation.