Photodeposition of Pd nanoparticles on TiO2 using sacrificial organic alcohols

Samples of deposited Pd on titania were prepared through photoreduction method in the absence and presence of different organic alcohols with different carbon numbers and molar weights as sacrificial electron donors (SED). It was observed that palladium nanoparticles were photoreduced and deposited with the rates of 0.55, 0.54, 0.44, and 0.38 mu mol/g/min on titania in the presence of methanol, ethanol, ethylene glycol, and 1-propanol, respectively. However, the deposition rate was 0.22 mu mol/g/min in the absence of any SED, indicating the significant enhancement of reduction rate in the presence of the alcohols. The results proved that the alcohols with lower carbon numbers and molar weights resulted in a higher reduction rate of Pd on TiO2. The highest rate of Pd photoreduction (0.55 mu mol/g/min) was obtained by using methanol, in which the highest dispersion percentage of metal palladium particles (22.32%) with the highest depositing amount (2.8 wt%) was measured. In addition to the FT-IR spectra of the surface palladium carbonyls, atomic absorbance spectroscopy and pulse CO chemisorption evaluations showed that employing a higher reduction rate is a key factor in obtaining a high palladium loading on TiO2. XRD patterns showed that all the Pd particles were deposited in metallic form. According to the EDS analysis, ethylene glycol was the most appropriate SED in complete removal of Cl.