Effects of Preparation Methods and Electronic States of the AuPd Bimetallic Nanoparticles on the Activity for Aerobic Oxidation of Alcohols

S. Nishimura, Y. Yakita, M. Katayama, K. Higashimine, K. Ebitani
Japan Advanced Institute of Science and Technology, JP

Keywords: bimetallic nanocatalyst, alcohol oxidation, electronic negativity, preparation method


Bimetallic nanoparticles (NPs) have attracted great interests and potentials in advanced nancatalysts because they achieved unique catalytic performances different from those of monometallic NPs. However, the contributions of their morphologies and/or electronic states to the catalytic performance over the bimetallic NPs catalyst is unclear still today. Herein, we synthesized the AuxPdy bimelattic NPs with different preparation methods, and compared their catalytic activities for aerobic oxidation to reveal the role of physical/chemical properties of AuxPdy NPs. The PVP-protected bimetallic gold/palladium NPs deposited onto the solid base hydrotalcite (AuPd-PVP/HT), AuxPdy ally NPs/HT, Pdy@Aux core-shell NPs/HT, and (mixture of Aux and Pdy) NPs/HT, were applied for alcohol oxidation. The Au60Pd40 alloy NPs/HT catalyst prepared with a simultaneous reduction method exhibited the highest activity among them. To further investigate the AuxPdy alloy NPs/HT, correlations between electron transfer and catalytic activities were investigated in the AuxPdy alloy NPs/HT catalysts with XPS and XANES analysis. We found that the electronic negativity in the Au 5d states controlled by the Pd contents accelerated the alcohol oxidation because the formation of highly active peroxio species was enhanced on the negatively-charged Au atoms. Enhancement of electron donation to Au atoms plays a key factor for the oxidation nanocatalyst.