We report here the significant enhancement of catalytic activity of Ag-Pd bimetallic nanocatalysts with the formation of Ag-Pd catalysts having an average diameter of 4.2 ± 1.5 nm on TiO2 nanoparticles using a two-step microwave (MW)-polyol method. Data obtained using XRD and STEM-EDS indicated that Ag-Pd bimetallic nanocatalysts consisted of Ag82Pd18 alloy core and about 0.5 nm thick Pd shell, denoted as AgPd@Pd. The hydrogen production rate of AgPd@Pd/TiO2 from formic acid, 16.00 ± 0.89 L g-1 h-1, was 23 times higher than that of bare AgPd@Pd prepared under MW heating at 27 °C. It was even higher by 2-4 times than the best Ag@Pd and CoAuPd catalysts at 20-35 °C reported thus far. The apparent activation energy of the formic acid decomposition reaction using AgPd@Pd catalyst decreased from 22.8 to 7.2 kJ mol-1 in the presence of TiO2. Based on negative chemical shifts of the Pd peaks in the XPS data and the measured activation energies, the enhancement of catalytic activity in the presence of TiO2 was explained by the lowered energy barrier in the reaction pathways because of the strong electron-donating effects of TiO2 to Pd shells, which enhance the adsorption of formate to the catalyst and dehydrogenation from formate.
All Science Journal Classification (ASJC) codes
- Renewable Energy, Sustainability and the Environment
- Materials Science(all)