Temperature-programmed reduction study on carbon-supported platinum–gold alloy catalysts

Alloy catalysts of Pt–Au/C with different Pt/Au ratios were prepared by the precipitation–deposition of metal chlorides and reduced by H2 at 470 K. The surface composition of alloy crystallites deposited on the prepared catalysts was characterized by a technique of temperature-programmed reduction (TPR). In the characterization, O2 was chemisorbed on the reduced catalysts and the chemisorbed O2 was reduced by TPR. A low-temperature routine (LT) in the temperature range between 120 and 430 K was used for the TPR characterization. Monometallic catalysts of Au/C and Pt/C showed a reduction peak in the LT-TPR at reduction temperature (Tr)=145(Tr)=145 and 240 K, respectively. TrTr from alloyed catalysts fell in the range and increased monotonously with their Pt/Au ratios. Interior Pt atoms in deposited alloy particles tended to segregate toward their surface during oxidation treatment at elevated temperatures.

Peak temperatures in the temperature-programmed reduction of PtxAuy/C varied with the surface composition of the alloy catalysts. Interior Pt atoms tended to segregate toward their surface during oxidation at 570 K.Figure optionsDownload as PowerPoint slide