Hydrogen-controlled structural reconstruction of palladium-bismuth oxide cluster to single atom alloy for low-temperature CO oxidation
Bing Nan, Lulu Li, Lulu Li, Yunan Li, Lingling Guo, Meng Du, Zhengwu Liu, Xin Tao, Chen Tian, Zhenye Liang, Yanxing Zhang, Chao Ma, Luming Shen, Rui Si, Lina Li, Lina Li
Abstract
Palladium (Pd) has been widely regarded as a high-performance catalyst for various oxidative reactions, however, the actual structure of active site remains controversial due to structural evolution under operation conditions. Herein, we prepared a series of bismuth (Bi)-doped silica-supported Pd catalysts and found a hydrogen-controlled structural reconstruction mechanism of palladium-bismuth oxide cluster to single atom alloy to efficiently catalyze low-temperature CO oxidation . The formation of Pd x Bi y O z clusters with unique Pd−O−Bi coordination structure could enhance the sinter-resistance ability of Pd species. This structural evolution of active site is clearly uncovered by in-situ XAFS results, in which metallic Bi−Pd shell gradually generates as the increase of reduction temperature without any metallic Bi−Bi bond. More importantly, PdBi 1 single atom alloy exhibits a good CO oxidation activity with a CO 2 production rate of 413 μmol CO2 ·g Pd −1 ·s −1 at 100 °C and excellent catalytic stability. Density function calculation (DFT) results indicate that there are geometric and electronic effects between Bi and Pd atoms, which favor total linear-CO adsorption, activate CO and O 2 molecules, and reduce the barrier for the formation of OO-CO intermediates in PdBi 1 single atom alloy.