Strong Metal–Support Interactions between Gold Nanoparticles and ZnO Nanorods in CO Oxidation

Abstract

The catalytic performances of supported gold nanoparticles depend critically on the nature of support. Here, we report the first evidence of strong metal-support interactions (SMSI) between gold nanoparticles and ZnO nanorods based on results of structural and spectroscopic characterization. The catalyst shows encapsulation of gold nanoparticles by ZnO and the electron transfer between gold and the support. Detailed characterizations of the interaction between Au nanoparticles and ZnO were done with transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), electron paramagnetic resonance (EPR), and FTIR study of adsorbed CO. The significance of the SMSI effect is further investigated by probing the efficiency of CO oxidation over the Au/ZnO-nanorod. In contrast to the classical reductive SMSI in the TiO(2) supported group VIII metals which appears after high temperature reduction in H(2) with electron transfer from the support to metals, the oxidative SMSI in Au/ZnO-nanorod system gives oxygen-induced burial and electron transfer from gold to support. In CO oxidation, we found that the oxidative SMSI state is associated with positively charged gold nanoparticles with strong effect on its catalytic activity before and after encapsulation. The oxidative SMSI can be reversed by hydrogen treatment to induce AuZn alloy formation, de-encapsulation, and electron transfer from support to Au. Our discovery of the SMSI effects in Au/ZnO nanorods gives new understandings of the interaction between gold and support and provides new way to control the interaction between gold and the support as well as catalytic activity.

Catalysis by gold: New insights into the support effect

“…• C under oxygen atmosphere, while the electrons fed back after the reduction was conducted at the same temperature [158]. This proved the electron transfer was reversible in the Au/ZnO-nanorod system.…”

“…• C), which proved that ZnO could become RMO under certain circumstances [158]. Here, gold is believed to promote the reduction of ZnO.…”

“…Recently, a breakthrough was made by Liu et al, who reported the direct evidence for SMSI between gold and ZnO nanorods for the first time. Not only the electron transfer between Au and ZnO but also the encapsulation of the GNPs by the ZnO was demonstrated [158].…”

Catalytic Properties of Cryogelated Noble Metal Aerogels

“…embedding them into metal organic frameworks, on metal oxides, on carbon supports or infiltrating them in aerogels [2,[8][9][10]. However, the interactions of NCs with the support can dramatically affect their properties [11,12]. If, on the one hand, this interaction largely determine the catalytic activity, on the other hand, it prevents the exploitation of the catalytic function of the bare metallic NCs, which could exhibit peculiar features.…”

Sputtered nano-cobalt on H-USY zeolite for selectively converting syngas to gasoline

“…In addition, the impregnation method is widely employed to synthesize zeolite supported FTS catalysts. However, the strong metal-support interactions (MSI) between FTS catalysts and support severely hindered the reduction of FTS catalysts, leading to suppression of H 2 and CO chemisorptions after reduction at high temperatures [9,10]. Moreover, sintering of active FTS sites is reinforced, accompanied with the treatment of high temperature.…”