Abstract
Commercial TiO2 (P25) supported gold (Au/P25) attracts increasing attention. In this work, atmospheric-pressure (AP) cold plasma was employed to activate the Au/P25-As catalyst prepared by a modified impregnation method. The influence of cold plasma working gas (oxygen, argon, hydrogen, and air) on the structure and performance of the obtained Au/P25 catalysts was investigated. X-ray diffraction (XRD), UV-Vis diffuse reflectance spectroscopy (DRS), transmission electron microscopy (TEM), and X-ray spectroscopy (XPS) were adopted to characterize the Au/P25 catalysts. CO oxidation was used as model reaction probe to test the Au/P25 catalyst. XRD results reveal that supporting gold and AP cold plasma activation have little effect on the P25 support. CO oxidation activity over the Au/P25 catalysts follows the order: Au/P25-O2P > Au/P25-As > Au/P25-ArP ≈ Au/P25-H2P > Au/P25-AirP. Au/P25-AirP presents the poorest CO oxidation catalytic activity among the Au/P25 catalysts, which may be ascribed to the larger size of gold nanoparticles, low concentration of active [O]s, as well as the poisoning [NOx]s. The poor catalytic performance of Au/P25-ArP and Au/P25-H2P is ascribed to the lower concentration of [O]s species. 100% CO conversion temperatures for Au/P25-O2P is 40 °C, which is 30 °C lower than that over the as-prepared Au/P25-As catalyst. The excellent CO oxidation activity over Au/P25-O2P is mainly attributed to the efficient decomposition of gold precursor species, small size of gold nanoparticles, and the high concentration of [O]s species.
Highlights
Supported gold catalysts have attracted increasing research interest after the pioneering work of Haruta [1,2]
Au/P25-AirP presents the poorest carbon monoxide (CO) oxidation catalytic activity among the Au/P25 catalysts, which may be ascribed to the larger size of gold nanoparticles (DAu = 3.7 nm), low concentration of active [O]s, as well as the poisoning [NOx]s [24,25]
AP cold plasma was adopted to activate the Au/P25-As catalyst prepared by a modified impregnation method, and the influence of working gas on the structure and performance of the obtained Au/P25catalysts was investigated
Summary
Supported gold catalysts have attracted increasing research interest after the pioneering work of Haruta [1,2]. The fast and low-temperature preparation process, and the Coulomb interaction between the charged species and metal precursors ions in cold plasma are conductive to fabrication of metal nanoparticles of small sizes with high dispersion [12]. The non-thermal equilibrium property of cold plasma is beneficial to enhanced metal–support interaction, amorphous metal nanoparticles [15,16], as well as metal alloy with specific structure [17,18], and metal nanoparticles with specific crystal facet [14] Thanks to these properties, cold plasma has been successfully employed to prepare and activate gold catalysts, and it has been efficient to enhance the catalytic performance of the gold catalysts [19,20,21,22,23,24,25]. The influence of cold plasma working gas (oxygen, argon, hydrogen, and air) on the structure and performance of the obtained Au/P25catalysts was investigated, and the influence mechanism is discussed
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