Kinetic control of CeO 2 nanoparticles for catalytic CO oxidation
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FOCUS ISSUE
INTRINSIC AND EXTRINSIC SIZE EFFECTS IN MATERIALS
Kinetic control of CeO2 nanoparticles for catalytic CO oxidation Bingqi Han1, Huixia Li1, Liping Li1
, Yan Wang1, Yuelan Zhang1, Guangshe Li1,a)
1
State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun 130012, People’s Republic of China a) Address all correspondence to this author. e-mail: [email protected] Received: 13 October 2018; accepted: 13 November 2018
This article reports on the growth kinetics of cerium oxide (CeO2) nanoparticles prepared via a sintering method. By varying the sintering temperatures and periods of time, particle size of CeO2 nanoparticles was tuned from 11 to 100 nm. Ostwald ripening mechanism prevails in the growth process, and the growth kinetics is determined to follow an equation, D5 5 16.25 1 3.6 1020 exp(344.20/RT) in the temperature range of 700 to 1000°C. After dispersing Pt on CeO2 nanoparticles, the size effect for the catalytic performance of the CO oxidation reaction was researched. When temperature and period of time are set at 700 °C and 2 h, respectively, dispersion of Pt onto CeO2 nanoparticles led to the largest quantity of chemisorbed oxygen species on the surface and the best catalytic performance. The findings reported here would provide a feasible path for the preparation of advanced catalysts in the future and moreover to discover novel size-dependent supports for many catalytic applications.
Introduction Nanomaterials have been widely investigated because of their special physical and chemical properties. One has witnessed many breakthroughs and discoveries when nanoparticles are applied as advanced catalysts [1, 2, 3, 4]. When material’s scale is reduced to the nanometer dimension, changes are expected in the electronic structures, which allows one to well tune physical and chemical properties. Usually, such properties, including adsorption and redox ability, are closely related to the catalytic performance. Therefore, there is an intimate connection between the catalytic performance and the particle size for the given nanoparticles. To make clear this relationship, a series of nanoparticles with the precisely controlled sizes should be prepared, because growth kinetics is necessary for particle size adjustment [5, 6, 7, 8]. With help of grain growth kinetics, one is able to set up a function relationship between the condition parameters over growth process and the obtained grain size of nanoparticles, and also to predict the other size-dependent properties, such as catalytic activities could be further studied. Here, cerium oxide (CeO2) nanoparticles were selected as a target for grain growth kinetic studies because of the following considerations: (i) CeO2 has been frequently studied as a catalytic material due to its excellent physical and chemical
ª Materials Research Society 2019
properties. Cerium ions can be stably maintained in trivalent or tetravalent state, and CeO2 has the ability to undergo electron transfer throug
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