This cluster-atom catalyst has extremely high atom efficiency and shows excellent stability and activity for CO oxidation. The result showed that the highest activity and stability of catalyst with wt.% loading of Pt are observed. These could be due to the partially vacant 5d orbitals of the positively charged, highvalent Pt atoms. | Journal of Science and Technology 54 (4B) (2016) 145-151 CO-OXIDATION REACTION ACTIVITY OF Pt CLUSTER CATALYSTS ON SUPPORT Trung Thanh Nguyen1, *, Bing Joe Hwang2 1 2 An Giang University, 18 Ung Van Khiem, Long Xuyen city, An Giang province, Vietnam National Taiwan University of Science and Technology, 34 Kee Lung road, Taipei, Taiwan * Email: ntthanh@ Received: 15 August 2016; Accepted for publication: 10 November 2016 ABSTRACT Platinum-based heterogeneous catalysts are critical to many important commercial chemical processes. However, their efficiency is extremely low on a per metal atom basis, because only the surface active-site atoms are used. Catalysts with clusters of atom dispersions are thus highly desirable to increase atom efficiency, but making them is challenging. Here we report the synthesis of a catalyst that consists of isolated clusters of Pt atoms anchored to the surfaces of Molybdenum-doped titanium oxide nanocrystallites. This cluster-atom catalyst has extremely high atom efficiency and shows excellent stability and activity for CO oxidation. The result showed that the highest activity and stability of catalyst with wt.% loading of Pt are observed. These could be due to the partially vacant 5d orbitals of the positively charged, highvalent Pt atoms. Keywords: cluster of Pt atoms, CO oxidation reaction, nanosupport. 1. INTRODUCTION Supported noble catalysts are the most widely used in industry due to they show high activity and/or selectivity in the large number of different and important chemical reactions [14]. Generally, the factors including size, shape, composition, oxidation state, geometry, chemical/physical environments can play an important role in determining nanocrystal reactivity [2]. Many experimental approaches for these nanocatalysts have focused on the fine dispersion of noble metals on a support with a high surface area for the efficient use of catalytically active component [1]. .