Vietnam Journal of Science and Technology 57 (3A) (2019) 54-60 doi:10.15625/2525-2518/57/3A/14074 HYDROGEN-PLASMA-TREATED NANO TiO 2 FOR PHOTOCATALYTIC OXIDATION OF VOCS IN AIR STREAM Le Nguyen Quang Tu 1 , Nguyen Van Dung 1 , Pham Trung Kien 2 , Ca Quoc Vuong 3 , Nguyen Quoc Thiet 3 , Cu Thanh Son 3 , Nguyen Quang Long 1, * 1 Faculty of Chemical Engineering, Ho Chi Minh City University of Technology – VNU- HCM 268 Ly Thuong Kiet, District 10, Ho Chi Minh City 2 Faculty of Materials Technology, Ho Chi Minh City University of Technology – VNU- HCM 268 Ly Thuong Kiet, District 10, Ho Chi Minh City 3 Institute of Applied Materials Science- Vietnam Academy of Science and Technology. 1A Thanh Loc 29, Thanh Loc, District 12, Ho Chi Minh City * Email: nqlong@hcmut.edu.vn Received: 31 July 2019; Accepted for publication: September 2019 Abstract. Unlike water treatment processes, the photocatalytic oxidation of VOCs in air stream exhibits many challenges. This study will develop the hydrogen-plasma-treated TiO 2 with improvement in photocatalytic activity. The hydrogen-plasma-treatment was carried out in the non-thermal atmospheric pressure reactor at room temperature. The catalysts were characterized by advanced techniques such as X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR) and N 2 adsorption at low temperature (77 K) for surface area analysis. The photocatalytic activity of the catalyst has been investigated under UV light with various relative humidity. Significantly, the conversion of toluene by a plasma-treated sample was 1.5 times higher than the non-treated TiO 2 in similar reaction condition. Keywords: plasma, TiO 2 , VOCs removal, hydrogen treatment, photocatalysis. Classification numbers: 2.4.2, 2.6.1, 3.4.5. 1. INTRODUCTION Volatile organic compounds (VOCs) are the potential pollutants due to their hazardous properties for environment and human. There are two major directions in treating VOCs: decomposition technology and recovery technology [1]. The photo-catalytic oxidation processes (PCO) have recently been proven to be a promising technology for VOCs removal and the reaction mechanism of photocatalytic removal of toluene, a typical VOC compound, using the common TiO 2 photocatalyst has been proposed [2-4]. The reaction of the photo-generated holes (h+) and the OH-(surface) or the adsorbed H 2 O produces hydroxyl radicals (OH), which are highly chemical active species for the toluene decomposition. Hence, the high water adsorption capacity of the photocatalysts should be desired to stably decompose the organic pollutants.