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CO Oxidation of Catalytic Filters Consisting of Ni Nanoparticles on Carbon Fiber
Seo, Hyun-Ook,Nam, Jong-Won,Kim, Kwang-Dae,Kim, Young-Dok,Lim, Dong-Chan Korean Chemical Society 2012 Bulletin of the Korean Chemical Society Vol.33 No.4
Catalytic filters consisting of Ni nanoparticle and carbon fiber with different oxidation states of Ni (either metallic or oxidic) were prepared using a chemical vapor deposition process and various post-annealing steps. CO oxidation reactivity of each sample was evaluated using a batch type quartz reactor with a gas mixture of CO (500 mtorr) and $O_2$ (3 torr) at $300^{\circ}C$. Metallic and oxidic Ni showed almost the same CO oxidation reactivity. Moreover, the CO oxidation reactivity of metallic sample remained unchanged in the subsequently performed second reaction experiment. We suggested that metallic Ni transformed into oxidic state at the initial stage of the exposure to the reactant gas mixture, and Ni-oxide was catalytically active species. In addition, we found that CO oxidation reactivity of Ni-oxide surface was enhanced by increase in the $H_2O$ impurity in the reactor.
Seo, Hyun Ook,Woo, Tae Gyun,Park, Eun Ji,Cha, Byeong Jun,Kim, Il Hee,Han, Sang Wook,Kim, Young Dok Elsevier 2017 APPLIED SURFACE SCIENCE - Vol.420 No.-
<P><B>Abstract</B></P> <P>We have studied the photo-catalytic degradation of acetaldehyde over the surface of TiO<SUB>2</SUB> films under UV light (365nm) irradiation both at dry and humid air conditions using a high vacuum chamber equipped with on-line gas-chromatography as a batch-type reactor. Changes of TiO<SUB>2</SUB> surfaces upon the photo-catalysis experiments were studied by X-ray photoelectron spectroscopy. The competitive adsorption of water and acetaldehyde resulted in the reduction of reaction rate of photo-catalytic degradation of acetaldehyde under the UV light irradiation. The photo-catalytic reaction rate of TiO<SUB>2</SUB> films towards acetaldehyde mineralization increased when the photo-catalysis experiments were performed repeatedly and it was much more pronounced under humid conditions. Our XPS analysis revealed that carbon impurities on the surface of TiO<SUB>2</SUB> films were removed by UV-light driven photo-catalytic mineralization under humid conditions. Water vapor facilitated the photo-catalytic removal of carbon impurities from TiO<SUB>2</SUB> surface generating additional active sites of TiO<SUB>2</SUB> which resulted in the enhanced photo-catalytic activity of TiO<SUB>2</SUB> films.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Changes of TiO<SUB>2</SUB> surfaces during photo-catalysis were studied by XPS. </LI> <LI> Role of humidity for photo-catalytic decomposition of acetaldehyde was studied. </LI> <LI> Competitive adsorption of water and acetaldehyde resulted in the reduction of reaction rate. </LI> <LI> Water vapor facilitated the photo-catalytic removal of carbon impurities from TiO<SUB>2</SUB>. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>