Thermal Activation of Semiconductive NiO1+x ($0<x<1$) for Use in Complete Removal of Volatile Organic Compounds

概要

論文の詳細を見る
We previously performed the complete removal of volatile organic compounds (VOCs) using thermally excited holes in TiO2 at high temperatures of about 350–500 °C. In this study, we intend to replace TiO2 with greenish NiO1+x ($0<x<1$) to lower operation temperature and elucidate the operation mechanism on the basis of the optical and electrical properties of NiO1+x. The decomposition of toluene (i.e., a representative VOC) starts at 250 °C and is completed at about 300 °C in pure powder. Furthermore, even honeycomb units coated with powdered NiO1+x exhibit a performance almost equivalent to that of a powdered system. The present performance of NiO1+x is found to exceed that of the previously investigated TiO2, although the specific surface of NiO1+x (1 m2/g) is two orders of magnitude smaller than that of TiO2 (298 m2/g). In parallel, a plausible band scheme for NiO1+x (which is consistent with toluene decomposition) has been proposed on the basis of the presence of Ni vacancies and the temperature dependences of electrical conductivity and Seebeck potential.
2009-09-25