Oxygen dependence of NO adsorption on Hollandite-type K_xGa_xSn_(8-x)O_(16) thin film

摘要

Thin films of hollandite-type K_(1.9)Ga_(1.9)Sn_(6.1)O_(16) (KGSO) were prepared by a spin-coating method. The films were colorless and transparent, 100-150 nm thick, and consisted of KGSO fine particles of about 20 nm in average size. The adsorption behavior of NO on the KGSO surface was examined by diffuse reflectance infrared fourier transform (DRIFTS). The KGSO was preheated at 968 K in a gas mixture of N_2 and O_2 prior to NO adsorption. As the oxygen ratio in the gas mixture increased up to 40%, absorption bands emerged and became stronger around 1400 cm~(-1). Those bands were assigned to NO_2 species in cheating and nitrite form. It was found that the coexistence of oxygen remarkably improves the adsorption ability of NO on KGSO surface.