Optical detection of carbon dioxide adsorption on epitaxial CuFe1-xGaxO2 Delafossite film grown by pulse laser deposition

摘要

A highly epitaxial delafossite CuFe1-xGaxO2 film was made with pulse laser deposition in high vacuum. The sample thickness was around 48 nm and it was terminated with CuFeO2. This delafossite sample was exposed to a CO2 atmosphere under controlled conditions and chemisorption of CO2 on the surface was observed. Transmittance and reflectance spectroscopies were recorded for the sample post surface heat treatment held in a vacuum chamber (0.05 Kpa) and after exposure to CO2. Both spectra were recorded over a wavelength range of 350-1100 nm. Chemisorption of CO2 was correlated with an increase in transmittance and decrease in reflectance in the pressure range 0-60 kPa. These observations were confirmed with X-ray photoelectron spectroscopy and thermal programmed desorption data obtained in an independent experiment. The CO2 is bound to the surface forming a carboxylate structure via coordination of a bent CO2-delta molecule to a Cu center. (C) 2015 Elsevier B.V. All rights reserved.