PREPARATION OF SENSORS BASED ON Fe OXIDE DOPED WITH Pt FOR DETECTION OF METHANE

Abstract

Some sensors based on pure α-Fe2O3 (hematite) and doped with %Pt-loadings (respect
to oxide) of 0,1; 0,2 y 0,3% have been prepared by precipitation method for detection of
methane, sodium carbonate as precipitating agent and polyethylene glycol (PEG) as antiagglomeration
agent. The samples were characterized by X-ray diffraction (XRD), sorption
of N2 (BET method) and transmission electron microscopy (TEM). The XRD patterns showed
that the crystalline structure of starting iron oxide has not been affected by the introduction of
Pt as doping material. All the sensors depicted micro-mesoporous isotherms corresponding
to type IV. TEM micrographs showed the average particle size of samples, ranging from 50
to 150 nm. Sensor tests were performed in a range of concentrations from 300 to 900 ppm
and operation temperatures between 150 and 400 ºC. The sensor with 0,3% of Pt and 0,3%
of PEG (20000) presented the highest gas response at 300ºC with an initial concentration of
900 ppm of methane probably due to the well-defined hematite crystalline structure, good
dispersion of nanoparticles and the best contact surface over Pt surface.