Characterization of carbon deposited from carbon dioxide on oxygen-deficient magnetites

Abstract

Oxygen-deficient magnetite (ODM) powder has been reacted with CO₂ at 300 °C; black particles of carbon separated from the ODM were studied by Raman, energy-dispersive X-ray (EDX) and wave-dispersive X-ray (WDX) spectroscopies. The carbon was a mixture of graphite and amorphous carbon in at least two levels of crystallization. Temperature-programmed desorption–mass spectrometry (TPD-MS) showed that a large portion of the carbon deposited on the ODM was released as CO and CO₂ gas in a flow of Ar at ca. 520 °C, indicating that the carbon particles formed on the ODM are reactive. X-Ray photoelectron spectra of the carbon-deposited ODM showed no indication of carbide (Fe₃C) or α-Fe phase formation.