Synthesis of cobalt–nitrogen-doped mesoporous carbon from chitosan and its performance for pollutant degradation as Fenton-like catalysts

Abstract

Supported cobalt oxides on mesoporous nitrogen-doped carbon (Co_xO_y/NC) were prepared by a simple pyrolysis method using cobalt acetate as the cobalt source and chitosan as the nitrogen and carbon source. The as-synthesized catalysts were characterized by XRD, N₂ adsorption/desorption, SEM, TEM and XPS. It was found that chitosan was transformed to mesoporous carbon after pyrolysis at 900 °C under N₂ atmosphere, while Co²⁺ was reduced to metallic Co covering with cobalt oxide, which was uniformly distributed in the surface of carbon. The catalytic performances were examined by Acid Orange 7 (AO7) degradation with H₂O₂ as an oxidant in bicarbonate aqueous solution. The dye was decolorized completely after 20 min at room temperature with the Co_xO_y/NC catalyst. The catalyst can be recycled up to four times without significant loss of activity. The addition of methanol as a hydroxyl radical scavenger confirmed that the radicals take part in the reaction as the major active species. In addition, intermediate products were identified by electrospray ionization-mass spectrometry during the degradation of AO7.