Applied Catalysis A: General, Vol.543, 61-66, 2017
Highly efficient single atom cobalt catalyst for selective oxidation of alcohols
Catalysts with atomically dispersed active sites are highly desirable to maximize atom efficiency. Herein, we reported atomically cobalt dispersed onto nitrogen-doped graphene (denoted as Co-NG) by heat-treating cobalt salts and graphene oxide in ammonia atmosphere. The Co-NG catalyst was characterized by various analysis techniques, such as XPS, XRD, Raman, TEM, SEM, HAADF-STEM and nitrogen adsorption. Characterization results showed that the surface 0 content decreased as the doping temperature increased, while the surface N content kept increasing up to 7.94 at% at the doping temperature of 750 degrees C. The coordination of N with Co should improve the catalytic behavior of Co-NG. The Co-NG catalyst has extremely high atom efficiency and shows high activity and excellent stability for the selective oxidation of various alcohols (e.g. benzyl alcohol, 4-chloro-benzyl alcohol, 4-methyl-benzyl alcohol, 4-methoxy-benzyl alcohol, 4-hydroxy-benzyl alcohol, phenethyl alcohol, 2-methyl heptanol, etc) by oxygen molecule. For example, 94.8% benzyl alcohol conversion and 97.5% benzaldehyde selectivity can be achieved over Co-NG after reaction for 5 h, and the catalyst yields an average TOF of over 500 h(-1).