Carbon layer derived carrier transport in Co/g-C₃N₄ nanosheet junctions for efficient H₂O₂ production and NO removal

Co nanoparticles are embedded in N-doped carbon nanotubes (Co-N-carbon nanotubes) using combinations of mechano-chemical pre-treatment and thermal polymerization process (at 760 degrees C). A further thermal polymerization process done on these Co-N-carbon nanotubes and ultrathin graphitic carbon nitrate (g-C3N4) leads to the formation of Co nanoparticles (coated with carbon layers) embedded g-C3N4 nanosheets composite, along with the disappearance of carbon nanotube morphology on the material. The Co/g-C3N4 junctions are constructed with a Schottky barrier formed between the carbon layer coated Co nanoparticles and the g-C3N4 nanosheets. The presence of carbon layers in the composite system facilitates transport of photogenerated electrons at the Fermi level of Co, which results in enhanced photocatalytic H2O2 generation and NO oxidation performances of the composite material in visible light irradiation condition with excellent cyclic stability. The Schottky junction composites constructed using optimized preparation conditions in case of no co-catalyst incorporation shows a photocatalytic H2O2 generation efficiency of 3618 mu molL(-1)h(-1) which is about 1000 times of that of pristine g-C3N4 nanosheets. A NO removal rate of 62 % (higher than that of the commercial P25 (TiO2)) is also observed. These results provide possible approaches on constructing advanced photocatalysts for energy and environmental applications.