A comparative study of H2O2 production over g-C3N4 photocatalysts made from different sources

The photocatalytic performance of graphitic carbon nitride (g-C3N4) in H2O2 production has been constantly studied, however, whether g-C3N4 made from different raw materials possess distinct photocatalytic ability is not fully explored. In this work, a comparative study of g-C3N4 made from urea, melamine, thiourea, and dicyandiamide respectively under the same thermal process condition was carried out to distinguish their photocatalytic activities. By determining the yield of H2O2 produced under the same light conditions, the ability of the above four g-C3N4 photocatalysts was compared and the amount of H2O2 produced within 5 h was 55.8, 112.7, 101, and 134 mu mol/L respectively. Photoelectrochemical and electrochemical impedance spectroscopy measurements indicated that g-C3N4 photocatalysts made from melamine and dicyandiamide with higher H2O2 production had higher photocurrent and lower charge transfer impedance. This might relate to the differences in material crystallinity and the band gap, which influenced their effective carrier concentration.