Assessment of Reaction Parameters in the Polymeric Carbon Nitride Thermal Synthesis and the Influence in Photocatalytic Hydrogen Production

In this work, the reaction parameters for polymeric carbon nitride synthesis by thermal polycondensation were assessed, such as type of precursor, heating rate and time of thermal treatment, in order to obtain crystalline materials with high photocatalytic performance. All synthesized materials were tested as photocatalysts in hydrogen production using ethylenediaminetetraacetic acid (EDTA) as a sacrificial reactant under visible light irradiation (λ ≥ 420 nm). The synthesis condition capable to obtain the material that reached the best performance in photocatalytic hydrogen production was using thiourea as the precursor, due to the band gap narrowing and charge recombination suppression; an intermediate heating rate (5 ºC min-1) and a longer thermal treatment time (6 h) that yielded a better crystalline solid. The combination of these effects led the S-doped polymeric carbon nitride (SPCN4 sample) to a higher photocatalytic activity, reaching the maximum hydrogen production rate of 214.75 µmol g-1 h-1.