Article published on: CARBON
Urea performs better than melamine for H2 production.
The best calcination atmosphere depends on the precursor used.
The gCNs prepared with urea as precursor in a CO2 atmosphere show the highest HER.
A relationship between the HER and the band gap of the photocatalyst was established.
The influence of precursor and gas atmosphere during graphitic carbon nitride (gCN) preparation on its performance in a photocatalytic water splitting process was studied. Urea and melamine were heated up to 600 °C for 2 h in N2, CO2, air, and static air. The crystalline structure, porosity, chemical composition, and light absorption of the gCNs synthesized were investigated in depth. In addition, their capacity for H2 production was studied in a quartz top Pyrex reactor connected on-line to a Micro-GC. The best results were obtained with urea heated in a CO2 atmosphere. The results were discussed, considering the band gap and the existence of amino groups in the photocatalysts. In addition, the importance of the presence of s-triazine units was emphasized.