Impact of carbon dot synthesis temperature on H2 production of photocatalytic CN systems

Carbon Quantum Dots (CQDs) also known as Carbon Dots (CDs) have emerged as a novel class of carbon-based nanomaterial due to their facile and cost-effective synthesis, good optoelectronic characteristics and potential use in different fields. However, their emission mechanism and the relationship between structure and property are still unclear. In this work, four types of CDs were successfully synthesised by a hydrothermal method, using citric acid and ethylenediamine (EDA) as precursors. The structural, compositional, and optical properties were examined in relation to the effects of raising the synthesis temperature from 130 to 260 °C. This analysis shows that the CDs exhibit a smaller diameter as the synthesis temperature increases and better incorporation of nitrogenated functionalities, as well as a decreased oxygen content due to higher carbonisation and dehydration processes, resulting in lowering the quantum yield. Finally, these carbon dots were used as dopants in polymeric carbon nitride systems (CN), to enhance photocatalytic activity in water splitting reactions.