Compositi di nano-particelle di Carbonio/TiO2 come fotocatalizzatori per luce visibile, per la degradazione di inquinanti

Abstract: Visible light driven photocatalytic approach is an attractive, clean way for various applications, such as pollutant degradation, hydrogen generation, water splitting and etc. In this work, firstly, six kinds of different carbon nanoparticles (CNPs) based on dibasic Ammonium Citrate via thermal decomposition and hydrothermal method were synthesized and characterized. In some cases, to increase nitrogen to carbon ratio Urea was also employed. In the next step, the CNPs@TiO2 composites have been prepared combining a commercial TiO2 (PC500, Tronox, pure anatase) with the six different carbon nanoparticles throughout a simple hydrothermal method. The obtained composites were successfully characterized by powder X-ray diffraction (XRD), RAMAN, attenuated total reflection (ATR), UV-visible, photoluminescence spectroscopy and electron paramagnetic resonance (EPR) in the both solid and solution state. A preliminary screening to identify the most promising photocatalytic composite was carried out via the Phenol degradation under the irradiation of visible light (470nm) and UV light (365nm). The experimental results showed that bare TiO2 and CNPs were not able to degrade the Phenol solution under the irradiation of visible light individually, while the CNPs@TiO2 composites significantly enhanced the photocatalytic activity. For the most promising composite, different CNPs loading was also tested and it was found that 5%w/w exhibited superior photocatalytic activity against photodegradation of Phenol (57%) rather than the other photocatalysts under the irradiation with visible light. By means of the EPR characterization, it was proven that the CNPs are able to generate singlet oxygen (1O2) under the visible light, while in the case of the composites, CNPs act as sensitizer to the visible light where by electron transferring throughout the junction, the production of Superoxide species (O2.-) was detected. The joint of these evidences could explain the observed visible light activity of the CNPs@TiO2.