Science and Technology Production
Structural and Physicochemical Properties of Carbon Nitride Nanoparticles via Precursor Thermal Treatment: Effect on Methyl Orange Photocatalytic Discoloration
Articulo
Authorship:
Gomez Velasquez, Laura ; Madriz, Lorean ; Rigolleto, Monica ; Laurenti, Enzo ; Bizarro, Montserrat ; DELL'ARCIPRETE, MARIA LAURA ; Gonzalez, Monica C.Date:
2023Publishing House and Editing Place:
ACSMagazine:
ACS Applied Nano Materials ACSSummary *
In this work, we synthesized and characterized carbon nitride nanoparticles (CN) obtained by thethermal treatment (550 oC) of urea, melamine, dicyandiamine and dicyandiamine-barbituric acid in an open reactor and evaluated the effect of the different precursors in the photocatalytic performance. Carbon nitrides obtained from melamine, dicyandiamine and dicyandiamine-barbituric acid were 3D melon-type structures. On the other hand, CN obtained from urea was a 2D microporous, amorphous structure whose melon or graphitic arrangement could not be determined. The presence of structural defective states (mainly C radicals) was corroborated by EPR studies of the solids.The photocatalytic activity of CN powders for methyl orange (MO) discoloration was investigatedusing 350 nm and simulated solar light (SSL) irradiation. MO removal efficiencies were correlated with the particle’s energy gap, specific surface area, degree of crystallinity, and C radical defects produced upon irradiation. Moreover, obtained conduction and valence band potentials in the range of -0.60 and +2.14 V vs. NHE (pH = 7), respectively, evidence CN capacity to oxidize water to hydroxyl radicals (HO) and reducing O2 to superoxide radical anions (O2-). The formation of both radicals upon SSL irradiation of CN suspensions was confirmed by EPR experiments. The largest specific surface area, the highest charge carrier density and amount of C radicals defects observed for CN obtained from urea (CNu), account for their highest photocatalytic performance. However, estimated CNu photonic efficiency of ca. 8% still indicates a deficient separation/migration efficiency of photoinduced charge carriers. Thus, despite CNu performance is higher than those of other CN obtained from the thermal treatment of simple precursors, further environmentally friendly strategies are still needed to overcome CN intrinsic disadvantage before it may be employed in technological applications. A discussion on probable CN mechanisms forming reactive species and leading to MO decolorization is given. Information provided by the agent in SIGEVAKey Words
visible lightamorphizationureadicyandiamidemelaminemelon