Structural and Physicochemical Properties of Carbon Nitride Nanoparticles via Precursor Thermal Treatment: Effect on Methyl Orange Photocatalytic Discoloration

Abstract

In this work, we synthesized and characterized carbon nitride (CN) nanoparticles obtained by the thermal treatment (550 °C) of urea, melamine, dicyandiamine, and dicyandiamine-barbituric acid in an open reactor and evaluated the effect of different precursors on the photocatalytic performance. CNs 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 investigated using 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, the 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 reduce 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 the amount of C radical defects observed for CN obtained from urea (CNu) account for their highest photocatalytic performance. However, the estimated CNu photonic efficiency of ca. 8% still indicates a deficient separation/migration efficiency of photoinduced charge carriers. Despite CNu performance being higher than those of other CNs obtained from the thermal treatment of simple precursors, further environmentally friendly strategies are still needed to overcome the intrinsic disadvantages of CN before it may be employed in technological applications. A discussion on probable CN mechanisms forming reactive species and leading to MO decolorization is given.

Untangling the Effect of Carbonaceous Materials on the Photoelectrochemical Performance of BaTaO2N

“…Consequently, the photocatalytic behavior of g-C 3 N 4 significantly influences and augments the overall photoelectrochemical response in the BT-CN composite, further enhancing its performance. Furthermore, it has been reported that in both darkness and light, , g-C 3 N 4 can promote the oxygen reduction reaction (ORR), and the arguments to be presented later on ORR remain consistent for the BT-CN.…”

“…Gomis-Berenguer et al , observed a varying trend in the photoelectrochemical response of WO 3 /nanoporous carbon-based photoanodes for photocatalytic water oxidation with different weight ratios of nanoporous carbon, and 20 wt % was found to be the most favorable content of nanoporous carbon. It is noteworthy to mention that the enhanced PEC performance of BT-CN, beyond the intrinsic properties of carbonaceous material, is anticipated not solely due to its typical characteristics but also because of the synergistic photoelectrochemical response arising from the inherent photocatalytic processes exhibited by g-C 3 N 4 . ,, Also, the photoactive nature of g-C 3 N 4 contributes to the observed improvements, creating a distinctive charge accumulation region within the BT-CN composite . Consequently, the photocatalytic behavior of g-C 3 N 4 significantly influences and augments the overall photoelectrochemical response in the BT-CN composite, further enhancing its performance.…”

Unlocking the effect of Zn2+ on crystal structure, optical properties, and photocatalytic degradation of perfluoroalkyl substances (PFAS) of Bi2WO6

“…The Bi 2− x Zn x WO 6+ δ photocatalysts were dip-coated on the carbon surface (0.13 cm 2 ) of the working electrode of the commercial screen-printed electrode (DS110), following the procedure previously reported elsewhere. 42,43 Linear scanning voltammetry (LSV) at 5 mV s −1 from 0.2 to 1.4 V (V vs. Ag–AgCl) and chronoamperometry (CA) at 1.4 V ( vs. Ag–AgCl) for 1 h were conducted.…”

Unveiling the origin of the efficient photocatalytic degradation of nitazoxanide over bismuth (oxy)iodide crystalline phases

“…Therefore, it is prudent to consider these reported potentials as initial approximations for our analysis, which allows us to Environmental Science: Nano Paper discern relative trends. For example, the relatively positive VB potential of BiOI suggests the feasibility of oxidizing hydroxyl ions to generate hydroxyl radicals (1.9 V vs. NHE at pH = 7 for HO − /HO˙) 44,45 within this photocatalyst. Meanwhile, in the CB of Bi 4 O 5 I 2 , the processes, such as oxygen reduction reaction (−0.18 V vs. NHE at pH = 7 for O 2 /O 2 ˙−) 44 and/or redox reactions associated with nitazoxanide photochemistry (Fig.…”