Photo–Redox Properties of –SO3H Functionalized Metal-Free g-C3N4 and Its Application in the Photooxidation of Sunset Yellow FCF and Photoreduction of Cr (VI)

Abstract

In this work, we synthesized a metal-free sulfonic functionalized graphitic carbon nitride using sulfuric acid through the wet impregnation technique. The functionalization of sulfonic groups (–SO3H) on g-C3N4 will promote a high surface charge density and charge separation owing to its high electronegativity. The g-C3N4–SO3H shows excellent optical/electronic and surface properties towards enhanced photo–redox reactions. The sulfonic groups also facilitate the availability of more separated charge carriers for photocatalytic oxidation and reduction reactions. The as-synthesized material has been characterized by different spectroscopic tools to confirm the presence of functionalized –SO3H groups and optoelectronic possessions. The photocatalytic responses of g-C3N4–SO3H result in 99.56% photoreduction of Cr (VI) and 99.61% photooxidation of Sunset Yellow FCF within 16 min and 20 min, respectively, of visible light irradiation. The g-C3N4–SO3H catalyst exhibits a high apparent rate constant (Kapp) towards the degradation of Cr (VI), and SSY, i.e., 0.783 min−1 and 0.706 min−1, respectively. The intense optical–electrochemical properties and potentially involved active species have been analyzed through transient photocurrent, electrochemical impedance, and scavenging studies. Consequently, the photocatalytic performances are studied under different reaction parameters, and the plausible photocatalytic mechanism is discussed based on the results.

Exploring the synthetic potential of a g-C3N4·SO3H ionic liquid catalyst for one-pot synthesis of 1,1-dihomoarylmethane scaffoldsviaKnoevenagel–Michael reaction

“…2) and well characterized by XRD, FT-IR, SEM and HRTEM studies and the results were in full agreement with previously reported literature. 43,50,51 The XRD spectrum of g-C 3 N 4 and g-C 3 N 4 $SO 3 H was analysed, as shown in Fig. 3.…”

“…3 was found to be almost identical, 2q = 12.17°with a (100) plane, and 2q = 27.92°with a (002) plane, indicating that the functionalization did not result in any signicant destruction of the carbon nitride web. 43,50 The g-C 3 N 4 and g-C 3 N 4 $SO 3 H was synthesized from urea and a comparative study of the FT-IR spectrum of urea, g-C 3 N 4 , and g-C 3 N 4 $SO 3 H was performed over wavenumber 4000-600 cm −1 region. For pure urea in Fig.…”

“…5A-C and it was observed that the structure was porous and agglomerated while the sheets were not clearly visible. 43,50 The HRTEM analysis in Fig. 5D-F displayed that g-C 3 N 4 -SO 3 H material exhibited a sheet-like structure that appeared to be wrinkled, which could be attributed to the attraction or repulsion of static charges between the layers of g-C 3 N 4 -SO 3 H. 50 The synthesized g-C 3 N 4 $SO 3 H catalyst was further studied for its catalytic activity.…”

“…[39][40][41] It is a stable and non-toxic material that is environmentally friendly and has attracted signicant attention due to its unique electronic, optical, photocatalytic, and chemical properties. 42,43 Its structure can be tuned by changing the preparation conditions and the starting materials used. 44 The addition of sulfonic acid groups to the surface of g-C 3 N 4 gives g-C 3 N 4 sulfonic acid (g-C 3 N 4 $SO 3 H).…”

“…g-C 3 N 4 $SO 3 H has a high surface area and unique electronic properties, making it a promising material for various applications. 43,45,46 It has also been used as a heterogeneous acid catalyst for esterication, aldol condensation, and acylation reactions. [47][48][49] Herein we have developed a highly efficient, green, and high-yielding multicomponent reaction for one-pot synthesis of 1,1-dihomoarylmethane scaffolds (bis-dimedones, bis-cyclohexanediones, bis-pyrazoles, and bis-coumarins) using substituted aryl aldehydes and C-H activated compounds, such as dimedone, 1,3-cyclohexanedione, 1phenyl-3-methyl-5-pyrazolone, and 4-hydroxycoumarin in aqueous ethanol using g-C 3 N 4 $SO 3 H as an ionic liquid catalyst.…”