Microwave Synthesis of Visible-Light-Activated g-C3N4/TiO2 Photocatalysts

Abstract

The preparation of visible-light-driven photocatalysts has become highly appealing for environmental remediation through simple, fast and green chemical methods. The current study reports the synthesis and characterization of graphitic carbon nitride/titanium dioxide (g-C3N4/TiO2) heterostructures through a fast (1 h) and simple microwave-assisted approach. Different g-C3N4 amounts mixed with TiO2 (15, 30 and 45 wt. %) were investigated for the photocatalytic degradation of a recalcitrant azo dye (methyl orange (MO)) under solar simulating light. X-ray diffraction (XRD) revealed the anatase TiO2 phase for the pure material and all heterostructures produced. Scanning electron microscopy (SEM) showed that by increasing the amount of g-C3N4 in the synthesis, large TiO2 aggregates composed of irregularly shaped particles were disintegrated and resulted in smaller ones, composing a film that covered the g-C3N4 nanosheets. Scanning transmission electron microscopy (STEM) analyses confirmed the existence of an effective interface between a g-C3N4 nanosheet and a TiO2 nanocrystal. X-ray photoelectron spectroscopy (XPS) evidenced no chemical alterations to both g-C3N4 and TiO2 at the heterostructure. The visible-light absorption shift was indicated by the red shift in the absorption onset through the ultraviolet-visible (UV-VIS) absorption spectra. The 30 wt. % of g-C3N4/TiO2 heterostructure showed the best photocatalytic performance, with a MO dye degradation of 85% in 4 h, corresponding to an enhanced efficiency of almost 2 and 10 times greater than that of pure TiO2 and g-C3N4 nanosheets, respectively. Superoxide radical species were found to be the most active radical species in the MO photodegradation process. The creation of a type-II heterostructure is highly suggested due to the negligible participation of hydroxyl radical species in the photodegradation process. The superior photocatalytic activity was attributed to the synergy of g-C3N4 and TiO2 materials.

Surface sensitization of g-C3N4/TiO2via Pd/Rb2O co-catalysts: accelerating water splitting reaction for green fuel production in the absence of organic sacrificial agents

“…A broad diffraction peak was found at 13.2° due to the presence of in-planar structures (N bridged repeated tri- s -triazine units). Maximum diffraction at 27.02° occurred due to the stacked conjugated aromatic system 49 as shown here in Fig. 1(b).…”

Enhancing NO degradation in visible light through plasma-treated photocatalytic substrates featuring TiO₂@g-C₃N₄ Z-scheme structure

“…This structure provides aligned macroporous channels and mesoporous walls, enabling efficient NO x adsorption and storage of NO x oxidation product while allowing visible light absorption [68]. TC showed four times higher NO conversion compared to TiO 2 and two times higher compared to g-C 3 N 4 [69]. Additionally, TC exhibited high NO x adsorption capacity and converted NO to nontoxic NO 3 with minimal formation of NO 2 , making it a more effective photocatalyst for NO x removal [70].…”

Hydrothermal Synthesis of Heterostructured g-C3N4/Ag–TiO2 Nanocomposites for Enhanced Photocatalytic Degradation of Organic Pollutants

“…In particular, heterostructured g-C 3 N 4 /Ag-TiO 2 nanocomposites have emerged as a promising area of research in the field of photocatalytic degradation of organic pollutants and have been extensively studied due to their remarkable visible-light-driven photocatalytic performance. Therefore, many strategies have been used to fabricate heterostructured g-C 3 N 4 /Ag-TiO 2 nanocomposites, including the microwave-assisted approach [37], freeze-drying route [9], hydrothermal method [36,38], calcination [39,40], physical mixing-calcination method [41], physical mixing [42,43], chemical reduction methods, and so on [11].…”