Solvothermal Synthesis of g-C3N4/TiO2 Hybrid Photocatalyst with a Broaden Activation Spectrum

Abstract

A solvothermal self-made composite of graphitic carbon nitride (g-C3N4) and commercially available titanium dioxide (TiO2) demonstrated the removal of commercial acid green-25 (AG-25) textile dye in a saline water matrix when activated by ultraviolet (UV) and visible light. The g-C3N4-TiO2 composite was characterized by X-ray diffraction (XRD), Nitrogen sorption–desorption recording and modeling by the Brunauer–Emmett–Teller (BET) theory, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL), and electron spin resonance (ESR). The solvothermal process did not modify the crystalline structure of the g-C3N4 and TiO2 but enhanced the surface area by interlayer delamination of g-C3N4. Under a simulated solar spectrum (including UVA/B and vis wavelengths), the degradation rate of AG-25 by the composite was two and four times higher than that of TiO2 and pure g-C3N4, respectively (0.04, 0.02, and 0.01 min−1). Unlike TiO2, the g-C3N4-TiO2 composite was activated with visible light (the UV portion of the solar spectrum was filtered out). This work provides insight into the contribution of various reactive oxidative species (ROS) to the degradation of AG-25 by the composite.

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

“…Several approaches have already been used to fabricate g-C 3 N 4 /TiO 2 heterostructures, such as sol-gel [ 65 ], hydrothermal [ 58 ]/solvothermal syntheses [ 66 ], wet impregnation [ 67 ] and microwave-assisted methods [ 68 , 69 ]. Apart from the microwave irradiation process, these methods typically require high temperatures and/or long reaction times, hence being energy consuming [ 58 , 66 , 67 , 70 , 71 ].…”

“…Several approaches have already been used to fabricate g-C 3 N 4 /TiO 2 heterostructures, such as sol-gel [ 65 ], hydrothermal [ 58 ]/solvothermal syntheses [ 66 ], wet impregnation [ 67 ] and microwave-assisted methods [ 68 , 69 ]. Apart from the microwave irradiation process, these methods typically require high temperatures and/or long reaction times, hence being energy consuming [ 58 , 66 , 67 , 70 , 71 ]. Taking into account the minimization of energy, microwave irradiation appears as a good alternative for the synthesis of complex inorganic materials, since higher reaction yields can be obtained in such a short amount of time.…”