Ultrasmall Plasmonic Nanoparticles Decorated Hierarchical Mesoporous TiO₂ as an Efficient Photocatalyst for Photocatalytic Degradation of Textile Dyes

Abstract

Hierarchical mesoporous TiO 2 was synthesized via a solvothermal technique. The sonochemical method was adopted to decorate plasmonic nanoparticles (NPs) (Ag, Au) on the pores of mesoporous TiO 2 . The crystallinity, structure, and morphology were determined to understand the physicochemical nature of the nanocomposites. The catalytic efficiency of the plasmonic nanocatalysts was tested for the azo dyes (congo red, methyl orange, acid orange 10, and remazol red) under solar and visible light irradiations. The generation of hydroxyl radicals was also studied using terephthalic acid as a probe molecule. An attempt was made to understand the influence of size, work function and Fermi level of the metal NPs toward the efficiency of the photocatalyst. The efficiency of the nanocomposites was found to be in the order of P25 < mesoporous TiO 2 < mesoporous Ag–TiO 2 < mesoporous Au–TiO 2 nanospheres under both direct solar light and visible light irradiation. The results indicated that the adsorption of dye, anatase phase, and surface plasmon resonance of NPs favored the effective degradation of dyes in aqueous solution. Further, the efficiency of the catalyst was also tested for xanthene (rose bengal), rhodamine (rhodamine B, rhodamine 6G), and thiazine (methylene blue) dyes. Both TiO 2 and NPs (Ag & Au) possess a huge potential as an eco-friendly photocatalyst for wastewater treatment.

Recent Advances in Plasmonic Photocatalysis Based on TiO2 and Noble Metal Nanoparticles for Energy Conversion, Environmental Remediation, and Organic Synthesis

“…[65] Generally, these parameters affect the surfaceactive sites, electron transport, and mass transfer events. Different morphologies of TiO 2 have already been explored such as microspheres, [66] nanospheres, [67] nanosheets, [68][69][70] nanorods, [71,72] nanotubes, [73] and nanowires. [74,75] There are well-established procedures for the synthesis of TiO 2 in the form of powder, crystals and thin films.…”

“…[74,75] There are well-established procedures for the synthesis of TiO 2 in the form of powder, crystals and thin films. [69] It can be inferred that the photocatalytic performance of TiO 2 -based plasmonic photocatalysts depends on the configuration, synthesis procedure and organization of the metal/TiO 2 system. Therefore, the synthesis of controllable hybrids is highly desirable.…”

“…In this strategy, TiO 2 in the form of powder, thin films and membranes [99][100][101][102][103] can be prepared by using alkoxide and non-alkoxide precursors by hydrolysis and polycondensation reactions (sol-gel method). [69,104,105] This method has many advantages such as control over the composition, stoichiometry, ease of processing, purity, and the possibility of introducing dopants in large concentrations. [106] Liu et al [99] employed a sol-gel method to synthesize mesoporous TiO 2 , wherein the solution was synthesized by adding Ti(OBu) 4 in ethanol.…”

Recent Advances on Plasmon-enhanced Titania Nanocatalysts for Photocatalytic Degradation of Organic Dyes

“…2 to 5.5 Ag NPs in a single TiO2 nanorod. Vandarkhuzali et al also reported the synthesis of ultrasmall Ag NPs decorated on hierarchical mesoporous TiO2 [53]. The size of Ag NPs was around 3 nm, uniformly distributed on mesoporous TiO2 matrices (Figure 3).…”

TiO2 nanofibres decorated with green-synthesized PAu/Ag@CQDs for the efficient photocatalytic degradation of organic dyes and pharmaceutical drugs

“…12 In this respect, a wide range of semiconductor materials, including TiO 2 , a well-known photocatalyst, has been mostly employed for the degradation of their pollutants owing to their main features including nontoxicity, low cost, biochemical inertness, and photo-stability; however, its wide-bandgap (3.2 eV) limits its efficiency. 13,14 Further, to enhance the photocatalytic activity of TiO 2 by modifying its absorbance towards visible light, several photosensitizers, plasmonic materials, small-bandgap semiconductors, and metallic and non-metallic doping agents have been reconnoitred. [15][16][17] For instance, modied TiO 2 -based photocatalysts are largely investigated towards photocatalytic degradation of pharmaceutical drugs under the UV-visible irradiation.…”