Au and AuCu Nanoparticles Supported on SBA-15 Ordered Mesoporous Titania-Silica as Catalysts for Methylene Blue Photodegradation

Abstract

The photocatalytic degradation of methylene blue (MB) dye has been performed under UV irradiation in aqueous suspension, employing photocatalysts based on Au (1.5 wt %) and AuCu (Au/Cu = 1, 2.0 wt %), and supported on SBA-15-ordered mesoporous silica, with and without titania (Si/Ti = 3), in order to evaluate the versatility of this mesoporous support in this type of reaction of great impact from the environmental point of view. Samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), N2 adsorption-desorption at −196 °C, and X-ray photoelectron spectroscopy (XPS), so as to study their structural, optical, and chemical properties. All the prepared catalysts were found to be active in the test reaction. The bimetallic AuCu-based catalysts attained very high MB degradation values, in particular AuCu/SBA-15 titania-silica sample reached 100% of dye oxidation after the monitored reaction period (120 min).

Ceria doping boosts methylene blue photodegradation in titania nanostructures

“…Titania, TiO 2 , an n-type semiconductor, is the most largely employed catalyst for UV-based AOPs operating at mild conditions (atmospheric pressure and room temperature), thanks to its outstanding photocatalytic properties, as well as its low cost, non-toxicity, great chemical and thermal stability and remarkable oxidation power [6,7]. Titania's photocatalytic performance strongly depends on several parameters such as crystallinity, nanostructures' morphology, specific surface area and pore size distribution [8][9][10] Thus, different strategies to modify and tune these parameters in order to obtain superior photocatalytic TiO 2 -based materials have been largely investigated. Morphology plays a key role in the transport and recombination of photogenerated charge carriers.…”

Cu@Au self-assembled nanoparticles as SERS-active substrates for (bio)molecular sensing

“…On the other hand, the preparation of AuCu SERS substrates typically requires the use of templates and/or high temperatures, which make synthesis methods costly and, therefore, not suitable for scale up production. Some of these methods include laser ablation [26], porous anodic aluminum oxide template method [27], nanolithography (electron-beam lithography and focused ion beam milling) [28], impregnation / calcination [19], among many others that also require long reaction times, the use of harmful organic reagents and/or high-energy [23,[29][30][31]. In such a way, the development of cost-effective preparation methods for highly active SERS substrates is a remaining goal in Raman scattering-based chemical sensing.…”

Advantages of the Incorporation of Luffa-Based Activated Carbon to Titania for Improving the Removal of Methylene Blue from Aqueous Solution

“…Methylene blue is the model dye compound used to evaluate the photocatalytic activity of the synthesized composite materials under UV irradiation following ISO procedure for photocatalytic characterization [35]. According to previous experiments [19,36], the initial MB concentration was 6.0 × 10 −5 M, the photocatalyst dosage was 1.25 g•L −1 , and the temperature was fixed at 20 • C using a thermostatic bath. The following two types of experiments were carried out: (a) the mixture MB solution and photocatalyst was maintained under stirring in the dark for 30 min to achieve the adsorption equilibrium before starting the irradiation, and (b) irradiation was started just after preparing the mixture that was kept under magnetic stirring.…”

“…Different materials and compounds have been incorporated to TiO 2 with the purpose of improving its photocatalytic activity. Among them, silica [18,19], noble metals [20], diatomite [21] and activated carbon [22,23] can be highlighted. The latter is gaining attention due to several advantages, mostly for being low cost, non-toxic, and its affinity for the adsorption of most organic molecules [24].…”