Enhanced Photocatalytic Activity of Au/TiO2 Nanoparticles against Ciprofloxacin

Abstract

In the last decades, photocatalysis has arisen as a solution to degrade emerging pollutants such as antibiotics. However, the reduced photoactivation of TiO2 under visible radiation constitutes a major drawback because 95% of sunlight radiation is not being used in this process. Thus, it is critical to modify TiO2 nanoparticles to improve the ability to absorb visible radiation from sunlight. This work reports on the synthesis of TiO2 nanoparticles decorated with gold (Au) nanoparticles by deposition-precipitation method for enhanced photocatalytic activity. The produced nanocomposites absorb 40% to 55% more radiation in the visible range than pristine TiO2, the best results being obtained for the synthesis performed at 25 °C and with Au loading of 0.05 to 0.1 wt. %. Experimental tests yielded a higher photocatalytic degradation of 91% and 49% of ciprofloxacin (5 mg/L) under UV and visible radiation, correspondingly. Computational modeling supports the experimental results, showing the ability of Au to bind TiO2 anatase surfaces, the relevant role of Au transferring electrons, and the high affinity of ciprofloxacin to both Au and TiO2 surfaces. Hence, the present work represents a reliable approach to produce efficient photocatalytic materials and an overall contribution in the development of high-performance Au/TiO2 photocatalytic nanostructures through the optimization of the synthesis parameters, photocatalytic conditions, and computational modeling.

Systematic Incorporation of Gold Nanoparticles onto Mesoporous Titanium Oxide Particles for Green Catalysts

“…The charge of the MPT particles was almost neutral in pure water but became negative in EtOH (−24.2 ± 5.0 mV). Upon the integration of AuNPs onto the MPT particles, all composite particles, regardless of the solvents and AuNP content, displayed slightly negative potentials ranging from −15 mV to −35 mV, which were comparable to the literature values, suggesting moderate stability [38,39]. The FT-IR spectra were also collected for examination before and after the incorporation of AuNPs onto the MPT particles, whereby the identical vibrational patterns clearly (Supplementary Figure S3) implied the absence of any detectable stabilizers or capping agents (i.e., free from physicochemical modification).…”

Enhanced visible-light photodegradation of fluoroquinolone-based antibiotics and E. coli growth inhibition using Ag–TiO2 nanoparticles

“…The degradation rate constants reported for similar catalysts, which were used in the photodegradation of CIP under similar irradiation conditions, are in the same range or even have lower values when compared with our ndings. 32,50 Higher degradation rate constants were also reported, but in this case the materials were either exhibiting different morphologies and/or Ag loading, or were tested under different irradiation conditions. 15,51,52 Concerning NFX, a direct comparison of our catalysts performance with respect to the literature is rather difficult since the reported catalysts for the degradation of NFX possess different morphologies or are used in different experimental conditions.…”

“…In order to investigate the photocatalytic activity of Ag-TiO 2 NPs thoroughly, a kinetic study of the photodegradation process was performed. The obtained photocatalytic degradation curve was tted by using a pseudo-rst-order kinetic model as in eqn (1): 32 Àln…”

“…26 Doping TiO 2 with metal or non-metal atoms or modifying the surface of TiO 2 with noble metals are some of the suggested solutions to overcome this problem. [27][28][29][30][31] Noble metals play an important role in the visible-light-activated photocatalytic process 24,32 by lowering the bandgap, promoting electron-hole pairs separation and/or introducing additional catalytically active sites on the surface of TiO 2 . Among them, Ag is a promising candidate, owing to its relatively low cost (compared with gold for instance), easy preparation and particularly high performance in enhancing the TiO 2 photocatalytic activity under visible light.…”

Reusable Ag@TiO2-Based Photocatalytic Nanocomposite Membranes for Solar Degradation of Contaminants of Emerging Concern

“…Different approaches have been employed to circumvent these limitations, such as doping [19], functionalisation with noble metals [20], and the development of hybrid materials [21]. In this scope, the functionalisation of TiO 2 with metals such as Co [22], Cu [23], Au [24], and Ag [25] has been applied to introduce intermediate energy levels and reduce the bandgap of TiO 2 since these metals, when irradiated, are able to receive electrons and prevent the recombination of electron/hole pairs [26]. The development of silver (Ag)/TiO 2 nanoparticles improves visible radiation absorption, favouring photocatalytic efficiency [27].…”