An enhanced photocatalytic response of nanometric TiO₂ wrapping of Au nanoparticles for eco-friendly water applications

Abstract

We propose a ground-breaking approach by an upside-down vision of the Au/TiO2 nano-system in order to obtain an enhanced photocatalytic response. The system was synthesized by wrapping Au nanoparticles (∼8 nm mean diameter) with a thin layer of TiO2 (∼4 nm thick). The novel idea of embedding Au nanoparticles with titanium dioxide takes advantage of the presence of metal nanoparticles, in terms of electron trapping, without losing any of the TiO2 exposed surface, so as to favor the photocatalytic performance of titanium dioxide. A complete structural characterization was made by scanning electron microscopy, transmission electron microscopy and X-ray diffraction. The remarkable photocatalytic performance together with the stability of the nano-system was demonstrated by degradation of the methylene blue dye in water. The non-toxicity of the nano-system was established by testing the effect of the material on the reproductive cycle of Mytilus galloprovincialis in an aquatic environment. The originally synthesized material was also compared to conventional TiO2 with Au nanoparticles on top. The latter system showed a dispersion of Au nanoparticles in the liquid environment, due to their instability in the aqueous solution that clearly represents an environmental contamination issue. Thus, the results show that nanometric TiO2 wrapping of Au nanoparticles has great potential in eco-friendly water/wastewater purification.

PMMA/TiO2 nanotubes composites for photocatalytic removal of organic compounds and bacteria from water

“…In fact, the initially blue solution became almost colorless after 240 min under UV-A light, indicating the significant degradation of MB. In the literature, a comparable activity was observed using about 50 mg/ml of TiO 2 NPs in dispersion form [15].…”

“…The literature shows several methods for the realization of titanium dioxide nanomaterials for developing useful photocatalytic tools for water purification [14][15][16][17]. However, significant limitations exist for the use of nanomaterials for the effects on human health and ecosystems due to their employment [18,19].…”

Black TiOx photocatalyst obtained by laser irradiation in water

“…The presence of both amorphous (or disordered) structure and electrons in the 3d titanium states has been addressed to be responsible for activity enhancement in black-TiO 2 nanoparticles [1,4]. Moreover, photoactivity can be improved with metal grafting [4][5][6][7][8][9]. Indeed, when in contact with small metal cluster, the charge separation and transfer process are faster and thermodynamically favoured [3].…”

One-dimensional porous Ag/AgBr/TiO2 nanofibres with enhanced visible light photocatalytic activity

“…However, the use of TiO 2 is limited by its nature (Zhang et al, 2013;Scuderi et al, 2014) (e.g., limited visible light utilisation, low quantum yields and poor adsorption capacity towards some organic molecules). In this context, various strategies such as doping with noble metals (Jiang et al, 2014;Bumajdad et al, 2014) or non-metals (Xiong & Zhao, 2012;Qiu et al, 2014) coupled with narrow-band gap semiconductors (Liu et al, 2014a(Liu et al, , 2014b have been developed to improve the performance of TiO 2 in photocatalysis.…”