Improving Photocatalytic Performance and Recyclability by Development of Er-Doped and Er/Pr-Codoped TiO₂/Poly(vinylidene difluoride)–Trifluoroethylene Composite Membranes

Abstract

Photocatalysis has become an attractive process to remove contaminants from aquatic environments, with TiO 2 being the most widely used photocatalyst. In spite of the advantages of the process, two main problems still have to be overcome: reutilization/recycling of TiO 2 nanoparticles, which is a time-consuming and expensive process, and the fast recombination rate of the electron−hole pairs. This work reports on the photocatalytic activity of rare earth metal doped (erbium, Er) and codoped (erbium and praseodymium, Er/Pr) TiO 2 nanoparticles immobilized in a poly(vinylidene difluoride)−trifluoroethylene (PVDF−TrFE) copolymer membrane as a suitable strategy to overcome the aforementioned limitations. It is shown that doped and codoped nanoparticles were successfully immobilized into the PVDF−TrFE membranes, with a controllable degree of porosity. A high surface area (273 m 2 /g) was attained for these nanoparticles. The low band gap (2.63 eV) of these TiO 2 -modified nanoparticles, coupled with a highly porous structure (∼75%) of the membrane microstructure, synergistically envisages the best photocatalytic performance by degrading 98% of a solution of methylene blue after 100 min of exposure to UV.

Photoelectrochemical Performance of Quantum dot-Sensitized TiO2 Nanotube Arrays: a Study of Surface Modification by Atomic Layer Deposition Coating

“…However, TiO 2 cannot effectively use the visible light because of its wide bandgap (∼3.2 eV). Transition metals [8] or nonmetals [9] doping can reduce the bandgap of TiO 2 , but the dopants can easily become the electron-hole recombination centers [10]. The other method is using narrow-bandgap materials such as quantum dots (QDs) to sensitize TiO 2 and enhance their photocatalytic activity in the visible-light region since the photogenerated charge can quickly separate and transfer between different semiconductors [11, 12].…”

Synthesis of rare earth doped TiO2nanorods as photocatalysts for lignin degradation

“…In order to enhance the interfacial charge-transfer efficiency and utilize a wider spectral range of solar energy, the TiO 2 catalyst has been modified by ion doping 19,20 and manipulating the nanomaterial composition. 21,22 Rare earth (RE) ion dopants, such as Ce, 23 La, 24 Er 25 and Pr, 26 have shown unique enhancement effects, resulting from the orbital hybridization of 4f electrons. Positive effects of 4f electron orbital hybridization on the photocatalytic activities of TiO 2 were reported previously.…”

Bi-Phasic photocatalytic particles prepared by sequential layer depositions for water cleaning and purification

“…In addition, the use of sol-gel enable doping with elements of different nature to improve the absorption efficiency of the semiconductors used. Several elements as nitrogen, [20] sulphur [19,56] or even different lanthanides [41,49,57] have been used to improve the properties of titanium dioxide. This methodology has been proved robust enough to support different doping of the layers as our previous work on nitrogen and neodymium doped particles has showed.…”

“…Using filters for deposition of nanoparticles introduces an advantageous porosity on the system for water cleaning. [49] Some authors have used micro-porous track etched polycarbonate membranes to deposit nanoparticles on them. [50] Commercial polycarbonate filters have been used in this paper but different membrane filters offer endless possibilities.…”