Simultaneous Oxidation of p-Chlorophenol and Reduction of Cr(VI) on Fluorinated Anatase TiO₂ Nanosheets with Dominant {001} Facets under Visible Irradiation

Abstract

A series of fluorinated anatase TiO 2 nanosheets with dominant {001} facets were synthesized to oxidize pchlorophenol (PCP) and reduce Cr(VI) simultaneously under visible light. The {001}/{101} surface facets ratio of TiO 2 was controlled by varying the initial HF concentration, and fluorine-free samples were obtained by alkaline-washing. A synergistic effect among TiO 2 , Cr(VI), and PCP was observed, which is ascribed to effective trapping of photogenerated electrons and holes by Cr(VI) and PCP, respectively. A maximum synergistic effect was obtained at a molar ratio of [PCP] to [Cr(VI)] of one. Using X-ray diffraction, X-ray photoelectron spectroscopy, electron paramagnetic resonance spectroscopy, field-emission scanning electron microscopy, transmission electron microscopy, and Brunauer−Emmett−Teller analyses, the optimum ratio of exposed {001} to {101} facets for TiO 2 was determined to be 80:20 because of selective transfer and charge balance of photogenerated carriers. Surface fluorination facilitates the formation of oxygen vacancies and unsaturated Ti atoms, which is useful for visible light activity induction, extending the lifetime of photogenerated electron-hole pairs, and enhancing the rate of PCP oxidation and Cr(VI) reduction.

Poly(vinylidene fluoride) derived fluorine-doped magnetic carbon nanoadsorbents for enhanced chromium removal

“…Nitrogen doping greatly enhanced the removal efficiency of carbon due to the improved interaction between the adsorbents and Cr(VI) ions [30]. More recently, fluorination was proposed as a novel process for the surface modification to improve the performance [31][32][33][34][35].…”

A facile synthesis of CdSe quantum dots-decorated anatase TiO2 with exposed {0 0 1} facets and its superior photocatalytic activity

“…Both theoretical and experimental studies demonstrate that the {0 0 1} facet of anatase TiO 2 is much more reactive than the thermodynamically more stable {1 0 1} facet [2][3][4]. Due to the high ratio of the exposed {0 0 1} facets, T001 has been reported to exhibit superior activity in many aspects of photocatalytic field [5][6][7][8][9][10]. Although enhanced photocatalytic activity can be obtained by increasing the percentage of {0 0 1} facets, T001 can be excited only under ultravoilet (UV) light irradiation owing to the large band gap of TiO 2 .…”

FacileSynthesis of Anatase TiO2Nanocrystals with Co‐Exposed{101}, {010}/{100} and [111]‐Facets for EfficientPhotodegradation of Methylene Blue

“…The d ‐values (3.498∼3.517 Å) calculated according to (101) planesof anatase TiO 2 are slightly different, which are caused by the different spacing of crystal planes. Compared with the theoretical value (3.520 Å), the diffraction peaks shift slightly to the lower angle (high interplanar distance),which is attributed to minor expansion of the crystal lattice due to the introduction of HF [24,25] . No characteristic diffraction peaks of other TiO 2 phases (i. e., rutile, brookite, and TiO 2 (B), et al.)…”

“…Morphology of the as‐synthesized anatase TiO 2 nanocrystals was determined by FESEM, as shown in Figure 2. It is observed that the synthesized anatase TiO 2 nanocrystals agglomerate together, which can be attributed to the high surface activities of anatase TiO 2 nanocrystals and the existence of strong intermolecular forces between the nanocrystals [25] . And the different contents of HF have unconspicuous effect on the morphology of the synthesized TiO 2 nanocrystals samples.…”