Enhanced Visible Light Photocatalysis of Bi₂O₃ upon Fluorination

Abstract

For the better utilization of solar light and complete oxidation of environmental organic pollutants, it is desired to develop small band gap semiconductors with a deep valence band as efficient visible light photocatalysts. In this work, we prepared the fluorinated Bi2O3 catalysts using a precipitation method, followed by a solvothermal process in the presence of NH4F. The fluorinated Bi2O3 catalysts, especially with the atomic ratio of F to Bi (R F) at 0.2, exhibit much higher photocatalytic activities than the pure Bi2O3 for the degradation of methyl orange (MO) under the visible light irradiation. The effects of the fluorination on the phase structure, special surface areas, morphologies, optical properties, surface-adsorbed species, and electronic band structure of the Bi2O3 were investigated in detail. It was revealed that both the surface-adsorbed and lattice-substituted fluorine, induced by the fluorination to Bi2O3, play critical roles in the enhanced photocatalytic performance of the fluorinated Bi2O3. The two types of fluorine species effectively inhibit the recombination of the photoexcited electron–hole pairs by withdrawing the photoexcited electrons and increase the oxidation power of the photoexcited hole by lowering the valence band edge, respectively.

Direct conversion mechanism from BiOCl nanosheets to BiOF, Bi7F11O5 and BiF3 in the presence of a fluorine resource

“…[1][2][3] Thus, it remains a big challenge to develop inexpensive, highly efficient photocatalysts for the practical applications. 28 These results have also been observed in fluorinated TiO 2 , 29 Bi 2 O 3 , 30 4 significantly improved photocatalytic activity. [4][5][6][7][8] Recently, bismuth-based compounds have been intensively investigated due to the outstanding optical and photocatalytic properties, including Bi 2 O(OH) 2 SO 4 , 9,10 Bi(C 2 O 4 )OH, 11 [Bi 6 O 6 (OH) 3 ](NO 3 ) 3 ·1.5H 2 O, 12 BiOCl, 13 BiPO 4 , 14 Bi 2 O 2 CO 3 , 15 BiOF, [16][17][18] BiF 3 ,19 Bi 7 F 11 O 5 , 20 BiOI, 21 BiVO 4 22,23 and so on.…”

Photocatalytic reactivity of {121} and {211} facets of brookite TiO2 crystals

“…To further investigate the photocatalytic oxidation pathway, methanol (10 mM) as hole scavenger, tertbutyl alcohol (TBA, 10 mM) as cOH radical scavenger, and AgNO 3 (10 mM) as e À scavenger were chosen, respectively, to participate in the RhB photodegradation test. 43 The photocatalytic H 2 evolution test was carried out in a glass reactor with a closed gas circulation system. The light source was a 300 W Xe lamp.…”

Multi-layer three-dimensionally ordered Bismuth trioxide/Titanium dioxide nanocomposite: Synthesis and enhanced photocatalytic activity

“…Bi 2 O 3 is an important non-poisonous narrow band gap photosensitizer with a direct band gap of 2.1-2.8 eV, and the high oxidation ability of electron holes of Bi 2 O 3 is regarded as an important condition for a kind of good photocatalytic materials. However, too many opportunities for the recombination of photoformed electrons and holes owing to the narrow band gap of Bi 2 O 3 semiconductors and then application is limited [11][12][13][14]. Accordingly, catalyst is prepared by the TiO 2 compounds with Bi 2 O 3 , exploiting the synergy to improve the utilization rate of catalyst for the light, so then to solve the aporia of Bi 2 O 3 electron holes easily recombination have been deserves special attention [15,16].…”