A Facile Method for the Preparation of Colored Bi4Ti3O12−x Nanosheets with Enhanced Visible-Light Photocatalytic Hydrogen Evolution Activity

Abstract

Bi4Ti3O12−x nanosheet photocatalysts with abundant oxygen vacancies are fabricated by a facile solid-state chemical reduction method for the first time. This method is simple in operation, has short reaction time, and can be conducted at mild temperatures (300~400 °C). The electron paramagnetic resonance, thermogravimetric analysis, X-ray photoelectron spectrometer, and positron annihilation lifetime spectra results indicate that oxygen vacancies are produced in Bi4Ti3O12−x, and they can be adjusted by tuning the reduction reaction conditions. Control experiments show that the reduction time and temperature have great influences on the photocatalytic activities of Bi4Ti3O12−x. The optimal Bi4Ti3O12−x is the sample undergoing the reduction treatment at 350 °C for 60 min and it affords a hydrogen evolution rate of 129 μmol·g−1·h−1 under visible-light irradiation, which is about 3.4 times that of the pristine Bi4Ti3O12. The Bi4Ti3O12−x photocatalysts have good reusability and storage stability and can be used to decompose formaldehyde and formic acid for hydrogen production. The surface oxygen vacancies states result in the broadening of the valence band and the narrowing of the band gap. Such energy level structure variation helps promote the separation of photo-generated electron-hole pairs thus leading to enhancement in the visible-light photocatalytic hydrogen evolution. Meanwhile, the narrowing of the band gap leads to a broader visible light absorption of Bi4Ti3O12−x.

SrTiO3/Bi4Ti3O12 Nanoheterostructural Platelets Synthesized by Topotactic Epitaxy as Effective Noble-Metal-Free Photocatalysts for pH-Neutral Hydrogen Evolution

“…Similar to SrTiO 3 , Bi 4 Ti 3 O 12 was also explored as a photocatalyst for H 2 generation. However, according to several reports, pure Bi 4 Ti 3 O 12 does not exhibit an outstanding H 2 evolution activity, 16 , 25 although modifications such as reduction (Bi 4 Ti 3 O 12– x ) 16 and substitution with Cr (Bi 4 Ti 3– x Cr x O 12 ) 25 − 27 were confirmed to enhance considerably visible-light photocatalytic H 2 evolution from water/methanol solutions (2–4 times). For both types of modified Bi 4 Ti 3 O 12 , the improvement was ascribed to the narrowing of the band gap and the decreased recombination of the photogenerated charges.…”

“…One of the reasons for the selection of the SrTiO 3 /Bi 4 Ti 3 O 12 heterostructure was the interesting photocatalytic properties of the individual materials. 2 , 5 , 7 , 16 SrTiO 3 meets the thermodynamic criteria for an overall photocatalytic water-splitting reaction in terms of the appropriate band-edge positions and bandgap. 3 , 7 , 17 Several efficient H 2 -evolution photocatalysts based on SrTiO 3 were developed using various design strategies, aiming to improve the light-harvesting capabilities and the charge-carrier separation.…”

“…For both types of modified Bi 4 Ti 3 O 12 , the improvement was ascribed to the narrowing of the band gap and the decreased recombination of the photogenerated charges. 16 , 25 …”

Growth Process and CQDs-modified Bi4Ti3O12 Square Plates with Enhanced Photocatalytic Performance

“…As an important titanium-based oxide semiconductor, bismuth titanate (Bi 4 Ti 3 O 12 ) has been extensively studied owing to its pronounced photocatalytic activity toward the degradation of organic pollutants and water splitting into hydrogen [33,34,35,36,37]. Bi 4 Ti 3 O 12 is composed of perovskite-like (Bi 2 Ti 3 O 10 ) 2 − blocks regularly interleaved with (Bi 2 O 2 ) 2+ units, forming a special layer structure along the [010] direction (b-axis) [38].…”

Enhanced Visible Light Driven Photocatalytic Behavior of BiFeO3/Reduced Graphene Oxide Composites

“…Semiconductor photocatalytic technology can convert solar energy into electrical energy and chemical energy [ 2 , 3 , 4 ]. Many semiconductor materials, such as TiO 2 , ZnO, Fe 2 O 3 , and CdS, have a suitable band structure as a photocatalyst [ 5 , 6 , 7 , 8 ]. Among them, TiO 2 has become the most widely used photocatalyst because of its stable chemical properties, strong oxidation reduction, corrosion resistance, non-toxic, and low cost.…”