Abstract
In recent years, defective TiO2-based composite nanomaterials have received much attention in the field of photocatalysis. In this work, TiB2 was used as a precursor to successfully prepare Ti3+ defective TiO2 (TiO2-B) with a truncated bipyramidal structure by a one-step method. Then, the SnS2 nanosheets were assembled onto the as-prepared TiO2-B through simple hydrothermal reaction. TiO2-B exhibits strong visible light absorption properties, but the recombination rate of the photo-generated electron-hole pair was high and does not exhibit ideal photocatalytic performance. Upon introducing SnS2, the heterojunction catalyst SnS2-Ti3+ defective TiO2 (SnS2/TiO2-B) not only possesses the strong light absorption from UV to visible light region, the lowest photo-generated charge recombination rate but also achieves a more negative conduction band potential than the reduction potential of CO2 to CO, and thereby, exhibits the significantly enhanced selectivity and yield of CO in photocatalytic CO2 reduction. Notably, SnS2/TiO2-B produces CO at a rate of 58 µmol·h−1·g−1 with CO selectivity of 96.3% under visible light irradiation, which is 2 and 19 times greater than those of alone TiO2-B and SnS2, respectively. Finally, a plausible photocatalytic mechanism on SnS2/TiO2-B was proposed that the electron transfer between TiO2 and SnS2 follows the Z-scheme mode. Our results present an effective way to gain highly efficient TiO2 based photocatalysts for CO2 reduction by combining different modification methods of TiO2 and make full use of the synergistic effects.
Highlights
In modern society, the energy crisis and global warming have been two serious issues for human beings to face
We report a facile approach to synthesize a heterojunction catalyst combing the Ti3+ defective TiO2 nanoplates and SnS2 nanosheets for enhancing the photocatalytic activity and selectivity towards CO2 reduction
We have successfully synthesized dark blue TiO2 nanoplates containing a large amount of Ti3+ defects
Summary
The energy crisis and global warming have been two serious issues for human beings to face As it is known, most of the energy demands are fulfilled through the combustion of fossil fuels, and the excessive utilization of fossil fuels cause the ever-increasing emission of greenhouse gas CO2 , a major contributor to global warming [1,2]. Titanium dioxide (TiO2 ), as a typical semiconductor, has gained lots of interest due to its environmental friendliness, low cost, resistance to light corrosion, and high stability [4,5,6]. It has drawbacks in terms of the ineffective utilization of visible light and low quantum efficiency. Catalysts 2019, 9, 927 due to its wide band gap (3.2 eV) and high recombination of photo-generated electron-hole pairs [7].
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