Hierarchical TiO 2 /AgBr core/shell microspheres with enhanced visible light photocatalytic activity
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Hierarchical TiO2/AgBr core/shell microspheres with enhanced visible light photocatalytic activity Kang Yang1 and Xiaogang Wen1,* 1
School of Materials Science and Engineering, Sichuan University, Chengdu 610065, People’s Republic of China
Received: 31 May 2020
ABSTRACT
Accepted: 4 October 2020
TiO2/AgBr core/shell microspheres have been successfully synthesized via a two-step solvothermal process. The TiO2 core (1.5 lm in average diameter) is coated with a shell (100 nm in average thickness) consisting of AgBr nanoparticles of 6 nm in average size. The composite nanomaterials demonstrate much stronger light absorbance, narrower bandgap, and lower recombination rate of photogenerated electron–hole pairs than both bare TiO2 microspheres and pure AgBr nanoparticles, which endue it with much enhanced photocatalytic activity. The as-prepared TiO2/AgBr photocatalyst exhibits excellent photocatalytic degradation performance towards methylene blue (MB) under visible light irradiation, and 92% MB could be degraded in 90 min, which is much higher than that of bare TiO2 (11%) and pure AgBr (52%). TiO2/AgBr core/shell microsphere photocatalyst also demonstrates good reusability, and the photocatalytic activity has no obvious decrease after five cycles. This study may provide a new insight into the design and synthesis of visible light photocatalytic materials.
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Springer Science+Business
Media, LLC, part of Springer Nature 2020
1 Introduction Semiconductor-based heterogeneous photocatalysis has been attracting a great deal of interest owing to its extensive applications especially in utilization of solar energy, environmental remediation and selective chemical synthesis [1–6]. Among various available semiconductor materials, TiO2, the ‘‘golden’’ photocatalyst, has been regarded as the most promising one and most widely employed in photocatalytic fields, because of its physical and chemical stability, high chemical inertness, easy availability,
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https://doi.org/10.1007/s10854-020-04612-z
nontoxicity, low cost, and unique electronic and optical properties [4–7]. However, the practical application of TiO2 has been greatly hampered by its large bandgap (3.2 eV), which leads to a low quantum efficiency because only about 4% (ultraviolet light part) solar spectrum can be used by pure TiO2. In order to extend the solar spectrum response to visible region, which accounts for about 43% of sunlight, a variety of strategies have been developed, for example, modifying with metals including Au [8, 9], Ag [8, 9], Pd [10], Pt [11], Rh [12], Cr [13], Mn [13], etc., or nonmetal elements including N [14], S [15], I [16], F [17], etc., compositing with
J Mater Sci: Mater Electron
semiconductor co-catalysts with narrower bandgap, for example, CdS [18, 19], Fe3O4 [20], CuS [21], surface photosensitization with dye [22], etc. Among all these strategies, combining TiO2 with narrow gap semiconductor co-catalyst has been confirmed to be significantly effective in strengthening the visi
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