Short communicationPhotothermal effect of antimony-doped tin oxide nanocrystals on the photocatalysis
Graphical abstract
Introduction
Nanocrystals of heavily doped-metal oxide semiconductors such as antimony-doped tin oxide (SnO2: Sb) possess strong and broad absorption due to the surface plasmon resonance (LSPR) in the red, near-infrared (NIR) and IR region. Owing to the controllability of the LSPR in a wide wavelength range by varying doping level [[1], [2], [3]], the heavily doped-metal oxide semiconductor nanocrystals have found widespread interest because of the potential applications to a new class of smart windows [4,5], chemical and biosensing, telecommunications, advanced optics and photonics [6,7], and photocatalysis [8]. Recently, gold nanoparticle-based plasmonic photocatalysts have attracted much interest as a solar-to-chemical transformer [[9], [10], [11], [12], [13]], but the study on the metal oxide semiconductor nanocrystal-based plasmonic photocatalyst is still in its infancy [14,15]. While there are many reports on the photocatalytic activity of SnO2 mainly for dye degradation [[16], [17], [18], [19]], the photocatalysis of SnO2: Sb was only reported for polymerization of polyethyleneglycol diacrylate under irradiation of UV- or visible (Vis) light [20]. However, the LSPR-induced plasmonic effect of SnO2: Sb nanocrystals on the photocatalytic activity is unknown.
As the target reaction of this study, we selected amine oxidation, which is one of the important organic synthetic processes [21]. This study shows that the Sb-doping into SnO2 enhances the photocatalytic activity and selectivity for the oxidation of amine to aldehyde due to the LSPR-induced photothermal effect.
Section snippets
Catalyst preparation and characterization
Commercially available Sb-doped SnO2 (SN-100P, Ishihara Sangyo Co., Sb doping amount = 11.6%, mean particle size = 9 nm, specific surface area = 70–80 m2g−1), TiO2 (anatase, SSP-M, Sakai Chemical Industry co. mean particle size = 15 nm, specific surface area = 100 m2g−1) were used for the reaction. For transmission electron microscopy (TEM) characterization, samples were prepared by dropping of a suspension in ethanol onto a copper grid with carbon support collodion film (grid-pitch 150 μm,
Catalysts characterization
SnO2: Sb particles with Sb-mole fraction (xSb / mol% = {Sb/(Sn + Sb)} × 100) = 0, 1.0, 11.6 (specific surface area = 70–80 m2 g−1, SN-100P, Ishihara Sangyo), and for comparison, TiO2 (anatase, SSP-M, Sakai Chemical Industry, mean particle size = 15 nm, specific surface area = 100 m2g−1) were used as the photocatalysts. The SnO2 samples doped with xSb = 1.0% and 11.6% are designated as SnO2: Sb (1) abd SnO2: Sb (12), respectively. Fig. 1a shows transmission electron microscopy (TEM) image of SnO2
Conclusion
This study has shown that Sb-doped SnO2 exhibits a high level of photocatalytic activity for the selective oxidation of amine to aldehyde due to the photothermal effect. We anticipate that Sb-doped SnO2 nanocrystals can be widely used as a key component of the catalysts effectively utilizing the red, NIR, and IR in the sunlight for chemical transformations.
Credit author statement
Shin-ichi Naya: Catalysts characterization, Photocatalytic reaction, and Adsorption properties, Yuya Shite: Catalysts characterization, Hiroaki Tada: Supervision the experimental work and data analysis.
Declaration of Competing Interest
The authors declare that there is no conflict of interest.
Acknowledgement
The authors acknowledge Ishihara Sangyo Co. for the gift of Sb doped-SnO2 samples, and Y. Hamada for experimental support. This work was supported by JST Adaptable and Seamless Technology Transfer Program through Target-driven R&D, JSPS KAKENHI Grant-in-Aid for Scientific Research (C) no. 18 K05280 and 20 K05674, the Futaba Foundation, and Nippon Sheet Glass Foundation for Materials Science and Engineering.
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