Mechanistic Insights and Photodegradation of Heterostructure Graphene Oxide/Titanium Dioxide
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ORIGINAL PAPER
Mechanistic Insights and Photodegradation of Heterostructure Graphene Oxide/Titanium Dioxide Kuo‑Chin Hsu1 · Te‑Hua Fang1 · Chun‑I Lee1 · Tao‑Hsing Chen1 · Tung‑Han Hsieh1
© Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract In this study, the electrospinning method was used to prepare graphene oxide/titanium dioxide (GO/TiO2) nanofibers with different contents of GO as photocatalysts used to degrade methylene blue (MB). Photocatalytic studies suggested that the GO/TiO2 composite nanofibers showed higher photocatalytic activity than pure TiO2 nanofibers under visible and ultraviolet light irradiation and the well-dispersed GO with the content even high as 7 wt%. In addition, the 7% GO/TiO2 nanofibers could almost completely decolor the MB solution that after 90 min under ultraviolet light irradiation, and it can degrade approximately 62% of the MB solution after 4 h under visible light irradiation. Finally, the photocatalysis mechanism for the GO/TiO2 is also discussed. Keywords GO doped TiO2 · Electrospinning · Photocatalytic · Methylene blue
1 Introduction With the rapid development of industry, environmental pollution, such as air pollution and water pollution, has become increasingly more serious. Determine methods by which to effectively reduce pollutants is an important current issue. Many compound semiconductors have been reported to have photocatalytic properties that degrade air and water pollutants. Generally, common semiconductor photocatalysts can be divided into oxide semiconductors, such as TiO2, ZrO2, Nb2O5, Ta2O5, WO3, CuO, Fe2O3 [1, 2] etc., and sulfide semiconductors, such as CdS, ZnS, ZnIn 2S4 [3–5] etc. However, sulfide semiconductors have poor stability due to photo-corrosion effects, so oxide semiconductors are more widely studied than sulfide semiconductors. Among oxide semiconductors, the photocatalytic effect of titanium dioxide (TiO2) may be the most promising for eliminating environmental pollutants, especially the degradation of organic pollutants, because it has high photocatalytic activity, as well as physical and chemical stability and is non-toxic, low cost, and widely available [6, 7]. * Te‑Hua Fang [email protected] 1
Department of Mechanical Engineering, National Kaohsiung University of Science and Technology, Kaohsiung 80778, Taiwan
TiO2 is an n-type semiconductor with a wide energy gap (anatase = 3.2 eV and rutile = 3.0 eV). This is the main disadvantage of T iO2 as a photocatalyst and limits its application in the visible light region, which accounts for approximately 45% of terrestrial sunlight. In order to overcome this problem and effectively use visible light to improve the efficiency of visible light degradation, many scholars have tried to add metals or metal oxides such as Au, Ag, Fe, Pt, Pd, SnO2, SiO2, WO3, and Ag2O [8–11] to titanium dioxide to change the absorption wavelength and reduce its band gap energy. TiO2 doped with metal or metal oxide exhibits better photocatalytic effect and stabili
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