Heterostructured Nitrogen and Sulfur co-doped Black TiO 2 /g-C 3 N 4 Photocatalyst with Enhanced Photocatalytic Activity
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doi: 10.1007/s40242-020-0175-2
Article
Heterostructured Nitrogen and Sulfur Co-doped Black TiO2/g-C3N4 Photocatalyst with Enhanced Photocatalytic Activity MENG Zeshuo1#, ZHOU Bo1,3#, XU Jian1, LI Yaxin1, HU Xiaoying2 and TIAN Hongwei1* 1. Key Laboratory of Automobile Materials of Ministry of Education, School of Materials Science and Engineering, Jilin University, Changchun 130012, P. R. China; 2. Laboratory of Materials Design and Quantum Simulation, College of Science, Changchun University, Changchun 130022, P. R. China; 3. State Key Laboratory of Metal Material for Marine Equipment and Application, Anshan Iron and Steel Group Corporation, Anshan 114009, P. R. China Abstract Conventional titanium dioxide(TiO 2) photocatalyst could absorb only ultraviolet light due to its wide bandgap. In this paper, black TiO2 with narrow bandgap was prepared by introducing oxygen vacancies. Meanwhile, nitrogen(N) and sulfur(S) elements were doped to further broaden the visible light response range of TiO 2(NS-BT), and then heterostructured N,S-doped black TiO2/g-C3N4(CN/NS-BT) was successfully constructed by easily accessible route. The formation of CN/NS-BT heterojunction structure increased the generation and separation efficiency of photogenerated electron-hole pairs, as well as accelerated the transfer rate of the carriers. The as-prepared CN/NS-BT exhibited excellent photocatalytic performance towards the degradation of Rhodamine B(RhB) under visible light irradiation with satisfactory stability. The apparent reaction rate constant of CN/NS-BT(0.0079) was 15.8-fold higher than that of commercial P25(0.0005). The structure, morphology, chemical composition and optical properties of the as-prepared CN/NS-BT were characterized by various analytical methods, and possible photocatalytic enhancement mechanism was proposed. Overall, CN/NS-BT composites look promising as photocatalytic material for future environmental treatment. Keywords Black TiO2; g-C3N4; N, S doping; Heterostructure photocatalyst; Visible light photodegradation
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Introduction
In the past decades, semiconductor photocatalysts have gained increasing attention for environment purification [1] and solar energy conversions[2] due to several features, such as rapid oxidation, high oxidation effect and low formation of byproducts[3―7]. The excellent photocatalytic properties of TiO2 single crystal electrode have been first reported by Fujishima et al. in 1972[8]. Since then TiO2 has been considered as a potential semiconductor photocatalyst because of its low cost, easy preparation, non-toxicity to the environment, and stable chemical properties[9]. However, pure phase TiO2 possesses a wide bandgap(ca. 3.2 eV) for practical applications, leading to low quantum utilization rates and high charge-carrier recombination rates[10]. Moreover, commercial TiO2 mainly works under UV light irradiation at wavelengths shorter than 387 nm, corresponding to only 4% of the solar spectrum. These short-
comings limited the practical applications of commercial TiO2[11]. In recent
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