Photocatalytic degradation of organic dyes on Li-doped graphitic carbon nitrides
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Photocatalytic degradation of organic dyes on Li‑doped graphitic carbon nitrides Aixia Geng1 · Yanbo Zhang1 · Xuelian Xu1 · Huiting Bi1 · Junjiang Zhu1 Received: 4 December 2019 / Accepted: 17 January 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract Lithium-doped graphitic carbon nitrides (g-C3N4) with varied lithium contents (i.e., L ir-CN) were synthesized using LiCl and melamine as precursors and then served as catalysts for photocatalytic degradation of dyes in aqueous solution. The samples were characterized by X-ray diffraction patterns, infrared spectroscopy, N2 physisorption isotherms, X-ray photoelectron spectroscopy, UV–Vis diffuse reflectance spectrum, Photoluminescence, and photocurrent measurements. Results indicated that the Li doping slightly increases the surface area and pore size, lowers the band gap, and improves the electron–hole separation efficiency, and in particular, results in the formation of polytriazineimide, which can cooperate with g-C3N4 and yield synergistic contribution to the reaction. Catalytic tests showed that the Li doping enhances the activity of g-C3N4 for photocatalytic degradation of rhodamine B (RhB), with the optimal efficiency obtained at molar ratio of LiCl to melamine equals to 0.5, i.e., L i0.5-CN, which exhibited 93.4% RhB conversion within 30 min. Moreover, L i0.5-CN is also highly active for the removal of other organic dyes, such as methyl orange and methylene blue, potentiating its promising applications for the removal of dyes in complex environment.
1 Introduction Energy crisis and environmental pollutions are two major problems encountered in our society, thus it would be of great significance if we can use inexhaustible solar energy to solve environmental problems. Many attentions have been paid to pollutants removal by photocatalytic techniques in the recent decades, e.g., the photocatalytic degradation of contaminants in wastewater by solar energy [1, 2]. The challenge of this technology is to find a catalyst with suitable band gap and ability to separate electron–hole pairs, in order to efficiently utilize the solar energy and activate the reactants. Aixia Geng and Yanbo Zhang have authors contributed equally to this work. Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10854-020-02932-8) contains supplementary material, which is available to authorized users. * Junjiang Zhu [email protected] 1
Hubei Key Laboratory of Biomass Fibers and Eco‑Dyeing & Finishing, College of Chemistry and Chemical Engineering, Wuhan Textile University, Wuhan 430200, China
Various photocatalysts including CdS [3], TiO2 [4], g-C3N4 [5], AB2O4 spinel oxides [6], and Bi-containing materials [7] have been reported in literatures. Among them, the g-C3N4 is of special interest owing to its low-cost, chemical stability, response to visible light, as well as the straightforward synthesis [8, 9]. However, this material has low surface area and the photo-induced electrons are easy to be r
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