La-Doped ZnO/g-C 3 N 4 Heterojunction for Efficient Degradation of Organic Contamination Under Visible Light Irradiation
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La-Doped ZnO/g-C3N4 Heterojunction for Efficient Degradation of Organic Contamination Under Visible Light Irradiation Gengsheng Xu1,2 · Fangfang You1 · Xu Li3 Received: 5 June 2020 / Accepted: 30 September 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract Considering the accelerated charge/mass transfer and the formation of active defects at the heterointerface, La-ZnO/g-C3N4 heterogeneous photocatalysts were facilely prepared via a two-step route consisting of hydrothermal and calcination processes in this work. The combination of La3+ doping in ZnO and the contact between La-ZnO and g-C3N4 endowed the heterogeneous composite with a much enhanced photocatalytic activity towards methyl blue (MB) dye decolorization under the visible light irradiation. It was found that La-ZnO/g-C3N4-4.6 showed an optimal degradation rate of MB (8.72 × 10− 2 min− 1), which is 14 times higher than that of pure g-C3N4 (6.23 × 10− 3 min− 1) under the same experimental conditions. The improved photocatalytic MB decolorization is attributed to the increased interfacial electron-hole separation efficiency through constructing La-ZnO/g-C3N4 heterogeneous interfaces. The present study manifests the advantage of heterogeneous interfaces as the charge carrier separation pathway towards boosting photocatalytic activity. Keywords Graphitic carbon nitride · Photocatalytic degradation · Heterostructure · La-doped ZnO
1 Introduction As a very cost-effective and environmental friendly technique, solar-driven photocatalysis using semiconductor photocatalysts has shown a great potential in hydrogen generation, carbon dioxide conversion as well as water/air purification [1–3], especially the removal of organic pollutant from waste water stream [4]. The main effort is to develop highly efficient and cost-effective photocatalysts with a superior durability. Graphitic carbon nitride (g-C3N4) [5, 6], as a polymeric photocatalyst, has been deeply studied because of various advantages such as nontoxicity, facile synthetic route, metal-free characteristic as well as a superior stability against thermal, chemical and light irradiation * Gengsheng Xu [email protected] 1
School of Chemistry and Chemical Engineering, Anhui University, Hefei 230601, People’s Republic of China
2
Anhui Province Key Laboratory of Chemistry for Inorganic/Organic Hybrid Functionalized Materials, Anhui University, Hefei 230601, People’s Republic of China
3
Center for Advanced Measurement Science, National Institute of Metrology, Beijing 100029, People’s Republic of China
or corrosion. Lacking of charge carrier transport channel, a rapid recombination of photogenerated charge carriers is a dominant factor limiting the photoquantum efficiency, thus leading to an unsatisfactory photocatalytic performance of bulk g-C3N4 [7, 8]. To address this problem, diverse strategies were developed mainly in terms of morphology control or compositional modification. Microstructurally, the size reduction via advanced exfoliation techniques or p
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