A new double Z‐scheme TiO₂/ZnO‐g‐C₃N₄ nanocomposite with enhanced photodegradation efficiency for Rhodamine B under sunlight

Abstract

The double Z-scheme TiO 2 /ZnO-g-C 3 N 4 nanophotocatalyst was prepared by sol-gel method and solvothermal method. X-ray diffractometer, FT-IR, transmission electron microscopy, energy dispersive X-ray spectrum, ultraviolet-visible (UV-vis), PL, EIS, and so on were used to characterize the structure, morphology, chemical composition, and optical properties of the prepared photocatalyst. And Rhodamine B (RhB) was used as a simulated organic pollutant to study the photocatalytic performance of the photocatalyst. The experimental results show that the double Z-scheme TiO 2 / ZnO-g-C 3 N 4 nanophotocatalyst exhibits high photocatalytic performance under both ultraviolet light and sunlight, and the RhB in the solution can be completely removed in 120 min. This article also proposes a possible Z-scheme photocatalytic mechanism to explain the increased photocatalytic activity.double Z-scheme photocatalysis, Rhodamine B, solar-driven photocatalyst, TiO 2 /ZnO/g-C 3 N 4 | INTRODUCTIONWith the rapid development of the world economy, various drugs, insecticides, and dyes have been used in large quantities, 1,2 such as dicofol, atrazine, methyl parathion, and macarbazepine, broadspectrum antibiotics, and so forth. These organic matter are widely present in water and soil, and long-term accumulation will inevitably cause harm to the environment and humans. [3][4][5] In order to solve these problems, semiconductor photocatalysis technology is considered to be one of the most effective methods to deal with organic pollutants. 6,7 Photocatalytic technology is a practical method to convert solar energy into chemical energy, because only solar radiation and suitable semiconductor materials can drive the photocatalytic reaction, and then degrade organic pollutants in the water into harmless inorganic small molecules. 8,9 The key to obtaining high photocatalytic activity is to find an efficient and stable photocatalyst, such as metal oxides, sulfides, MoF materials, and so forth, and then apply it to the treatment of organic pollutants in the environment. 10,11 At present, the most studied photocatalyst is TiO 2 , because it is chemically and biologically inert, nontoxic, and can be used under normal temperature conditions. 12 However, it still has some shortcomings, such as a large forbidden band width (Eg = 3.2 eV), a faster e À -h + pairs recombination rate, and weak redox ability. [13][14][15] Researchers have carried out a series of studies on these shortcomings of TiO 2 , such as improving its photocatalytic performance by modifying its structure, size, microscopic morphology, and so forth, or combining or supporting TiO 2 with other substances. 16,17 Hayati 18 synthesized dendrimer-titania nanocomposite, which can effectively remove direct blue 78 (DB78) and direct red 80 (DR80). Jinse 19 successfully synthesized Au-NPsdecorated ZnO-TiO 2 core-shell NW on Si wafers by chemical vapor deposition and photo precipitation, which has high light conversion efficiency. Shi 20 synthesized hydrogenated TiO 2 , fluorine-doped TiO 2 , an...

Synthesis of TiO₂/ZnO Nanocomposites by the Electrochemical Method and Their Application in Dye-Sensitized Solar Cells (DSSCs)

“…6 indicated that the NPs were prepared in the nanometer range and some of the NPs were well separated from each other, while most of them were present in the agglomerated form of tiny crystals. This agglomeration is due to electrostatic effects, which reveals that this agglomeration behavior of NPs is consistent with a behavior similar to the agglomeration of NPs in previous studies [24][25]. In addition, they provide evidence of ZnO NPs' rod-like morphology.…”

Reusable isotype heterojunction g-C3N4/alginate hydrogel spheres for photocatalytic wastewater treatment

“…Fortunately, heterojunction device designs may improve charge separation. [17][18][19] In a typical charge transfer pathway through a heterojunction (Type II), excited electrons move to a semiconductor with a relatively lower conduction band, whereas holes move to another semiconductor with a higher valence band, thus enhancing charge separation. 20 Previous efforts to produce g-C 3 N 4 heterojunctions have involved the complex, prolonged, and wasteful synthesis of composites that include metal oxides.…”

Visible-Light Photocatalytic Degradation Efficiency of Tetracycline and Rhodamine B Using a Double Z-Scheme Heterojunction Catalyst of UiO-66-NH2/BiOCl/Bi2S3

“…Among them, construction of heterojunctions, especially Z-scheme hetero- junctions, has been shown to be an effective route that can broaden the light response range and increase the separation of photogenerated electron−hole pairs. 32 Compared with a conventional heterojunction, the Z-scheme heterojunction can retain high redox potential of the system 33 and have stronger photocatalytic performance. In addition, optimal redox ability for a specific photocatalytic reaction and the possibility to adjust the migration path of photogenerated charges are provided by the unique Z-type channel.…”

“…However, the photocatalytic ability of BiOCl under visible light is still limited because of its weak visible light absorption capacity and low photogenerated electron–hole pair separation rate. − Various strategies to enhance the photocatalytic performance of BiOCl include defect construction, , impurity doping, , construction of heterojunctions, , and so on. Among them, construction of heterojunctions, especially Z-scheme heterojunctions, has been shown to be an effective route that can broaden the light response range and increase the separation of photogenerated electron–hole pairs . Compared with a conventional heterojunction, the Z-scheme heterojunction can retain high redox potential of the system and have stronger photocatalytic performance.…”