Cellulose-Derived Hierarchical g-C₃N₄/TiO₂-Nanotube Heterostructured Composites with Enhanced Visible-Light Photocatalytic Performance

Abstract

A novel cellulose-derived hierarchical g-C3N4/TiO2-nanotube heterostructured nanocomposite was fabricated by in situ coating thin g-C3N4 layers onto the surfaces of the TiO2 nanotubes, which were synthesized by utilizing the natural cellulose substance (e.g., commercial ordinary filter paper) as the structural template. These g-C3N4/TiO2-nanotube composites with varied thicknesses (ca. 3–30 nm) of the outer g-C3N4 layers displayed improved visible-light (λ > 420 nm)-driven photocatalytic degradation performances toward methylene blue. The optimal nanocomposite with an outer g-C3N4 layer of ca. 7.5 nm composed of 46 wt % g-C3N4 displayed an apparent rate constant of 0.0035 min–1, which was 8.5- and 4-fold larger than those of the referential TiO2-nanotube and g-C3N4 powder. The excellent and durable photocatalytic activities of these cellulose-derived g-C3N4/TiO2-nanotube composites were ascribed to their hierarchically network porous structures replicated from the cellulose template, as well as the formation of close heterojunctions in-between the g-C3N4 and TiO2 phases. Moreover, it was demonstrated that the photocatalytic mechanism matched with the type-II heterostructured model, while the main effective species during the photocatalytic processes of the nanocomposite were proved to be superoxide radicals.

Synthesis of g‐C3N4, Zn3(PO4)2 and g‐C3N4/Zn3(PO4)2 Composites for Application in Photodegradation of Crystal Violet Dye under Solar Light

“…The peak at 398.4 eV and 400.1 eV is ascribed to sp 2 hybridized nitrogen atoms in C=N−C groups and derives from the NHx groups in g‐C 3 N 4 respectively [68,69] . Besides these peaks, two other peaks at 399.3 eV and 396.5 eV are described by the N‐C 3 groups [70] and the N−Zn respectively [54]…”

“…The peak at 398.4 eV and 400.1 eV is ascribed to sp 2 hybridized nitrogen atoms in C=NÀ C groups and derives from the NHx groups in g-C 3 N 4 respectively. [68,69] Besides these peaks, two other peaks at 399.3 eV and 396.5 eV are described by the N-C 3 groups [70] and the NÀ Zn respectively. [54] The high-resolution spectra of Zn 2p (Figure 8d) exhibited two major peaks at 1021.2 and 1044.2 eV corresponding to Zn 2p 3/2 and Zn 2p 1/2 respectively.…”

Carbon Nanomaterials for Wastewater Treatment

“…This has been attributed to the higher porosity of g-C 3 N 4 by added graphene (G) and due to the significant reduction in combinatorial charge carriers in TiO 2 . Similarly to these studies, recently cellulose-derived hierarchical composites of g-C 3 N 4 were also prepared in combination with TiO 2 (g-C 3 N 4 / TiO 2 -nanotube), which displayed a higher photocatalytic activity than pure g-C 3 N 4 [27].…”

“…Due to high porosity and high surface-to-volume ratio, CNTs have revealed an exceptionally high sorption capacity [26] as compared to conventional granular and powdered activated carbon (AC) [24]. The CNTs as nanoporous adsorbents are also used effectively in removal of various biological contaminants and to enhance the photocatalytic activities of TiO 2 semiconductors by controlling charge separation [27]. CNTs in combination with TiO 2 are able to enhance the decomposition of organic pollutants in the presence of UV light radiation.…”

Functionalized Graphitic Carbon Nitrides for Environmental and Sensing Applications

“…Another limitation of g‐C 3 N 4 ‐based hierarchical structures is their inadequate structural porosity and recombination of photogenerated charges. Thus, Huang and coworkers [ 127 ] fabricated a unique cellulose‐derived hierarchical g‐C 3 N 4 /TiO 2 ‐nanotube heterostructure. As shown in Figure , the surface sol–gel process was used to fabricate the g‐C 3 N 4 /TiO 2 ‐NT nanocomposite.…”