Aligned macroporous TiO2/chitosan/reduced graphene oxide (rGO) composites for photocatalytic applications

Abstract

In this paper ice templating is used to fabricate novel TiO 2 /chitosan/reduced graphene oxide (rGO) composites with a highly aligned macroporous structure for photocatalytic applications. The structure of the composites was readily tailored using the composite composition, for example the lamellar pore width decreased from 50-45 µm to 5-10 µm, while the lamellar thickness increased from 2-3 to 20-25 µm, with an increase of the TiO 2 content from 45 to 77 vol.%. Lamellar pore channels between the layers exhibited a more uniform distribution when the rGO content was 1.0 wt.%. The increase in viscosity of the composites with high TiO 2 contents led to the formation of smaller ice crystals and smaller lamellar pore sizes to enable the production of composite structures with improved mechanical strength. The TiO 2 /chitosan/rGO composites exhibited excellent photocatalytic degradation of methyl orange and the photocatalytic efficiency was optimized by control of the active material content and microstructure. The hybrid composites with 1.0 wt.% rGO showed a degradation percentage of 97%, which makes these novel TiO 2 /chitosan/rGO freeze cast structures attractive materials as high performance and high strength substrates for photocatalytic degradation applications.

Chitosan-TiO2: A Versatile Hybrid Composite

“…Amin and Panhius [23] reported that TiO 2 (30% vs. 70% CS) significantly improves the mechanical properties (an increase of Young's modulus in 11.8-fold, a six-fold increase for both tensile strength and toughness) of the CS film. Similar trends were reported during the evaluation of CS-TiO 2 mechanical properties [27,[58][59][60][61]. Al-Sagheer and Merchant [62] mentioned that the viscoelastic properties for hybrid composites, particularly CS/TiO 2 -based composites, depend on the bonding between the polymer-particle interfaces.…”

“…Zhu et al [97] mentioned that the addition of ZnO into the TiO 2 matrix (TiO 2 :ZnO) and then to the CS matrix has a beneficial role in improving the charge separation and extending the response of the composite to visible light. Additionally, it has been reported that a CS-TiO 2 -rGo composite performs well as a MO degrader (97%) [58]. Meanwhile, Dhanya and Aparna [88] reported that CS may be a good and economically support for TiO 2 immobilization (by hydrogel method), and the resultant composite exhibited a 100% of degradation of MO and alizarin red dyes after 3 h of treatment under UV light (293 nm) irradiation.…”

Reduced Graphene Oxide–P25 Nanocomposites as Efficient Photocatalysts for Degradation of Bisphenol A in Water

“…For instance, fast h + /e − recombination [13]; the large bandgap energy of 3.2 eV can only be excited by ultraviolet light (UV) with a wavelength less than 387 nm [3,6,[14][15][16][17]. In recent years, scientists have advanced many strategies in order to further improve the photocatalytic performance of TiO 2 , such as doping with non-metallic elements, combining with metal ions, depositing noble metals, and creating heterojunctions with other semiconductors [12,[18][19][20][21][22]. More recently, in contrast to other materials, graphene, graphene oxide (GO), and the graphene monolith formed by the stripping of GO, reduced graphene oxide (rGO) used in this experiment received wider attention because of its good mechanical strength, high electron mobility, chemical stability, optical properties, and high surface area [23][24][25][26][27].…”

Production of Titanium Dioxide/Reduced Graphene Oxide Composites and Investigation of Their Photocatalytic Properties

“…Son yıllarda özellikle karbon esaslı malzemelerden; karbon nanotüp [13], grafen [14] ve indirgenmiş grafen oksit [15] [16][17][18]. Grafen, geniş yüzey alanına sahip olmasının yanı sıra yüksek elektron mobilitesi, absorplama ve ışığa karşı duyarlılığı arttırma yetenekleri sayesinde ışıkla uyarılmış olan elektronları TiO2 bant aralığında hızlıca ileterek yarıiletken malzemelerin fotokatalitik aktivitesini geliştirmektedir [16,[19][20][21][22]. Ancak, grafenin hidrofobik yapıda olması çözelti içerisinde homojen bir şekilde dağılmasını engellemektedir.…”