A Facile One-Pot Approach to the Fabrication of Nanocellulose-Titanium Dioxide Nanocomposites with Promising Photocatalytic and Antimicrobial Activity

The combination of cellulosic materials and metal oxide semiconductors can provide composites with superior functional properties compared to cellulose. By using nanocellulose derived from agricultural waste, we propose a one-pot and environmentally friendly approach to the synthesis of nanocellulose-TiO₂ (NC-TiO₂) nanocomposites with peculiar photocatalytic activity and antibacterial effects. The as-prepared NC-TiO₂ composites were fully characterized by different techniques, such as X-ray diffraction (XRD), μ-Raman, Fourier transform infrared spectroscopy (FTIR), thermogravimetry analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and diffuse reflectance spectroscopy (DRS). The results showed that well crystalline anatase TiO₂ nanoparticles of about 5-6 nm were obtained. The photocatalytic activity in particular was evaluated by using methyl orange (MO) solution as a target pollutant at different pH values. It was found that all the tested NC-TiO₂ nanocomposites showed stable photocatalytic activity, even after consecutive photocatalytic runs. In addition, NCT nanocomposites with higher TiO₂ content showed degradation efficiency of almost 99% towards MO after 180 min of UV illumination. Finally, NC-TiO₂ nanocomposites also showed intriguing antimicrobial properties, demonstrating to be effective against Gram-positive (Staphylococcus aureus, Bacillus subtilis) with 20-25 mm of inhibition zone and Gram-negative bacteria (Escherichia coli, Pseudomonas aeuroginosa) with 21-24 mm of inhibition zone, and fungi (Candida albicans) with 9-10 mm of inhibition zone.

Block Copolymer and Cellulose Templated Mesoporous TiO2-SiO2 Nanocomposite as Superior Photocatalyst

A dual soft-templating method was developed to produce highly crystalline and mesoporous TiO2-SiO2 nanocomposites. Pluronic F127 as the structure-directing agent and pure cellulose as the surface area modifier were used as the templating media. While Pluronic F127 served as the sacrificing media for generating a mesoporous structure in an acidic pH, cellulose templating helped to increase the specific surface area without affecting the mesoporosity of the TiO2-SiO2 nanostructures. Calcination at elevated temperature removed all the organics and formed pure inorganic TiO2-SiO2 composites as revealed by TGA and FTIR analyses. An optimum amount of SiO2 insertion in the TiO2 matrix increased the thermal stability of the crystalline anatase phase. BET surface area measurement along with low angle XRD revealed the formation of a mesoporous structure in the composites. The photocatalytic activity was evaluated by the degradation of Rhodamine B, Methylene Blue, and 4-Nitrophenol as the model pollutants under solar light irradiation, where the superior photo-degradation activity of Pluronic F127/cellulose templated TiO2-SiO2 was observed compared to pure Pluronic templated composite and commercial Evonik P25 TiO2. The higher photocatalytic activity was achieved due to the higher thermal stability of the nanocrystalline anatase phase, the mesoporosity, and the higher specific surface area.

Adsorption-photocatalysis performance of polyaniline/dicarboxyl acid cellulose@graphene oxide for dye removal

A novel 3-D biopolymer-based adsorption-photocatalytic composite, polyaniline/dicarboxyl acid cellulose@graphene oxide was synthesized and was employed to remove the reactive brilliant red K-2G from aqueous solution. The addition of dicarboxyl acid cellulose could improve the morphology, structure, stability and dispersity of the nanocomposite, thus providing excellent adsorption and photocatalysis performance to the product. Batch of experiments were conducted in two scenarios: adsorption followed by photocatalysis process and simultaneous adsorption-photocatalysis process. For the first scenario, adsorption equilibrium can be reached within 25 min, the expected adsorption capacity was 447.0 mg·g^-1; the subsequent photocatalysis process was carried out under light irradiation and the removal capacity could further improve to 729.0 mg·g^-1 under equilibrium state (about 180 min). For the simultaneous adsorption-photocatalytic process, the removal capacity was about 558.1 mg·g^-1 at about 25 min and the total removal capacity could reach to 733.3 mg·g^-1 under equilibrium state. PANI-DCC@GO exhibited excellent reusability and had potential in the treatment of dyes polluted wastewater.

A Bio-Inspired Nanotubular Na2MoO4/TiO2 Composite as a High-Performance Anodic Material for Lithium-Ion Batteries

A train of bio-inspired nanotubular Na₂MoO₄/TiO₂ composites were synthesized by using a natural cellulose substance (e.g., commercial ordinary filter paper) as the structural template. The TiO₂ gel films were coated on the cellulose nanofiber surfaces via a sol-gel method firstly, followed with the deposition of the poly(diallyldimethylammonium chloride)/Na₂MoO₄ (PDDA/Na₂MoO₄) bi-layers several times, through the layer-by-layer self-assembly route, yielding the (PDDA/Na₂MoO₄)_n/TiO₂-gel/cellulose composite, which was calcined in air to give various Na₂MoO₄/TiO₂ nanocomposites containing different Na₂MoO₄ contents (15.4, 24.1, and 41.4%). The resultant nanocomposites all inherited the three-dimensionally porous network structure of the premier cellulose substance, which were formed by hierarchical TiO₂ nanotubes anchored with the Na₂MoO₄ layers. When employed as anodic materials for lithium-ion batteries, those Na₂MoO₄/TiO₂ nanocomposites exhibited promoted electrochemical performances in comparison with the Na₂MoO₄ powder and pure TiO₂ nanotubes, which was resulted from the high capacity of the Na₂MoO₄ component and the buffering effects of the TiO₂ nanotubes. Among all the nanotubular Na₂MoO₄/TiO₂ composites, the one with a Na₂MoO₄ content of 41.4% showed the best electrochemical properties, such as the cycling stability with a capacity of 180.22 mAh g⁻¹ after 200 charge/discharge cycles (current density: 100 mA g⁻¹) and the optimal rate capability.

Factors Affecting the Nonsolvent-Induced Phase Separation of Cellulose from Ionic Liquid-Based Solutions

In the present work, we report for the first time an in-depth study of the factors influencing porous cellulose film structure formation during the nonsolvent-induced phase separation (NIPS) process from biopolymer solutions in ionic liquid-based solvents. The length of the alkyl chain of the ionic liquid's cation, the solvent/co-solvent ratio, and the type of the cellulose precursor used were found to have great influence both on cellulose solution formation and properties and to the NIPS process with water acting as nonsolvent. In the undiluted form, both studied ionic liquids proved to dissolve almost equally well the cellulose; however, due to differences in viscosities of the formed biopolymer solutions and due to differences in miscibility with water of the two ionic liquids, the used ionic liquid had a strong influence on the film's porous structure formation. The use of increasing amounts of an aprotic co-solvent, here dimethylsulfoxide, improved biopolymer solubilization and also led to the formation of a more pronounced macroporous structure during the NIPS process. The cellulose type also affected the porous structure generation during the NIPS process: with the increase of the molecular weight of the precursor, the viscosity of the formed biopolymer solution increased and the tendency to generate macroporous structures decreased.

An overview on cellulose-based material in tailoring bio-hybrid nanostructured photocatalysts for water treatment and renewable energy applications

A combination between the nanostructured photocatalyst and cellulose-based materials promotes a new functionality of cellulose towards the development of new bio-hybrid materials for various applications especially in water treatment and renewable energy. The excellent compatibility and association between nanostructured photocatalyst and cellulose-based materials was induced by bio-combability and high hydrophilicity of the cellulose components. The electron rich hydroxyl group of celluloses helps to promote superior interaction with photocatalyst. The formation of bio-hybrid nanostructured are attaining huge interest nowadays due to the synergistic properties of individual cellulose-based material and photocatalyst nanoparticles. Therefore, in this review we introduce some cellulose-based material and discusses its compatibility with nanostructured photocatalyst in terms of physical and chemical properties. In addition, we gather information and evidence on the fabrication techniques of cellulose-based hybrid nanostructured photocatalyst and its recent application in the field of water treatment and renewable energy.

A hierarchically structured anatase-titania/indium-tin-oxide nanocomposite as an anodic material for lithium-ion batteries

A nanotubular titania/ITO nanocomposite is synthesized, exhibiting enhanced electrochemical performance as an anodic material for lithium-ion batteries.

Cellulose-Rich Nanofiber-Based Functional Nanoarchitectures

Surface self-assembly of functional molecules or nanoscale building blocks is an effective strategy for the syntheses of advanced materials. Natural cellulose-rich substances have unique macro-to-nano hierarchical structural features. The fabrication of nanoarchitectures, employing specific guest species on the surfaces of the fine structures of such substances, results in corresponding artificial nanomaterials that possess the chemical functionalities and physical properties of both sides. Metal oxide thin film coatings with nanometer precision on the nanofibers of bulk cellulose-rich substances not only yield replicas of nanostructured materials, but also make it possible for further assemblies of functional units on the surfaces. Hence, nanostructured metal oxides and further composites, as well as surface-functionalized cellulose-based composites are fabricated by employing cellulose-rich substances as templates or scaffolds. The three-dimensional cross-linked porous structures, with the high surface area of the resultant nanomaterials or composites, lead to superior performance when employed as photocatalysts, electrode materials, and sensing matrices, on which this report is focused.

Solution combustion synthesis and physico-chemical properties of ultrafine CeO2 nanoparticles and their photocatalytic activity

Solution combustion method was adopted for the preparation of ultrafine cerium oxide nanoparticles, which act as excellent photocatalysts for the degradation of dye from aqueous solution.

In situ growing directional spindle TiO2 nanocrystals on cellulose fibers for enhanced Pb(2+) adsorption from water

TiO2/cellulose nanocomposite was synthesized by in situ generation of titanium dioxide (TiO2) nanocrystals on cellulose fibers (CF) via facile hydrolysis of TiOSO4. Cellulose was intended as a scaffold to immobilize TiO2 nanoparticles (NPs), but turned out surprisingly to be also a chemical template that directed the crystal growth. As a result, spindle rutile TiO2 crystals were nicely formed on the surface of cellulose. These crystals were further controlled to disperse uniformly without agglomeration for better use of their surface area to adsorb heavy metals. The TiO2/CF composite showed enhanced adsorption capacity, good regenerability and selectivity for lead (Pb(2+)) removal. In addition, the composite fibers were readily fabricated into a nonwoven filter bed through which dynamic filtration experiment was conducted. A 12-fold increase in filtered bed volume was achieved for TiO2/CF bed compared with pure CF bed before breakthrough took place. This work provides a green pathway for fabricating low cost, high efficiency and engineering application possible nanosorbents for water decontamination.

Two step and one step preparation of porous nanocomposite cellulose membranes doped with TiO2

A facile and easily up-scalable method for the preparation of catalytically active TiO₂ doped cellulose membranes has been developed.

Titania synthesized through regulated mineralization of cellulose and its photocatalytic activity

Cellulose mineralization by titania is brought under control via restricted hydration of fibrils that provides precise localization of the fast hydration/condensation reactions proceeding in situ.

Routes towards catalytically active TiO2 doped porous cellulose

Cellulose–TiO₂ membranes with photocatalytic activity were prepared by non-solvent induced phase separation from cellulose solutions in ionic liquids or from cellulose acetate solutions in organic solvents followed by deacetylation.