Cellulose nanocrystal/hexadecyltrimethylammonium bromide/silver nanoparticle composite as a catalyst for reduction of 4-nitrophenol

Preparation of nanocellulose/reduced graphene oxide matrix loaded with cuprous oxide nanoparticles for efficient catalytic reduction of 4-nitrophenol

The paper reports on the preparation of cellulose nanocrystals/reduced graphene oxide matrix loaded with cuprous oxide nanoparticles (CNC/rGO-Cu2O) through a simple solvothermal method and its application for 4-nitrophenol reduction to 4-aminophenol using sodium borohydride. The CNC/rGO-Cu2O nanocomposite was formed chemically by first mixing CNC and graphene oxide (GO) followed by complexation of the negatively charged functional groups of CNC/GO with Cu2+ ions and subsequent heating at 100°C. This resulted in the simultaneous reduction of GO to rGO and the formation of Cu2O nanoparticles. The as-elaborated nanocomposite was firstly characterized using different techniques such as atomic force microscopy, scanning electron microscopy, transmission electron microscopy, UV-Vis spectrophotometry, Raman spectroscopy and x-ray photoelectron spectroscopy. Then, it was successfully applied for efficient catalytic reduction of 4-nitrophenol to 4-aminophenol using sodium borohydride: the reduction was completed in about 6 min. After eight times use, the catalyst still maintained good catalytic performance. Compared to CNC/rGO, rGO/Cu2O and free Cu2O nanoparticles, the CNC/rGO-Cu2O nanocomposite exhibits higher catalytic activity even at lower copper loading.

B and N Codoped Cellulose-Supported Ag-/Bi-Doped Mo(S,O)3 Trimetallic Sulfo-Oxide Catalyst for Photocatalytic H2 Evolution Reaction and 4-Nitrophenol Reduction

Cellulose plays a significant role in designing efficient and stable cellulose-based metallic catalysts, owing to its surface functionalities. Its hydroxyl groups are used as anchor sites for the nucleation and growth of metallic nanoparticles and, as a result, improve the stability and catalytic activity. Meanwhile, cellulose is also amenable to surface modifications to be more suitable for incorporating and stabilizing metallic nanoparticles. Herein, the Ag-/Bi-doped Mo(S,O)3 trimetallic sulfo-oxide anchored on B and N codoped cellulose (B-N-C) synthesized by a facile approach showed excellent stability and catalytic activity for PHER at 573.28 μmol/h H2 with 25 mg of catalyst under visible light, and 92.3% of the 4-nitrophenol (4-NP) reduction was achieved within 135 min by in situ-generated protons. In addition to B and N codoping, our use of the calcination method for B-N-C preparation further increases the structural disorders and defects, which act as anchoring sites for Ag-/Bi-doped Mo(S,O)3 nanoparticles. The Ag-/Bi-doped Mo(S,O)3@B-N-C surface active site also stimulates H2O molecule adsorption and activation kinetics and reduces the photogenerated charge carrier's recombination rate. The Mo4+ → Mo6+ electron hopping transport and the O 2p and Bi 6s orbital overlap facilitate the fast electron transfer by enhancing the electron's lifetime and photoinduced charge carrier mobility, respectively. In addition to acting as a support, B-N-C provides a highly conductive network that enhances charge transport, and the relocated electron in B-N-C activates the H2O molecule, which enables Ag-/Bi-doped Mo(S,O)3@B-N-C to have appreciable PHER performance.

Fabrication of silver nanoparticles decorated on sodium alginate microbeads enriched with keratin and investigation of its catalytic and antioxidant activity

In this study, an environmentally friendly, effective, easily synthesizable and recoverable nano-sized catalyst system (Ag@NaAlg-keratin) was designed by decorating Ag nanoparticles on microbeads containing sodium alginate (NaAlg) and keratin obtained from goose feathers. The structure, morphology and crystallinity of the Ag@NaAlg-keratin nanocatalyst were evaluated by XRD, FT-IR, FE-SEM, EDS/EDS mapping and TEM analyses. Catalytic ability of designed Ag@NaAlg-keratin nanocatalyst was then investigated against 4-nitrophenol (4-NP) and methyl orange (MO) reductions. Ag@NaAlg-keratin nanocatalyst effectively reduced 4-NP in 6 min and MO in 5 min, with rate constants of 0.17 min-1 and 0.16 min-1, respectively. Additionally, activation energies (Ea) were found as 39.8 kJ/mol for 4-NP and 37.9 kJ/mol for MO. Performed recyclability tests showed that the Ag@NaAlg-keratin nanocatalyst was easily recovered due to its microbead form and successfully reused five times, maintaining both its activity and structure. Furthermore, antioxidant activity of Ag@NaAlg-keratin nanocatalyst was the highest (73.16 %).

Polydopamine modified cellulose nanocrystals (CNC) for efficient cellulase immobilization towards advanced bamboo fiber flexibility and tissue softness

Herein, a green facile approach to improve the flexibility of unbleached bamboo kraft pulp (UBKP) via an immobilized enzyme technology is proposed. Polydopamine (PDA) acts as versatile modification and coating materials of cellulose nanocrystals (CNC) for assembling versatile bio-carriers (PDA@CNC). Cellulase biomacromolecules are efficiently immobilized on PDA@CNC to form cellulase@PDA@CNC nanocomposites. The relative enzyme activity, temperature/pH tolerance, and storage stability of cellulase were significantly improved after immobilization. The degree of polymerization treated UBKP decreased by 5.42 % (25 U/g pulp) compared to the control sample. The flexibility of treated fibers was 6.61 × 1014/(N·m2), which was 96.93 % higher (25 U/g) compared to the control and 3.88 times higher than that of the blank fibers. Cellulase@PDA@CNC performs excellent accessibility to fiber structure and induces high degree of fibrillation and hydrolysis of UBKP fibers, which contributes high softness of obtained tissue handsheets. The bio-carrier PDA@CNC within paper framework may further enhance tissue tensile strength. This study proposes a practical and environmentally friendly immobilization approach of cellulase@PDA@CNC for improving the hydrolysis efficiency and flexibility of UBKP fibers, which provides the possibility to maintain the strength of tissue paper while improving its softness, thus broadening the high-value application of immobilized enzyme technology in tissue production.

Microscopic dissolution process of cellulose in alkaline aqueous solvents and its application in CNFs extraction - Investigating temperature as a variable

The target of this study is to gain a deeper understanding of the micro-dissolution process of cellulose in alkaline aqueous solutions and to develop a novel method for extracting cellulose nanofibrils (CNFs). Herein, the dissolution process of cellulose in alkaline aqueous solutions will be controlled by varying the temperature, and the undissolved cellulose will be analyzed to reveal the microscopic dissolution process of cellulose, and a novel process for extracting cellulose nanofibrils (CNFs) will be developed based on the findings. The crystalline structure of cellulose was gradually disrupted as the dissolution progressed, and the crystal form of cellulose changed gradually from cellulose I to cellulose II during the dissolution process, while all undissolved cellulose crystals remained as cellulose I. Cellulose, after its structure is disrupted during the dissolution process, will inevitably decompose into CNFs, and the microscopic dissolution process of cellulose follows a "top-down" dissolution sequence. The CNFs extraction method developed in this study can extract CNFs with high yield (>60 %) in a stable manner, as well as narrow particle size distribution, high crystallinity (>77 %), and good thermal stability. This study enhances the comprehension of the dissolution process of cellulose and paves a possible way for industrialization of CNFs production.

Cellulose/inorganic nanoparticles-based nano-biocomposite for abatement of water and wastewater pollutants

Nanostructured materials offer a significant role in wastewater treatment with diminished capital and operational expense, low dose, and pollutant selectivity. Specifically, the nanocomposites of cellulose with inorganic nanoparticles (NPs) have drawn a prodigious interest because of the extraordinary cellulose properties, high specific surface area, and pollutant selectivity of NPs. Integrating inorganic NPs with cellulose biopolymers for wastewater treatment is a promising advantage for inorganic NPs, such as colloidal stability, agglomeration prevention, and easy isolation of magnetic material after use. This article presents a comprehensive overview of water treatment approaches following wastewater remediation by green and environmentally friendly cellulose/inorganic nanoparticles-based bio-nanocomposites. The functionalization of cellulose, functionalization mechanism, and engineered hybrid materials were thoroughly discussed. Moreover, we also highlighted the purification of wastewater through the composites of cellulose/inorganic nanoparticles via adsorption, photocatalytic and antibacterial approach.

Cellulose nanocrystals isolated from corn leaf: straightforward immobilization of silver nanoparticles as a reduction catalyst

As the most abundant natural biopolymer on earth, celluloses have long-term emerged as a capable platform for diverse purposes. In the context of metal nanoparticles applied to catalysis, the alternatives to traditional catalyst supports by using biomass-derived renewable materials, likely nanocelluloses, have been paid a great effort, in spite of being less exploited. In this study, cellulose nanocrystals were isolated from corn leaf via chemical treatment involving alkalizing, bleaching and acid hydrolysis. The crystallinity of obtained cellulose was evaluated in each step, focusing on the effects of reactant concentration and reaction time. Cellulose nanocrystals were characterized by powder X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), evidencing the presence of cellulose nanospheres (crystallinity index of 67.3% in comparison with 38.4% from untreated raw material) in the size range of 50 nm. Without using any additional surfactants or stabilizers, silver nanoparticles (AgNPs) well-dispersed on the surface of cellulose nanocrystals (silver content of 5.1 wt%) could be obtained by a simple chemical reduction using NaBH4 at room temperature. The catalytic activity was evaluated in the selective reductions of 4-nitrophenol towards 4-aminophenol and methyl orange towards aromatic amine derivatives in water at room temperature. The effects of catalyst amount and reaction time were also studied in both reduction processes, showing near-quantitative conversions within 5 minutes and obeying the pseudo-first-order kinetics, with the apparent kinetic rate constants of 8.9 × 10-3 s-1 (4-nitrophenol) and 13.6 × 10-3 s-1 (methyl orange). The chemical structure of the catalytic system was found to be highly stable during reaction and no metal leaching was detected in reaction medium, evidencing adaptability of cellulose nanocrystals in immobilizing noble metal nanoparticles.

Designed Growth of AgNP Arrays for Anti-counterfeiting Based on Surface-Enhanced Raman Spectroscopy Signals

Based on etched PS sphere arrays, the different growths of Ag nanoparticles with tunable LSPR are designed when SiO2-25 nm/Ag-30 nm/SiO2-100 nm sandwich nanocavity structures are annealed at 500 °C, including the hexagonal silver nanoparticle rings, circular silver nanoparticle rings, and aggregated silver nanoparticles. The uniformity of particle size and regularity of position generate enhanced electromagnetic field and good surface-enhanced Raman spectroscopy signals as confirmed by UV-vis observation and finite difference time domain method simulation. The developed nanostructures are effectively used as stable, nonreproducible, and markable anti-counterfeiting signs.

TEMPO-oxidized cellulose for in situ synthesis of Pt nanoparticles. Study of catalytic and antimicrobial properties

In this work, platinum nanoparticles (PtNPs) were synthesized by a modified polyol process using TEMPO-oxidized nanocellulose (TOCN) as a stabilizing and co-reducing agent. Different ratios of TOCN nanocellulose to Pt⁴⁺ ions were studied to establish the optimum stabilizing effect of PtNPs. The effect of different pH of aqueous TOCN suspensions on the morphology of PtNPs was also examined. It was proved that PtNPs can be obtained solely in the presence of TOCN without the use of an additional reducing agent or ethylene glycol. The morphology and structural properties of the nanocellulose‑platinum nanoparticles composites were assessed using spectroscopic, microscopic and diffraction techniques, The catalytic performance in 4-nitrophenol reduction was evaluated. Significant differences in reaction rate constants k were found depending on the pH of the TOCN suspension applied during Pt⁴⁺ reduction. The crucial effect of reaction conditions on PtNPs performance was confirmed in tests of antibacterial efficacy against E. coli.

Evaluation of the multifunctional activity of silver bionanocomposites in environmental remediation and inhibition of the growth of multidrug-resistant pathogens

Imperata cylindrica cellulose supported Ag bionanocomposites purified industrial water and controlled the contagious diseases with high potential activity.

Modified cellulose nanofibril aerogel: Tunable catalyst support for treatment of 4-Nitrophenol from wastewater

4-Nitrophenol (4-NP) is a hazardous aromatic compound widely used for various industries. Catalytic reduction of 4-NP using metal nanoparticles (NPs) is a highly effective method to treat 4-NP from waste effluent. Even though lots of methods have investigated to prepare efficient metal NPs composites, the nano and/or micro size of composites makes it hard to recover after wastewater treatment, limiting its practical use. Here, we fabricate 3-dimensional polyethylene imine grafted cellulose nanofibril (CNF-PEI) aerogel as a porous support material for platinum (Pt) NPs to practically and effectively treat 4-NP from wastewater. The Pt NPs are formed in-situ mode on cylindrical CNF-PEI aerogel by adsorption reaction with amine groups of PEI and subsequently reduction with NaBH₄. Control of PEI grafting density and the initial concentration of Pt ions allows manipulation of the loading mass, size, and distribution of Pt NPs on 3D scaffold of CNF-PEI aerogel. The composite aerogel shows high catalytic activity for conversion of 4-NP. The 4-NP conversion activity is strongly affected by the size of Pt NPs and effective surface area of aerogels. The 2.74 nm size Pt NPs with even distribution in the aerogel show fast reaction kinetics (k = 0.12 min^-1). Finally, 4-NP reduction efficiency does not decrease during 5 times reuse cycle of Pt NPs loaded CNF-PEI aerogel. This CNF-PEI aerogel loaded with Pt NPs is recovered easily from wastewater after treatment, so it is reusable and offers high potential as a practical recyclable environmental catalyst.

Versatile nanocellulose-based nanohybrids: A promising-new class for active packaging applications

The food packaging industry is rapidly growing as a consequence of the development of nanotechnology and changing consumers' preferences for food quality and safety. In today's globalization of markets, active packaging has achieved many advantages with the capability to absorb or release substances for prolonging the food shelf life over the traditional one. Therefore, it is critical to developing multifunctional active packaging materials from biodegradable polymers with active agents to decrease environmental challenges. This review article addresses the recent advances in nanocelluloses (NCs)- baseds nanohybrids with new function features in packaging, focusing on the various synthesis methods of NCs-based nanohybrids, and their reinforcing effects as active agents on food packaging properties. The applications of NCs-based nanohybrids as antioxidants, antimicrobial agents, and UV blocker absorbers for prolonging food shelf-life are also reviewed. Overall, these advantages make the CNs-based nanohybrids with versatile properties promising in food and packaging industries, which will impact more readership with concern for future research.

Reducing end thiol-modified nanocellulose: Bottom-up enzymatic synthesis and use for templated assembly of silver nanoparticles into biocidal composite material

Nanoparticle-polymer composites are important functional materials but structural control of their assembly is challenging. Owing to its crystalline internal structure and tunable nanoscale morphology, cellulose is promising polymer scaffold for templating such composite materials. Here, we show bottom-up synthesis of reducing end thiol-modified cellulose chains by iterative bi-enzymatic β-1,4-glycosylation of 1-thio-β-d-glucose (10 mM), to a degree of polymerization of ∼8 and in a yield of ∼41% on the donor substrate (α-d-glucose 1-phosphate, 100 mM). Synthetic cellulose oligomers self-assemble into highly ordered crystalline (cellulose allomorph II) material showing long (micrometers) and thin nanosheet-like morphologies, with thickness of 5-7 nm. Silver nanoparticles were attached selectively and well dispersed on the surface of the thiol-modified cellulose, in excellent yield (≥ 95%) and high loading efficiency (∼2.2 g silver/g thiol-cellulose). Examined against Escherichia coli and Staphylococcus aureus, surface-patterned nanoparticles show excellent biocidal activity. Bottom-up approach by chemical design to a functional cellulose nanocomposite is presented. Synthetic thiol-containing nanocellulose can expand the scope of top-down produced cellulose materials.

Novel porous ceramic sheet supported metal reactors for continuous-flow catalysis

A novel porous ceramic sheet supported nickel particles reactor was obtained by an in-situ preparation method. This reactor was then used to investigate continuous-flow catalysis of nitroaromatic compounds and methyl orange. The details of the structure and morphology were characterized by XRD, SEM, XPS, Raman, element mapping, mercury intrusion method and Archimedes principle. The porous ceramic sheet supported Ni particles reactor exhibited excellent catalytic performance in the catalytic reduction of p-nitrophenol and methyl orange by sodium borohydride at room temperature. Both the conversion of p-nitrophenol (5 mM) and methyl orange (0.3 mM) reached nearly 100% at the injection speed of 2.67 mL·min^-1. In addition, it maintained conversions of 100% after 10 recycling time since the porous ceramic sheet could reduce the aggregation for Ni particles. Furthermore, the chemisorbed oxygen, and the strong interaction between Ni and porous ceramic sheet resulted in a highly efficient, recoverable, and cost-effective multifunctional reactor. All of these advantages present new opportunities to be implemented in the field of waste water treatment and environmental toxicology. Ultimately, the porous ceramic sheet could also support other metal nanomaterial, and used in other fields of environmental catalysis.

Chronicle of Nanocelluloses (NCs) for Catalytic Applications: Key Advances

Nanocellulose (NC) is a biomaterial with growing interest in the field of nanocomposites and sustainable materials. NC has various applications including biodegradable materials, reinforcing agents, packaging films, transpiring membranes and medical devices. Among the many applications, the use of NC functionalized with organic and inorganic groups has found wide use as a catalyst in chemical transformations. The goal of this review is to collect the current knowledge on its catalytic applications for chemical groups conversion. We have chosen to organize the manuscript according to subdivision of NC into Bacterial Nanocellulose (BNC), Cellulose Nanocrystals (CNCs), and Cellulose Nanofibers (CNFs) and their role as inorganic- and organic-functionalized NC-catalysts in organic synthesis. However, in consideration of the fact that the literature on this field is very extensive, we have decided to focus our attention on the scientific productions of the last five years.

Fabrication and catalytic performance of a novel tubular PMIA/Ag@RGO nanocomposite nanofiber membrane

A novel tubular PMIA/Ag@RGO composite nanofiber membrane, which could be used in continuous catalysis process was fabricated via a facile and effective method.

Design of Organic/Inorganic Hybrid Catalysts for Energy and Environmental Applications

Controlling selectivity between competing reaction pathways is crucial in catalysis. Several approaches have been proposed to achieve this goal in traditional heterogeneous catalysts including tuning nanoparticle size, varying alloy composition, and controlling supporting material. A less explored and promising research area to control reaction selectivity is via the use of hybrid organic/inorganic catalysts. These materials contain inorganic components which serve as sites for chemical reactions and organic components which either provide diffusional control or directly participate in the formation of active site motifs. Despite the appealing potential of these hybrid materials to increase reaction selectivity, there are significant challenges to the rational design of such hybrid nanostructures. Structural and mechanistic characterization of these materials play a key role in understanding and, therefore, designing these organic/inorganic hybrid catalysts. This Outlook highlights the design of hybrid organic/inorganic catalysts with a brief overview of four different classes of materials and discusses the practical catalytic properties and opportunities emerging from such designs in the area of energy and environmental transformations. Key structural and mechanistic characterization studies are identified to provide fundamental insight into the atomic structure and catalytic behavior of hybrid organic/inorganic catalysts. Exemplary works are used to show how specific active site motifs allow for remarkable changes in the reaction selectivity. Finally, to demonstrate the potential of hybrid catalyst materials, we suggest a characterization-based approach toward the design of biomimetic hybrid organic/inorganic materials for a specific application in the energy and environmental research space: the conversion of methane into methanol.

Towards the scalable isolation of cellulose nanocrystals from tunicates

In order for sustainable nanomaterials such as cellulose nanocrystals (CNCs) to be utilized in industrial applications, a large-scale production capacity for CNCs must exist. Currently the only CNCs available commercially in kilogram scale are obtained from wood pulp (W-CNCs). Scaling the production capacity of W-CNCs isolation has led to their use in broader applications and captured the interest of researchers, industries and governments alike. Another source of CNCs with potential for commercial scale production are tunicates, a species of marine animal. Tunicate derived CNCs (T-CNCs) are a high aspect ratio CNC, which can complement commercially available W-CNCs in the growing global CNC market. Herein we report the isolation and characterization of T-CNCs from the tunicate Styela clava, an invasive species currently causing significant harm to local aquaculture communities. The reported procedure utilizes scalable CNC processing techniques and is based on our experiences from laboratory scale T-CNC isolation and pilot scale W-CNC isolation. To our best knowledge, this study represents the largest scale where T-CNCs have been isolated from any tunicate species, under any reaction conditions. Demonstrating a significant step towards commercial scale isolation of T-CNCs, and offering a potential solution to the numerous challenges which invasive tunicates pose to global aquaculture communities.

Green assembly of high-density and small-sized silver nanoparticles on lignosulfonate-phenolic resin spheres: Focusing on multifunction of lignosulfonate

In this work, sodium lignosulfonate (SL) was introduced in the hydrothermal preparation of phenol-formaldehyde (PF) resin sphere that was subsequently used as a green reducer and support for synthesis of Ag nanoparticles (Ag NPs). The results showed that the addition amount of SL had a remarkable effect on the size of the SL incorporated PF (SLPF) spheres and the smallest particle size was obtained when 20% of SL (based on phenol mass) was added. The addition of SL increased the surface area and negative charge of SLPF spheres, which enhanced the Ag NPs loading amount accordingly. Moreover, SL also prevented Ag NPs from aggregating effectively, resulting in the high-density loading of small size Ag NPs on the SLPF spheres. Therefore, the as-prepared Ag@SLPF composites exhibited significantly enhanced catalytic activities in the 4-nitrophenol reduction than that of SL-free Ag@PF. Besides, the Ag@SLPF catalyst demonstrated superior recyclability owing to strong anchoring between the Ag NPs and the support. Consequently, the work demonstrates the incorporation of SL enables the green formation of high-density and tunable Ag NPs on the SLPF support and then endows the composite catalyst with enhanced catalytic performance, which presents a promising value-added application of lignosulfonate for functional catalyst preparation.

Highly stable AgNPs prepared via a novel green approach for catalytic and photocatalytic removal of biological and non-biological pollutants

Increases in biological and non-biological pollutants pose a significant threat to environmental systems. In an effort to develop an effective means to treat such pollutants, the use of Phaseolus vulgaris (kidney beans) as reducing and capping agents is proposed for the green synthesis of highly stable silver nanoparticles (AgNPs) with a face-centered cubic (fcc) crystalline structure (size range: 10-20 nm). The potent role of the resulting AgNPs was found as triple platforms (photocatalyst, catalyst, and antimicrobial disinfectant). AgNPs were able to photocatalytically degrade approximately 97% of reactive red-141 (RR-141) dye within 150 min of exposure (quantum efficiency of 3.68 × 10^-6 molecule.photon^-1 and a removal reaction kinetic rate of 1.13 × 10^-2 mmol g^-1 h^-1). The role of specific reactive oxygen species (ROS) in the photocatalytic process and complete mineralization of dye was also explored through scavenger and chemical oxygen demand (COD) experiments, respectively. As an catalyst, AgNPs were also capable of reducing 4-nitrophenol to 4-aminophenol within 15 min. Overall, AgNPs showed excellent stability as catalyst and photocatalyst even after five test cycles. As an antimicrobial agent, the AgNPs are effective against both gram-positive (Bacillus subtilis) and -negative bacteria (Escherichia coli), with the zones of clearance as 15 and 18 mm, respectively. Thus, the results of this study validate the triple role of AgNPs derived via green synthesis as a photocatalyst, catalyst, and antimicrobial agent for effective environmental remediation.

Silver Nanoparticles for Water Pollution Monitoring and Treatments: Ecosafety Challenge and Cellulose-Based Hybrids Solution

Silver nanoparticles (AgNPs) are widely used as engineered nanomaterials (ENMs) in many advanced nanotechnologies, due to their versatile, easy and cheap preparations combined with peculiar chemical-physical properties. Their increased production and integration in environmental applications including water treatment raise concerns for their impact on humans and the environment. An eco-design strategy that makes it possible to combine the best material performances with no risk for the natural ecosystems and living beings has been recently proposed. This review envisages potential hybrid solutions of AgNPs for water pollution monitoring and remediation to satisfy their successful, environmentally safe (ecosafe) application. Being extremely efficient in pollutants sensing and degradation, their ecosafe application can be achieved in combination with polymeric-based materials, especially with cellulose, by following an eco-design approach. In fact, (AgNPs)-cellulose hybrids have the double advantage of being easily produced using recycled material, with low costs and possible reuse, and of being ecosafe, if properly designed. An updated view of the use and prospects of these advanced hybrids AgNP-based materials is provided, which will surely speed their environmental application with consequent significant economic and environmental impact.

Smart paper transformer: new insight for enhanced catalytic efficiency and reusability of noble metal nanocatalysts

Although noble metal nanocatalysts show superior performance to conventional catalysts, they can be problematic when balancing catalytic efficiency and reusability. In order to address this dilemma, we developed a smart paper transformer (s-PAT) to support nanocatalysts, based on easy phase conversion between paper and pulp, for the first time. The pulp phase was used to maintain the high catalytic efficiency of the nanocatalysts and the transformation to paper enabled their high reusability. Herein, as an example of smart paper transformers, a novel chromatography paper-supported Au nanosponge (AuNS/pulp) catalyst was developed through a simple water-based preparation process for the successful reduction of p-nitrophenol to demonstrate the high catalytic efficiency and reusability of the noble metal nanocatalyst/pulp system. The composition, structure, and morphology of the AuNS/pulp catalyst were characterized by XRD, TGA, FE-SEM, ICP, TEM, FT-IR, and XPS. The AuNS/pulp catalyst was transformed into the pulp phase during the catalytic reaction and into the paper phase to recover the catalysts after use. Owing to this smart switching of physical morphology, the AuNS/pulp catalyst was dispersed more evenly in the solution. Therefore, it exhibited excellent catalytic performance for p-nitrophenol reduction. Under optimal conditions, the conversion rate of p-nitrophenol reached nearly 100% within 6 min and the k value of AuNS/pulp (0.0106 s⁻¹) was more than twice that of a traditional chromatography paper-based catalyst (0.0048 s⁻¹). Additionally, it exhibited outstanding reusability and could maintain its high catalytic efficiency even after fifteen recycling runs. Accordingly, the unique phase switching of this smart paper transformer enables Au nanosponge to transform into a highly efficient and cost-effective multifunctional catalyst. The paper transformer can support various nanocatalysts for a wide range of applications, thus providing a new insight into maintaining both high catalytic efficiency and reusability of nanocatalysts in the fields of environmental catalysis and nanomaterials.

A smart paper transformer supported nanocatalyst platform is developed based on the facile phase conversion between paper and pulp for both high-efficiency and high-reusability catalysis, with wide applications demonstrated by using Au nanosponge.

Reducing-agent-free facile preparation of Rh-nanoparticles uniformly anchored on onion-like fullerene for catalytic applications

Herein we report a very simple ‘mix and heat’ synthesis of a very fine Rh-nanoparticle loaded carbon fullerene-C60 nanocatalyst (Rh(0)NPs/Fullerene-C60) for the very first time.

Preparation of Magnetic CuFe2O4@Ag@ZIF-8 Nanocomposites with Highly Catalytic Activity Based on Cellulose Nanocrystals

A facile approach was successfully developed for synthesis of cellulose nanocrystals (CNC)-supported magnetic CuFe2O4@Ag@ZIF-8 nanospheres which consist of a paramagnetic CuFe2O4@Ag core and porous ZIF-8 shell. The CuFe2O4 nanoparticles (NPs) were first prepared in the presence of CNC and dispersant. Ag NPs were then deposited on the CuFe2O4/CNC composites via an in situ reduction directed by dopamine polymerization (PDA). The CuFe2O4/CNC@Ag@ZIF-8 nanocomposite was characterized by TEM, FTIR, XRD, N2 adsorption-desorption isotherms, VSM, and XPS. Catalytic studies showed that the CuFe2O4/CNC@Ag@ZIF-8 catalyst had much higher catalytic activity than CuFe2O4@Ag catalyst with the rate constant of 0.64 min-1. Because of the integration of ZIF-8 with CuFe2O4/CNC@Ag that combines the advantaged of each component, the nanocomposites were demonstrated to have an enhanced catalytic activity in heterogeneous catalysis. Therefore, these results demonstrate a new method for the fabrication of CNC-supported magnetic core-shell catalysts, which display great potential for application in biocatalysis and environmental chemistry.

Highly efficient and stable catalysis of p-nitrophenol via silver/lignin/polyacrylic acid hydrogel

As the second largest natural polymer in nature, lignin has a large amount of reserves and has important practical application value, which has attracted increasing attention. Ag@LPAH, a nanometer silver catalyst with a 3D structure, was successfully prepared in a simple operation. In batch experiment and fixed-bed experiment, it showed excellent catalytic degradation ability and stability of 4-NP. Thanks to the large number of carboxyl groups present in the lignin-polyacrylic acid hydrogel, the silver nanoparticles are well controlled to grow with no agglomeration. Ag@LPAH-20 exhibited optimal catalytic performance and stability, requiring only 123 s to complete the reaction and maintaining 99% catalytic efficiency after 10 cycles. In addition, the catalytic efficiency can be maintained over 90% for more than 120 min in fixed bed experiment.

Methods and applications of nanocellulose loaded with inorganic nanomaterials: A review

Nanocellulose obtained from natural renewable resources has attracted enormous interests owing to its unique morphological characteristics, excellent mechanical strength, biocompatibility and biodegradability for a variety of applications in many fields. The template structure, high specific surface area, and active surface groups make it feasible to conduct surface modification and accommodate various nano-structured materials via physical or chemical deposition. The review presented herein focuses on the methodologies of loading different nano-structured materials on nanocellulose, including metals, nanocarbons, oxides, mineral salt, quantum dots and nonmetallic elements; and further describes the applications of nanocellulose composites in the fields of catalysis, optical electronic devices, biomedicine, sensors, composite reinforcement, photoswitching, flame retardancy, and oil/water separation.

Multifunctional nanocellulose/metal and metal oxide nanoparticle hybrid nanomaterials

Nanocellulose materials are derived from cellulose, the most abundant biopolymer on the earth. Nanocellulose have been extensively used in the field of food packaging materials, wastewater treatment, drug delivery, tissue engineering, hydrogels, aerogels, sensors, pharmaceuticals, and electronic sectors due to their unique chemical structure and excellent mechanical properties. On the other hand, metal and metal oxide nanoparticles (NP) such as Ag NP, ZnO NP, CuO NP, and Fe₃O₄ NP have a variety of functional properties such as UV-barrier, antimicrobial, and magnetic properties. Recently, nanocelluloses materials have been used as a green template for producing metal or metal oxide nanoparticles. As a result, multifunctional nanocellulose/metal or metal oxide hybrid nanomaterials with high antibacterial properties, ultraviolet barrier properties, and mechanical properties were prepared. This review emphasized recent information on the synthesis, properties, and potential applications of multifunctional nanocellulose-based hybrid nanomaterials with metal or metal oxides such as Ag NP, ZnO NP, CuO NP, and Fe₃O₄ NP. The nanocellulose-based hybrid nanomaterials have huge potential applications in the area of food packaging, biopharmaceuticals, biomedical, and cosmetics.