Dual-functional CDs@ZIF-8/chitosan luminescent film sensors for simultaneous detection and adsorption of tetracycline.

Tetracycline (TC) residues have been noted as an important class of emerging contaminants in the environment, thus fast, straightforward, highly sensitive detection method is becoming an issue that must be addressed. Herein, a novel CDs@ZIF-8 sensing material was fabricated by encapsulating luminescent carbon dots (CDs) into the metal-organic framework (ZIF-8) to achieve highly luminescent porous composites. Furthermore, to avoid the secondary contamination caused by powders, a shapable CDs@ZIF-8/CS film sensor as a portable disposable test strip with dual-function of TC detection and adsorption was designed by crosslinking CDs@ZIF-8 with chitosan (CS). The as-prepared CDs@ZIF-8/CS hybrid film exhibited the high sensitivity and selectivity for TC fluorescence detection and rapid decontaminate capability, as well as high optical transmittance and robust mechanical property, which were essential for the practical sensing application. This paper-based dual-functional luminescent sensor exhibits promising practicability for TC detection and contaminant removal in pharmaceutical analysis, food safety and water treatment.

TEMPO-Oxidized Nanofibrillated Cellulose Assisted Exfoliation of MoS2 /Graphene Composites for Flexible Paper-Anodes.

TEMPO-oxidized nanofibrillated cellulose (ONFC) with charged carboxyl groups is introduced for the efficient exfoliation of two-dimensional (2D) MoS2 /graphene composites. As an effective dispersant agent, ONFC can be easily absorbed between the adjacent layers, so as to prevent the accumulation of the exfoliated nanosheets. With the assistance of charged ONFC, the exfoliated MoS2 /graphene is gradually increased in the aqueous dispersions with the elongated sonication time. After dewatering, self-standing MoS2 /Graphene/ONFC/CNTs composite films are rationally constructed using ONFC as flexible fibrous skeleton, and CNTs/graphene as 1D/2D interpenetrating electrical networks. Ultrathin MoS2 nanosheets anchored on the 1D/2D heterogeneous networks is directly acted as an ideal paper-anode for lithium-ion batteries (LIBs) without using traditional metallic current collector. The self-standing flexible electrode materials based on natural cellulose will promote the future green electronics with high flexibility, miniaturization, and increased portability.

Highly thermally conductive Ti3C2Tx/h-BN hybrid films via coulombic assembly for electromagnetic interference shielding.

With the development of electronic equipment, heat problem and electromagnetic pollution severely affect both their functions and human health, which leads to great interests in developing materials synchronously with outstanding thermal conductivity and electromagnetic interference (EMI) shielding performance. Here, ultrathin Ti3C2Tx/h-BN two-dimensional (2D) heterostructure films were prepared via coulombic assembly between Ti3C2Tx MXene and h-BN nanosheet through ultrasonic blending. After the addition of h-BN nanosheet as thermal conductive nanofillers, the hybrid films achieved a higher value of thermal conductivity, compared to Ti3C2Tx composite film without h-BN. The higher thermal conductivity offered by h-BN enables the Ti3C2Tx/h-BN films have good potential for EMI shielding applications on wearable and portable electronic devices. When the mass ratio of Ti3C2Tx/h-BN is 7:3, the hybrid film with the thickness of 47.60 µm exhibited electrical conductivity of 57.67 S/cm and the maximum EMI shielding effectiveness of 37.29 dB.

Yarn-ball-shaped CNF/MWCNT microspheres intercalating Ti3C2Tx MXene for electromagnetic interference shielding films.

Ti3C2Tx MXenes with excellent metallic conductivity have proved promising in its application of electromagnetic interference (EMI) shielding. A hierarchical hybrid film with ultrathin thickness composed of Ti3C2Tx MXene layers embedded with yarn-ball-shaped microspheres of cellulose nanofibrils (CNF) and multiwalled carbon nanotube (MWCNT) was designed to improve the absorption of electromagnetic waves (EMWs). The addition of yarn-ball-shaped microspheres is to shield more EMWs via multiple reflections in the inner space and reduce the undesirable emissions into the air. After thermal annealing treatment, the ultrathin film with intercalation of the carbonized yarn-ball-shaped CNF/MWCNT microspheres exhibited enhanced EMWs absorption as an important part of shielding effectiveness (45.1±0.9 dB) as well as excellent mechanical stability (≈0.9 million bending times). Thus, the well-designed structure of multilayered hybrid films with intercalated conductive microspheres can be a good candidate for higher absorption in EMI shielding effectiveness and outstanding mechanical properties.

Ultrathin Biomimetic Polymeric Ti3C2T x MXene Composite Films for Electromagnetic Interference Shielding.

Lightweight, ultrathin, and flexible electromagnetic interference (EMI) shielding materials with high electromagnetic shielding effectiveness (SE) and excellent mechanical robustness are greatly desired for miniaturized and highly integrated electronics. Herein, for the first time, a freestanding, ultrathin, and flexible Ti3C2T x/poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) composite film with a "brick-and-mortar" structure is biomimetically designed and fabricated via a vacuum-assisted filtration process. The ultrathin polymeric composite film with a weight ratio 7:1 of Ti3C2T x to PEDOT:PSS is only 11.1 µm in thickness but exhibits a high EMI SE value of 42.10 dB. Meanwhile, the tensile strength increases considerably from 5.62 to 13.71 MPa and the corresponding ruptured strain increases from 0.18 to 0.29% compared with pure Ti3C2T x MXene film, respectively. Moreover, the hybrid film displays a superior conductivity of 340.5 S/cm and an outstanding specific EMI shielding efficiency of 19 497.8 dB cm2 g-1. The superior electrical conductivity and specific EMI shielding efficiency imply the excellent potential of the Ti3C2T x/PEDOT:PSS composite films for ultrathin, lightweight, and flexible EMI shielding materials.

Use of carbon dots to enhance UV-blocking of transparent nanocellulose films.

High-efficient transparent UV-blocking nanocellulose (NC) films were successfully assembled by pressured-extrusion of the composites of carbon dots (CDs), 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) radical mediated oxidized nanocellulose (ONC) and ZnO nanostructures. ONC nanofibrils were firstly extracted from bamboo fibers and subsequently prepared by applying TEMPO oxidation. The as-obtained CDs-ONC-ZnO films exhibited high visible light transparency, excellent thermal stability and enhanced UV-blocking properties. Compared to the previously designed NC-ZnO films, CDs-ONC-ZnO films presented significant increase of UV-blocking ratio (UVR) with the same amounts of ZnO. Moreover, the UVR of CDs-ONC-s-ZnO film with 4wt% sheet-like ZnO (s-ZnO) at 300nm and 225nm is 92.74% and 98.99%, better than the same condition of CDs-ONC-b-ZnO film added with belt-like ZnO (b-ZnO) and CDs-ONC-p-ZnO film added with commercial particulate ZnO (p-ZnO). An interesting discovery is that when adding 4wt% p-ZnO, the UVR of CDs-ONC-p-ZnO film is very close to the value of NC-s-ZnO film with the same amount of s-ZnO.

In Situ Carbonized Cellulose-Based Hybrid Film as Flexible Paper Anode for Lithium-Ion Batteries.

Flexible free-standing carbonized cellulose-based hybrid film is integrately designed and served both as paper anode and as lightweight current collector for lithium-ion batteries. The well-supported heterogeneous nanoarchitecture is constructed from Li4Ti5O12 (LTO), carbonized cellulose nanofiber (C-CNF) and carbon nanotubes (CNTs) using by a pressured extrusion papermaking method followed by in situ carbonization under argon atmospheres. The in situ carbonization of CNF/CNT hybrid film immobilized with uniform-dispersed LTO results in a dramatic improvement in the electrical conductivity and specific surface area, so that the carbonized paper anode exhibits extraordinary rate and cycling performance compared to the paper anode without carbonization. The flexible, lightweight, single-layer cellulose-based hybrid films after carbonization can be utilized as promising electrode materials for high-performance, low-cost, and environmentally friendly lithium-ion batteries.

TEMPO-mediated oxidized winter melon-based carbonaceous aerogel as an ultralight 3D support for enhanced photodegradation of organic pollutants.

Natural biomass based carbonaceous aerogels are becoming promising lightweight, biodegradable matrices to supersede traditional support materials in realizing future sustainable photochemistry and environmental protection. Herein, flower-like BiOBr loaded onto an ultralight TEMPO-mediated oxidized carbonaceous aerogel (BOB@OWMCA) support was successfully prepared using the edible winter melon as source material via a simple solvothermal method. The three-dimensional sponge-like OWMCA with surface functionalization displayed an ultralow density (17.7 mg cm(-3)) and large special surface area (30.6 m(2) g(-1)). The BiOBr was homogeneously anchored on the surface of the hierarchical porous OWMCA and the material exhibited synergetic properties of the BiOBr photocatalyst and OWMCA support to strengthen its photodegradation capacity. The results indicated that the as-prepared BOB@OWMCA composite demonstrated an outstanding adsorption and photodegradation capacity for organic pollutants (rhodamine B) under visible light irradiation. Of importance here, the BOB@OWMCA composite showed a prominent advantage for easy collection and separation from the aqueous system, making it a promising candidate as a robust visible light responsive photocatalyst for a range of applications.

Combined bleaching and hydrolysis for isolation of cellulose nanofibrils from waste sackcloth.

A convenient and low cost process to prepare cellulose nanofibrils (CNF) from waste sackcloth by using H2O2/HNO3 solution as both bleaching agent and hydrolysis medium was recommended. The resultant CNF with high crystallinity was initially synthesized by the chemical disintegration process for the removal of non-cellulosic components and the crystallinity of CNF was 68.11% compared with that of sackcloth fibers (48.28%). The decomposition temperature of CNF was about 340°C, which indicated that the thermal stability of the fibers was increased after the combined bleaching and hydrolysis. Subsequently, the homogenous CNF colloidal suspensions in water, ethanol and acetone were obtained after sonication treatment. The CNF in water suspensions with 20-50nm in width and hundreds of nanometers in length was ultimately prepared under the conditions of different ultrasonic time.

Solution-processed assembly of ultrathin transparent conductive cellulose nanopaper embedding AgNWs.

Natural biomass based cellulose nanopaper is becoming a promising transparent substrate to supersede traditional petroleum based polymer films in realizing future flexible paper-electronics. Here, ultrathin, highly transparent, outstanding conductive hybrid nanopaper with excellent mechanical flexibility was synthesized by the assembly of nanofibrillated cellulose (NFC) and silver nanowires (AgNWs) using a pressured extrusion paper-making technique. The hybrid nanopaper with a thickness of 4.5 µm has a good combination of transparent conductive performance and mechanical stability using bamboo/hemp NFC and AgNWs cross-linked by hydroxypropylmethyl cellulose (HPMC). The heterogeneous fibrous structure of BNFC/HNFC/AgNWs endows a uniform distribution and an enhanced forward light scattering, resulting in high electrical conductivity and optical transmittance. The hybrid nanopaper with an optimal weight ratio of BNFC/HNFC to AgNWs shows outstanding synergistic properties with a transmittance of 86.41% at 550 nm and a sheet resistance of 1.90 ohm sq(-1), equal to the electronic conductivity, which is about 500 S cm(-1). The BNFC/HNFC/AgNW hybrid nanopaper maintains a stable electrical conductivity after the peeling test and bending at 135° for 1000 cycles, indicating remarkably strong adhesion and mechanical flexibility. Of importance here is that the high-performance and low-cost hybrid nanopaper shows promising potential for electronics application in solar cells, flexible displays and other high-technology products.

Integrated fast assembly of free-standing lithium titanate/carbon nanotube/cellulose nanofiber hybrid network film as flexible paper-electrode for lithium-ion batteries.

A free-standing lithium titanate (Li4Ti5O12)/carbon nanotube/cellulose nanofiber hybrid network film is successfully assembled by using a pressure-controlled aqueous extrusion process, which is highly efficient and easily to scale up from the perspective of disposable and recyclable device production. This hybrid network film used as a lithium-ion battery (LIB) electrode has a dual-layer structure consisting of Li4Ti5O12/carbon nanotube/cellulose nanofiber composites (hereinafter referred to as LTO/CNT/CNF), and carbon nanotube/cellulose nanofiber composites (hereinafter referred to as CNT/CNF). In the heterogeneous fibrous network of the hybrid film, CNF serves simultaneously as building skeleton and a biosourced binder, which substitutes traditional toxic solvents and synthetic polymer binders. Of importance here is that the CNT/CNF layer is used as a lightweight current collector to replace traditional heavy metal foils, which therefore reduces the total mass of the electrode while keeping the same areal loading of active materials. The free-standing network film with high flexibility is easy to handle, and has extremely good conductivity, up to 15.0 S cm(-1). The flexible paper-electrode for LIBs shows very good high rate cycling performance, and the specific charge/discharge capacity values are up to 142 mAh g(-1) even at a current rate of 10 C. On the basis of the mild condition and fast assembly process, a CNF template fulfills multiple functions in the fabrication of paper-electrode for LIBs, which would offer an ever increasing potential for high energy density, low cost, and environmentally friendly flexible electronics.

Luminescent and transparent nanopaper based on rare-earth up-converting nanoparticle grafted nanofibrillated cellulose derived from garlic skin.

Highly flexible, transparent, and luminescent nanofibrillated cellulose (NFC) nanopaper with heterogeneous network, functionalized by rare-earth up-converting luminescent nanoparticles (UCNPs), was rapidly synthesized by using a moderate pressure extrusion paper-making process. NFC was successfully prepared from garlic skin using an efficient extraction approach combined with high frequency ultrasonication and high pressure homogenization after removing the noncellulosic components. An efficient epoxidation treatment was carried out to enhance the activity of the UCNPs (NaYF4:Yb,Er) with oleic acid ligand capped on the surface. The UCNPs after epoxidation then reacted with NFC in aqueous medium to form UCNP-grafted NFC nanocomposite (NFC-UCNP) suspensions at ambient temperature. Through the paper-making process, the assembled fluorescent NFC-UCNP hybrid nanopaper exhibits excellent properties, including high transparency, strong up-conversion luminescence, and good flexibility. The obtained hybrid nanopaper was characterized by transmission electron microscopy (TEM), atomic force microscope (AFM), Fourier transform infrared spectroscopy (FTIR), field emission-scanning electron microscope (FE-SEM), up-conversion luminescence (UCL) spectrum, and ultraviolet and visible (UV-vis) spectrophotometer. The experimental results demonstrate that the UCNPs have been successfully grafted to the NFC matrix with heterogeneous network. And the superiorly optical transparent and luminescent properties of the nanopaper mainly depend on the ratio of UCNPs to NFC. Of importance here is that, NFC and UCNPs afford the nanopaper a prospective candidate for multimodal anti-counterfeiting, sensors, and ion probes applications.