Mismatched Refractive Index Strategy for Fabricating Laser-Driven Wood Diffusers from Bulk Wood for Illumination Applications.

Laser-diode-based solid-state lighting is primarily used in state-of-the-art illumination systems. However, these systems rely on light-converting inorganic phosphors, which have low quantum efficiencies and complex manufacturing conditions. In this study, a mismatched refractive index strategy is proposed to directly convert natural bulk wood into a laser-driven wood diffuser using a simple delignification and polymer infiltration method. The resulting material has the potential to be used in laser-driven diffuse illumination applications. The optical performance of the laser-driven wood diffuser is optimized by changing the density of natural wood. The optimal coefficient of illuminance variation of the wood diffuser is as low as 17.7%, which is significantly lower than that of commercial diffusers. The illuminance uniformity is larger than 0.9, which is significantly higher than the ISO requirements for indoor workplace lighting. The laser damage threshold is 7.9 J cm-2, which is considerably higher than those of the substrates of commercially available phosphors. Furthermore, the optimized wood diffuser exhibits outstanding mechanical properties, excellent thermal stability, tolerance to harsh environmental conditions, and low speckle contrast. These results show that the laser-driven wood diffuser is a promising laser-color converter that is suitable for indoor, long-distance outdoor, undersea, and other high-luminance laser lighting applications.

Selective Phosphorization Boosting High-Performance NiO/Ni2Co4P3 Microspheres as Anode Materials for Lithium Ion Batteries.

Phosphorization of metal oxides/hydoxides to promote electronic conductivity as a promising strategy has attracted enormous attention for improving the electrochemical properties of anode material in lithium ion batteries. For this article, selective phosphorization from NiCo2O4 to NiO/Ni2Co4P3 microspheres was realized as an efficient route to enhance the electrochemical lithium storage properties of bimetal Ni-Co based anode materials. The results show that varying phosphorizaed reagent amount can significantly affect the transformation of crystalline structure from NiCo2O4 to intermediate NiO, hybrid NiO/Ni2Co4P3, and, finally, to Ni2Co4P3, during which alterated sphere morphology, shifted surface valance, and enhanced lithium-ion storage behavior are detected. The optimized phosphorization with 1:3 reagent mass ratio can maintain the spherical architecture, hold hybrid crystal structure, and improve the reversibly electrochemical lithium-ion storage properties. A specific capacity of 415 mAh g-1 is achieved at 100 mA g-1 specific current and maintains at 106 mAh g-1 when the specific current increases to 5000 mA g-1. Even after 200 cycles at 500 mA g-1, the optimized electrode still delivers 224 mAh g-1 of specific capacity, exhibiting desirable cycling stability. We believe that understanding of such selective phosphorization can further evoke a particular research enthusiasm for anode materials in lithium ion battery with high performances.

Polyaniline nanorods random assembly on sugarcane bagasse pith-based carbon sheets with promising capacitive performance.

Polyaniline (PANI) nanorods were randomly deposited on oxidized 2D sugarcane pith-based porous carbon nanosheets by using dilute polymerization methods. The random stacked morphology of the PANI nanorods on the oxidized pith-based porous carbon nanosheets (SPCN) can be effectively controlled by simply changing the molar mass of aniline monomer. When the molar mass of the aniline monomer is increased to 0.02 M, the PANI nanorods can be randomly and uniformly stacked on the oxidized SPCN. Most of these stacked pores derived from random stack of the PANI nanorods on the oxidized SPCN are mesopore and macropore. These stacked pores not only facilitate the diffusion of ions in the stacked layer of the PANI nanorods, but also mitigate mechanical deformation of the PANI nanorods during the doping/dedoping process. Furthermore, the relationship between the properties of the oxidized SPCN/PANI-X (X represents the molar mass of aniline monomer) electrode materials and molar mass of aniline monomer is explored in detail. The oxidized SPCN/PANI-0.02 exhibits the best electrochemical performance in 1 M H2SO4. The largest specific electrode capacitance is up to 513 F g-1 at a current density of 0.25 A g-1. The oxidized SPCN/PANI-0.02 also exhibits excellent electrochemical cycling stability.

Heteroatom-doped porous carbons derived from moxa floss of different storage years for supercapacitors.

Two novel carbons (MCs) derived from moxa floss of different storage years have been prepared by two low-cost and facile approaches, which are hydrothermal carbonization at a low temperature (200 °C) and direct pyrolysis at a moderate temperature (500 °C) followed by potassium hydroxide (KOH) activation strategy at a high temperature (800 °C), respectively. The physicochemical properties of MCs are investigated by Raman spectra, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and nitrogen adsorption-desorption isotherms. Results show that MCs derived from moxa floss of different storage years by two facile approaches possess different morphologies: MCs by hydrothermal carbonization (denoted as MC-1, MC-2 and MC-3) exhibit porous nanosheet structures, the highest specific surface area is about 1788.6 m2 g-1, and the largest total pore volumes is around 0.8170 cm3 g-1, while MCs by direct pyrolysis (denoted as MC-4, MC-5 and MC-6) have basically blocky and rod-like morphologies, the highest specific surface area is about 1628.0 m2 g-1, and the largest total pore volume is around 0.7058 cm3 g-1. However, despite the different morphologies, all MCs possess a similar hierarchical porous structure, numerous heteroatom groups and good electrical conductivity. Therefore, these low-cost, biomass-derived porous carbons with promising capacitive performance are used for supercapacitors application with high performance, for example, the as-assembled supercapacitor based on MC-5 exhibits a high specific capacitance of 288.3 F g-1 at 0.25 A g-1, an excellent rate performance of 243.5 F g-1 even at 30 A g-1 with 84.5% capacitance retention of its initial specific capacitance, and an outstanding long-term cycling stability with 98.7% capacitance retention after 10 000 cycles at 5 A g-1. Furthermore, the maximum energy density for these supercapacitors with an aqueous electrolyte in a two-electrode system is about 10.0 W h kg-1 at a power density of 70.3 W kg-1. Therefore, this work opens up a whole new field for the applications of moxa floss and this novel concept of moxa floss use is an extremely promising strategy for developing high-performance carbons with porous structures and heteroatom-doping from renewable sources.

Facile fabrication of hierarchical film composed of Co(OH)2@Carbon nanotube core/sheath nanocables and its capacitive performance.

A hierarchical film composed of Co(OH)2@carbon nanotube (CNT) core/sheath nanocables (CCNF) was generated via a simple and rapid electrophoretic deposition method. It is found that the Co(OH)2 sheath was uniformly anchored on the surface of conductive CNT core. The Co(OH)2 sheath, with a thickness of ∼20 nm, was composed of numerous very tiny nanoparticles. Such a unique nanostructure endows the CCNF with a high surface area of 126 m2 g-1 and a hierarchical porosity, resulting in a large accessible surface area for redox activity. As expected, the CCNF exhibits high specific capacitance and excellent rate performance. Its specific capacitance reached 1215 F g-1 under a low current density of 1 A g-1 and was maintained at 832 F g-1 when the current density was increased 20 times to 20 A g-1. A high capacitance retention of 99.3% was achieved after 10 000 cycles at 1 A g-1. Such intriguing capacitive behavior is attributed to the synergistic effect of the CNT core and the Co(OH)2 sheath.

Cellulose nanofibril based graft conjugated polymer films act as a chemosensor for nitroaromatic.

A cellulose nanofibril film is modified by chemical assembly of boronate-terminated conjugated polymer chains at its specific sites, C-6 carboxyl groups. The modified cellulose nanofibril film is used as a fluorescent sensor for nitroaromatic vapor. Thanks to the specific reactive sites, numerous loose cavities or pathways located in the film sensor's out-layer have been formed, and the fraction of easily accessible cavities of the novel fluorescent film sensor is up to 0.97, which could benefit the penetration and diffusion of analyte vapor. Therefore, the novel fluorescent film sensor exhibits high sensitivity toward nitroaromatic vapor with a fast response. The fluorescence quenching efficiency of the chemical-assembly film sensor is about 3 times larger than that of the spin-cast film sensor using the same conjugated polymer for 600 s exposure to DNT vapor. In addition, the novel fluorescent film sensor shows good reversibility.

Cellulose nanofiber/single-walled carbon nanotube hybrid non-woven macrofiber mats as novel wearable supercapacitors with excellent stability, tailorability and reliability.

Non-woven macrofiber mats are prepared by simply controlling the extrusion patterns of cellulose nanofiber/single-walled carbon nanotube suspensions in an ethanol coagulation bath, and drying in air under restricted conditions. These novel wearable supercapacitors based on non-woven macrofiber mats are demonstrated to have excellent tailorability, electrochemical stability, and damage reliability.

Surface molecular-imprinting engineering of novel cellulose nanofibril/conjugated polymer film sensors towards highly selective recognition and responsiveness of nitroaromatic vapors.

We designed and synthesized two conjugated polymer-grafted cellulose nanofibril film sensors via surface molecular-imprinting. These two surface TNT- or DNT-imprinted film sensors exhibit highly selective recognition and fast response towards target explosive vapor.

Cellulose nanofibers/reduced graphene oxide flexible transparent conductive paper.

The cellulose nanofibers (CNFs) paper exhibit high visible light transmittance, high mechanical strength, and excellent flexibility. Therefore, CNFs paper may be an excellent substrate material for flexible transparent electronic devices. In this paper, we endeavor to prepare CNFs-based flexible transparent conductive paper by layer-by-layer (LbL) assembly using divalent copper ions (Cu(2+)) as the crosslinking agent. The thickness of the reduced graphene oxide (RGO) active layer in the CNFs paper can be controlled by the cycle times of the LbL assembly. CNFs/[RGO]20 paper has the sheet resistances of ∼2.5 kΩ/□, and the transmittance of about 76% at a wavelength of 550 nm. Furthermore, CNFs/[RGO]20 paper inherits the excellent mechanical properties of CNFs paper, and the ultimate strength is about 136 MPa. CNFs-based flexible transparent conductive paper also exhibits excellent electrical stability and flexibility.

Paper-based transparent flexible thin film supercapacitors.

Paper-based transparent flexible thin film supercapacitors were fabricated using CNF-[RGO]n hybrid paper as an electrode material and charge collector. Owing to the self-anti-stacking of distorted RGO nanosheets and internal electrolyte nanoscale-reservoirs, the device exhibited good electrochemical performance (about 1.73 mF cm(-2)), and a transmittance of about 56% (at 550 nm).