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Rational design and facile preparation of low-cost and efficient catalysts for the selective converting of biomass-derived monosaccharides into high value-added chemicals is highly demanded, yet challenging. Herein, we first demonstrate a N doped defect-rich carbon (NC-800-5) as metal-free catalyst for the selective oxidation of d -xylose into d -xylonic acid in alkaline aqueous solution at 100 °C for 30 min, with 57.4% yield. The doped graphitic N is found to be the active site and hydroxyl ion participating in the oxidation of d -xylose. Hydroxyl ion and d -xylose first adsorb on NC-800-5 surface, and the aldehyde group of d -xylose is catalyzed to form germinal diols ion. Then, C–H bond break to yield carboxylic group. Furthermore, NC-800-5 catalyst shows high stability in recycled test.

Interfacial design is one of the most promising ways in improving mechanical properties of nanocomposites. In this work, a multifunctional aerogel with excellent mechanical performances, sensing sensitivity, and fire retardancy is fabricated by taking advantage of metal coordination between biopolymer and Fe3+. Montmorillonite (MMT) nanosheets are added to induce a ‘brick and mortar’ structure. The coordination remarkably reduces structural defects, leading to well-formed lamellas that can effectively distribute stress under sever compression without plastic deformation. The structural merits impart the aerogel highly reversible compressibility even at 99 % strain and superior durability. Besides, it demonstrates high sensing performance in wearable health monitoring devices, and shows fire resistance property that can maintain elasticity in a flame. The work offers a facile and effective method to create multifunctional aerogels from various polymers.

Mesoporous graphitic carbon nitride (mpg-C3N4) has been developed as a metal-free heterogeneous photocatalyst for thiocyanation transformations. The reaction proceeds efficiently by utilizing air as a green oxidant under mild reaction conditions, which affords SCN-containing compounds in moderate to excellent yields. Meanwhile, the practicality of this protocol is further demonstrated by the reusability of the mpg-C3N4 photocatalyst and the scaled-up reaction. Furthermore, detailed mechanistic studies clearly demonstrate the role of oxygen.

Photoreforming of lignocellulose for sustainable H2 generation appears to be a good option at the time that biomass wastes are being degraded. Recently, polymeric carbon nitride (PCN) has emerged as a promising alternative for the photorefoming reaction, however, its photocatalytic performance is largely limited by its severe recombination of charge carriers. Here, we developed an approach, for the first time, to construct a curly-like carbon nitride nanosheets with the formation of in-plane surface dyadic heterostructure for steering the charge transfer and optimizing the electronic band structure. This PCN material shows superior photoreforming H2 evolved activity of 122.77 μmolh−1 (i.e. 4092 μmolh−1g−1) from the aqueous lignocellulose solution (using Pt as cocatalyst), 15.6 folds of pristine PCN under visible light irradiation, together with an apparent quantum efficiency (AQE) of 7.87% (λ = 420 nm). It enables the visible-light-driven conversion of several kinds of lignocellulose including the monosaccharides, disaccharides, hemicellulose, and cellulose. Additionally, when used as a photocatalyst for water splitting, it achieves a remarkable H2 production rate of 22043 μmolh−1g−1 (∼56.0 folds’ increases than pristine PCN) with a superior high AQE of 41.2%, as well as a high CO reduction rate of 56.3 μmolh−1 from the photocatalytic CO2 conversion, 24.5 times than pristine PCN.

Poly(ethylene oxide) (PEO)-based polymer electrolytes are promising candidates for solid-state electrolytes in safer, next generation lithium metal batteries. Despite their benefits however, PEO-based electrolyte exhibits highly crystalline ethylene oxide chains that provide poor ionic conductivity and, thus severely limit its practical application. Here, we report the use of hydroxypropyl trimethylammonium bis(trifluoromethane) sulfonimide chitosan salt (HACC-TFSI), which is an amorphous poly(ionic liquid) based biomass chitosan derivative, as a modifier for PEO-based solid polymer electrolytes (SPEs) to address these deficiencies. Hybrid SPEs with HACC-TFSI display enlarged amorphous regions with enhanced ionic conductivity. Interactions between quaternary ammonium cations and TFSI− anions in hybrid SPEs are also found to promote dissociation between Li+ and TFSI−, which further increases ionic mobility. Moreover, the electrochemical stability, mechanical strength, and thermal stability of hybrid SPEs are collectively superior to blank SPEs without HACC-TFSI. LiFePO4/SPEs/Li full-cells assembled using 10wt% HACC-TFSI in PEO (10%HACC-TFSI/SPEs) electrolyte provide a capacity of 161.3 mAh g−1 and operate with excellent cycle performances at 0.2 C and 60 °C. Even when the temperature is increased to 150 °C, LiFePO4/SPEs/Li cells with 10%HACC-TFSI/SPEs still display remarkable cycle performance with 73% capacity retention after 100 cycles at 1 C rate.

A facile strategy for the preparation of a nanoconfined Ti3C2/Ru cocatalyst by direct reduction of Ru3+ ions without an additional reductant was developed. The in situ formation of TiO2 nanosheets on the Ti3C2/Ru surface ensures the separation of the semiconductor and cocatalyst (TiO2-Ti3C2/Ru), resulting in charge segregation and migration more effective than those achieved by traditionally prepared Ru-TiO2-Ti3C2. Owing to its low Fermi level, the self-assembled Ti3C2/Ru cocatalyst accepted the photogenerated electrons and promoted H2 evolution without an induction period, while exhibiting high surface structure stability. The changes in the work function and surface terminations of Ti3C2 during the photocatalysis were revealed by DFT calculations and in situ diffuse reflectance infrared Fourier transform spectroscopy. The efficient electron transfer enabled by the structurally separated Ti3C2/Ru-based photocatalyst significantly reduced the electron-hole recombination, increasing the photocatalytic H2 evolution activity. This work provides a guiding design approach for future solar energy conversion with the semiconductor-cocatalyst system.

Background: Bio-based materials, as the plentiful and renewable resources for natural constituents which are essential for biomedical and pharmaceutical applications, have not been exploited adequately yet. Chitosan is a naturally occurring polysaccharide obtained from chitin, which has recently attracted widespread attention owing to its excellent activity. This review shows the methods of extraction and modification of chitosan and provides recent progress of synthesis and use of chitosan-based materials in biological applications. Methods: By consulting the research literature of the last decade, the recent progresses of functional chitosan-based materials for biological applications were summarized and divided into the methods of extraction chitosan, the chemical modification of chitosan, chitosan-based materials for biological applications were described and discussed. Results: Chemical modification of chitosan broadens its applications, leading to developing numerous forms of chitosan-based materials with excellent properties. The excellent bioactivity of chitosan-based material enables it serves potential applications in biomedical fields. Conclusion: Chitosan-based materials not only exhibit the excellent activities of chitosan but also show other appealing performance of combined materials, even give the good synergistic properties of chitosan and its composite materials. Further studies are needed to define the ideal physicochemical properties of chitosan for each type of biomedical applications. The development of various functional chitosan-based materials for biological applications will be an important field of research, and this kind of material has important commercial value.

Compressible and elastic carbon aerogels with low density, excellent conductivity, high porosity, and chemical stability have attracted much attention in wearable energy storage and sensing devices...

The design and development of electrocatalysts composed of non-noble-metal catalysts with both large surface area and high electrical conductivities are crucial for the hydrogen evolution reaction (HER). Here, a xylose-based porous carbon is coupled with a MoS2−MoP heterojunction (MoS2−MoP/FPC) hybrid and used as a promising catalyst for HER. The hybrid is prepared by immobilizing petal-like MoS2 nanosheets on porous carbon (MoS2/FPC), followed by controlling the phosphidation in Ar/H2 to form MoS2−MoP/FPC. Red phosphorus provides the P species that can induce the construction of the heterojunction under the reducing atmosphere, along with the generation of a MoP phase and the splitting of the MoS2 phase. The as-prepared MoS2−MoP/FPC catalyst offers a low overpotential of 144 mV at a current density of 10 mA cm−2 and a small Tafel slope of 41 mV dec−1 for the HER in acidic media, as well as remarkable stability. Apart from the active nature of the hybrid, its outstanding activity is attributed to the MoS2−MoP heterojunction, and the good charge/mass-transfer ability of porous carbon. This strategy provides a new method to develop and design low-cost and high-performance catalysts for the HER.

The reduction of CO2 into C1 feedstocks (e.g., CO) by utilizing solar energy has attracted increasing attention for the efficient production of renewable energy. However, a significant challenge in the reduction of CO2 is achieving high conversion efficiency due to the high CO dissociation energy of CO2 and difficultly in accessing the surface of photocatalysts. Herein, we fabricated a polymeric carbon nitride (PCN) catalyst with hydroxyethyl groups grafted on its edge via a facile bottom-up strategy, facilitating the efficient surface absorption of CO2 and lowering the CO2 transformation energy barrier; this was accompanied with exceptional extended optical absorption ability to the near-infrared region and increase in the density of states at the Fermi level. Thus, concentrated CO2 molecules could contact the surface of PCN and be easily activated; this resulted in an excellent CO production rate of up to 209.24 μmol h−1 g−1 in the modified PCN (i.e., 39.5-fold increase compared to that of pristine PCN) and a selectivity of 98.5% under white LED illumination, exceeding that of most PCN-based energy conversion systems reported to date. Notably, this PCN matrix also exhibited photocatalytic activity for the production of CO in the near-infrared region from 780 to 850 nm. These results pave the way for the development of structured photocatalysts with easy accessibility for CO2 and broadband spectral response for the efficient photocatalytic reduction of CO2.

The key for graphene applications is the successful transfer of graphene from a growth metal substrate to a substrate for application without compromising its high quality. However, state-of-the-art polymethyl methacrylate (PMMA) assisted transfer methods introduce wrinkles, folds and cracks, which are exacerbated for porous substrates. Here we report a novel in situ technique to transfer graphene onto a porous substrate which resolves these issues. Using phase-inversion a porous substrate is grown onto a graphene film with strong adhesion that perfectly matches graphene's topography, and the growth metal substrate is subsequently etched away. We achieve 63 cm2 high-quality single-layered graphene with almost 100% coverage over the pores of the substrate and pore ratios up to 35%. Our study resolves the three main challenges of transferring graphene to porous substrates, which are matching the topographies between the graphene and the porous substrate, achieving high pore ratios and minimizing the stresses on the suspended graphene; this approach may therefore serve as a general guide for attaching graphene or other 2D materials to scaffold structures.

Hydroxyl-rich waste fibers have been utilized as support to synthesize paper derived monodispersed Ag composites. We utilized the one-step thermal reduction and carbonization method to synthesize a meso-pore carbon frame with mono-dispersed silver nanoparticles (Ag@C). The Ag@C showed excellent catalytic activity in 4-nitrophenol reduction reactions attributing to their well dispersed silver nanoparticles and high surface area. The Ag@C catalyst could be recycled for ten times without significant loss of its catalytic activity. Furthermore, the Ag@C could be used as a Surface-enhanced Raman scattering (SERS) substrate, and the SERS signals strength were shown to be seven times higher than unloaded carbon membrane. The results clearly indicated that the Ag nanoparticle-loaded recycled fibers exhibited SERS activity, rendering it an excellent SERS substrate for practical applications. The efficient utilization of the widely accessible waste fibers from paper-making industry could provide a sustainable feature of this work to reduce manufacturing cost and contribute it to be an environment-friendly bifunctional material.

Novel thiol functionalized xylose hydrochar microspheres supported palladium nanoparticles (C–SH–Pd) were synthesized by gentle heating of palladium (II) acetate and thiol functionalized xylose hydrochar (C–SH) in ethanol. The as-prepared C–SH–Pd exhibited high catalytic activity towards Suzuki reactions with a yield of high up to 100%. Moreover, it could be reused for at least five times without heavily loss of the catalytic activity. The amount of palladium entrapped on C-SH microspheres was measured by AAS and found to be 1.42 mmol/g. Leaching studies showed that the filtrate contained less than 0.2 ppm Pd. Due to the superior catalytic performance and stability of the C–SH–Pd catalyst, it can be exploited in other cross coupling reactions in the long run.

Carbon dots (CDs), with high photostability, tunable excitation and emission wavelength, excellent biocompatibility, and environmental friendliness, attract great interest because of their promising applications in various fields. The synthesis of CDs from renewable biomass is especially attractive due to its sustainable and cost-efficient feature. However, one of the major problems for this route is the low yield of CDs. To overcome this issue, we propose a facile, universal, and highly effective synthesis method to prepare fluorescent CDs from various biomass hydrothermal carbons (HTCs). As compared with the current methods for synthesizing biomass derived CDs, our approach offers ultrahigh yield (42.5% based on the weight of biomass and 99.0% based on the weight of HTC) that is much higher than those obtained from other methods. The physiochemical properties of the as-prepared CDs can be tuned by reaction temperature. Furthermore, the PL quantum yield is high up to 16.6%, and is correlated with the surface chemical groups and conjugated π-domains of the carbon core in CDs. The fluorescence of CDs is effectively and selectively quenched by Cu2+, which enables CDs applying as fluorescent Cu2+ nanoprobe with a linear range of 0–30 μmol L−1 and a detection limit of 85 nmol L−1. Due to simple operation, mild condition, and low cost of the process, this method have a great potential in the large-scale synthesis and application of CDs from biomass.

Integrating high electrocatalytic activities for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) into one nonprecious catalyst entity is highly desired for simplifying the fabrication, operation as well as lowering the production cost of rechargeable Zn-air batteries. Herein, zeolite imidazole framework-67 (ZIF-67) polyhedron nanocrystals are used as N-containing carbonaceous precursors to synthesize N-rich hollow carbon cage composites with Co nanoparticles (Co@NHCC) in the presence of silica nanoparticles and graphitic carbon nitride (g-C3N4), an additional high-temperature decomposable nitrogen source. The assembly of dense silica nanoparticles on ZIF-67 surface may serve as hard encapsulation layers, which not only facilitates the incorporation of nitrogen atoms onto graphitized carbon skeletons, but also prevents the ZIF-67 polyhedrons from collapsing and effectively impedes the growth of carbon nanotubes during pyrolysis through surface confinement. Gasification in such an encapsulated environment concurrently generates abundant mesopores in the thin walls of carbonized ZIF-67 polyhedrons, which contributes to a high specific surface area of 910.71 m2 g−1 in the resulting Co@NHCC-800 sample, and hence endows an efficient bifunctional electrocatalyst, with a half-wave potential of +0.837 V for ORR in 0.1 M KOH aqueous solution and a required potential of only +1.512 V to reach 10 mA cm−2 in OER catalysis. When used as a breathable electrode for Zn-air batteries, Co@NHCC-800 shows a much higher open-circuit voltage of 1.490 V, a higher discharge power density of 248 mW cm−2 as well as a smaller increasement of only 0.100 V for the charge-discharge voltage gap after cycling for 12 h, as compared with commercial Pt/C catalyst. The results in present work pave a new avenue to the synthesis of sophisticated carbon nanomaterials for electrocatalysis.

Herein, a facile and easy scale-up method of interfacial covalent assembly was presented to fabricate solvent-responsive nanoparticles (NPs) through Schiff base reaction between dialdehyde cellulos...

B, N co-doped porous carbon is fabricated by using chitosan as a carbon precursor, boric acid as a boron source and porogen, and ferric chloride as a multifunctional reagent (i.e., solvent, templat...

While pseudocapacitive electrodes have potential to store more energy than electrical double-layer capacitive electrodes, their rate capability is often limited by the sluggish kinetics of the Faradaic reactions or poor electronic and ionic conductivity. Unlike most transition-metal oxides, MoO2 is a very promising material for fast energy storage, attributed to its unusually high electronic and ionic conductivity; the one-dimensional tunnel is ideally suited for fast ionic transport. Here we report our findings in preparation and characterization of ultrathin MoO2 sheets with oriented tunnels as a pseudocapacitive electrode for fast charge storage/release. A composite electrode consisting of MoO2 and 5 wt % GO demonstrates a capacity of 1097 C g-1 at 2 mV s-1 and 390 C g-1 at 1000 mV s-1 while maintaining ∼80% of the initial capacity after 10,000 cycles at 50 mV s-1, due to minimal change in structural features of the MoO2 during charge/discharge, except a small volume change (∼14%), as revealed from operando Raman spectroscopy, X-ray analyses, and density functional theory calculations. Further, the volume change during cycling is highly reversible, implying high structural stability and long cycling life.

Compressible and elastic carbon aerogels (CECAs) hold great promise for applications in wearable electronics and electronic skins. MXenes, as new two-dimensional materials with extraordinary proper...

Hydrothermal synthesis of carbon quantum dots (CQDs) from biomass is a green and sustainable route for CQDs applications in various fields. However, one of the major problems is the low CQDs yield because the traditional hydrothermal treatment would produce large amounts of hydrochar byproduct. In this work, we present a novel, facile, and effective method for large-scale synthesis of CQDs from biomass-derived carbon including hydrochar and carbonized biomass through mild oxidation (NaOH/H2O2 solution). An ultrahigh CQDs yield of 76.9 wt % can be obtained, which is much higher than those obtained from traditional hydrothermal and strong acid oxidation processes. Furthermore, the CQDs have excellent quantum yield (QY) that is higher than (or comparable to) those from other methods. In addition, the CQDs have uniform size (∼2.4 nm) and their surface states can be regulated to significantly improve the QY by adjusting the concentration of oxidants. The CQDs displayed excellent sensitivity for Pb2+ detection ...

Efficient valorization of cellulose is a sustainable route yet a challenging topic to solve the crisis of fossil resources. Although heterogeneous catalysts such as metal oxides have various advantages, the low surface contact area between metal oxides and cellulose is unfavourable for the hydrolysis of cellulose and thus restricts the application of metal oxides in direct conversion of cellulose to 5-hydroxymethylfurfural (HMF). This work presented the utilization of in-situ carbonic acid from CO2 as a green acid to enhance the conversion of cellulose to HMF in the presence of ZrO2 and TiO2. Combination of in-situ carbonic acid, ZrO2 and TiO2 exhibited a distinctive catalysis on the hydrolysis of cellulose and monosaccharide, isomerization of glucose and monosaccharide conversion in tetrahydrofuran (THF)/H2O/NaCl system. Especially, in-situ carbonic acid played a significant role in cellulose degradation and accelerated transforming insoluble polysaccharide into soluble oligosaccharide or monosaccharide, and thus promoted the cellulose conversion catalyzed by metal oxides. A high yield of HMF from cellulose (48.4%) was achieved by physically mixing commercial TiO2, ZrO2, and CO2. Due to the significant effects on cellulose degradation and HMF selectivity improvement, in-situ carbonic acid offers a green, low-cost and environmentally friendly co-catalyst for highly effective converting cellulose into HMF.

Metallic zinc (Zn) is considered to be a safe and low-cost anode for rechargeable batteries. Thus, several zinc metal batteries (ZMBs) have been well developed, i. e., zinc silver batteries, Zn−MnO batteries, nickel-zinc batteries, zinc-air batteries and other kinds of zinc ion batteries. ZMBs are strongly correlated with electrochemistry, electrodes, electrolytes and battery structures. To support the development of this field, we herein invite some famous research experts to write this roadmap for giving some guidance in future research. The roadmap will include their research status, challenge, opportunities, and the technology advance in their fields. We expect this roadmap will produce active influence in developing green, low-cost, safe ZMBs for our bright life in future.

Nitrogen-doped graphitized carbon nanosheets embedded with crystalline cobalt nanoparticles are facilely synthesized with the aid of melamine-containing hydrogen-bonded organic frameworks (HOF). Experimentally, HOF microrods with an in situ polymerized dopamine (DA) overlayer are coordinated with Co2+ cations and used as a precursor. After pyrolyzing the Co@DA-HOF precursor, irregular sheet-like carbons comprising a large number of Co nanoparticles as well as abundant mesopores are obtained (Co@MPC-T). The thermal decomposition of melamine-containing HOF microrods during high-temperature pyrolysis helps generate the abundant porous structures in the resulting catalyst samples. Thus, synthesized Co@MPC-T catalysts display an apparent ORR activity, and the one pyrolyzed at 800 °C is determined to show the highest ORR catalytic activity among the series, with a half-wave potential of + 0.796 V, a diffusion-limiting current density of 5.492 mA cm−2 at + 0.200 V and a kinetic current of 51.40 mA cm−2 that is even two times higher than the 20.10 mA cm−2 for commercial Pt/C catalyst. Moreover, benefiting from the protection of graphitized carbon overlayer, Co@MPC-800 shows a substantially higher operation stability as well as superior tolerance to fuel crossover, as compared with the commercial Pt/C catalyst. The remarkable ORR performance of Co@MPC-800 highlights the high potential of graphitized two-dimensional carbon composites with nonprecious transition metal nanoparticles in electrocatalysis.

The aims of this study are to prepare quaternized xylan-Fe2O3 (QX-Fe2O3) core/shell nanocomposites and explore their potential application in the biomedical fields. γ-Fe2O3 nanoparticles synthesized by a facile solvothermal process are coated with QX via reverse microemulsion method and further modified by polylysine (PLL) and folic acid (FA) to prepare PLL-QX-Fe2O3 and FA-QX-Fe2O3 nanoparticles. An obvious strong absorption of γ-Fe2O3 at 580 cm−1 in the spectra of QX-Fe2O3 is observed, the Fe element content of QX-Fe2O3 is 30–75 μg/mL and the saturation magnetization of QX-Fe2O3 nanoparticles is 1.49 emu/g. The γ-Fe2O3 and QX-Fe2O3 nanoparticles are of regular sphericity with diameter of 50–100 nm and 60–150 nm, respectively. The highest zeta potential of QX-Fe2O3 nanoparticles is −41 mV, and the PLL-QX-Fe2O3 nanoparticles have a positive potential with a maximum value of 45.2 mV. In addition, FA-QX-Fe2O3 showed excellent performance in T2-weighted Magnetic Resonance (MR) imaging with an r2 value of 190 mM−1S−1. Each nanocomposite has its own inherent properties, which contributes to its versatile utilization and application potential.

Biodegradable nanoparticles (NPs) have shown great promise as intracellular imaging probes, nanocarriers and drug delivery vehicles. In this study, we designed and prepared amphiphilic cellulose derivatives via Schiff base reactions between 2,3-dialdehyde cellulose (DAC) and amino compounds. Polymeric NPs were facilely fabricated via the self-assembly of the as-synthesized amphiphilic macromolecules. The size distribution of the obtained NPs can be tuned by changing the amount and length of the grafted hydrophobic side-chains. Anticancer drugs (DOX) were encapsulated in the NPs and the drug-loaded NPs based on cellulose derivatives were stable in neutral and alkaline environments for at least a month. They rapidly decomposed with the efficient release of the drug in acidic tumor microenvironments. These drug-loaded NPs have the potential for application in cancer treatment.

Electrocatalysts with a high efficiency and durability for the hydrogen evolution reaction (HER) hold tremendous promise for next-generation energy conversion. Among the state-of-art catalysts for HER, organic-inorganic hybrid nanosheets exhibit a great potential with the merits of high activity, good durability, and low cost. Nevertheless, there is no general method for the synthesis of binary metal phosphide hybrid nanosheet HER catalysts with a tunable morphology and composition. Herein, we report a facile approach for the synthesis of nanosheets consisting of a binary cobalt nickel phosphide hybrid with a hierarchically porous nanostructures using an oxidation- phosphorization process. The as-optimized hybrid nanosheets annealed at 350 °C yield the highest pH-universal activity with overpotentials of 148, 111, and 173 mV in acidic, alkaline, and neutral media, respectively. Besides the promoted mass diffusion in the hierarchically porous structure, the extraordinary performance can be also attributed to the weakened adsorption of hydrogen as a result of the tunable composition of Co and Ni, which was revealed by first-principles calculations.

Global warming arising from the influx of excessive greenhouse gases, has highlighted the importance of reducing them from the atmosphere. Intensive efforts were made to uncover biomass-based materials that can catalyze the synthesis of cyclic carbonate from CO2 and epoxides. In this work, a biomass based catalyst system consisting of 1, 8-Diazabicyclo (5.4.0) undec-7-ene (DBU) and xylan was developed for efficient fixation of CO2 with epoxides to synthesize cyclic carbonates. The results showed that the catalyst composition, reaction time, temperature and pressure had remarkable influences on the catalytic activity of DBU/xylan. A high yield of 85% propylene carbonate (PC) was achieved under the optimal reaction conditions (DBU: xylan = 5:1, 3.0 MPa, 4 h, and 120 °C). In addition, the catalytic system could be suitable for the cycloaddition between CO2 and other epoxides or aziridines. Compared with other biomass-based catalysis system, the DBU/xylan exhibited a better catalytic activity, owing to the exceptional synergistic effect between DBU and xylan.

Although hierarchical porous carbons (HPCs) are greatly emphasized in electrochemical energy storage, it is still difficult to develop a facile and cost-effective method for fabricating HPCs. Herei...

Compressible carbon materials hold great promise for application in various wearable or flexible electronic devices because of their low density, chemical and thermal stability, and high electrical conductivity. However, it is a great challenge to fabricate a carbon material with excellent mechanical performance and high sensitivity due to the brittleness of carbon. In this work, we fabricate a high-performance and lightweight CNT/rGO–CNF carbon aerogel by two key strategies: (1) forming continuous and ordered wave-shaped rGO layers and (2) reinforcing the carbon layers. It is found that cellulose nanofibers (CNFs) play a very important role in enhancing the interaction of rGO and CNTs, while CNTs give rise to strong yet flexible wave-shape layers. Benefiting from the synergistic effect of CNTs and CNFs, the carbon aerogel exhibits ultrahigh compressibility (up to 95% strain), superior elasticity (94.6% height retention for 50 000 cycles), high sensitivity, and an ultralow detection limit for pressure (0.875 Pa). These advantages make it an excellent candidate for fabricating flexible wearable electronic devices for biosignal detection.

Selective oxidation of biomass-based monosaccharides into value-added sugar acids is highly desired, but limited success of producing D-xylonic acid has been achieved. Herein, we report an efficient catalyst system, viz., Au nanoparticles anchored on the inner walls of hollow Al2O3 nanospheres (Au@h-Al2O3), which could catalyze the selective oxidation of D-xylose into D-xylonic acid under base-free conditions. The mesoporous Al2O3 shell as the adsorbent first adsorbed D-xylose. Then, the interface of Au nanoparticles and Al2O3 as active sites spontaneously dissociated O2, and the exposed Au nanoparticle surface as the catalytic site drove the transformation. With this catalyst system, the valuable D-xylonic acid was produced with excellent yields in the aerobic oxidation of D-xylose. Extensive investigation showed that Au@h-Al2O3 is an efficient catalyst with high stability and recyclability.

There is an increasing demand for developing environment-friendly and cost-effective strategies to synthesize high-performance flexible supercapacitor electrode materials. Biomass-derived carbon materials are very promising and attractive candidates due to their outstanding advantages. Herein, we prepared a foldable composite electrode based on a chitosan-derived N-self-doped carbon sheet (N-CS) and a microfibrillated cellulose fiber (MCF) framework. The N-CS plays a key role in tailoring the electrochemical behavior of electrode, while the MCF framework offers a porous structure with excellent mechanical foldability. In situ PANI improves the conductivity of the MCF framework and provides abundant active redox sites for energy storage. This foldable composite electrode possesses a high specific areal capacitance of 1688.8 mF cm−2 (139.6 F g−1, 84.4 F cm−3) at 1 mA cm−2 and an energy density of 11.75 mW h cm−3 at a power density of 25 mW cm−3. Furthermore, benefitting from the mechanical foldability of the MCF framework, the composite can perform well in the folded state. Besides, as a PANI-containing electrode material, its long-term cycling stability is pretty good (more than 84% retention after 5000 cycles). Therefore, this work provides an environment-friendly, cost-effective and high-performance electrode material for foldable electronic devices.

The application of biomass-based carbonaceous solid acids in catalysis is attracting increasing attention in the field of chemistry. In this study, a heterogeneous carbon-based solid acid biocatalyst (CXH-SO3H) with regular spherical structure was synthesized from xylan-type hemicellulose (XH) by a simple two-step method. The catalyst was successfully applied in the synthesis of O- and N-heterocycles with yields of 80–99% and 60–97%, respectively. In view of environment and economy, CXH-SO3H shows the merits of environmental friendliness, easy operation, simple work-up, excellent yields, and the avoidance of use of organic solvents and expensive catalysts. Moreover, the as-synthesized solid acid catalyst could be used for several cycles without significant loss in its catalytic activity. The results of FT-IR, XRD, and SEM showed that no distinct differences in physico-chemical structures of CXH-SO3H were observed. Thus, the eco-friendly CXH-SO3H catalyst is a promising candidate for green synthesis of O- and N-heterocycles from low-cost feed-stocks and has good prospect in partially substituting commercially available solid and liquid acid catalysts and precious metal catalysts.

A novel amphiphilic biopolymer was synthesized by incorporating hydrophobic segment cholic acid (CA) into hydrophilic segment carboxymethyl xylan (CX) through coupling agent. Structural characteristics and self-assembly behaviors of the amphiphilic conjugates in aqueous solution were investigated in detail. Results showed that the conjugates provided monodispersed self-assembled micelles in distilled water, with average diameters in the range of 90–135 nm, depending on the DS of CA. TEM and AFM images proved that the self-assembly micelles were spherical. The micelles were covered with negatively charged carboxymethyl xylan shells, exhibiting zeta potential about − 38 mV. The aggregation concentration of the conjugate (0.0079–1.25 × 10−2 g/L) was closely related to the DS of CA and solution pH. Moreover, CX–CA nanoparticles were sensitive to the pH of release media. The cellular uptake of DOX-loaded CX–CA nanoparticles was better than that of free DOX, and thus CX–CA nanoparticles can be used as a new carrier for antitumor drug delivery.

Herein, a new hydrothermal method has been reported for one-step controllable synthesis of ZnS@Bi2S3 nanosheets, which were used for the highly selective oxidation of biomass-derived monosaccharides to produce value-added sugar acids. The results of the photocatalytic oxidation by ZnS@Bi2S3 were compared with that by pure Bi2S3, under the same reaction conditions. Compared to pure Bi2S3, ZnS@Bi2S3 nanosheets has showed broadened band gap and improved stability. The relative band alignment indicated that the ZnS@Bi2S3 nanosheets could suppress the recombination of photogenerated charge carriers to improve the photocatalytic activity. Density functional theory (DFT) calculations were performed to investigate the photocatalytic reaction mechanism where xylose and oxygen are adsorbed on Bi2S3 (113) and ZnS (111). The xylose adsorbed on the catalytic surfaces reacted with the active free radicals generated from the photocatalytic process, and then was selectively oxidized to xylonic acid.

Solid polymer electrolytes (SPEs) are promising candidates for all-solid-state lithium batteries (ASSLBs) due to their advantages of good interfacial adhesion and shape flexibility. However, the low ionic conductivity at room temperature (RT) and inferior electrochemical stability at high voltages limit the practical applications of SPEs. In this work, we demonstrate a cryogenic engineering to improve PEO-based SPEs for ASSLBs operated at RT. The rapid in situ cooling process will lead to the uniform formation of PEO crystal nuclei, which can limit the PEO crystal growth in SPEs. The novel crystallization structure could promote the ionic conductivity of SPEs effectively. Such improved cryogenic SPEs display a superior ionic conductivity of 2.17 × 10−5 S cm−1 and a superior electrochemical stability at RT. A discharge capacity of 154.9 mAh g−1 can be achieved at 0.1 C and RT when LiFePO4 (LFP) is used as the cathode. The discharge capacity can remain at ~98%, even after 100 cycles performed at 0.1 C. Notably, cryogenic SPEs can be utilized in 4 V-class ASSLBs. A high discharge capacity of 118 mAh g−1 can be achieved at 0.2 C and RT with the LiNi0.6Co0.2Mn0.2O2 (NCM622) as the cathode and can retain a 94.1% capacity even after 100 cycles. These extraordinary performances of cryogenic SPEs break new ground for the fabrication of ASSLBs operated at RT and high voltages.

Composites combining electrostatic charge accumulation and faradic reaction mechanisms are especially attractive high-performance supercapacitor electrodes for electrochemical energy storage. Up to now, it is difficult to prepare low-cost carbon composites from renewable resources. In this work, an outstanding and low-cost composite was fabricated by using sustainable N-self-doped carbon framework as a hierarchical porous carbon substrate from renewable resource. The N-self-doped carbon framework was fabricated from chitosan via a facile yet unique self-assembly and ice template method without any physical or chemical activation, and exhibited hierarchical porous structure. This texture not only allowed the efficient infiltration and uniform coating of polyaniline (PANI) in the inner network but also permitted a rapid penetration and desorption of electrolytes. Due to short diffusion pathway, uniformly coating of PANI, and high accessibility of PANI to electrolytes, the composite electrode had a very high...

Producing hierarchical porous N-doped carbon from renewable biomass is an essential and sustainable way for future electrochemical energy storage. Herein we cost-efficiently synthesized N-doped porous carbon from renewable cellulose by using urea as a low-cost N source, without any activation process. The as-prepared N-doped porous carbon (N-doped PC) had a hierarchical porous structure with abundant macropores, mesopores and micropores. The doping N resulted in more disordered structure, and the doping N content in N-doped PC could be easily tunable (0.68-7.64%). The doping N functionalities could significantly improve the supercapacitance of porous carbon, and even a little amount of doping N (e.g. 0.68%) could remarkably improve the supercapacitance. The as-prepared N-doped PC with a specific surface area of 471.7m2g-1 exhibited a high specific capacitance of 193Fg-1 and a better rate capability, as well as an outstanding cycling stability with a capacitance retention of 107% after 5000 cycles. Moreover, the N-doped porous carbon had a high energy density of 17.1Whkg-1 at a power density of 400Wkg-1.

Polyimides (PIs) as a dielectric material have attracted much attention due to their good mechanical properties and thermal stability. However, the low dielectric constant of traditional PIs greatly restricts their applications in dielectric capacitors. Here we introduce crown ether groups into PI to increase the polarization of molecular chains. The resultant crown ether-containing PI films showed high dielectric constant and low dielectric loss, but without sacrificing the mechanical and thermal properties.

A water-soluble, ratiometric fluorescent pH probe, L-SRhB, was synthesized via grafting spirolactam Rhodamine B (SRhB) to lignosulfonate (LS). As the ring-opening product of L-SRhB, FL-SRhB was also prepared. The pH-response experiment indicated that L-SRhB showed a rapid response to pH changes from 4.60 to 6.20 with a pKa of 5.35, which indicated that L-SRhB has the potential for pH detection of acidic organelle. In addition, the two probes were internalized successfully by living cells through the endocytosis pathway and could distinguish normal cells from cancer cells by different cell staining rates. In addition, L-SRhB showed obvious cytotoxicity to cancer cells, whereas it was nontoxic to normal cells in the same condition. L-SRhB might have potential in cancer therapy. L-SRhB might be a promising ratiometric fluorescent pH sensor and bioimaging dye for the recognition of cancer cells. The results also provided a new perspective to the high-value utilization of lignin.

A controllable drug delivery system demonstrates a promising tool for diverse biomedical applications. In this work, a group of amphiphilic macromolecules was designed and prepared via Schiff base reactions between 2,3-dialdehyde cellulose (DAC) with oleylamine and amino-containing compounds. Benefiting from the self-assemble process of these amphiphilic macromolecules in the poor solvent, a group of novel pH-responsive nanoparticles (NPs) were facilely fabricated by using nanoprecipitation dropping technique. The high amount of aldehyde groups on DAC chains enabled immobilization of tunable amounts of amine compounds (up to 1.67 mmol/g) in the NPs. Furthermore, the Schiff base bonds in NPs allowed the efficient release of the drug in acidic tumor microenvironment by cleaving the Schiff base linkages. This study demonstrates the formation of a group of novel pH-sensitive and drug-loadable NPs, which provide a simple and efficient drug delivery system for the potential application for cancer treatment.

An efficient one-pot approach for the production of levulinate ester from renewable carbohydrates is demonstrated over heteropolyanion-based ionic liquid (IL-POM) catalysts with alcohols as the promoters and solvents. The relationships between the structure, acidic strength, and solubility of the IL-POM in methanol and the catalytic performance were studied intensively. A cellulose conversion of 100 % could be achieved with a 71.4 % yield of methyl levulinate over the catalyst [PyPS]3PW12O40 [PyPS=1-(3-sulfopropyl)pyridinium] at 150 °C for 5 h. This high efficiency is ascribed to the reasonably high activity of the ionic liquid (IL) catalyst and reaction coupling with rapid in situ esterification of the generated levulinic acid with the alcohol promoter, which allows the insolubility of cellulose encountered in biomass conversion to be overcome. Furthermore, the present process exhibits high feedstock adaptability for typical carbohydrates and handy catalyst recovery by a simple self-separation procedure through temperature control.

Polymer dielectrics with high dielectric constant, low dielectric loss, high breakdown strength, and high temperature capability are attractive for applications such as capacitive energy-storage. Commercially available polymer dielectrics such as biaxially oriented polypropylene (BOPP), poly(ethylene terephthalate) (PET), poly(ethylene naphthalate) (PEN), polycarbonate (PC), and poly(vinylidene) fluoride (PVDF) can be just operated below 200 °C. Great effort has been put into exploring high temperature polymer dielectrics to fulfill the demand of high temperature applications, such as the aerospace and military power supply. In this study, a series of polyimides containing bipyridine units with good dielectric performance and high temperature capability were prepared by using a newly synthesized diamine monomer, (5,5′-bis [(4-amino) phenoxy]-2,2′-bipyridine (BPBPA)). These polyimides possessed high dielectric constant of the as -synthesized polyimides can be up to7.2, the dielectric loss was 3 . Furthermore, the polyimides exhibited high glass transition temperature (Tg) of 275–320 °C and tensile strengths of 175–221 MPa. These obtained polyimides promise potential applications in high temperature flexible polymer film capacitor operated at high temperature.

Fabrication of cost-effective and eco-friendly hierarchical porous carbons from the most abundant and widely available biomass cellulose represents a critical and sustainable way to solve the crisis of fossil resources. In this work, a hierarchical porous carbon aerogel with desirable macropores, mesopores, and micropores was obtained via dissolving-gelling and subsequent carbonizing-activating process. The CO2 activated carbon aerogel had a high specific surface area of 1364 m2/g and a high specific capacitance of 328 F g−1 (0.5 A g−1, 1.0 M H2SO4) as well as an outstanding cycling stability with 96% of the capacitance retention after 5000 charge/discharge cycles. More importantly, for the first time, we demonstrated that the cellulose-derived hierarchical porous carbon aerogel showed a good CO2 adsorption capacity of 3.42 mmol/g (at 1 atm and 298 K), which indicates the possibility of using this carbon aerogel for CO2 capture.

Converting cellulose to renewable energies and chemicals is the most promising and sustainable route to solving the crisis of fossil fuel resources. Up to now, however, it is still a big challenge to effectively transform recalcitrant cellulose into targeted compounds. For the first time, this study proposes a new and highly effective catalysis system with a synergy effect to convert cellulose into formic acid and levulinic acid simultaneously by using in situ carbonic acid from CO2 as a green acid in the presence of CrCl3. The synergy effect of in situ carbonic acid and CrCl3 could highly effectively hydrolyze cellulose to glucose, isomerize glucose to fructose, dehydrate fructose to HMF, and rehydrate HMF to formic acid and levulinic acid in a one-pot way. Here, 49% formic acid and 32% levulinic acid could be obtained from cellulose at a moderate condition. Our results demonstrated that this new catalysis system is comparable to other catalysis systems, and in situ carbonic acid can be used as a low-cos...

Flexible supercapacitors are extremely important for future various electronic devices. However, the development of cost-efficient and high-performance flexible supercapacitor electrodes remains a big challenge today. Herein, we present a novel flexible nanocomposite based on a cellulose-derived framework coated with polyaniline (PANI). In this nanocomposite, the cellulose nanofiber (CNF) provides mechanical strength due to its interconnected network, while the strapped cellulose-derived carbon sheet (CCS) with a unique morphology produces a porous structure and offers fast transfer pathways for the efficient diffusion of electrode ions. PANI imparts conductivity to the CNF and provides abundant active sites for charge storage. The porous structure and supercapacitive performance of this kind of nanocomposite can be easily tailored by changing the feeding mass ratio of the CNF, CCS, and PANI. A relatively low CCS loading can produce a flexible electrode with an ultrahigh specific areal capacitance of 1838.5 mF cm−2 (150 F g−1) (1 mA cm−2), while high CCS loading can produce a free-standing electrode with a higher specific areal capacitance of 3297.2 mF cm−2 (220 F g−1) (1 mA cm−2). Besides, the robust three-dimensional network guarantees good cycling stability of the nanocomposite electrode (more than 83% retention after 3000 cycles). The tunable structure and electrochemical performance make the nanocomposite an ideal electrode for various electronic devices.

Hierarchical porous N-doped carbons have attracted great interest in energy storage and CO2 capture applications due to their unique porous structure and physicochemical properties. Fabrication of cost-effective and eco-friendly hierarchical porous N-doped carbons from renewable biomass resources is a sustainable route for future energy storage. However, it is still a big challenge to produce N-doped carbons with hierarchical porous structure from cellulose, which is the most abundant and widely available renewable resource on earth. Here, we designed a facile and effective strategy to produce hierarchical porous N-doped carbons from cellulose for high-performance supercapacitor and CO2 capture applications. In this method, hierarchical porous cellulose aerogels were first obtained via a dissolving–gelling process and then carbonized in NH3 atmosphere to give hierarchical porous N-doped carbon aerogels with more interconnected macropores and micropores. Due to the unique porous structure and physicochemical properties, the as-prepared N-doped carbon aerogels had a high specific capacitance of 225 F g−1 (0.5 A g−1) and an outstanding cycling stability. For the first time, we also demonstrated that this N-doped carbon aerogel exhibited a exceptional CO2 adsorption capacity of 4.99 mmol g−1, which is much higher than those of other porous carbons. This novel hierarchical porous N-doped carbon has great potential applications in CO2 capture, energy storage, porous supports, and electrochemical catalysis.

A simple and effective synthesis of 3,4-dihydropyrimidin-2(1H)-ones/thiones and their derivatives from aldehydes, β-dicarbonyl compounds and urea or thiourea using D-xylonic acid both as a green solvent and an effective catalyst is described. Taking the environment and economy into account, the work presented here has the merits of environmental friendliness, easy operation, simple work-up, excellent yields and the avoidance of organic solvents and inexpensive catalysts. In addition, the good properties of D-xylonic acid have also been validated by the synthesis of 5-phenyl-1(4-methoxyphenyl)-3[(4-methoxyphenyl)-amino]-1H-pyrrol-2(5H)-one and 12-phenyl-9,9-dimethyl-8,9,10,12-tetrahydrobenzo[a]xanthen-11-one. The synthesized compounds were characterized by FT-IR, 1H NMR, 13C NMR and melting point.

Hierarchical porous N-doped carbons show great potential applications in energy storage and CO2 capture. Renewable biomass chitosan, which is abundant and simultaneously contains large amounts of N and C, is an ideal alternative to fossil resources for sustainable and scale-up production of cost-effective N-self-doped carbons. In this work, we employed a new and effective strategy to obtain 3D hierarchical porous N-self-doped carbons from chitosan. The hierarchical porous structure of the N-self-doped carbons could be easily tailored to obtain nanorod interconnected and fiber-wall interconnected architectures without using any porogen, catalyst or activator. The nanorod interconnected porous carbon displayed a high specific surface area of 1408 m2 g−1 while the fiber-wall interconnected porous carbon exhibited an excellent specific capacitance of 261 F g−1 (0.5 A g−1) due to the desirable hierarchical framework. In addition, these hierarchical porous carbons had a good CO2 capture performance (3.07–3.44 mmol g−1 at 25 °C). This unique method is supposed to be a new strategy to create novel 3D hierarchical porous carbons for promising applications in supercapacitors, lithium ion batteries, fuel cells and sorbents.

Catalytic process is the key process for many chemical industries. In this study, a novel heterogeneous Pd (CMH–Pd(0)) has been prepared by the deposition of palladium nanoparticles (Pd NPs) onto the surface of carboxymethyl functionalized hemicelluloses using ethanol as solvent and in situ reducing agent. The as prepared catalyst was characterized by TEM, HR-TEM, XRD, FT-IR, TGA and XPS. The loading level of Pd in the CMH–Pd(0) catalyst was 0.38 mmol g−1. The catalyst showed high catalytic activity and versatility towards Heck coupling reactions under aerobic conditions and could be readily recovered and reused in at least five successive cycles without obvious loss in activity. The catalyst is promising for its renewability, environmental benefits, efficient catalytic activity, mild reaction conditions, simple product work-up and easy catalyst recovery.

Novel polyimide–copper complexes (PICuCs) with a high dielectric constant of up to 133 were prepared by polymerization, complexation and imidization of a newly synthesized bipyridine-containing diamine monomer. The PICuCs showed high dielectric constant because of the enhanced electronic depolarization. Moreover, the PICuCs presented better mechanical and thermal properties than neat PI, which are promising materials for polymer film capacitors.