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Long-wavelength afterglow has been a key issue in the investigation of afterglow materials. Herein, the orange/red (Sr/Ba)1−xCaxGe4−yO9:0.01Mn2+ is prepared by the introduction of vacancy induction and solid solution. The (Sr/Ba)Ge4O9:Mn2+ hardly possesses an afterglow phenomenon and exhibits only red/orange photo-luminescence (PL) attributed to the d–d transition of Mn2+, while samples with reduction of the Ge4+ content and with replacement by Ca2+ show bright afterglow emission with the peak located at about 612 nm/620 nm. The emerging broadband peak comes from charge transfer involving Mn2+ and nearby defect clusters and the bottom of the conduction band (CB). The introduction of V′′′′Ge creates a defective energy level above the valence band, but the ground state energy difference with Mn2+ is too large (>1 eV) to allow hole transfer, which was confirmed by ultraviolet photoelectron spectroscopy (UPS), spherical aberration-corrected transmission electron microscopy (AC-STEM), charge differential density (CDD) analysis, electron paramagnetic resonance (EPR) analysis, etc. With this achievement, we propose an original design strategy for long-wavelength afterglow and a more reasonable afterglow mechanism, which is of great importance for the investigation of long-wavelength afterglow materials. [ABSTRACT FROM AUTHOR]

Three isostructural lanthanide metal–organic frameworks (Ln-MOFs), {[Ln(L)(H2O)2]·H2O}n (M-Ln, Ln = Eu/Tb/Dy), were prepared with a flexible 3,5-(4-carboxybenzyloxy) benzoic acid (H3L) ligand and lanthanide ions by a solvothermal method. M-Ln are two-dimensional (2D) grid layer-stacking frameworks. M-Eu exhibits excellent chemical stabilities against organic solvents and shows strong luminescence. The experimental results indicated that M-Eu could be used as an ideal fluorescent probe to detect nitrobenzene (NB) in different solvents with a lower detection limit. M-Eu can also be used as a pH sensor because of its superior water stability. Furthermore, M-Eu and M-Tb show unique strong luminescence properties with high absolute quantum yields. The quantum yields can even reach up to 11.8% and 60.5%, respectively. Simultaneously, various kinds of heterometallic doped M-Eu x Tb 1−x MOFs were acquired by tuning the ratios of Eu3+/Tb3+ ions, showing the unique color changes from red, orange-red, orange, orange-yellow, light yellow, yellow to green. [ABSTRACT FROM AUTHOR]

Asymmetrical five ring fused compounds based on S,S-dioxide benzothiophene, 9,9-dioctylfluorene[2,3-b]benzo[d]thiophene-S,S-dioxide(BTOF) and N-(2-decyltetradecyl)carbazole[2,3-b]benzo[d]thiophene-S,S-dioxide (BTOCz) were synthesized and characterized. BTOF and BTOCz were readily soluble in common organic solvents and exhibited high thermal stability with the melting points (Tms) of 119 °C and 150 °C, and thermal decomposition temperatures (Tds) of 280 °C and 338 °C, respectively. The highest occupied molecular orbital energy levels (HOMOs), the lowest unoccupied molecular orbital energy levels (LUMOs) and the band gaps (Egs) of BTOF and BTOCz were −6.11, −2.66 and 3.45 eV, −5.86, −2.52 and 3.34 eV, respectively. The photoluminescence (PL) spectra of BTOF and BTOCz were peaked at 404 and 420 nm in film, and the photoluminescence quantum yields (QPLs) were 30% and 10% in toluene solution, respectively. BTOF and BTOCz showed strong intramolecular charge transfer (ICT) character, relatively high QPLs and deeper HOMO and LUMO levels compared with compounds BTF and BTCz. Compared with the symmetrical seven ring fused compounds FBTO and CzBTO, the asymmetrical five ring fused compounds BTOF and BTOCz showed relatively shallow HOMO levels, which can facilitate hole injection, and therefore, could be potential construction units in organic semiconductors. [ABSTRACT FROM AUTHOR]

Renewable hemicellulose with a unique structure exhibits a wide range of potential applications. However, it has been a formidable challenge to isolate hemicellulose with an intact structure from lignocellulosic materials. In this study, LiBr·3H2O (LBTH) was used as a green solvent for the effective fractionation of hemicellulose from bleached hardwood kraft pulp (BHKP) under mild conditions (25–85 °C). It was found that hemicellulose in BHKP can be dissolved in LBTH with ease and high selectivity owing to the breaking of hydrogen bonds between hemicellulose and cellulose, and the dissolved hemicellulose can be regenerated with a high degree of polymerization (DP) in the range of 240–264 using ethanol precipitation. The highest removal rate of hemicellulose from BHKP was as high as 95.2%, and the corresponding yield of pure hemicellulose reached 84.3%. Moreover, simultaneously obtained undissolved cellulose pulp through LBTH treatment had a high content of α-cellulose (96.7%), high DP (880), and trace levels of Fe (2 ppm), which met the standard requirement for dissolving pulp for the production of lyocell. In addition, LBTH can be easily recycled to guarantee a green and sustainable process. This work provides a new approach for highly selective fractionation of hemicellulose and cellulose from commercial BHKP based on an efficient and environmentally friendly LBTH treatment, which could be very promising for better valorization of hemicellulose and cellulose in many advanced applications. [ABSTRACT FROM AUTHOR]

Novel carbon nitride polymer sensitized TiO2nanotube arrays with high photocatalytic activity and photoelectrochemical response under visible light irradiation are prepared by electrodeposition. [ABSTRACT FROM AUTHOR]

MnO2 nanoparticles with high theoretical capacitance were successfully synthesized on a reduced graphene oxide/lignin-based porous carbon (RGO/PC) composite membrane by a simple electrodeposition method, and a ternary RGO/PC/MnO2 composite electrode for flexible supercapacitors was prepared. The RGO/PC/MnO2-1200s composite electrode exhibited a maximum specific capacitance of 1136 mF cm−2 (MnO2 mass loading of 6.25 mg cm−2 and a mass specific capacitance of 135 F g−1) at a current density of 1 mA cm−2. This is attributed to the high surface area of the MnO2 nanoparticles and the conductive pathway provided by the RGO/PC framework. The assembled flexible solid-state symmetric supercapacitors have outstanding cycling stability (approximately 85.2% capacitance retention after 5000 cycles) and good mechanical flexibility (about 87.6% of the original capacitance after 500 bending cycles). Importantly, the device can possess a maximum energy density of 0.253 mW h cm−3 at 0.5 mA cm−2 and a maximum power density of 0.018 W cm−3 at 5 mA cm−2. The results above indicate that the RGO/PC/MnO2 composite has potential applications in flexible energy storage devices. [ABSTRACT FROM AUTHOR]

Polyelectrolytes with ultra-low glass transition temperatures (Tg) are still a rarity. Herein, we report a series of free-flowing lignin polyelectrolytes with ultra-low Tg in the range of −57–9 °C, namely, deep eutectic supramolecular lignin (DESL). The enabling key principle is to couple the eutectic strategy with supramolecular polymerization, bypassing the exclusive reliance on the large size and flexible cation/anion pairs for flowable polyelectrolytes. Following this principle, various sugars have been successfully integrated with lignosulfonic acid via multiple hydrogen bondings, allowing for bulk yet free-flowing supramolecular materials. These DESLs are processible, adaptive, and compatible to serve as macromolecular solvents and are distinct from traditional polyelectrolyte solutions or chemical modification derivatives. The robustness and versatility of our approach provide a fresh opportunity for booming polyelectrolyte utilization, opening access to a yet unknown fluidic material class. [ABSTRACT FROM AUTHOR]

Developing green and effective solvents is of significant importance for the utilization of lignin. Here, we demonstrated that biomass-derived polar aprotic solvents can serve as co-solvents with poly-deep eutectic solvents (PDESs) for massively dissolving various lignin samples at room temperature. The pristine PDESs were composed of polyethylene glycol derivatives and levulinic acid, while all of them exhibited poor solubility to enzymatic hydrolysis lignin (EHL), sodium lignosulfonate (LS), and organosolv lignin (OL). With the further introduction of polar aprotic solvents, including dimethylisosorbide (DMI), dihydrolevoglucosenone (Cyrene), N-formylmorpholine (NFM), and propylene carbonate (PC), synergy between the polar aprotic solvents and PDESs dramatically increased lignin solubility to 96.82%. PC and DMI were more suitable for assisting the solubilization of EHL and OL, while Cyrene and PC were targeted at the solubilization of LS in PDESs, respectively. Moreover, a new unified co-solvent solubilization mechanism relative to the Kamlet–Taft empirical parameters was proposed. The novel polar aprotic/PDES systems provide a new avenue for boosting the high utilization of lignin. [ABSTRACT FROM AUTHOR]

Developing aqueous stable and catalytic Ti3C2Tx MXene suspensions remains a grand challenge. MXene nanosheets always undergo rapid degradation when exposed to water and oxygen, and the incorporation of reducing or capping agents may deteriorate the intrinsic characteristics of MXenes. Here, we coupled dialdehyde xylan (DAX) with MXene nanosheets to significantly increase the long-term storage of MXene in an aqueous solution (>3 months) with a dramatic enhancement of their room temperature catalytic activity for ultrafast gelation. DAX can form thick and smooth layers on the nanosheets via multiple hydrogen bonds, providing a reduction environment to prevent the occurrence of oxidation. Meanwhile, DAX can accelerate the generation of free radicals from the potassium persulfate (KPS)/MXene pair, reducing the polymerization time of vinyl monomers from ∼30 min to ∼90 s. Moreover, the DAX layer is capable of serving as additional crosslinks by leveraging Schiff base bonds with chitosan (CS), with the elongation at break increasing from 100% to 909%. The resultant MXene-based hydrogel can be further explored as a sustainable sensor for real-time physical signal monitoring. This work offers an enticing prospect for the development of eco-friendly and high-performance MXene-based materials. [ABSTRACT FROM AUTHOR]

A simple and template-free method for the fabrication of modified pulp fiber (PF)–polyacrylamide (PAM)–graphene (RGO) composite electrodes was developed. The pulp fiber–graphene electrodes decorated with polyacrylamide were synthesized via a facile vacuum-filtration process, and further optimized through different mass ratios. Benefiting from the porous structure and large amounts of hydrophilic groups in the paper fiber, the PF–PAM–RGO composite electrode demonstrated good hydrophilic property and ion transport capacity within the electrode. After adding the polyacrylamide molecule (PF–RGO), the PF–PAM–RGO composite electrode exhibited good mechanical properties and capacitance performance due to PF–RGO hydrogen bonding. Moreover, the PF–PAM–RGO composite electrode displayed a high area specific capacitance of 498.4 mF cm−2 with a mass of 2.32 mg cm−2 (specific capacitance of 214.8 F g−1) at 0.2 mA cm−2. The assembled PF–PAM–RGO composite electrode showed a good cycling stability (92.36% capacitance retention after 8000 charging/discharging cycles) and mechanical flexibility (87.65% capacitance retention after 500 bending/unbending cycles). Remarkably, the flexible device could achieve superior energy density of 80.59 μWh cm−2 and high power density of 2549.83 μW cm−2. [ABSTRACT FROM AUTHOR]

The present report focuses on the solvent effect on furfural production from xylose in biphasic systems with methods including combined experiments, molecular dynamics (MD) simulations and density functional theory (DFT) calculations. Six most effective and commonly used biphasic solvents for furfural production were comparatively analyzed and discussed based on the kinetic study, partition coefficient, degradation behavior of furfural in organic solvents, distribution of solvent molecules around xylose/furfural molecules, hydrogen bonding, moving trajectories of xylose/furfural, and the solvation free energy. During the hydrothermal reaction of xylose to furfural in biphasic systems, it was found that the conversion efficiency of biphasic systems can be ordered as DCM/H2O > 2-MTHF/H2O > 2-butanol/H2O ≈ MIBK/H2O > CPME/H2O > toluene/H2O according to the xylose conversion and furfural yield, which are dominated by the solvation free energy (ΔGsol) of furfural in organic solvents, and also be affected by three other factors, namely, the maximum solubility of furfural in organic solvents, the ΔGsol value of organic solvents in water, and the side reaction of furfural in organic solvents. The degradation rate of furfural in 2-butanol was detected to be the fastest, and molecular dynamics simulation data showed that the hydrogen bonding between furfural and 2-butanol may accelerate the degradation of furfural. DCM has excellent extraction ability for furfural, and the maximum furfural yield in the DCM/H2O system (81.64%) is much higher than that in other systems during the hydrothermal reaction without additional catalysts. [ABSTRACT FROM AUTHOR]

Liquid metal (LM)-based nano-inks are facing challenges for their use in wearable electronics due to their low colloidal/chemical stability, cost, potential hazards, and the lack of multifunction. Here, we demonstrate a dialdehyde xylan (DAX) stabilizing LM ink encompassing low-cost, long-term stability, biocompatibility, and catalytic activity. DAX with a high molecular weight was obtained by converting the industrial pulping byproducts, xylan, in water directly with sodium periodate (NaIO4) at room temperature. The DAX/LM ink revealed remarkable chemical and colloidal stability for a period of approximately 7 d, as well as high affinity to various substrates. Compared with other LM nano-inks, the DAX/LM ink showed a remarkable catalytic feature for ultrafast polymerization of vinyl monomers, as well as chemical reactivity to construct double network (DN) gels with motion-sensing properties. This work holds promises for the high value-added utilization of lignocellulosic biomass in the fields of future flexible electronic materials. [ABSTRACT FROM AUTHOR]

A new polymer acceptor, PS1, was developed by connecting the non-fullerene acceptor building block of dithienothiophen[3,2-b]pyrrolobenzotriazole capped with 3-(dicyanomethylidene)-indan-1-one through a thiophene spacer. The solubilizing alkyl side groups in the central unit enabled PS1 to be readily dissolved in non-chlorinated solvents. By using 2-methyltetrahydrofuran as the processing solvent, the all-polymer solar cell (all-PSC) containing PS1 and a polymer donor PTzBI-oF in the light-harvesting layer exhibited an impressively high power conversion efficiency of 13.8%. [ABSTRACT FROM AUTHOR]

Fluidic materials that exhibit an engineered non-Newtonian response are highly desirable in industrial and military applications. For example, shear thickening is highly intriguing in the case of flexible body armor or damping devices; however, shear thinning is more suitable in industrial processes with confining flow or painting. Herein we present a new class of non-Newtonian polymeric fluids with switchable rheological properties being mediated by carbon dioxide (CO2). Several pH-sensitive associative amphiphilic polymers were designed by copolymerizing N,N-dimethylacrylamide (DMA) and N,N-dimethylaminoethyl methacrylate (DMAEMA), followed by hydrophobic modification. In the beginning, polymers carrying an optimal balance of hydrophilic and hydrophobic moieties exhibit shear thinning properties in an alkaline environment. After CO2 aeration, the protonation of tertiary amine groups on the polymer backbone induces coil expansion and promotes interchain cross-linking under shear, leading to an abnormal shear thickening. The fluidic material can regain its shear thinning properties after sparging the solution with N2. Such a gas-controlled process is reversible and clean, which can be performed over multiple cycles. This study taps the potential of CO2 utilization in the dynamic fluidic materials science. [ABSTRACT FROM AUTHOR]

We herein report a 12-armed photo-responsive supramolecular star centered by a pillar[6]arene-coated M6L12 metal–organic polyhedron (MOP) via a core-first approach. [ABSTRACT FROM AUTHOR]

In this study, experiments and molecular dynamics simulations were combined to get insights into the role of solvent during the process of xylose conversion under catalyst-free conditions. Solvents used for furfural production were comparatively discussed, including traditional and emerging biomass-derived solvents – water, dimethyl sulfoxide (DMSO), dimethyl formamide (DMF), isopropanol (ISO), γ-butyrolactone (GBL) and γ-valerolactone (GVL). The degradation behavior of solvents, the solubility and α/β ratio of xylose, the distribution of the solvent around xylose/furfural and the hydrogen bonding between them were also studied. The results showed that in pure solvents, the different hydrogen bonding between xylose and the solvent resulted in different products. Water was a favourable solvent for xylose to form furfural among these pure solvents because less formic acid was produced from xylose in water under catalyst-free conditions. Furfural could be produced in mixed solvents if there was more water around xylose, which was similar to the case in pure water. Otherwise, the situation in mixed solvents was similar to that in the corresponding pure organic solvents. GBL and GVL, as green solvents, had weaker affinities with xylose than DMSO, DMF and ISO, but were intensively attracted by furfural, thus they could provide protective shells for furfural, which played a positive role during the production of furfural. The highest furfural yield of 46.4% was achieved in GBL–H2O at 180 °C – 150 min in the absence of catalysts. [ABSTRACT FROM AUTHOR]

In order to realize the dream of the practical application of hydrogen energy from solar energy and water, it is necessary to use efficient and earth-abundant cocatalysts for photocatalytic H2 evolution. Compared with a one-component cocatalyst, the multicomponent cocatalysts with a synergistic effect can effectively accelerate the separation of photogenerated electron–hole pairs in photocatalysis. Hence, a novel bicomponent Co3S4/Co@C cocatalyst on a CdS semiconductor photocatalyst is successfully synthesized by a one-step hydrothermal method. The Co3S4/Co-CdS photocatalyst obtained exhibits a highly efficient photocatalytic H2 evolution rate of 15.17 mmol h−1 g−1, which is 2.8 times higher than that of Pt-CdS. Furthermore, the quantum efficiency of Co3S4/Co-CdS reaches a maximum value of 16.80% at 475 nm. The significant improvement in the performance is because of the unique energy level structure of the Co3S4/Co-CdS photocatalyst, which has the maximum efficiency of charge separation and migration. This work not only presents a new protocol for constructing bicomponent cocatalysts on a semiconductor structure, but also proves that the bicomponent Co3S4/Co@C is a promising and low-cost cocatalyst. [ABSTRACT FROM AUTHOR]

In recent years, nanocrystals of metal sulfide materials have attracted scientific research interest for renewable energy applications due to the abundant choice of materials with easily tunable electronic, optical, physical and chemical properties. Metal sulfides are semiconducting compounds where sulfur is an anion associated with a metal cation; and the metal ions may be in mono-, bi- or multi-form. The diverse range of available metal sulfide materials offers a unique platform to construct a large number of potential materials that demonstrate exotic chemical, physical and electronic phenomena and novel functional properties and applications. To fully exploit the potential of these fascinating materials, scalable methods for the preparation of low-cost metal sulfides, heterostructures, and hybrids of high quality must be developed. This comprehensive review indicates approaches for the controlled fabrication of metal sulfides and subsequently delivers an overview of recent progress in tuning the chemical, physical, optical and nano- and micro-structural properties of metal sulfide nanocrystals using a range of material fabrication methods. For hydrogen energy production, three major approaches are discussed in detail: electrocatalytic hydrogen generation, powder photocatalytic hydrogen generation and photoelectrochemical water splitting. A variety of strategies such as structural tuning, composition control, doping, hybrid structures, heterostructures, defect control, temperature effects and porosity effects on metal sulfide nanocrystals are discussed and how they are exploited to enhance performance and develop future energy materials. From this literature survey, energy conversion currently relies on a limited range of metal sulfides and their composites, and several metal sulfides are immature in terms of their dissolution, photocorrosion and long-term durability in electrolytes during water splitting. Future research directions for innovative metal sulfides should be closely allied to energy and environmental issues, along with their advanced characterization, and developing new classes of metal sulfide materials with well-defined fabrication methods. [ABSTRACT FROM AUTHOR]

Glycerol oxidation over a Pt catalyst can be effectively enhanced by a Bi additive in terms of activity and 1,3-dihydroxyacetone (DHA) selectivity. However, this catalyst system can suffer from serious deactivation. Here, a Bi-promoted Pt catalyst was developed to selectively produce DHA by maintaining the glycerol solution with Bi(NO3)3·5H2O to meet the continuous operation of practical applications. The catalyst deactivation mechanism was investigated in terms of leaching, over-oxidation, agglomeration and poisoning. It was ascertained that the catalyst deactivation was due to the adsorption of chelating intermediates on the catalyst surfaces. A regeneration method by post-heat-treatment at 200–300 °C could remove the intermediates and regenerate the catalyst, allowing recycling for at least 5 runs without clear catalyst deactivation. [ABSTRACT FROM AUTHOR]

A new luminescent metal–organic framework, {[Cd3(HL)2(H2O)3]·3H2O·2CH3CN}n (1) (H4L = 1-(3,5-dicarboxylatobenzyl)-3,5-pyrazole dicarboxylic acid), has been synthesized by solvothermal reaction and characterized by infrared spectroscopy, powder X-ray diffraction, thermogravimetry measurements and so on. 1 shows a new trinodal (4,4,6)-connected topology. Importantly, 1 displays intense luminescence in the solid state and high luminescent sensitivity and selectivity for Fe3+, CrO42− and Cr2O72− ions in aqueous solution, making it a potential probe for detecting these substances. The quenching mechanisms are also further discussed in detail. In addition, further research on the adsorption of dyes shows that 1 can selectively adsorb Congo red dye from other dye molecules. [ABSTRACT FROM AUTHOR]

Bulk nitrogen doping can efficiently improve the catalytic performance of carbon nanotubes (CNT) in oxidative dehydrogenation of propane (ODH). The graphitic nitrogen plays a determining role in enhancing their activity by speeding up the activation of oxygen and decreasing the overall activation energy of the reaction. [ABSTRACT FROM AUTHOR]