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Conductive hydrogels have great potential in wearable electronic devices for motion detection and medical monitoring applications. However, poor tissue adhesion and underwater swelling remain challenging for most hydrogels as in vitro wearable electronic devices. Herein, a tri-network (TN) hydrogel consisting of agarose (AG), amphoteric sulfobetaine methacrylate (SBMA) and polypyrrole (PPy) is developed to solve these problems. Owing to the ionic dipole interactions and cation–π interactions of SBMA, the novel developed hydrogel exhibits good adhesion capability. AG and PPy improve the cross-linking density of the hydrogels, thus improving their resistance to swelling underwater. In addition, the TN hydrogel has less substrate noise interference and high strain sensitivity, which enables it to monitor electrical signals generated by subtle motion variation. Due to the cross-linking of double helical bundles formed by hydrogen bonding in AG linear molecules, the dipole-ionic interactions between sulfonic acid groups and quaternary ammonium cations in SBMA, and the conjugated π-system constituted by alternating single and double bonds in Ppy, the TN hydrogel exhibits good mechanical and electrical conductivity properties. Therefore, this study provides a strategy to generate stretchable, compressive, and conductive hydrogels with adhesive properties and can be used in underwater environments, expanding the potential applications of hydrogels as wearable electronic devices. [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]

Most of the non-fullerene acceptors that have recently emerged for application in organic solar cells are based on fused rings as the central unit, typically requiring multi-step reactions that inevitably increase the overall cost of the target molecules. To explore more synthetically accessible non-fullerene acceptors, here we designed and synthesized two naphtho[1,2-c:5,6-c′]bis([1,2,5]thiadiazole) derivatives, containing fluorinated and chlorinated dicyanomethylidene-indan-1-one units as the flanking end-groups, which were denoted as NTIC-4F and NTIC-4Cl, respectively. The halogen substitution has trivial effects on the optical and frontier molecular orbital energy levels, while the fluorinated NTIC-4F showed distinct thermal properties and crystallinity compared to the chlorinated counterpart NTIC-4Cl. When blended with the electron-donating polymer PTzBI-dF, both compounds showed good miscibility and favorable molecular orientation, as shown in both atomic force microscopy and transmission electron microscopy images. After processing the PTzBI-dF:NTIC-4F or PTzBI-dF:NTIC-4Cl bulk-heterojunction layer with a trivial amount of chloronaphthalene as the solvent additive, it is noted that the film based on NTIC-4Cl showed a more favorable morphology and thus resulted in slightly higher power conversion efficiency of the organic solar cells. These findings provide guidance for the design of non-fused non-fullerene acceptors based on naphthobisthiadiazole as the central unit. [ABSTRACT FROM AUTHOR]

Solvent-controlled extraction and precipitation are the most fundamental methods for obtaining hemicellulose from lignocellulosic biomass and purification processes. However, the dissolution and precipitation mechanisms involved have scarcely been mentioned. In this study, the molecular scale behavior of xylan-type hemicellulose during solvent-controlled extraction and precipitation is investigated using molecular dynamics (MD) simulations and density functional theory (DFT) calculations. To bring the model closer to the real extracted xylan, a high degree of polymerization (DP100) of xylan is established, and hemicelluloses with low DP (DP15 and DP50) are also investigated. Four phenomena are explained at the molecular level, including the influence of the polymerization degree and side chain on the solubility of xylan in water, the improvement of the xylan's solubility in NaOH, the precipitation of xylan in ethanol, and the acetyl group preservation of xylan in DMSO. This study contributes to an increased understanding of the dissolution and precipitation mechanisms of hemicellulose and provides a resource for the simulation of high DP hemicellulose, which gives a theoretical basis for the efficient extraction of high-purity hemicellulose as well as economic biorefining. [ABSTRACT FROM AUTHOR]

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]

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]

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]

The phase stability and superconductivity of lutetium polyhydrides under pressure were systematically explored via particle swarm optimization. Several lutetium hydrides, such as LuH, LuH3, LuH4, LuH6, LuH8, and LuH12, were found to be dynamically and thermodynamically stable. Combined with the electronic properties, there are a large number of H-s states and low density of Lu-f states at the Fermi level, leading to superconductivity. The phonon spectrum and electron–phonon coupling interaction are considered to calculate the superconducting critical temperature (Tc) of stable lutetium hydrides at high pressure. The new predicted cubic LuH12 has the highest Tc value of 187.2 K at 400 GPa in all the stable LuHn compounds, which was estimated by directly solving the Eliashberg equation. The calculated results provide insights into the design of new superconducting hydrides under pressure. [ABSTRACT FROM AUTHOR]

High pressure is a powerful tool in material sciences which can lead to the discovery of novel inorganic species in high oxidation states. Based on the prediction of the stability of PdF6 with a high Pd oxidation state of +6, we propose three potential guiding rules for finding stable transition metal (TM) fluorides with high +6 oxidation states: (1) the existence of a large (>7 eV) valence orbitals energy differences of atoms between the TM d orbital and the F 2p orbital; (2) an appropriate number of valence electrons within the range of 6–11; and (3) suitable electronegativity values less than 2.3 on the Pauli scale. More importantly, by synergistically invoking all of these rules, we predict, by combining a particle swarm optimization algorithm with first-principles calculation on the phase stabilities of the various TM–F compounds, a collection of new TMF6 species with the space group Pnma that have a +6 oxidation state. Subsequently, we develop an understanding of the high +6 oxidation state for the TM elements. These findings are expected to play a crucial role in the predictive discoveries of new fluorides with high oxidation states of +6. [ABSTRACT FROM AUTHOR]

Phosphides have been used in a wide range of applications due to their excellent optical, mechanical, and catalytic properties. Using an effective unbiased structure searching method combined with first-principles calculations, the phase diagram and physical and chemical properties of aluminum phosphides have been determined at high pressures. The results reveal that the unconventional stoichiometries of Al2P, AlP2, and AlP3 remain stable above 66, 91, and 116 GPa, respectively. Interestingly, the analysis of the phonon spectrum suggests that AlP2 with P21 symmetry can be dynamically stable at atmospheric pressure. In addition, the band gap of 1.51 eV at the HSE06 level and the estimated Vickers hardness of ∼10.54 GPa make P21-AlP2 a hard photoelectric material. Moreover, our electronic properties show that AlP3 with Immm symmetry and AlP2 with I4/mmm structure are metallic at high pressures and further electron–phonon coupling calculations indicate Immm-AlP3 and I4/mmm-AlP2 are superconductors with estimated Tc values of 3.9 K at 150 GPa and 10.2 K at 100 GPa, respectively. Our work provides significant inputs toward understanding novel chemical bonding in aluminum phosphides and gives a direction for the experimental synthesis of multifunctional materials at high pressures. [ABSTRACT FROM AUTHOR]

Temperature measurement based on thermally dependent emissions from intra-configurational 4f–4f transitions of rare earth ions has been developed as an efficient method for non-contact thermometry, but it remains challenging for high resolution temperature measurement due to the inherent limitation of the energy gap (200–2000 cm−1) between the thermally coupled energy levels (TCELs). In this work, a group of oxide phosphors, Y2O3:xEr3+, yLi+, prepared by a low-temperature combustion method (LCM) were developed for dual-mode optical thermometry by leveraging the temperature-responsive upconversion (UC) emission from Er3+ ions. We discover that the introduction of the dopant (Li+ ion) into Y2O3: Er3+ synthesized by the LCM can significantly regulate the original crystal configuration and its surface structure. Its transition to a monocrystalline state can solve the problem of high impurity defects and possible high dislocation density that cannot be overcome by a polycrystalline state, thus remarkably increasing the emission intensity of UC (about 28 times). In addition, the dual-mode optical thermometry based on thermally coupled energy levels (TCELs) and non-thermally coupled energy levels (NTCELs) was examined with respect to the different temperature dependence of the three characteristic emission peaks of the Er3+ ions (i.e., from excited levels of 2H11/2, 4S3/2 and 4F9/2). At temperatures from 123 to 443 K, the maximum relative sensitivities (SRmax) are 6.67% K−1 and 1.13% K−1 and the maximum absolute sensitivity (SAmax) reaches 0.42% K−1and 2.48% K−1, respectively. The excellent sensitivity at low temperatures indicates that our results not only provide an effective doping strategy for improving the crystal type character and surface structure of oxide phosphors, but also provide an effective guideline for the low temperature environmental applications of functional upconversion optical thermometers. [ABSTRACT FROM AUTHOR]

Natural luminogens with long-lived room temperature phosphorescence (RTP) are charming and useful since the artificial one always requires complicated synthesis and lacks sustainability. Herein, milk powder (MP) has been found to emit striking afterglow with the duration and lifetime exceeding 10 s and 2 s under ambient conditions, respectively, not inferior to most advanced artificial organic phosphors. There are mainly three emission species in MP, one comes from aromatic amino acid residues, one comes from the combination of oxidation products, Maillard products, nicotinamide adenine dinucleotide (NADH) coenzyme, and clusteroluminescence of nonaromatic amino acid residues, and one comes from riboflavin and/or flavin adenine dinucleotide (FADH), leading to three distinguishable emission bands. Mechanistic studies indicate that the natural hybrid of milk minerals and various emission species, which can provide a rigid environment to suppress the excited-state molecular motion and enhance triplet exciton radiative transition, is responsible for the long-lived RTP. Consequently, MP with unique visible RTP properties is utilized as a versatile platform for green screen printing and information security. This interesting work will shed new light on natural long-lived RTP materials and inspire the design of other high performance RTP materials. [ABSTRACT FROM AUTHOR]

The progress in all-polymer solar cells (all-PSCs) is often accompanied with morphology evolution of the light-harvesting layer. However, the regulation of the bulk-heterojunction (BHJ) morphology of the active layer often encounters obstacles, mainly because of the undesired miscibility of the polymer donor and acceptor. Here, we regulated the BHJ morphology of all-PSCs based on an electron-donating PBDB-T (poly[(2,6-(4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)-benzo[1,2-b:4,5-b′]dithio-phene))-alt-(5,5-(1′,3′-di-2-thienyl-5′,7′-bis(2-ethylhexyl)benzo[1′,2′-c:4′,5′-c′]dithiophene-4,8-dione)]) and an electron-accepting polymer PFA1 via selection of solvents, and found that the PBDB-T:PFA1 film processed with chlorobenzene revealed a smaller phase separation scale than the chloroform processed film, mainly because of the significantly improved miscibility in the PBDB-T:PFA1 blend. Benefitting from the optimized BHJ morphology, the PBDB-T:PFA1 device processed by chlorobenzene achieved a satisfactory power conversion efficiency (PCE) of 15%, obviously higher than that of 12.25% for the chloroform processed device. Meanwhile, the voltage loss of the chlorobenzene processed device is well suppressed comparing with the chloroform processed device, demonstrating unexpected advances of morphology evolution for all-PSCs. [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]

Rapid fabrication of organohydrogels at room temperature without external stimuli is a challenge. Inspired by plant catechol chemistry, a self-catalytic system established using sodium lignosulfonate and copper(II) ions (Ls–Cu2+) has been developed and applied to fabricate organohydrogels rapidly with fascinating multifunctional properties. The Ls–Cu2+ pair can induce ammonium persulfate (APS) to generate free radicals at room temperature, and subsequently initiate the free radical polymerization of hydroxyethyl acrylamide (HEAA) in water–glycerol binary phases in less than 30 s, without the removal of oxygen. The presence of the Ls–Cu2+ pair also endows the organohydrogel materials with fascinating UV-blocking (∼100%) and electrically conductive properties, and thereby they can be exploited as epidermal sensors. Owing to the presence of glycerol, the as-prepared organohydrogel exhibits intriguing anti-freezing (∼−50 °C) and anti-drying abilities (22–60 °C). This work taps the potential of dynamic plant catechol chemistry in the field of organohydrogel materials. [ABSTRACT FROM AUTHOR]

Long-wavelength afterglow has been a key issue in the investigation of afterglow materials. Herein, the orange/red (Sr/Ba) 1- x Ca x Ge 4- y O 9 :0.01Mn 2+ is prepared by the introduction of vacancy induction and solid solution. The (Sr/Ba)Ge 4 O 9 :Mn 2+ hardly possesses an afterglow phenomenon and exhibits only red/orange photo-luminescence (PL) attributed to the d-d transition of Mn 2+ , while samples with reduction of the Ge 4+ content and with replacement by Ca 2+ show bright afterglow emission with the peak located at about 612 nm/620 nm. The emerging broadband peak comes from charge transfer involving Mn 2+ 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 Mn 2+ 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.

The phase stability and superconductivity of lutetium polyhydrides under pressure were systematically explored via particle swarm optimization. Several lutetium hydrides, such as LuH, LuH 3 , LuH 4 , LuH 6 , LuH 8 , and LuH 12 , were found to be dynamically and thermodynamically stable. Combined with the electronic properties, there are a large number of H-s states and low density of Lu-f states at the Fermi level, leading to superconductivity. The phonon spectrum and electron-phonon coupling interaction are considered to calculate the superconducting critical temperature ( T c ) of stable lutetium hydrides at high pressure. The new predicted cubic LuH 12 has the highest T c value of 187.2 K at 400 GPa in all the stable LuH n compounds, which was estimated by directly solving the Eliashberg equation. The calculated results provide insights into the design of new superconducting hydrides under pressure.

Unique multicenter bonding in boron-rich materials leads to the formation of complicated structures and intriguing properties. ScB 6 , as a sister compound, possibly possesses high hardness and superconducting critical temperature in this family under ambient pressure. Here, phase transitions, chemical bonding states and electronic properties of ScB 6 at high pressure are uncovered using particle swarm optimization (PSO) combined with first-principles calculations. The phase sequence of P 2 1 / m → C 2/ m → Cmcm for ScB 6 has been identified under high pressure. Interestingly, the evolution of a boron framework is from a graphene-like layer to a planar B 4 ring, B 6 and B 7 cycle, and non-planar B 8 cycle, which interconnect a graphene-like network. These phases of ScB 6 are expected to be hard materials due to the excellent mechanical behaviors by the mechanical property calculations. Although the metallic features of the three phases reduce their hardness, the further electron-phonon coupling calculations indicate that the three phases of ScB 6 are superconducting phases under high pressures.