Sustainable Biochar Nanosheets Derived from Sweet Sorghum Residues via Superbase Pretreatment.

Two-dimensional (2D) sheet-like biochar as promising alternatives to graphene nanosheets has gained significant attention in materials science while being highly restricted by its complicated synthetic steps. In this study, the dimethyl sulfoxide/potassium hydroxide (DMSO/KOH) superbase system was first used to pretreat sweet sorghum residues (SS) and then carbonized to prepare sheet-like biochar. Ascribing to the strong nucleophilicity of DMSO/KOH, a synergistic effect was achieved by partially removing non-cellulosic components in SS and swelling the amorphous region of cellulose, leaving more layered cellulose behind (∼46.5 wt %), which was favorable for the formation of 2D biochar nanosheets with high graphitization degrees (∼93.1%). This strategy was also suitable for other biomass fibers (e.g., straw, wood powders, and nuclear shells) to obtain sheet-like biochar. The resulting sheet-like biochar could be compounded with cellulose nanofibers to achieve the structural design of composites and solve the molding problem of biochar, which was beneficial for dyeing wastewater treatment. Thus, this work provides insight into a simple strategy for developing 2D ultrathin sheet-like biochar from sustainable biomass wastes.

Green conversion of delignified sorghum straw and polyethylene glycol into form-stable phase change materials with promising solar energy capture, transition, and storage capabilities.

Phase change materials (PCMs) have attracted considerable attention as a thermal energy management technology for thermal storage. However, achieving high energy-storing abilities, low leakage rates, and solar absorption abilities simultaneously in PCMs remains greatly challenging. This research proposed a green strategy for preparing sorghum straw-based PCMs. By facile delignification and solvothermal process, delignified sorghum straw (DSS) and carbon quantum dots (CQDs) derived from removal lignin are prepared. The obtained PEG@CQDs/DSS possessed considerable reusable stabilities, excellent photo-thermal conversion properties, and thermal energy management capacities due to the delicate micropores and intrinsic noncovalent interactions among components. Especially, the PEG@CQDs-7.5/DSS exhibited superior solar-thermal conversion capabilities (with conducive photo-thermal conversion efficiency ~90.84%), and kept stable after 100 cycles of heating and cooling, in which the melting enthalpy value is ~168.1 J/g (enthalpy efficiency of ~91.11%). In conclusion, the synthesized PCMs showed potential for application in energy-saving and building thermal management.

Lignin reinforced tough, adhesive, and recoverable protein organohydrogels for wearable strain sensing under sub-zero temperatures.

Protein-based hydrogels with promising biocompatibility and biodegradability have attracted considerable interest in areas of epidermal sensing, whereas, which are still difficult to synchronously possess high mechanical strength, self-adhesion, and recoverability. Hence, the bio-polymer lignosulfonate-reinforced gluten organohydrogels (GOHLx) are fabricated through green and simple food-making processes and the following solvent exchange with glycerol/water binary solution. Ascribing to the uniform distribution of lignosulfonate in gluten networks, as well as the noncovalent interactions (e.g., H-bond) between them, the resultant GOHLx exhibit favorable conductivity (∼14.3 × 10-4 S m-1), toughness (∼711.0 kJ m-3), self-adhesion (a maximal lap-shear strength of ∼33.5 kPa), high sensitivity (GF up to ∼3.04), and durability (∼3000 cycles) toward shape deformation, which are suitable for the detection of both drastic (e.g., elbow and wrist bending) and subtle (e.g., swallowing and speaking) human movements even under -20 °C. Furthermore, the GOHLx is also biocompatible, degradable, and recoverable (by a simple kneading process). Thus, this work may pave a simple, green, and cheap way to prepare all-biomass-based, tough, sticky, and recoverable protein-based organohydrogels for epidermal strain sensing even in harsh environments.

Polymerizable deep eutectic solvent treated lignocellulose: Green strategy for synergetic production of tough strain sensing elastomers and nanocellulose.

Liquid free ion-conductive elastomers (ICEs) have demonstrated promising potential in various advanced application scenarios including sensor, artificial skin, and human-machine interface. However, ICEs that synchronously possess toughness, adhesiveness, stability, and anti-bacterial capability are still difficult to achieve yet highly demanded. Here, a one-pot green and sustainable strategy was proposed to fabricate multifunctional ICEs by extracting non-cellulose components (mainly lignin and hemicellulose) from lignocellulose with polymerizable deep eutectic solvents (PDES) and the subsequent in-situ photo-polymerization process. Ascribing to the uniform dispersion of non-cellulose components in PDES, the resultant ICEs demonstrated promising mechanical strength (a tensile strength of ~1200 kPa), high toughness (~9.1 MJ m-3), favorable adhesion (a lap-shear strength up to ~61.5 kPa toward metal), conducive stabilities, and anti-bacterial capabilities. With the help of such advantages, the ICEs exhibited sensitive (a gauge factor of ~23.5) and stable (~4000 cycles) performances in human motion and physiological signal detection even under sub-zero temperatures (e.g., -20 °C). Besides, the residue cellulose can be mechanically isolated into nanoscale fibers, which matched the idea of green chemistry.

Properties evaluation of biochar/high-density polyethylene composites: Emphasizing the porous structure of biochar by activation.

Activated biochars (AB-0.5, AB-1, AB-1.5, AB-2) prepared under different concentrations of an activating agent were used to manufacturing composites (ABHC-0.5, ABHC-1, ABHC-1.5, ABHC-2) based on high-density polyethylene (HDPE) by compounding and injection molding. Thermal and mechanical properties of the composites were characterized and analyzed. The addition of activated biochars improved the thermal properties of HDPE shown by Differential scanning calorimetry and Thermogravimetric analysis. Additionally, ABHC-0.5 exhibited the best flexural strength (38.66 MPa), flexural modulus (2.46 GPa), tensile strength (32.17 MPa), tensile modulus (1.95 GPa), rigidity, elasticity, creep resistance, and anti-stress relaxation ability due to the best porous structure of AB-0.5. A decrease of mechanical properties was observed in ABHC-1, ABHC-1.5, ABHC-2 compared to ABHC-0.5, which was due to the fact that the porous structure was damaged by an excessive activating agent. The results of this study provided a predictive insight in view of optimizing process parameters and establishing the meaningful relationship between biochar porous structure and its resulting composites.

Conductive Core-Shell Aramid Nanofibrils: Compromising Conductivity with Mechanical Robustness for Organic Wearable Sensing.

One-dimensional organic nanomaterials with a combination of electric conductivity, flexibility, and mechanical robustness are highly in demand in a variety of flexible electronic devices. Herein, conducting polymers were combined with robust Kevlar nanofibrils (aramid nanofibrils, abbreviated as ANFs) via in situ polymerization. Owing to the strong interactions between ANFs and conjugated polymers, the resultant core-shell ANFs showed high electric conductivity in combination with flexibility, robustness, physical stability, and endurance to bending and solvents, in sharp contrast to many inorganic conductive nanomaterials. Due to their responsivity of conductivity to different stimuli (e.g., humidity and strain), their membranes were capable not only of sensing human motions and speech words, but also of showing high sensitivity to variation of environmental humidity. In such a way, these core-shell ANFs may pave the way for combining both conductivity and mechanical properties applicable for diverse wearable devices.

Supramolecular proteinaceous biofilms as trapping sponges for biologic water treatment and durable catalysis.

Inspired by the bacterial biofilms and chorions of living organisms which are made by proteinaceous assemblies and functional for multi-applications, various artificial protein fibrils-based nanoporous films are developed, and show their potential applications in multiple fields. Here, a simple and environmental friendly method was identified to produce bovine serum albumin (BSA) nanofibrils based biofilms, through a combination of protein fibrillation and reverse dialysis. BSA nanofibrils formed biofilms through intermolecular interactions, the resultant biofilms showed tunable thickness by altering the initial protein amount, good stability in organic and salty solvents, transparency and fluorescence properties, hold high capacity of trapping different substances (e.g. nanomaterials, organic dyes, heavy-metal ions and enzymes), and further enabled applications in biologic water treatment and enzyme stabilization. Taken o-phenylenediamine as substrate, the trapped horseradish peroxidase showed a catalytic activity 9-38 folds higher than free ones in organic phase, together with enhanced stability. These protein nanofibrils-based films offered an attractive biologic platform to hybridize diverse materials for on-demand functions and applications.