In Situ Lignin Adhesion for High-Performance Bamboo Composites.

Bamboo composite is an attractive candidate for structural materials in applications such as construction, the automotive industry, and logistics. However, its development has been hindered due to the use of harmful petroleum-derived synthetic adhesives or low-bonding biobased adhesives. Herein, we report a novel bioadhesion strategy based on in situ lignin bonding that can process natural bamboo into a scalable and high-performance composite. In this process, lignin bonds the cellulose fibrils into a strong network via a superstrong adhesive interface formed by hydrogen bonding and nanoscale entanglement. The resulting in situ glued-bamboo (glubam) composite exhibits a record-high shear strength of ∼4.4 MPa and a tensile strength of ∼300 MPa. This in situ lignin adhesion strategy is facile, highly scalable, and cost-effective, suggesting a promising route for fabricating strong and sustainable structural bamboo composites that sequester carbon and reduce our dependence on petrochemical-based adhesives.

Rapid one-step preparation of hierarchical porous carbon from chitosan-based hydrogel for high-rate supercapacitors: The effect of gelling agent concentration.

Herein, chitosan-based hydrogel beads (CHBs) were used to prepare N- and O-enriched hierarchical porous carbon (PC) by microwave heating for only 10 min. Water molecules in CHBs can act as heating carriers, and the resulting steam not only squeeze out air to create an oxygen-free atmosphere but act as physical activating agent to generate pores. Furthermore, the increased temperature contributed to form chitosan-based char, which, in turn, facilitated microwave absorption to further increase temperature. Considering that KOH as gelling agent of CHBs can also generate pores, the effect of KOH concentration on physicochemical properties of PCs was investigated in detail. Significantly, appropriately higher KOH concentration (3-7%) would cause fiercer reactions to achieve more developed porous structure, while excessive KOH concentration (10%) led to over-etching phenomenon and limited the further development on porous structure. The obtained PCs exhibited large specific surface area up to 1743 m2 g-1 and O, N-enriched structure (O: 25.1%, N: 4.9%). Particularly, the optimized PC-based electrode prepared by using 7% KOH solution showed remarkably high rate capability (89%). This work provides a one-step and cost-effective method to prepare a promising electrode material for high-rate supercapacitors.

Multifunctional Wet-Spun Filaments through Robust Nanocellulose Networks Wrapping to Single-Walled Carbon Nanotubes.

Cellulose nanofibrils (CNFs) and single-walled carbon nanotubes (SWNTs) hold potential for fabricating multifunctional composites with remarkable performance. However, it is technically tough to fabricate materials by CNFs and SWNTs with their intact properties, mainly because of the weakly synergistic interaction. Hence, constructing sturdy interfaces and sequential connectivity not only can enhance mechanical strength but also are capable of improving the electrical conductivity. In that way, we report CNF/SWNT filaments composed of axially oriented building blocks with robust CNF networks wrapping to SWNTs. The composite filaments obtained through the combination of three-mill-roll and wet-spinning strategy display high strength up to ∼472.17 MPa and a strain of ∼11.77%, exceeding most results of CNF/SWNT composites investigated in the previous literature. Meanwhile, the filaments possess an electrical conductivity of ∼86.43 S/cm, which is also positively dependent on temperature changes. The multifunctional filaments are further manufactured as a strain sensor to measure mass variation and survey muscular movements, leading to becoming optimistic incentives in the fields of portable gauge measuring and wearable bioelectronic therapeutics.

Green Preparation of Fluorescent Carbon Quantum Dots from Cyanobacteria for Biological Imaging.

Biomass-based carbon quantum dots (CQDs) have become a significant carbon materials by their virtues of being cost-effective, easy to fabricate and low in environmental impact. However, there are few reports regarding using cyanobacteria as a carbon source for the synthesis of fluorescent CQDs. In this study, the low-cost biomass of cyanobacteria was used as the sole carbon source to synthesize water-soluble CQDs by a simple hydrothermal method. The synthesized CQDs were mono-dispersed with an average diameter of 2.48 nm and exhibited excitation-dependent emission performance with a quantum yield of 9.24%. Furthermore, the cyanobacteria-derived CQDs had almost no photobleaching under long-time UV irradiation, and exhibited high photostability in the solutions with a wide range of pH and salinity. Since no chemical reagent was involved in the synthesis of CQDs, the as-prepared CQDs were confirmed to have low cytotoxicity for PC12 cells even at a high concentration. Additionally, the CQDs could be efficiently taken up by cells to illuminate the whole cell and create a clear distinction between cytoplasm and nucleus. The combined advantages of green synthesis, cost-effectiveness and low cytotoxicity make synthesized CQDs a significant carbon source and broaden the application of cyanobacteria and provide an economical route to fabricate CQDs on a large scale.