In situ carbothermal synthesis of carbonized bacterial cellulose embedded with nano zero-valent iron for removal of Cr(VI).

Carbonized bacterial cellulose embedded with highly dispersed nano zero-valent iron (nZVI), denoted as nZVI@CBC, was prepared through one-step in situ carbothermal treatment of bacterial cellulose adsorbing iron(III) nitrate. The structure characteristics of nZVI@CBC and its performance in removing hexavalent chromium Cr(VI) were investigated. Results showed the formation of nZVI@CBC with a surface area of 409.61 m2/g at 800 °C, with nZVI particles of mean size 28.2 nm well distributed within the fibrous network of CBC. The stability of nZVI was enhanced by its carbon coating, despite some inevitable oxidation of exposed nZVI. Batch experiments demonstrated that nZVI@CBC exhibited superior removal efficiency compared to bare nZVI and CBC. Under optimal conditions, nZVI@CBC exhibited a high Cr(VI) adsorption capacity of up to 372.42 mg/g. Therefore, nZVI@CBC shows promise as an effective adsorbent for remediating Cr(VI) pollution in water.

Rational Design of Dynamic Interface Water Evolution on Turing Electrocatalyst toward the Industrial Hydrogen Production.

Manipulating the structural and kinetic dissociation processes of water at the catalyst-electrolyte interface is vital for alkaline hydrogen evolution reactions (HER) at industrial current density. This is seldom actualized due to the intricacies of the electrochemical reaction interface. Herein, this work introduces a rapid, nonequilibrium cooling technique for synthesizing ternary Turing catalysts with short-range ordered structures (denoted as FeNiRu/C). These advanced structures empower the FeNiRu/C to exhibit excellent HER performance in 1 m KOH with an ultralow overpotential of 6.5 and 166.2 mV at 10 and 1000 mA cm-2, respectively, and a specific activity 7.3 times higher than that of Pt/C. Comprehensive mechanistic analyses reveal that abundant atomic species form asymmetric atomic electric fields on the catalyst surface inducing a directed evolution and the dissociation process of interfacial H2O molecules. In addition, the locally topologized structure effectively mitigates the high hydrogen coverage of the active site induced by the high current density. The establishment of the relationship between free water population and HER activity provides a new paradigm for the design of industrially relevant high performance alkaline HER catalysts.

Quaternized chitosan/oxidized bacterial cellulose cryogels with shape recovery for noncompressible hemorrhage and wound healing.

Management of noncompressible torso hemorrhage is an urgent clinical requirement, desiring biomaterials with rapid hemostasis, anti-infection and excellent resilient properties. In this research, we have prepared a highly resilient cryogel with both hemostatic and antibacterial effects by chemical crosslinking and electrostatic interaction. The network structure crosslinked by quaternized chitosan and genipin was interspersed with oxidized bacterial cellulose after lyophilization. The as-prepared cryogel can quickly return to the original volume when soaking in water or blood. The appropriately sized pores in the cryogel help to absorb blood cells and further activate coagulation, while the quaternary ammonium salt groups on quaternized chitosan inhibit bacterial infections. Both cell and animal experiments showed that the cryogel was hypotoxic and could promote the regeneration of wound tissue. This research provides a new pathway for the preparation of double crosslinking cryogels and offers effective and safe biomaterials for the emergent bleeding management of incompressible wounds.

Oriented bacterial cellulose microfibers with tunable mechanical performance fabricated via green reassembly avenue.

Bacterial cellulose has garnered remarkable interest from researchers, particularly those working in the biomedical field. In this work, BC microfibers were fabricated via green dissolution (ZnCl2) and regeneration (ethanol). The orientation of cellulose chains was investigated during extrusion and simple post-processing via polarized optical microscopy and small-angle X-ray scattering. The results implied that the mechanical properties of BC microfibers can be tuned by rational pre-stretching. The BC microfibers can be programmable, and be used to suture hard or soft tissues. The as-designed paralleled BC microfibers have good biocompatibility and can regulate the directional growth of cells on their surface. The as-obtained BC microfiber with a high tensile strength of up to ∼115 MPa is suitable for surgical sutures. The tunable BC microfibers may be utilized as an adequate fiber-derived biomedical material product.

Sulfur-doped carbonized bacterial cellulose as a flexible binder-free 3D anode for improved sodium ion storage.

Carbon-based materials have received wide attention as electrodes for energy storage and conversion owing to their rapid mass transfer processes, outstanding electronic conductivities, and high stabilities. Here, sulfur-doped carbonized bacterial cellulose (S-CBC) was prepared as a high-performance anode for sodium-ion batteries (SIBs) by simultaneous carbonization and sulfidation using the bacterial cellulose membrane produced by microbial fermentation as the precursor. Doping sublimed sulfur powder into CBC results in a greater degree of disorder and defects, buffering the volume expansion during the cycle. Significantly, the three-dimensional (3D) network structure of bacterial cellulose endows S-CBC with flexible self-support. As an anode for sodium ion batteries, S-CBC exhibits a high specific capacity of 302.9 mA h g-1 at 100 mA g-1 after 50 cycles and 177.6 mA h g-1 at 2 A g-1 after 1000 cycles. Compared with the CBC electrode, the S-CBC electrode also exhibits enhanced rate performance in sodium storage. Moreover, theoretical simulations reveal that Na+ has good adsorption stability and a faster diffusion rate in S-CBC. The doping of the S element introduces defects that enlarge the interlayer distance, and the synergies of adsorption and bonding are the main reasons for its high performance. These results indicate the potential application prospects of S-CBC as a flexible binder-free electrode for high-performance SIBs.

Constructing built-in electric field via ruthenium/cerium dioxide Mott-Schottky heterojunction for highly efficient electrocatalytic hydrogen production.

Ensuring the consumption rate of noble metals while guaranteeing satisfactory hydrogen evolution reaction (HER) performance at different pH values is imperative to the development of Ru-based catalysts. Herein, we design a Mott-Schottky electrocatalyst (Ru/CeO2) with a built-in electric field (BEF) based on density functional theory (DFT). The Ru/CeO2 achieves the criterion current density of 10 mA cm-2 at overpotentials of 55 mV, 80 mV, and 120 mV in alkaline, acidic and neutral media, respectively. Both theoretical calculations and experimental analysis confirm that the improved HER activity in the Ru/CeO2 catalyst could be due to the successful construction of BEF at the interface between the prepared Ru clusters and CeO2. Under the action of BEF, the electron-deficient Ru atoms can optimize the adsorption energy of H* and H2O and thus promote HER kinetics. Furthermore, the Ru/CeO2 catalyst delivers a power density of approximately 94.5 mW cm-2 in alkaline-acidic Zn-H2O cell applications while maintaining good H2 production stability. In this work, we optimize the electrocatalytic performance of the Ru/CeO2 catalyst through examination of the interfacial BEF electrical charge, which combines hydrogen production with power generation and provides a promising method for sustainable energy conversion.

Sustainable bacterial cellulose derived composites for high-efficiency hydrogen evolution reaction.

Incorporating heteroatoms into carbon structure has been demonstrated to be efficient for hydrogen evolution reaction (HER). However, the preparation complexity and poor durability are insufficient for the future hydrogen economy. In this work, the preparation of ZIF-67/BC precursor with BC as the template was done for the in-situ growth of MOFs (ZIF-67) crystals, followed by the carbonization and phosphating of ZIF-67/BC to prepare the CoP-NC/CBC N-doped composite carbon material with CoP as the primary active material. The results show that as an HER catalyst, CoP-NC/CBC can provide a current density of 10 mA cm-2 at an overpotential of 182 mV in the acidic electrolyte of 0.5 M H2SO4 or the same current density at an overpotential of 151 mV in the alkaline electrolyte of 1.0 M KOH. The work validates a design idea for advanced non-precious metal-based HER catalysts with high activity and stability.

The biosynthesis of amidated bacterial cellulose derivatives via in-situ strategy.

Bacterial cellulose, as a kind of natural biopolymer produced by bacterial fermentation, has attracted wide attention owing its unique physical and chemical properties. Nevertheless, the single functional group on the surface of BC greatly hinders its wider application. The functionalization of BC is of great significance to broaden the application of BC. In this work, N-acetylated bacterial cellulose (ABC) was successfully prepared using K. nataicola RZS01-based direct synthetic method. FT-IR, NMR and XPS confirmed the in-situ modification of BC by acetylation. The SEM and XRD results demonstrated that ABC has a lower crystallinity and higher fiber width compare with pristine 88 BCE % cell viability on NIH-3 T3 cell and near zero hemolysis ratio indicate its good biocompatibility. In addition, the as-prepared acetyl amine modified BC was further treated by nitrifying bacteria to enrich its functionalized diversity. This study provides a mild in-situ pathway to construct BC derivatives in an environmentally friendly way during its metabolism.

Highly efficient construction of sustainable bacterial cellulose aerogels with boosting PM filter efficiency by tuning functional group.

Air pollution has become a major public health concern, attracting considerable attention from researchers working on environmentally friendly and sustainable materials. In this work, bacterial cellulose (BC) derived aerogels were fabricated by the directional ice-templated method and used as filters to remove PM particles. We modified the surface functional groups of BC aerogel with reactive silane precursors, and investigated the interfacial and structural properties of those aerogels. The results show that BC-derived aerogels have excellent compressive elasticity, and their directional growth orientation inside the structure significantly reduced pressure drop. Moreover, the BC-derived filters exhibit an exceptional quantitative removal effect on fine particulate matter, which, in the presence of high concentrations of fine particulate matter, they can achieve a high-efficiency removal standard of 95 %. Meanwhile, the BC-derived aerogels showed superior biodegradation performance in the soil burial test. These results paved the way for BC-derived aerogels development as a great sustainable alternative to treat air pollution.

Nickel-decorated RuO2 nanocrystals with rich oxygen vacancies for high-efficiency overall water splitting.

Designing transition metal-oxide-based bifunctional electrocatalysts with excellent activity and stability for OER/HER to achieve efficient water splitting is of great importance for renewable energy technologies. Herein, a highly efficient bifunctional catalysts with oxygen-rich vacancies of nickel-decorated RuO2 (NiRuO2-x) prepared by a unique one-pot glucose-blowing approach were investigated. Remarkably, the NiRuO2-x catalysts exhibited excellent HER and OER activity at 10 mA cm-2 in alkaline solution with only a minimum overpotential of 51 mV and 245 mV, respectively. Furthermore, the NiRuO2-x overall water splitting exhibited an ultra-low voltage of 1.6 V to obtain 10 mA cm-2 and stability for more than 10 h. XPS measurement and theoretical calculations demonstrated that the introduction of Ni-dopant and oxygen vacancies make the d-band center to lie close to the Fermi energy level, the chemical bonds between the active site and the adsorbed oxygen intermediate state are enhanced, thereby lowering the reaction activation barriers of HER and OER. The assembly of solar-driven alkaline electrolyzers facilitate the application of the NiRuO2-x bifunctional catalysts.

Dynamically Tunable All-Weather Daytime Cellulose Aerogel Radiative Supercooler for Energy-Saving Building.

A passive cooling strategy without any electricity input has shown a significant impact on overall energy consumption globally. However, designing tunable daytime radiative cooler to meet requirement of different weather conditions is still a big challenge, especially in hot, humid regions. Here, a novel type of tunable, thermally insulating and compressible cellulose nanocrystal (CNC) aerogel coolers is prepared via chemical cross-linking and unidirectional freeze casting process. Such aerogel coolers can achieve a subambient temperature drop of 9.2 °C under direct sunlight and promisingly reached the reduction of ∼7.4 °C even in hot, moist, and fickle extreme surroundings. The tunable cooling performance can be realized via controlling the compression ratio of shape-malleable aerogel coolers. Furthermore, energy consumption modeling of using such aerogel coolers in buildings in China shows 35.4% reduction of cooling energy. This work can pave the way toward designing high-performance, thermal-regulating materials for energy consumption savings.

Effect of Culture Conditions on Cellulose Production by a Komagataeibacter xylinus Strain.

Bacterial cellulose (BC) is an abundant biopolymer with a wide range of potential industrial applications. However, the industrial application of BC has been hampered by inefficient production. This study aims to investigate the influence of a spontaneous mutation that results in decreased cellulose production by a Komagataeibacter xylinus strain. The yields of cellulose are significantly different under different culture conditions, which imply that the shearing force is responsible for the selection of spontaneous mutants. Fermenter culture conditions under shake-flask culture conditions are further simulated. The shearing force activates the conversion of microbial cells to Cel- mutants, and the accumulation of water-soluble exopolysaccharides is observed. The Cel+ cells under agitated culture are not easily converted into Cel- mutants upon the addition of water-soluble exopolysaccharides synthesized by K. xylinus and a viscous polysaccharide, such as xanthan gum. The conversion ratio of Cel+ cells to Cel- mutants is strongly related to the shearing force and viscosity of the fermentation broth. The synthetic pathways of bacterial cellulose and water-soluble polysaccharides are independent of each other at the genetic level. However, a substrate competitive relationship between these two polysaccharides is found, which is significant in terms of the optimization of cellulose production in commercial processes.

Enhanced mechanical properties and biocompatibility on BC/HAp composite through calcium gluconate fortified bacterial.

Bacterial cellulose/hydroxyapatite (BC/HAp) composite is an outstanding candidate for bone tissue engineering. The conventional biomimetic mineralization method takes a long time with unsatisfactory mechanical properties and biocompatibility. Herein, we modified the BC by changing the carbon source to calcium gluconate during the biosynthesis process of BC by bacteria, providing nucleation sites for further mineralization in simulated body fluid. Results show spherical porous HAp in the size of 100-200 nm was fully filled in the three-dimensional network structure of BC nanofibers uniformly within five days of mineralization. Molecular dynamics simulation shows that the aggregation of cellulose units in aqueous solution can enhance the adsorption of calcium ions. By this means, we significantly improved the mechanical properties and biocompatibility of the BC/HAp composite, as well as simplified the preparation process, compared to conventional method, which, therefore, suggests, it could be further studied for biomedical applications such as bone tissue engineering.

Influence of pyrolysis temperature on characteristics and Cr(VI) adsorption performance of carbonaceous nanofibers derived from bacterial cellulose.

The effects of pyrolysis temperature on properties and adsorption performance of carbonized bacterial cellulose (CBC) produced from bacterial cellulose at 300, 400, 600 and 800 °C were investigated. As pyrolysis temperature increased, the BET surface area, C and ash contents of CBC increased while its mass yield and the contents of H, N and O decreased. Higher pyrolysis temperature resulted in CBC having more aromatic structure and less hydrophilic. The impacts of pyrolysis temperature, solution pH, contact time and initial concentration on the absorption of Cr(VI) onto CBC were systematically studied as well. The results showed that CBC400 prepared at 400 °C exhibited the highest Cr(VI) adsorption capacity for Cr(VI) up to 250.0 mg/g. The equilibrium adsorption and adsorption kinetics fitted the Langmuir isotherm and pseudo-second-order kinetic models well. The mechanisms of adsorption of Cr(VI) on CBC included electrostatic interaction, π-π interaction and functional groups complexation.

Gas assisted in situ biomimetic mineralization of bacterial cellulose/calcium carbonate bio composites by bacterial.

Biomineralization inspired process to produce polymer of desired need is a promising approach in the field of research. In the present work, the bacterial cellulose (BC) based nanocomposites with a 3D network were synthesized via a biological route by choosing the calcium salt of primary metabolites (calcium gluconate) as the carbon source. The BC based composites were characterized by employing with Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). During the preparation of nanocomposites, the calcium ions embedded on the cellulose fibrils were served as the nucleation center and calcium carbonate was deposited into BC network in the assistance of CO2. The uniform distribution of embedded objects on the cellulose nanofibers between internal and external was achieved. The exploitation of organisms for inorganic growth, shape and self-assembling explores new opportunities to the design of original nanostructures.

Efficient catalytic reduction of highly toxic aqueous Cr(VI) with Fe@CBC/Pd composites at room temperature.

We report a facile approach to fabricating catalytic active palladium nanoparticles (NPs) immobilized on Fe-loaded carbonized bacterial cellulose nanofibers (Fe@CBC) for the catalytic reduction of toxic Cr(VI) to Cr(III) at room temperature. The formed nanofiber composites (Fe@CBC/Pd) was investigated by various physicochemical characterization and its catalytic activity, and reusability were evaluated as well. The results demonstrated that the Fe@CBC/Pd exhibited favorable catalytic activity for the reduction of Cr(VI) to Cr(III) in the presence of HCOOH. Moreover, the catalyst could be easily recovered from reaction system in a facile manner and recycled four times without obvious loss in activity.

Defect enrich ultrathin TiO2 nanosheets for rapid adsorption and visible light mediated PPCPs degradation.

Recently, PPCPs have attracted extensive attention as emerging pollutants. Due to the strong hydrophilicity and small molecular weight, PPCPs are difficult to be fully removed by adsorption and other processes, posing a serious threat to the ecological environment. Here, we demonstrate solvothermal synthesis of defect enrich TiO2 nanosheets through simple copper doping. Novel TiO2 nanosheets were found to be mesoporous with high specific surface area and exhibited excellent visible light response. Performance of the developed TiO2 nanosheets were evaluated towards photocatalytic degradation of two model pollutants, tetracycline and acetaminophen. Results showed robust degradation of tetracycline and acetaminophen under visible-light irradiation within 100 min. Meanwhile, the potential relationship between the structural characteristics and excellent ability of the catalyst was discussed, as well as probable mechanism. Additionally, a study on the toxicity of tetracycline solution to human skin epidermal cells showed that the toxicity of the treated solution to cells is greatly reduced. The prepared catalysts show good repeatability (a slightly decrease ca.3% after 5 cycles) and applicability, providing a reasonable design for water remediation.

In situ structural modification of bacterial cellulose by sodium fluoride.

Bacterial cellulose could be produced in any shape due to its high moldability during fermentation process, but structural modification often requires the inclusion of templates or other polymeric materials. In this work, sodium fluoride was introduced in bacterial cultivation process to modify the microstructure. Under static conditions, the final pH, BC yield, morphology, structure and properties of the obtained BC were investigated. Because of the stronger hydrogen bonding formed between fluoride and hydroxyl groups, majority of cellulose chains were no longer restricted and could not aggregate into wider cellulose ribbons. After the removal of fluoride, the cellulose chains undergo random rearrangement into bulky ribbon due to inter-fibril hydrogen bonding of hydroxyl groups, of which the crystallinity can remain as high as ∼60 % in dry state. The treatment of sodium fluoride led to different mechanical properties. The modification of BC structure can be easily achieved in situ by controlling NaF concentrations.

Bacterial cellulose/attapulgite magnetic composites as an efficient adsorbent for heavy metal ions and dye treatment.

In recent decades, increased industrial activities have led to the release of various pollutants, such as toxic heavy metals, inorganic anions, and organics. It is imperative but challenging to develop an eco-friendly treatment technology with easy operation, low cost, and high efficiency. Here, we describe a design of magnetic purifier, which has biomass-based structure by blending attapulgite/chitosan (ATP/CS) composite with bacterial cellulose nanofibrils (BCNs). Compared to similar materials reported previously, our product exhibited efficient adsorption capacities towards various metal ions including Pb2+, Cu2+, and Cr6+, and anionic organic dyes including Congo red. The adsorption process could be well fitted by Langmuir isotherm and pseudo-second order equation. Additionally, the adsorption capacity only decreased less than 8% after five adsorption-desorption cycles. We expect our design will inspire more efforts to build a multifunctional water purifier with simple operation, and hopefully effectively remove pollutants from wastewater in future practical applications.

Macroporous bacterial cellulose grafted by oligopeptides induces biomimetic mineralization via interfacial wettability.

Bacterial cellulose (BC) has a role in tissue repair and regenerative medicine, which has already attracted tremendous interest from researchers, especially those working in the field of hybrid materials. Herein, we designed BC-based macroporous functional materials by dialdehyde bacterial cellulose (DBC) cross-linking with oligopeptides under mild reactive conditions. The interfacial properties of the surface modified BC were examined by biomimetic mineralization. The results showed that a macroporous structure was achieved by using oligopeptides as chemical cross-linking agents with an interconnected macroporosity ranging from 20 µm to 80 µm. Their mechanical properties were barely altered compared to the pristine BC. Their enhanced surface charges stemmed from the carboxyl groups of the oligopeptides engaging in reactions with amine and aldehyde groups. The oligopeptides cross-linked DBC showed a faster initial induction towards minerals via interfacial wettability resulting in promotion of mineralization, the hybrid materials had excellent biocompatibility relative to the pristine BC. These findings are vital to the development of other biopolymers with essential macroporous structures as well as improved interfacial wettability, which enables their possible uses in tissue repair and regenerative medicine.