Heterogeneous and microporous structure evolution of heated/radiated polyacrylonitrile fibers revealed by X-ray micro-computed tomography and scattering.

Heat treatment, a critical pre-oxidation process, plays an essential role in the preparation of carbon fibers. Most defects arising from this stage are likely to be transferred to the final carbon fibers. Electron beam irradiation is an effective modification method to optimize the structure of polyacrylonitrile (PAN) pre-oxidized fibers.

Heterogeneous microstructure of γ-irradiated pre-oxidized PAN fiber revealed by microfocus SR-SAXS reconstruction and molecular simulation.

The microstructure plays a crucial role in the manufacturing and application of polyacrylonitrile fibers, which serve as precursors for carbon fibers. Synchrotron radiation small angle x-ray scattering (SR-SAXS) is a non-destructive and precise technique for analyzing fiber structures. This study employed one-dimensional SR-SAXS mapping to extract key structural parameters such as periodicity, lamellae thickness, and the extent of amorphous regions, as well as the directional orientation in γ-irradiated, pre-oxidized polyacrylonitrile fibers.

Dimerized M-Series Acceptors with Low Diffusion Coefficients for Efficient and Stable Polymer Solar Cells.

As the simplest oligomeric acceptors, dimerized acceptors (DAs) are easier to synthesize, and more importantly, they can retain good intermolecular interaction and photovoltaic properties of their parent small-molecule acceptors (SMAs). Nevertheless, currently most efficient DAs are derived from banana-shaped acceptors and they might suffer from inferior device stability with high diffusion coefficients. Herein, we design and synthesize two planar DAs (DMT-FH and DMT-HF) by bridging two linear-shaped M-series SMAs with a thiophene unit.

High-Strength MOF-Based Polymer Electrolytes with Uniform Ionic Flow for Lithium Dendrite Suppression.

The uneven formation of lithium dendrites during electroplating/stripping leads to a decrease in the utilization of active lithium, resulting in poor cycling stability and posing safety hazards to the battery. Herein, introducing a 3D continuously interconnected zirconium-based metal-organic framework (MOF808) network into a polyethylene oxide polymer matrix establishes a synergistic mechanism for lithium dendrite inhibition. The 3D MOF808 network maintains its large pore structure, facilitating increased lithium salt accommodation, and expands anion adsorption at unsaturated metal sites through its diverse large-space cage structure, thereby promoting the flow of Li.

Oxygen Vacancy and Bandgap Simultaneous Modulation to Achieve High Lithiophilicity and Mechanical Strength of Lithium Metal Anodes.

Metal oxides with conversion and alloying mechanisms are more competitive in suppressing lithium dendrites. However, it is difficult to simultaneously regulate the conversion and alloying reactions. Herein, conversion and alloying reactions are regulated by modulation of the zinc oxide bandgap and oxygen vacancies.

SAXS unveils porous anodes for potassium-ion batteries: dynamic evolution of pore structures in Fe@FeO/PCNFs composite nanofibers.

The porous structure of composite nanofibers plays a key role in improving their electrochemical performance. However, the dynamic evolution of pore structures and their action during ion intercalation/extraction processes for negative electrodes are not clear. Herein, porous carbon composite nanofibers (Fe@FeO/PCNFs) were prepared as negative electrode materials for potassium-ion batteries.

FeO for stable K-ion storage: mechanism insight into dimensional construction from stress distribution and micro-tomography.

FeO is considered a potential electrode material owing to its high theoretical capacity, low cost, and non-toxic characteristics. However, the significant volume expansion and structural degradation during charging and discharging hinder its application in potassium ion batteries. The electrochemical properties of the electrode material are primarily influenced by the diffusion efficiency of ions and the mechanics of the object.

Boosting Potassium Storage via Multifunctional Interface with High Lattice-Matching.

Atomic-scale interface engineering is a prominent strategy to address the large volume expansions and sluggish redox kinetics for reinforcing K-storage. Here, to accelerate charge transport and lower the activation energy, dual carbon-modified interfacial regions are synthesized with high lattice-matching degree, which is formed from a CoSe /FeSe heterostructure coated onto hollow carbon fibers. State-of-the-art characterization techniques and theoretical analysis, including ex-situ soft X-ray absorption spectroscopy, synchrotron X-ray tomography, ultrasonic transmission mapping, and density functional theory, are conducted to probe local atomic structure evolution, mechanical degradation mechanisms, and ion/electron migration pathways.

Biomass Separators as a "Lifesaver" for Safe and Long-Life Lithium Metal Batteries.

The growth of lithium dendrites and the shuttle of polysulfides in lithium metal batteries (LMBs) have hindered their development. In LMBs, the cathode and anode are separated by a separator, although this does not solve the battery's issues. The use of biomass materials is widespread for modifying the separator due to their porous structure and abundant functional groups.

Homogeneous regulation of arranged polymorphic manganese dioxide nanocrystals as cathode materials for high-performance zinc-ion batteries.

Rechargeable aqueous zinc-ion batteries have emerged as attractive energy storage devices by virtue of their low cost, high safety and eco-friendliness. However, zinc-ion cathodes are bottlenecked by their vulnerable crystal structures in the process of zinc embedding and significant capacity fading during long-term cycling. Herein, we report the rational and homogeneous regulation of polycrystalline manganese dioxide (MnO) nanocrystals as zinc cathodes via a surfactant template-assisted strategy.

Tuning Interface Mechanics Via β-Configuration Dominant Amyloid Aggregates for Lithium Metal Batteries.

Owing to abundant polar groups and good lithiophilicity, protein materials regain interest for application in lithium metal batteries (LMBs). Current proteins with an -conformation for modifying lithium (Li) anodes possess typically poor mechanical properties, and there is therefore a significant need for advanced protein materials. Herein, a lysozyme-modified layer is coated onto the poly(vinylidene fluoride) electrospun mat for high mechanical strength and uniform Li-ion flux.

MXene/TiO Heterostructure-Decorated Hard Carbon with Stable Ti-O-C Bonding for Enhanced Sodium-Ion Storage.

Hard carbon (HC) has attracted considerable attention in the application of sodium-ion battery (SIB) anodes, but the poor realistic capacity and low rate performance severely hinder their practical application. Herein we report a solvent mechanochemical protocol for the in situ fabrication of the HC-MXene/TiO electrode by functionalizing MXene to improve the electrochemical performance of the batteries. MXene (TiCT) with abundant oxygen-containing functional groups reacts with HC particles in the ball milling process to form a Ti-O-C covalent cross-linked HC-MXene composite, in which the edge of the MXene nanosheets is in situ oxidized by air to form TiO nanorods, forming a regular 1D/2D MXene/TiO heterojunction structure.

Mechanistic Insights into the Structural Modulation of Transition Metal Selenides to Boost Potassium Ion Storage Stability.

Atomic-level structure engineering is an effective strategy to reduce mechanical degradation and boost ion transport kinetics for battery anodes. To address the electrode failure induced by large ionic radius of K ions, herein we synthesized Mn-doped ZnSe with modulated electronic structure for potassium ion batteries (PIBs). State-of-the-art analytical techniques and theoretical calculations were conducted to probe crystalline structure changes, ion/electron migration pathways, and micromechanical stresses evolution mechanisms.

Construction of MoS/Mxene heterostructure on stress-modulated kapok fiber for high-rate sodium-ion batteries.

Molybdenum disulfide (MoS) has possession of a layered structure and high theoretical capacity, which is a candidate anode material for sodium ion batteries. However, unmodified MoS are inflicted with a poor cycling stability and an inferior rate capability upon charge/discharge processes. Considering that the shape and size of anode materials play a key role in the performance of anode materials, this paper proposes a multi-level composite structure formed by the micro-nano materials based on self-assembled molybdenum disulfide (MoS) nanoflowers, Mxene and hollow carbonized kapok fiber (CKF).

Reduce and concentrate graphene quantum dot size via scissors: vacancy, pentagon-heptagon and interstitial defects in graphite by gamma rays.

Graphene quantum dots (GQDs) with ultrafine particle size and centralized distribution have advantages of small size, narrow size distribution and large specific surface area, which make it be better applied in bioimaging, drug delivery and so on. In our research, we used graphite irradiated by-rays to successfully prepare GQDs with ultrafine particle size, narrow size distribution and high quantum yields through solvothermal method. Vacancy defects, pentagon-heptagon defects and interstitial defects were introduced to graphite structure after irradiation, which caused the abundance and concentrated distribution of defects.

"Self-doping" defect engineering in SnP@gamma-irradiated hard carbon anode for rechargeable sodium storage.

Reasonable design of defect engineering in the electrode materials for sodium-ion batteries (SIBs) can significantly optimize battery performance. Here, compared with the traditional "foreign-doping" defects method, we report an innovative gamma-irradiation technique to introduce the "self-doping" defects in the popcorn hard carbon (HC). Considering the advantages of adsorption-intercalation-alloying sodium storage mechanism, the defect-rich HC-coated alloy structure (SnP@HC-γ) was integrated.

Analysis of Mg/Li separation mechanism by charged nanofiltration membranes: visual simulation.

The mechanism of the nanofiltration (NF) membrane separation of Mg and Li needs to be further investigated, but some commonly used model theories are abstract, which makes them difficult to understand. More importantly, the relationship between the membrane charge and separation performance of Mg and Li cannot be quantitatively analyzed. It is worth studying these challenges and providing a performance boost for Mg/Li filtration applications of NF membranes.

Nitrogen-enriched carbon nanofibers with tunable semi-ionic CF bonds as a stable long cycle anode for sodium-ion batteries.

The quest for getting more efficient carbonous anodes for sodium ion batteries (NIBs) prepared by simple and economical methods continues to be an important endeavor. Herein, a plasma-controlled method is developed for preparing semi-ionic CF bonds decorating nitrogen-enriched electrospinning carbon nanofibers (NCNFs) as a free-standing anode for NIBs. The semi-ionic CF bonds are beneficial to the fast ion and electron transfer for a free-standing electrode, which remarkably improves the rate performances of NCNFs as the NIBs anodes.

Shape inducer-free polygonal angle platinum nanoparticles in graphene oxide as oxygen reduction catalyst derived from gamma irradiation.

In this report, polygonal angle platinum nanoparticles (PtNPs) anchored on nitrogen doping reduced graphene oxide (NrGO) as oxygen reduction reaction (ORR) catalyst was synthesized by gamma irradiation assisted with in situ hydrolysis of urea without using any shape inducer, seed, or template. Urea was not only employed as the nitrogen source, but also offered more reductive radicals in the gamma system. The uniform dispersion and homogeneous size distribution of PtNPs are obtained on reduced graphene oxide (rGO), which is attributed to the synergy of restriction effects of GO and crush capacity of high energy gamma rays.

Improvement of PVDF nanofiltration membrane potential, separation and anti-fouling performance by electret treatment.

Electret treatment was a simple method to enhance the charge-electrode properties of polyvinylidene fluoride (PVDF) materials due to the increase of space charge and polarization charge of PVDF materials. The polarization charge was due to the electric dipole orientation change in loose nanofiltration PVDF membrane, which increased the electric dipole moment and improved the polarity of surface potential. Importantly, electret charges were less affected by ambient humidity.

Polypyrrole/cadmium sulfide hollow fiber with high performance contaminant removal and photocatalytic activity fabricated by layer-by-layer deposition and fiber-sacrifice template approach.

A recyclable polypyrrole (PPy)/cadmium sulfide (CdS) hollow fiber photocatalyst was innovatively fabricated for solving the loss issue of the current powder-form photocatalyst in slurry system. Core-sheath structure CdS/polyacrylonitrile (PAN) fiber was prepared via successive ionic layer adsorption and reaction (SILAR) method on the surface of PAN fiber. PPy was further deposited on the CdS/PAN fiber by vapor deposition polymerization.

Control of Electron Flow Direction in Photoexcited Cycloplatinated Complex Containing Conjugated Polymer-Single-Walled Carbon Nanotube Hybrids.

Conjugated polymers incorporated with cycloplatinated complexes (P1-Pt and P2-Pt) were used as dispersants for single-walled carbon nanotubes (SWCNTs). Significant changes in the UV-vis absorption spectra were observed after the formation of the polymer/SWCNT hybrids. Molecular dynamics (MD) simulations revealed the presence of a strong interaction between the cycloplatinated complex moieties and the SWCNT surface.

Direct Observation of an Efficient Triplet Exciton Diffusion Process in a Platinum-Containing Conjugated Polymer.

We report the synthesis and characterization of a conjugated polymer incorporated with cyclometalated platinum complexes on the main chain. The polymer may serve as an efficient triplet sensitizer in light-harvesting systems. The photophysical properties of the polymer were studied by nanosecond and femtosecond time-resolved transient absorption spectroscopies.

Comb-shaped glycopolymer/peptide bioconjugates by combination of RAFT polymerization and thiol-ene "click" chemistry.

Comb-shaped glycopolymer/peptide bioconjugates are constructed by grafting reduced glutathione (GSH) onto acrylate-functional block glycocopolymers via thiol-ene click chemistry. In aqueous solution, the glycopolymer/GSH bioconjugate self-assembles to sugar-installed spherical micelles. The size of micelles decreases with increasing pH, demonstrating pH-responsive character.