Conversion of Lignin into Porous Carbons for High-Performance Supercapacitors via Spray Drying and KOH Activation: Structure-Properties Relationship and Reaction Mechanism

Lignin-derived porous carbons have emerged as promising electrode materials for supercapacitors.However,the challenge remains in designing and controlling their structure to achieve ideal electrochemical performance due to the complex molecular structure of lignin and its intricate chemical reactions during the activation process.In this study,three porous carbons were synthesized from lignin by spray drying and chemical activation with vary-ing KOH ratios.The specific surface area and structural order of the prepared porous carbon continued to increase with the increase of the KOH ratio.Thermogravimetric-mass spectrometry(TG-MS)was employed to track the molecular fragments generated during the pyrolysis of KOH-activated lignin,and the mechanism of the thermochemical conversion was investigated.During the thermochemical conversion of lignin,KOH facili-tated the removal of H2 and CO,leading to the formation of not only more micropores and mesopores,but also more ordered carbon structures.The pore structure exhibited a greater impact than the carbon structure on the electrochemical performance of porous carbon.The optimized porous carbon exhibited a capacitance of 256 F g-1 at a current density of 0.2 A g-1,making it an ideal electrode material for high-performance supercapacitors.

Molten Salt-Shielded Synthesis(MS^(3))of MXenes in Air

MXenes are two-dimensional transition metal carbides and/or nitrides with unique physiochemical properties and have attracted extensive interest in numerous fields.However,current MXene synthesis methods are limited by hazardous synthesis conditions,high production costs,or difficulty in largescale production.Therefore,a general,safe,cost-effective,and scalable synthesis method for MXenes is crucial.Here,we report the fast synthesis of MXenes in the open air using a molten salt-shielded synthesis(MS^(3))method,which uses Lewis-acid salts as etchants and a low-melting-point eutectic salt mixture as the reaction medium and shield to prevent MXene oxidation at high temperatures.Carbide and nitride MXenes,including Ti_(3)C_(2)T_(x),Ti_(2)CT_(x),Ti_(3)CNT_(x),and Ti_(4)N_(3)T_(x),were successfully synthesized using the MS^(3) method.We also present the flexibility of the MS^(3) method by scaling the etching process to large batches of 20 and 60 g of Ti_(3)AlC_(2) MAX precursor in one pot.When used as negative electrodes,the prepared MS^(3)-MXenes delivered excellent electrochemical properties for high-rate Li-ion storage.

Proton‑Prompted Ligand Exchange to Achieve High‑Efficiency CsPbI_(3) Quantum Dot Light‑Emitting Diodes

CsPbI_(3)perovskite quantum dots(QDs)are ideal materials for the next generation of red light-emitting diodes.However,the low phase stability of CsPbI_(3)QDs and long-chain insulating capping ligands hinder the improvement of device performance.Traditional in-situ ligand replacement and ligand exchange after synthesis were often difficult to control.Here,we proposed a new ligand exchange strategy using a proton-prompted insitu exchange of short 5-aminopentanoic acid ligands with long-chain oleic acid and oleylamine ligands to obtain stable small-size CsPbI_(3)QDs.This exchange strategy maintained the size and morphology of CsPbI_(3)QDs and improved the optical properties and the conductivity of CsPbI_(3)QDs films.As a result,high-efficiency red QD-based light-emitting diodes with an emission wavelength of 645 nm demonstrated a record maximum external quantum efficiency of 24.45%and an operational half-life of 10.79 h.

Corrosion-Resistant Polymer-Derived SiOC Membrane for Effective Organic Removal via Synergistic Adsorption and Peroxymonosulfate Activation

A major challenge is to construct ceramic membranes with tunable structures and functions for water treatment.Herein,a novel corrosion-resistant polymer-derived silicon oxycarbide(SiOC)ceramic membrane with designed architectures was fabricated by a phase separation method and was applied in organic removal via adsorption and oxidation for the first time.The pore structure of the as-prepared SiOC ceramic membranes was well controlled by changing the sintering temperature and polydimethylsiloxane content,leading to a pore size of 0.84–1.62μm and porosity of 25.0–43.8%.Corrosion resistance test results showed that the SiOC membranes sustained minimal damage during 24 h exposure to high-intensity acid–base conditions,which could be attributed to the chemical inertness of SiOC.With rhodamine 6G(R6G)as the model pollutant,the SiOC membrane demonstrated an initial eff ective removal rate of 99%via adsorption;however,the removal rate decreased as the system approached adsorption saturation.When peroxymonosulfate was added into the system,efficient and continuous degradation of R6G was observed throughout the entire period,indicating the potential of the as-prepared SiOC membrane in oxidation-related processes.Thus,this work provides new insights into the construction of novel polymer-derived ceramic membranes with well-defined structures and functions.

Electrochemical Lithium Storage Performance of Molten Salt Derived V_(2)SnC MAX Phase

MAX phases are gaining attention as precursors of two-dimensional MXenes that are intensively pursued in applications for electrochemical energy storage.Here,we report the preparation of V_(2)SnC MAX phase by the molten salt method.V_(2)SnC is investigated as a lithium storage anode,showing a high gravimetric capacity of 490 mAh g−1 and volumetric capacity of 570 mAh cm^(−3) as well as superior rate performance of 95 mAh g^(−1)(110 mAh cm^(−3))at 50 C,surpassing the ever-reported performance of MAX phase anodes.Sup-ported by operando X-ray diffraction and density functional theory,a charge storage mechanism with dual redox reaction is proposed with a Sn-Li(de)alloying reaction that occurs at the edge sites of V_(2)SnC particles where Sn atoms are exposed to the electrolyte followed by a redox reaction that occurs at V_(2)C layers with Li.This study offers promise of using MAX phases with M-site and A-site elements that are redox active as high-rate lithium storage materials.

Materials and device engineering to achieve high-performance quantum dots light emitting diodes for display applications

Quantum dots(QDs)have attracted wide attention from academia and industry because of their advantages such as high emitting efficiency,narrow half-peak width,and continuously adjustable emitting wavelength.QDs light emitting diodes(QLEDs)are expected to become the next generation commercial display technology.This paper reviews the progress of QLED from physical mechanism,materials,to device engineering.The strategies to improve QLED performance from the perspectives of quantum dot materials and device structures are summarized.

Topotactic transition of Ti_(4)AlN_(3) MAX phase in Lewis acid molten salt

MAX phases and its derived two-dimensional MXenes have attracted considerable interest because of their rich structural chemistry and multifunctional applications.Lewis acid molten salt route provides an opportunity for structure design and performance manipulation of new MAX phases and MXenes,Although a series of new MAX phases and MXenes were successfully prepared via Lewis acid melt route in recent years,few work is explored on nitride MAX phases and MXenes.Herein,a new copper-based 413-type Ti_(4)CuN_(3)MAX phase was synthesized through isomorphous replacement reaction using Ti_(4)CuN_(3)MAX phase precursor in molten CuCl2.In addition,it was found that at high temperature Ti4N3Clx MXene will transform into two-dimensional cubic TiNa nanosheets with improved structural stability.

Multifunctional RGD coated a single-atom iron nanozyme:A highly selective approach to inducing ferroptosis and enhancing immunotherapy for pancreatic cancer

Nanozyme is a new promising approach to cancer therapy for its ability to induce ferroptosis by activating H_(2)O_(2)via a traditional radical pathway and enhance cancer immunotherapy.However,short half-life period of hydroxyl radical(·OH)results in unsatisfied effectiveness.Herein,we synthesized a single-atom iron nanozyme(Fe-SAzyme),which can activate H_(2)O_(2)via a non-radical pathway to generate Fe-based reactive oxygen species(ROS)(O=FeO_(3)=O)for promoting the ferroptosis of pancreatic cancer cells.This Fe-SAzyme could be specifically phagocytosed by pancreatic cancer cells,increasing ROS levels and inhibiting glutathione(GSH)synthesis,which activates ferroptosis.Tumor magnetic resonance imaging(MRI)showed decreased T2 signal after intravenous injection of RGD@Fe-AC(AC=activated carbon).Moreover,RGD@Fe-AC promoted dendritic cell(DC)maturation,overcame Treg-mediated immunosuppression,activated T cells to trigger adaptive immune responses,and enhanced the efficacy ofα-PD-L1 immunotherapy.Our research demonstrated that RGD@Fe-AC provided a straightforward,easily implemented,and selective approach for pancreatic cancer treatment and immunotherapy.

In-situ growth of MAX phase coatings on carbonised wood and their terahertz shielding properties

Electromagnetic interference(EMI)shielding materials have received considerable attention in recent years.The EMI shielding effectiveness(SE)of materials depends on not only their composition but also their microstructures.Among various microstructure prototypes,porous structures provide the advantages of low density and high terahertz wave absorption.In this study,by using carbonised wood(CW)as a template,1-mm-thick MAX@CW composites(Ti2AlC@CW,V2A1C@CW,and Cr2AlC@CW)with a porous structure were fabricated through the molten salt method.The MAX@CW composites led to the formation of a conductive network and multilayer interface,which resulted in improved EMI SE.The average EMI SE values of the three MAX@CW composites were>45 dB in the frequency of 0.6-1.6 THz.Among the composites,V2A1C@CW exhibited the highest average EMI SE of 55 dB.