Electrochemical detection of toxic anti-scald agent diphenylamine using oxidized carbon nanofiber encapsulated titanium carbide electrocatalyst

Two dimensional (2D) titanium carbide (Ti-C) is an analogues of graphene have tremendous attention in recent years due to their high electrical conductivity and catalytic activity. Herein, we have synthesized Ti-C micro particles based on the template-assisted method and subsequently integrated with oxidized carbon nanofiber (f-CNF) through ultrasonication technique. The prepared Ti-C/f-CNF composite was subjected to various structural and morphological characterization techniques including the X-ray diffraction (XRD), scanning electron microscope (SEM), Energy Dispersive X-ray (EDX) and X-ray photoelectron spectroscopy (XPS). The all followed studies confirmed the formation and crystalline nature of prepared Ti-C/f-CNF nanocomposite. Further, the proposed Ti-C/f-CNF composite modified electrode was successfully applied as an electrocatalyst for the electrochemical detection of diphenylamine (DPA) in food. DPA is known as an anti-scald agent used to post harvest treatment of fruits. However, the higher concentration of DPA causes some hazardous side effects to human. Thus, the detection of DPA is an important concern in healthcare research. Eventually, the proposed Ti-C/f-CNF/SPCE exhibited ultra-low detection limit of (0.003 μM) with a linear range of 0.04-56.82 μM towards the detection of DPA. Moreover, the practicability of the proposed sensor was tested by real sample analysis by using fresh apple extract. Remarkably, the proposed sensor showed an excellent recovery range from 106.8% to 108% for the detection of DPA in spiked apple extract. Finally, we concluded that the integration of f-CNF with Ti-C is significantly enhanced both electrical conductivity and electrocatalytic activity for sensor application.

Rational Surface Tailoring Oxygen Functional Groups on Carbon Spheres for Capacitive Mechanistic Study

Porous carbons represent a typical class of electrode materials for electric double-layer capacitors. However, less attention has been focused on the study of the capacitive mechanism of electrochemically active surface oxygen groups rooted in porous carbons. Herein, the degree and variety of oxygen surface groups of HNO₃-modified samples (N-CS) are finely tailored by a mild hydrothermal oxidation (0.0-3.0 mol L^-1), while the micro-meso-macroporous structures are efficiently preserved from the original sample. Thus, N-CS is a suitable carrier for separately discussing the contribution of oxygen functional groups to the electrochemical property. The optimized N-CS shows a high capacitance of 279.4 F g^-1 at 1 A g^-1, exceeding 52.8% of pristine carbon sphere (CS) (182.8 F g^-1 at 1 A g^-1) in KOH electrolyte. On further deconvoluting the redox peaks of cyclic voltammetry curves, we find that the pseudocapacitance not only associates with the surface-controlled faradic reaction at high scan rate but also dramatically stems from the diffusion-controlled capacitance through potassium and hydroxyl ion insertion/deinsertion into the underutilized micropores at low scan rate. The assembled supercapacitor based on N-CS presents a stable energy density of 5 Wh kg^-1 over a wide range of power density of 250-5000 W kg^-1, which is higher than 0.0N-CS in KOH electrolyte. In TEABF₄ electrolyte, the N-CS supercapacitor has an energy density of 26.9 Wh kg^-1 at the power density of 1350 W kg^-1 and exhibits excellent cycling stability with a capacitance retention of 93.2% at 2 A g^-1 after 10 000 cycles. These results demonstrate that surface oxygen groups alter the capacitive mechanism and contribution of porous carbons.

Ordered Mesoporous Graphitic Carbon/Iron Carbide Composites with High Porosity as a Sulfur Host for Li-S Batteries

The lithium-sulfur battery (LSB) is a promising candidate for future energy storage but faces technological challenges including the low electronic conductivity of sulfur and the solubility of intermediates during cycling. Additionally, current host materials often lack sufficient conductivity and porosity to raise the sulfur loading to over 80 wt %. Here, ordered mesoporous graphitic carbon/iron carbide nanocomposites were prepared via an evaporation-induced self-assembly process using soluble resol, prehydrolyzed tetraethyl orthosilicate (TEOS), and iron(III) chloride as the carbon, silica (SiO₂), and iron precursors, respectively. Graphitization and SiO₂ etching were conducted simultaneously via Teflon-assisted, solid-state decomposition at high temperature. A high surface area (∼3100 m² g^-1), large pore volume (∼3.3 cm³ g^-1), and graphitized carbon frame were achieved, giving a high sulfur loading (85 wt %) while tolerating volumetric expansion during discharge. Electrochemical testing of a LSB containing the composite/sulfur cathode exhibited a superior reversible capacity exceeding 1300 mAh g^-1 at a moderate current (C/10) and a low decay in capacity of 9% after 500 cycles at C/5. The interaction between mesoporous graphitic carbon and sulfur is proposed.

High-Performance Li-SeSx All-Solid-State Lithium Batteries

All-solid-state Li-S batteries are promising candidates for next-generation energy-storage systems considering their high energy density and high safety. However, their development is hindered by the sluggish electrochemical kinetics and low S utilization due to high interfacial resistance and the electronic insulating nature of S. Herein, Se is introduced into S cathodes by forming SeS_x solid solutions to modify the electronic and ionic conductivities and ultimately enhance cathode utilization in all-solid-state lithium batteries (ASSLBs). Theoretical calculations confirm the redistribution of electron densities after introducing Se. The interfacial ionic conductivities of all achieved SeS_x -Li₃ PS₄ (x = 3, 2, 1, and 0.33) composites are 10^-6 S cm^-1 . Stable and highly reversible SeS_x cathodes for sulfide-based ASSLBs can be developed. Surprisingly, the SeS₂ /Li₁₀ GeP₂ S₁₂ -Li₃ PS₄ /Li solid-state cells exhibit excellent performance and deliver a high capacity over 1100 mAh g^-1 (98.5% of its theoretical capacity) at 50 mA g^-1 and remained highly stable for 100 cycles. Moreover, high loading cells can achieve high areal capacities up to 12.6 mAh cm^-2 . This research deepens the understanding of Se-S solid solution chemistry in ASSLB systems and offers a new strategy to achieve high-performance S-based cathodes for application in ASSLBs.

Pyrrolic-Type Nitrogen-Doped Hierarchical Macro/Mesoporous Carbon as a Bifunctional Host for High-Performance Thick Cathodes for Lithium-Sulfur Batteries

Lithium-sulfur (Li-S) batteries are highly considered as a next-generation energy storage device due to their high theoretical energy density. For practical viability, reasonable active-material loading of >4.0 mg cm^-2 must be employed, at a cost to the intrinsic instability of sulfur cathodes. The incursion of lithium polysulfides (LiPS) at higher sulfur loadings results in low active material utilization and poor cell cycling capability. The use of high-surface-area hierarchical macro/mesoporous inverse opal (IOP) carbons to investigate the effects of pore volume and surface area on the electrochemical stability of high-loading, high-thickness cathodes for Li-S batteries is presented here. The IOP carbons are additionally doped with pyrrolic-type nitrogen groups (N-IOP) to act as a polar polysulfide mediator and enhance the active-material reutilization. With a high sulfur loading of 6.0 mg cm^-2 , the Li-S cells assembled with IOP and N-IOP carbons are able to attain a high specific capacity of, respectively, 1242 and 1162 mA h g^-1 . The N-IOP enables the Li-S cells to demonstrate good electrochemical performance over 300 cycles.

Carbon Nanomaterials for Energy and Biorelated Catalysis: Recent Advances and Looking Forward

Along with the wide investigation activities in developing carbon-based, metal-free catalysts to replace precious metal (e.g., Pt) catalysts for various green energy devices, carbon nanomaterials have also shown great potential for biorelated applications. This article provides a focused, critical review on the recent advances in these emerging research areas. The structure-property relationship and mechanistic understanding of recently developed carbon-based, metal-free catalysts for chemical/biocatalytic reactions will be discussed along with the challenges and perspectives in this exciting field, providing a look forward for the rational design and fabrication of new carbon-based, metal-free catalysts with high activities, remarkable selectivity, and outstanding durability for various energy-related/biocatalytic processes.

Semiactive Hybrid Energy Management System: A Solution for Electric Wheelchairs

Many disabled people use electric wheelchairs (EWs) in their daily lives. EWs take a considerable amount of time to charge and are less efficient in high-power-demand situations. This paper addresses these two problems using a semiactive hybrid energy storage system (SA-HESS) with a smart energy management system (SEMS). The SA-HESS contained a lithium-ion battery (LIB) and supercapacitor (SC) connected to a DC bus via a bidirectional DC–DC converter. The first task of the proposed SEMS was to charge the SA-HESS rapidly using a fuzzy-logic-controlled charging system. The second task was to reduce the stress of the LIB. The proposed SEMS divided the discharging operation into starting-, normal-, medium-, and high-power currents. The LIB was used in normal conditions, while the SC was mostly utilized during medium-power conditions, such as starting and uphill climbing of the EW. The conjunction of LIB and SC was employed to meet the high-power demand for smooth and reliable operation. A prototype was designed to validate the proposed methodology, and a comparison of the passive hybrid energy management system (P-HESS) and SA-HESS was performed under different driving tracks and loading conditions. The experimental results showed that the proposed system required less charging time and effectively utilized the power of the SC compared with P-HESS.

Superior Sodium Storage of Carbon-Coated NaV6O15 Nanotube Cathode: Pseudocapacitance Versus Intercalation

To realize the effect of Na⁺ pseudocapacitance on the sodium storage of cathode materials, clewlike carbon-coated sodium vanadium bronze (NaV₆O₁₅) nanotubes (Na-VBNT@C) were synthesized via a facile combined sol-gel/hydrothermal method. The resultant Na-VBNT@C delivers high reversible capacities of 209 and 105 mA h g^-1 at the rates of 0.1 and 10 C, respectively. Notably, at the higher rate of 5 C (1250 mA g^-1), it can retain 94% of the initial capacity after 3000 cycles. It was found that the outstanding rate performance and the long-term cycling life of Na-VBNT@C are primarily due to the Na⁺ pseudocapacitance. Our study reveals that the design of Na⁺ pseudocapacitance is beneficial for harvesting the superior performance of NaV₆O₁₅ cathode material in sodium-ion batteries.

Bridging the academic and industrial metrics for next-generation practical batteries

Batteries have shaped much of our modern world. This success is the result of intense collaboration between academia and industry over the past several decades, culminating with the advent of and improvements in rechargeable lithium-ion batteries. As applications become more demanding, there is the risk that stunted growth in the performance of commercial batteries will slow the adoption of important technologies such as electric vehicles. Yet the scientific literature includes many reports describing material designs with allegedly superior performance. A considerable gap needs to be filled if we wish these laboratory-based achievements to reach commercialization. In this Perspective, we discuss some of the most relevant testing parameters that are often overlooked in academic literature but are critical for practical applicability outside the laboratory. We explain metrics such as anode energy density, voltage hysteresis, mass of non-active cell components and anode/cathode mass ratio, and we make recommendations for future reporting. We hope that this Perspective, together with other similar guiding principles that have recently started to emerge, will aid the transition from lab-scale research to next-generation practical batteries.

Polymer-Based Synthetic Routes to Carbon-Based Metal-Free Catalysts

Carbons are increasingly important as possible alternatives to expensive metal catalysts owing to the wide range of chemical properties they can exhibit and the growing set of synthetic routes available to produce them. This progress report discusses the process of making catalytic carbons from polymeric precursors, focusing on mechanisms of carbonization and how the polymer structures and synthetic procedures affect the resulting carbons. In considering what is necessary to move laboratory catalytic carbons to industrial and commercial applications, the cost and complexity to produce them are a considerable challenge to overcome. Industrially produced carbons are typically made from biopolymers such as lignin while many of the catalytic carbons studied in literature are from synthetic polymers. Thus, studying polymer-derived carbons can provide insights into the carbonization process and the properties of catalytic carbons, which can subsequently be translated to improve biopolymer-derived carbons in an economical way. Aspects of polymer carbonization discussed include carbonization mechanisms, effects of crosslinkers, polymer microstructure, heteroatom control, and effects of nanostructuring.

Guiding Principles for Designing Highly Efficient Metal-Free Carbon Catalysts

Carbon nanomaterials are promising metal-free catalysts for energy conversion and storage, but the catalysts are usually developed via traditional trial-and-error methods. To rationally design and accelerate the search for the highly efficient catalysts, it is necessary to establish design principles for the carbon-based catalysts. Here, theoretical analysis and material design of metal-free carbon nanomaterials as efficient photo-/electrocatalysts to facilitate the critical chemical reactions in clean and sustainable energy technologies are reviewed. These reactions include the oxygen reduction reaction in fuel cells, the oxygen evolution reaction in metal-air batteries, the iodine reduction reaction in dye-sensitized solar cells, the hydrogen evolution reaction in water splitting, and the carbon dioxide reduction in artificial photosynthesis. Basic catalytic principles, computationally guided design approaches and intrinsic descriptors, catalytic material design strategies, and future directions are discussed for the rational design and synthesis of highly efficient carbon-based catalysts for clean energy technologies.

Recent Advances in Hollow Porous Carbon Materials for Lithium-Sulfur Batteries

Lithium-sulfur (Li-S) batteries are considered as one of the most potential next-generation rechargeable batteries due to their high theoretical energy density. However, some critical issues, such as low capacity, poor cycling stability, and safety concerns, must be solved before Li-S batteries can be used practically. During the past decade, tremendous efforts have been devoted to the design and synthesis of electrode materials. Benefiting from their tunable structural parameters, hollow porous carbon materials (HPCM) remarkably enhance the performances of both sulfur cathodes and lithium anodes, promoting the development of high-performance Li-S batteries. Here, together with the templated synthesis of HPCM, recent progresses of Li-S batteries based on HPCM are reviewed. Several important issues in Li-S batteries, including sulfur loading, polysulfide entrapping, and Li metal protection, are discussed, followed by a summary on recent research on HPCM-based sulfur cathodes, modified separators, and lithium anodes. After the discussion on emerging technical obstacles toward high-energy Li-S batteries, prospects for the future directions of HPCM research in the field of Li-S batteries are also proposed.

Carbon-Based Metal-Free Catalysts for Energy Storage and Environmental Remediation

Owing to their high earth-abundance, eco-friendliness, high electrical conductivity, large surface area, structure tunability at the atomic/morphological levels, and excellent stability in harsh conditions, carbon-based metal-free materials have become promising advanced electrode materials for high-performance pseudocapacitors and metal-air batteries. Furthermore, carbon-based nanomaterials with well-defined structures can function as green catalysts because of their efficiency in advanced oxidation processes to remove organics in air or from water, which reduces the cost for air/water purification and avoids cross-contamination by eliminating the release of heavy metals/metal ions. Here, the research and development of carbon-based catalysts in supercapacitors and batteries for clean energy storage as well as in air/water treatments for environmental remediation are reviewed. The related mechanistic understanding and design principles of carbon-based metal-free catalysts are illustrated, along with the challenges and perspectives in this emerging field.

Room-Temperature Potassium-Sulfur Batteries Enabled by Microporous Carbon Stabilized Small-Molecule Sulfur Cathodes

Potassium-sulfur (K-S) batteries are a promising alternative to lithium ion batteries for large-area energy storage applications, owing to their high capacity and inexpensiveness, but they have been seldom investigated. Here we report room-temperature K-S batteries utilizing a microporous carbon-confined small-molecule sulfur composite cathode. The synergetic effects of the strong confinement of microporous carbon matrix and the small-molecule sulfur structure can effectually eliminate the formation of soluble polysulfides and ensure a reversible capacity of 1198.3 mA h g^-1 and retain 72.5% after 150 cycles with a Coulombic efficiency of ∼97%. The potassium-storage mechanism was investigated by X-ray photoelectron spectroscopy analysis and theoretical calculations. The results suggest that K₂S is the final potassiation product along with the reaction of 2K + S ↔ K₂S, giving a theoretical capacity of 1675 mA h g^-1. Our findings not only provide an effective strategy to fabricate high-performance room-temperature K-S batteries but also offer a basic comprehension of the potassium storage mechanism of sulfur cathode materials.

Doping of Carbon Materials for Metal-Free Electrocatalysis

Carbon atoms in the graphitic carbon skeleton can be replaced by heteroatoms with different electronegative from that of the carbon atom (i.e., heteroatom doping) to modulate the charge distribution over the carbon network. The charge modulation can be achieved via direct charge transfer with an electron acceptor/donor (i.e., charge transfer doping) or through introduction of defects (i.e., defective doping). Various doping strategies, including heteroatom doping, charge-transfer doping, and defective doping, have now been devised for modulating the charge distribution of numerous graphite carbon materials to impart new properties to carbon materials. Consequently, carbon nanomaterials with defined doping have recently become prominent members in the carbon family, promising for a variety of applications, including catalysis, energy conversion and storage, environmental remediation, and important chemical production and industrial processes. The purpose of this review is to present an overview on the doping of carbon materials for metal-free electrocatalysis, especially the development of doping strategies and doping-induced structure and property changes for potential catalytic applications. Current challenges and future perspectives in the doped carbon-based metal-free catalyst field are also discussed.

Flexible Zn-Ion Batteries: Recent Progresses and Challenges

To keep pace with the increasing pursuit of portable and wearable electronics, it is urgent to develop advanced flexible power supplies. In this context, Zn-ion batteries (ZIBs) have garnered increasing attention as favorable energy storage devices for flexible electronics, owing to the high capacity, low cost, abundant resources, high safety, and eco-friendliness. Extensive efforts have been devoted to developing flexible ZIBs in the last few years. This work summarizes the recent achievements in the design, fabrication, and characterization of flexible ZIBs. Representative structures, such as sandwich and cable type, are particularly highlighted. Special emphasis is put on the novel design of electrolyte and electrode, which aims to endow reliable flexibility to the fabricated ZIBs. Moreover, current challenges and future opportunities for the development of high-performance flexible ZIBs are also outlined.

In Operando Synchrotron Diffraction and in Operando X-ray Absorption Spectroscopy Investigations of Orthorhombic V2O5 Nanowires as Cathode Materials for Mg-Ion Batteries

Orthorhombic V₂O₅ nanowires were successfully synthesized via a hydrothermal method. A cell-configuration system was built utilizing V₂O₅ as the cathode and 1 M Mg(ClO₄)₂ electrolyte within acetonitrile, together with Mg _xMo₆S₈ ( x ≈ 2) as the anode to investigate the structural evolution and oxidation state and local structural changes of V₂O₅. The V₂O₅ nanowires deliver an initial discharge/charge capacity of 103 mAh g^-1/110 mAh g^-1 and the highest discharge capacity of 130 mAh g^-1 in the sixth cycle at C/20 rate in the cell-configuration system. In operando synchrotron diffraction and in operando X-ray absorption spectroscopy together with ex situ Raman and X-ray photoelectron spectroscopy reveal the reversibility of magnesium insertion/extraction and provide information on the crystal structure evolution and changes of the oxidation states during cycling.

Shape-controlled metal nanoparticles for electrocatalytic applications

The application of shape-controlled metal nanoparticles is profoundly impacting the field of electrocatalysis. On the one hand, their use has remarkably enhanced the electrocatalytic activity of many different reactions of interest. On the other hand, their usage is deeply contributing to a correct understanding of the correlations between shape/surface structure and electrochemical reactivity at the nanoscale. However, from the point of view of an electrochemist, there are a number of questions that must be fully satisfied before the evaluation of the shaped metal nanoparticles as electrocatalysts including (i) surface cleaning, (ii) surface structure characterization, and (iii) correlations between particle shape and surface structure. In this chapter, we will cover all these aspects. Initially, we will collect and discuss about the different practical protocols and procedures for obtaining clean shaped metal nanoparticles. This is an indispensable requirement for the establishment of correct correlations between shape/surface structure and electrochemical reactivity. Next, we will also report how some easy-to-do electrochemical experiments including their subsequent analyses can enormously contribute to a detailed characterization of the surface structure of the shaped metal nanoparticles. At this point, we will remark that the key point determining the resulting electrocatalytic activity is the surface structure of the nanoparticles (obviously, the atomic composition is also extremely relevant) but not the particle shape. Finally, we will summarize some of the most significant advances/results on the use of these shaped metal nanoparticles in electrocatalysis covering a wide range of electrocatalytic reactions including fuel cell-related reactions (electrooxidation of formic acid, methanol and ethanol and oxygen reduction) and also CO2 electroreduction.

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Promoting Shewanella Bidirectional Extracellular Electron Transfer for Bioelectrocatalysis by Electropolymerized Riboflavin Interface on Carbon Electrode

The extracellular electron transfer (EET) that connects the intracellular metabolism of electroactive microorganisms to external electron donors/acceptors, is the foundation to develop diverse microbial electrochemical technologies. For a particular microbial electrochemical device, the surface chemical property of an employed electrode material plays a crucial role in the EET process owing to the direct and intimate biotic-abiotic interaction. The functional modification of an electrode surface with redox mediators has been proposed as an effectual approach to promote EET, but the underlying mechanism remains unclear. In this work, we investigated the enhancement of electrochemically polymerized riboflavin interface on the bidirectional EET of Shewanella putrefaciens CN32 for boosting bioelectrocatalytic ability. An optimal polyriboflavin functionalized carbon cloth electrode achieved about 4.3-fold output power density (∼707 mW/m2) in microbial fuel cells and 3.7-fold cathodic current density (∼0.78 A/m2) for fumarate reduction in three-electrode cells compared to the control, showing great increases in both outward and inward EET rates. Likewise, the improvement was observed for polyriboflavin-functionalized graphene electrodes. Through comparison between wild-type strain and outer-membrane cytochrome (MtrC/UndA) mutant, the significant improvements were suggested to be attributed to the fast interfacial electron exchange between the polyriboflavin interface with flexible electrochemical activity and good biocompatibility and the outer-membrane cytochromes of the Shewanella strain. This work not only provides an effective approach to boost microbial electrocatalysis for energy conversion, but also offers a new demonstration of broadening the applications of riboflavin-functionalized interface since the widespread contribution of riboflavin in various microbial EET pathways together with the facile electropolymerization approach.

Enhanced Roles of Carbon Architectures in High-Performance Lithium-Ion Batteries

Lithium-ion batteries (LIBs), which are high-energy-density and low-safety-risk secondary batteries, are underpinned to the rise in electrochemical energy storage devices that satisfy the urgent demands of the global energy storage market. With the aim of achieving high energy density and fast-charging performance, the exploitation of simple and low-cost approaches for the production of high capacity, high density, high mass loading, and kinetically ion-accessible electrodes that maximize charge storage and transport in LIBs, is a critical need. Toward the construction of high-performance electrodes, carbons are promisingly used in the enhanced roles of active materials, electrochemical reaction frameworks for high-capacity noncarbons, and lightweight current collectors. Here, we review recent advances in the carbon engineering of electrodes for excellent electrochemical performance and structural stability, which is enabled by assembled carbon architectures that guarantee sufficient charge delivery and volume fluctuation buffering inside the electrode during cycling. Some specific feasible assembly methods, synergism between structural design components of carbon assemblies, and electrochemical performance enhancement are highlighted. The precise design of carbon cages by the assembly of graphene units is potentially useful for the controlled preparation of high-capacity carbon-caged noncarbon anodes with volumetric capacities over 2100 mAh cm^-3. Finally, insights are given on the prospects and challenges for designing carbon architectures for practical LIBs that simultaneously provide high energy densities (both gravimetric and volumetric) and high rate performance.

Ion- and Electron-Conductive Buffering Layer-Modified Si Film for Use as a High-Rate Long-Term Lithium-Ion Battery Anode

The rational design of electrochemically and mechanically stable Si anodes is of great importance for the development of high energy density lithium-ion batteries. In this study, patterned Si-based (Si/ZnO/C) trilayer composite films were synthesized by magnetron sputtering with the assistance of a patterned mask. The electron-conductive C layer at the top of the composite film is deposited to enhance the interfacial stability between active film and electrolyte. The ion- and electron-conductive Li₂ O-Zn middle layer can be ingeniously introduced by means of the poor reversed conversion reaction between ZnO and Li⁺ ions after the first cycle. The resultant Si/Li₂ O-Zn/C trilayer composite film delivers a high reversible capacity of 1536 mAh g^-1 after 800 cycles at a current density of 1.0 A g^-1 and a long high-rate cycling stability (1400 mAh g^-1 after 6000 cycles even at a high current density of 10.0 A g^-1 ). Excellent rate capability and improved Coulombic efficiency are also achieved. The influences of the patterned structure and each modified layer on the electrochemical properties are analyzed systematically. This work offers a new and promising direction to enhance the lithium-storage properties of Si-based thin-film anodes.

A bi-functional redox mediator promoting the ORR and OER in non-aqueous Li–O2 batteries

A bi-functional homogeneous redox mediator is employed to promote both the ORR and OER processes in Li–O₂ batteries.

Printed electronics based on inorganic conductive nanomaterials and their applications in intelligent food packaging

The diverse demands of consumers for packaging functions and increasingly complex product circulation systems have spurred the development of intelligent food packaging (IFP).

Systematic exploration of N,C coordination effects on the ORR performance of Mn–Nx doped graphene catalysts based on DFT calculations

Five-coordination Mn–N_x experiences a significant increase in ORR catalytic activity due to its moderate binding ability compared with Mn–N₄ and Mn–N₃.

In Operando analysis of the charge storage mechanism in a conversion ZnCo2O4 anode and the application in flexible Li-ion batteries

Intermediate phases of LiCo₂O₃, CoO and ZnO are evidenced during the 1^st lithiation of a ZnCo₂O₄ anode.

Polydiaminoanthraquinones with tunable redox properties as high performance organic cathodes for K-ion batteries

Polydiaminoanthraquinones with redox-active quinone-based segments linked by polyanilines were developed as advanced K storage cathodes with tunable redox properties.

NaCl protected synthesis of 3D hierarchical metal-free porous nitrogen-doped carbon catalysts for the oxygen reduction reaction in acidic electrolyte

A high-performance 3D hierarchical porous metal-free N-doped carbon catalyst for oxygen reduction reaction in acidic medium was synthesized with ZnO as a mesoporous template and NaCl as both a macroporous template and a structure protective agent.

Asynchronous reactions of “self-matrix” dual-crystals effectively accommodating volume expansion/shrinkage of electrode materials with enhanced sodium storage

The dual-crystal FeS₂ shows a better tolerance towards large volume changes because of the asynchronous reaction.

Core@shell nanostructured Au-d@NimPtm for electrochemical oxygen reduction reaction: effect of the core size and shell thickness

Au-d@Ni_mPt_m nanostructures are studied to address the effects of the Au-core size (d) and NiPt-shell thickness (m) on the electrocatalytic performance of Pt for the ORR.

The effect of different organic solvents and anion salts on sodium ion storage in cylindrical carbon nanopores

In this article fully atomistic Molecular Dynamics simulations were employed to study the behaviour of electrolyte salts and different organic solvents in cylindrical carbon nanotubes, in order to reveal the storage mechanism.

Silver vanadium oxide@water-pillared vanadium oxide coaxial nanocables for superior zinc ion storage properties

The Ag_0.333V₂O₅@V₂O₅·nH₂O coaxial nanocables with optimal ion/electron conductivity enable synergistic enhancement of zinc ion storage properties.

Bio-inspired chitosan-heme-vitamin B12-derived Fe–Co bimetallic-doped mesoporous carbons for efficiently electro-activating oxygen

Biomass-derived chitosan-heme-vitamin B₁₂ with definitive molecular structures was converted to bimetallic Fe–Co-doped mesoporous carbon for efficient oxygen electroreduction.

Utilizing an autogenously protective atmosphere to synthesize a Prussian white cathode with ultrahigh capacity-retention for potassium-ion batteries

Prussian white with ultrahigh capacity-retention was synthesized by utilizing an autogenously protective atmosphere.

On-going applications of Shewanella species in microbial electrochemical system for bioenergy, bioremediation and biosensing

Microbial electrochemical system (MES) has attracted ever-growing interest as a promising platform for renewable energy conversion and bioelectrochemical remediation. Shewanella species, the dissimilatory metal reduction model bacteria with versatile extracellular electron transfer (EET) strategies, are the well-received microorganisms in diverse MES devices for various practical applications as well as microbial EET mechanism investigation. Meanwhile, the available genomic information and the unceasing established gene-editing toolbox offer an unprecedented opportunity to boost the applications of Shewanella species in MES. This review thoroughly summarizes the status quo of the applications of Shewanella species in microbial fuel cells for bioelectricity generation, microbial electrosynthesis for biotransformation of valuable chemicals and bioremediation of environment-hazardous pollutants with synoptical discussion on their EET mechanism. Recent advances in rational design and genetic engineering of Shewanella strains for either promoting the MES performance or broadening their applications are surveyed. Moreover, some emerging applications beyond electricity generation, such as biosensing and biocomputing, are also documented. The challenges and perspectives for Shewanella-based MES are also discussed elaborately for the sake of not only discovering new scientific lights on microbial extracellular respiratory but also propelling practical applications.

Co9 S8 -Catalyzed Growth of Thin-Walled Graphite Microtubes for Robust, Efficient Overall Water Splitting

Co₉ S₈ crystals can catalyze the growth of thin-walled graphite microtubes (GMTs) through a catalytic chemical vapor deposition (CCVD) process using thiourea as the precursor. The growth of GMTs follows a tip-growth mechanism with tube diameters up to a few micrometer. The hollow interiors of the GMTs are filled with carbon nanotubes and wrinkled graphene layers, which form a unique nanotube/graphene-in-microtube structure. As-formed GMTs are N,S-codoped with lots of Co₉ S₈ nanoparticles encapsulated in their inner walls. These GMTs are room-temperature ferromagnets and can be loaded on Ni foams to work as binder-free electrocatalysts with low overpotential (310 mV at 50 mA cm^-2 for the oxygen evolution reaction (OER) and 284 mV at 50 mA cm^-2 for the hydrogen evolution reaction (HER)) and long-term durability (continuous work for 120 h without loss in performance). Our research proves that metal sulfides can catalyze the growth of graphite microtubes and as-formed GMTs may potentially be used as functional building blocks to construct new kinds of electrochemical devices for various energy-related applications.

Ultrahigh-Desalination-Capacity Dual-Ion Electrochemical Deionization Device Based on Na3V2(PO4)3@C-AgCl Electrodes

Seawater desalination is a promising way to alleviate water scarcity nowadays. Present capacitive desalination methods have limitation of salt removal capacity. Herein, a new dual-ion electrochemical desalination system with an ultrahigh desalination capacity is reported. It is composed of Na₃V₂(PO₄)₃@C wires as a sodium ion Faradaic electrode, AgCl as a chloride ion Faradaic electrode, and salt feed solution as the electrolyte. When a constant current is applied, redox reactions occur on electrodes, releasing or removing sodium ions and chloride ions. Na₃V₂(PO₄)₃ has a high sodium specific capacity, and as a sodium superionic conductor, Na₃V₂(PO₄)₃@C wires form an ion conductor network, providing high sodium ion mobility. Additionally, both the wire structure and carbon shell enhance the electrical conductivity of Na₃V₂(PO₄)₃. Benefiting from these, outstanding desalination performance, rate capability, and cycle capability have been achieved with the Na₃V₂(PO₄)₃@C wire-AgCl device. An ultrahigh desalination capacity of 98.0 mg/g is obtained at a current density of 100 mA/g for more than 50 cycles. This system provides a viable dual-ion electrochemical desalination strategy, which outperforms most of the existing desalination methods.

Understanding the Electrochemical Compatibility and Reaction Mechanism on Na Metal and Hard Carbon Anodes of PC-Based Electrolytes for Sodium-Ion Batteries

Electrolytes as an important part of sodium-ion batteries have a pivotal role for capacity, rate, and durability of electrode materials. On account of the high reduction activity of sodium metal with organic solvents, it is very important to optimize the electrolyte component to realize high stability on Na metal and hard carbon anodes. Herein, chemical and electrochemical stability of propylene carbonate (PC)-based electrolytes on sodium metal and hard carbon anodes is investigated systematically. The results demonstrate that whether using NaClO₄ or NaPF₆, the PC-based electrolytes are not stable on Na metal, but adding of FEC can immensely enhance the stability of the electrolyte because of the compact solid electrolyte interphase film formed. The electrolytes containing FEC also exhibit high electrochemical compatibility on hard carbon anodes, showing high reversible capacity and excellent cycling performance. A reaction mechanism based on the Na⁺ induction effect is proposed by spectrum and electrochemical measurements. This study can provide a new insight to optimize and develop stable PC-based electrolytes and be helpful for understanding the other electrolyte systems.

Sintering Temperature Induced Evolution of Microstructures and Enhanced Electrochemical Performances: Sol-Gel Derived LiFe(MoO4)2 Microcrystals as a Promising Anode Material for Lithium-Ion Batteries

A facile sol-gel process was used for synthesis of LiFe(MoO₄)₂ microcrystals. The effects of sintering temperature on the microstructures and electrochemical performances of the as-synthesized samples were systematically investigated through XRD, SEM and electrochemical performance characterization. When sintered at 650°C, the obtained LiFe(MoO₄)₂ microcrystals show regular shape and uniform size distribution with mean size of 1–2 μm. At the lower temperature (600°C), the obtained LiFe(MoO₄)₂ microcrystals possess relative inferior crystallinity, irregular morphology and vague grain boundary. At the higher temperatures (680 and 700°C), the obtained LiFe(MoO₄)₂ microcrystals are larger and thicker particles. The electrochemical results demonstrate that the optimized LiFe(MoO₄)₂ microcrystals (650°C) can deliver a high discharge specific capacity of 925 mAh g⁻¹ even at a current rate of 1 C (1,050 mA g⁻¹) after 500 cycles. Our work can provide a good guidance for the controllable synthesis of other transition metal NASICON-type electrode materials.

A Lithium-Sulfur Battery using a 2D Current Collector Architecture with a Large-Sized Sulfur Host Operated under High Areal Loading and Low E/S Ratio

While backless freestanding 3D electrode architectures for batteries with high loading sulfur have flourished in the recent years, the more traditional and industrially turnkey 2D architecture has not received the same amount of attention. This work reports a spray-dried sulfur composite with large intrinsic internal pores, ensuring adequate local electrolyte availability. This material offers good performance with a electrolyte content of 7 µL mg^-1 at high areal loadings (5-8 mg cm^-2 ), while also offering the first reported 2.8 µL mg^-1 (8 mg cm^-2 ) to enter into the second plateau of discharge and continue to operate for 20 cycles. Moreover, evidence is provided that the high-frequency semicircle (i.e., interfacial resistance) is mainly responsible for the often observed bypassing of the second plateau in lean electrolyte discharges.