Carbon Surface Chemistry: New Insight into the Old Story

Symmetry Breaking of FeN4 Moiety via Edge Defects for Acidic Oxygen Reduction Reaction

Fe-N-C catalysts, with a planar D4h symmetric FeN4 structure, show promising as noble metal-free oxygen reduction reaction catalysts. Nonetheless, the highly symmetric structure restricts the effective manipulation of its geometric and electronic structures, impeding further enhancements in oxygen reduction reaction performance. Here, a high proportion of asymmetric edge-carbon was successfully introduced into Fe-N-C catalysts through morphology engineering, enabling the precise modulation of the FeN4 active site. Electrochemical experimental results demonstrate that FeN4@porous carbon (FeN4@PC), featuring enriched asymmetric edge-FeN4 active sites, exhibits higher acidic oxygen reduction reaction catalytic activity compared to FeN4@flaky carbon (FeN4@FC), where symmetric FeN4 is primarily distributed within the basal-plane. Synchrotron X-ray absorption spectra, X-ray emission spectra, and theoretical calculations indicate that the enhanced oxygen reduction reaction catalytic activity of FeN4@PC is attributed to the higher oxidation state of Fe species in the edge structure of FeN4@PC. This finding paves the way for controlling the local geometric and electronic structures of single-atom active sites, leading to the development of novel and efficient Fe-N-C catalysts.

Carbon Surface Chemistry: Benchmark for the Analysis of Oxygen Functionalities on Carbon Materials

The explicit roles of the hardly avoidable oxygen species on carbon materials in various fields remain contentious due to the limitations of characterization techniques, which lead to a lack of fundamental understanding of carbon surface chemistry. This study delves exhaustively into the comprehension of the features of different oxygen-modified carbons through the dynamic evolution of surficial oxygen functional groups. Significant differences of thermal stability and electronic properties among various oxygen species are elucidated via in situ characterizations and theoretical calculations, providing a reliable benchmark for identifying oxygen functional groups on carbon materials. The chemical properties of the carbon materials are simultaneously investigated to show the influence of the oxygen functional groups on carbon structures, redox stability, and scalable metal adsorption. These findings not only consider the common misconception that oxygen species produced under various conditions possess identical properties but also raise awareness of understanding carbon surface chemistry in the atomic level.

Modulating Defect Concentration of Boron Nitride Flowers for CO2 Photoreduction

The efficient conversion of carbon dioxide into high-value chemicals presents a promising strategy for achieving carbon neutrality. Defects play a critical role in numerous catalytic reactions. However, an excessive number of defects can lead to electron trapping, deactivating the catalyst surface. Optimizing the defect concentration is crucial for significantly enhancing catalytic performance. In this work, two types of flower-like BN-based photocatalysts composed of nanofibers were synthesized by in situ self-assembly and high-temperature calcination. The BN-based photocatalyst with fewer defects (Vpoor-BNF) achieved a CO2 reduction rate 2 times higher than that of the BN-based photocatalyst with more defects (Vrich-BNF), with a CO yield of 32 μmol g-1 h-1 with 86.9% selectivity. Importantly, the mechanism of enhanced CO2 reduction activity over BN-like photocatalysts was investigated in combination with various advanced characterization. The results show that excessive C doping causes carbon deposition, creating more defects that trap photogenerated electrons and affect the photocatalytic activity. In contrast, the Vpoor-BNF has longer photogenerated carrier lifetime and better photoelectric properties, which are beneficial for the CO2 photoreduction reaction. In addition, the good stability of the catalyst was confirmed by the cyclic experiment. This study presents an effective approach for synthesizing defect-controlled catalysts, which is beneficial for the development of advanced photocatalysts.

Exploring Local Reactivity of Large Systems through Combining Conceptual DFT and the GFN2-xTB Method

This study evaluates the ability of the GFN2-xTB method and Conceptual Density Functional Theory-derived tools to predict local reactivity in large systems. Carbon-based systems such as C60, C70, Li+@C70, C240, C360, C648, and C720 have been used as test sets, and the orbital-weighted dual descriptor was employed to identify nucleophilic and electrophilic regions, providing a comprehensive analysis of their reactivity patterns. The results confirm that the GFN2-xTB method accurately reproduces reactivity profiles observed experimentally and at the DFT level, particularly in well-known fullerenes like C60 and C70. The addition of an endohedral Li+ cation to C70 demonstrated enhanced electrophilicity and reduced unfavorable nucleophilic regions, consistent with previous studies. For larger and less-studied systems, such as C240, C360, C648, and C720, the analysis revealed distinct reactivity features, including the localization of nucleophilic regions in -C≡C- units of C240/C648, the nucleophilic regions at the ends of the C360 nanoparticle model, and the emergence of electrophilic zones due to the reduction in aromaticity of the benzenoid rings in C720. These findings validate the GFN2-xTB method as a computationally efficient alternative for exploring the reactivity of large structures and contribute valuable insights into their potential applications in molecular design for material science and nanotechnology.

Molecular-level Modulation of N, S-Co-Doped Mesoporous Carbon Nanospheres for Selective Aqueous Catalytic Oxidation of Ethylbenzene

Selective oxidation of aromatic alkanes into high value-added products through benzylic C-H bond activation is one of the main reactions in chemical industry. On account of the constantly increasing demand for mass production, efficient, eco-friendly and sustainable catalysts are urgently needed. Herein, we describe a facile and versatile emulsion-assisted interface self-assembly strategy towards molecular-level fabrication of co-doped mesoporous carbon nanospheres with controllable active N and S species. The method enables a high degree of control over nanoparticle sizes, mesoporous nanostructures, contents of heteroatoms and the chemical composition. The optimized catalyst exhibits high catalytic performance of 97 % ethylbenzene conversion and 98 % selectivity to acetophenone. Density functional theory simulations reveal that N, S-co-doping leads to the redistribution of charge and spin densities, introducing more active carbon atoms and realizing aerobic oxidation of ethylbenzene efficiently. This work presents a general strategy for molecular-level design of carbon-based catalysts, and also provides new insight into the influence of heteroatom-doping on catalytic properties.

Can Carbon be Used as an Anode for Water Splitting?

Carbon materials, whose structural and electronic properties can be fine-tuned, are promising material solutions for many energy-related systems. However, due to the lack of fundamental understanding of the carbon surface chemistry, especially when they are used in electrolytes, the rapid development of carbon as electrodes has led to many widely accepted misunderstandings. Focusing on the case of carbon-based electrode for water splitting, this Viewpoint tries to highlight the main problems of the area and demonstrates/presents the dynamic carbon surface chemistry in the application. The role of carbon as an anode for water splitting is revealed and if it can be practically used in water splitting is discussed.

Impact of Activation Conditions on the Electrochemical Performance of Rice Straw Biochar for Supercapacitor Electrodes

Biochar, derived from agricultural waste, has gained significant attention as a sustainable material for energy storage applications due to its high surface area, tunable porosity, and environmental benefits. This study investigates the electrochemical performance of rice straw biochar (RSBC) as an electrode material, with a focus on the effects of activation temperature, activation ratio, and activation time. Among the prepared samples, RSBC-2, activated at 800 °C with a 1:2 KOH ratio for 0.5 h, exhibited the best electrochemical performance. Characterization of RSBC and RSBC-2 showed significant improvements in surface area and pore structure. Specifically, the BET surface area of RSBC-2 increased to 939.40 m2 g-1, with a reduced average pore size of 2.27 nm. Electrochemical testing revealed that RSBC-2 achieved specific capacitances of 296, 281, 272, 260, and 240 F g-1 at current densities of 0.2, 0.5, 1, 2, and 5 A g-1, respectively, with a capacity retention rate of 81%. The improved electrochemical performance of RSBC-2 is attributed to its larger surface area and enhanced pore structure, which facilitate better charge storage and overall electrochemical behavior, making it a promising candidate for energy storage applications.

Revealing the Effect of Curvature Structure in Hard Carbon Anodes for Lithium/Sodium Ion Batteries

Heteroatom doping is the most common means to enhance the Li+/Na+ ions storage of hard carbon (HC). The explanation of the storage mechanism of heteroatom-doped HC is to increase the active site or widen the layer spacing while ignoring the effect of local bending structure induced by it. Meanwhile, the storage mechanism by the localized bending structure also lacks in-depth study. Herein, a locally curved configuration and an amorphous structure are designed by introducing different heteroatoms, respectively, and the mechanism of the two types of structures on the Li+/Na+ ions storage is explored. The density functional theory (DFT) calculation shows that the adsorption energy of Li+/Na+ ions is optimal at the appropriate curvature of 27.72 m-1. Serving as anode for lithium/sodium ion batteries in ester electrolytes, the optimized HCs demonstrate satisfied specific capacity and high-rate capability, respectively. Furthermore, the charging capacity below 1.0 V of HC with suitable curvature microstructure reaches 84.8% and 90.1% of the total charge capacity, confirming that the curvature defects can better control the delithiation/desodiation process, and provide a higher energy density. This study enlightens new insights into the storage mechanisms of Li+/Na+ ions and provides guidance for better design of heteroatom-doped carbon anodes with superior performance.

Surface Oxygen Engineering Catalytic Pore Tailoring of Coal-Based Needle Coke toward Capacitive Porous Carbon

Coal-based needle coke (CNC) is an ideal carbon precursor for capacitive materials due to its layered graphitic structure and high electrical conductivity. However, the pore-rich engineering and graphitic structural inheriting of CNC-derived carbon during the conventional activation process present challenges. Herein, a surface oxygen engineering catalytic pore tailoring strategy is developed to manipulate the porous structures of CNC-derived porous carbon. This synthesis uses air oxidation to form oxygen-rich microregions on the CNC surface, which can effectively tear the graphite protective shell, accelerate the bonding of KOH with oxygen groups, and catalyze the etching reaction between potassium compounds and carbon atoms. Thanks to the low activation temperature of 600 °C and alkali-to-carbon ratio of 1:1, the obtained porous carbon (PC) inherits the long-range graphitic structure from CNC, and its specific surface areas can be adjusted from 182.6 to 855.4 m2 g-1 by adjusting the oxidation temperature, which is far more than that of PC (7.6 m2 g-1) derived from CNC direct activation. The optimized PC shows a high specific capacitance of 308.3 F g-1 at 0.5 A g-1 and a capacitive retention of 212.2 F g-1 at 20 A g-1 with a capacitive retention of 68.8%. The assembled supercapacitor delivers an energy density of 8.12 Wh kg-1 at a power density of 50.0 W kg-1 and ultralong cycle stability with capacitance retention of 99% and Coulombic efficiency of 100% after 50,000 cycles. This study validates the feasibility of pore tailoring by surface oxygen engineering catalysis in soft carbon for enhancing capacitance.

Self-sacrificing and self-supporting biomass carbon anode-assisted water electrolysis for low-cost hydrogen production

Electrooxidation of renewable and CO2-neutral biomass for low-cost hydrogen production is a promising and green technology. Various biomass platform molecules (BPMs) oxidation assisted hydrogen production technologies have obtained noticeable progress. However, BPMs anodic oxidation is highly dependent on electrocatalysts, and the oxidation mechanism is ambiguous. Meanwhile, the complexity and insolubility of natural biomass severely constrain the efficient utilization of biomass resources. Here, we develop a self-sacrificing and self-supporting carbon anode (SSCA) using waste corncobs. The combined results from multiple characterizations reveal that the structure-property-activity relationship of SSCA in carbon oxidation reaction (COR). Theoretical calculations demonstrate that carbon atoms with a high spin density play a pivotal role in reducing the adsorption energy of the reactive oxygen intermediate (*OH) during the transition from OH- to *OH, thereby promoting COR. Additionally, the HER||COR system allows driving a current density of 400 [Formula: see text] at 1.24 V at 80 °C, with a hydrogen production electric consumption of 2.96 kWh Nm-3 (H2). The strategy provides a ground-breaking perspective on the large-scale utilization of biomass and low-energy water electrolysis for hydrogen production.

A comprehensive approach for the recycling of anode materials from spent lithium-ion batteries: Separation, lithium recovery, and graphite reutilization as environmental catalyst

The effective recovery of valuables from anodes coming from spent lithium-ion batteries (LIBs) is of great importance to ensure resource supply and reduce the environmental burden for recycling. In this work, a simple and low energy consumption roasting method was proposed by employing low-temperature eutectic NaOH-KOH as reaction medium, in order to simultaneously separate graphite from Cu foils, extract lithium from it and set it up for reuse as environmental catalyst through one-step water washing process. Our results show that polyvinylidene difluoride (PVDF) was effectively deactivated due to dehydrofluorination/carbonization at a relatively low temperature and short time (150 °C, 20 min) when a mass ratio of 1:1 for eutectic NaOH-KOH to spent LIBs anodes was used, yielding 97.3 % of graphite detached. Moreover, a remarkable lithium extraction efficiency of 93.2 % was simultaneously obtained. Afterwards, the reusability of the recycled graphite was tested by employing it as a catalyst for the treatment of a contaminant organic dye (Rhodamine B) in the presence of NaClO. Our results show that a superior NaClO activation was obtained with the addition of recycled graphite, being this fact closely associated to the abundant active sites formed during the long-term charging/discharging cycles in the original battery. The alkaline-mediated roasting process presented in this work presents an energy-saving scheme to efficiently recover useful components from spent anodes, whereas the reusability example highlighted a useful option for repurposing the severely damaged graphite as an environmental catalyst rather than disposing it in landfills, turning waste into a valuable material.

Minimizing Undesired Side Reactions Induced by Nanoscale Conductive Carbon Enables Stable Cycling of Semi-Solid Li-Ion Full Batteries

Semi-solid lithium-ion batteries (SSLIBs) based on "slurry-like" electrodes hold great promise to enable low-cost and sustainable energy storage. However, the development of the SSLIBs has long been hindered by the lack of high-performance anodes. Here the origin of low initial Coulombic efficiency (iCE, typically <60%) is elucidated in the graphite-based semi-solid anodes (in the non-flowing mode) and develop rational strategies to minimize the irreversible capacity loss. It is discovered that Ketjen black (KB), a nanoscale conductive additive widely used in SSLIB research, induces severe electrolyte decomposition during battery charge due to its large surface area and abundant surface defects. High iCEs up to 92% are achieved for the semi-solid graphite anodes by replacing KB with other low surface-area, low-defect conductive additives. A semi-solid full battery (LiFePO4 vs graphite, in the non-flowing mode) is further demonstrated with stable cycle performance over 100 cycles at a large areal capacity of 6 mAh cm-2 and a pouch-type semi-solid full cell that remains functional even when it is mechanically abused. This work demystifies the SSLIBs and provides useful physical insights to further improve their performance and durability.

Remarkable Active Site Utilization in Edge-Hosted-N Doped Carbocatalysts for Fenton-Like Reaction

Improving the utilization of active sites in carbon catalysts is significant for various catalytic reactions, but still challenging, mainly due to the lack of strategies for controllable introduction of active dopants. Herein, a novel "Ar plasma etching-NH3 annealing" strategy is developed to regulate the position of active N sites, while maintaining the same nitrogen species and contents. Theoretical and experimental results reveal that the edge-hosted-N doped carbon nanotubes (E-N-CNT), with only 0.29 at.% N content, show great affinity to peroxymonosulfate (PMS), and exhibit excellent Fenton-like activity by generating singlet oxygen (1O2), which can reach as high as 410 times higher than the pristine CNT. The remarkable utilization of edge-hosted nitrogen atom is further verified by the edge-hosted-N enriched carbocatalyst, which shows superior capability for 4-chlorophenol degradation with a turnover frequency (TOF) value as high as 3.82 min-1, and the impressive TOF value can even surpass those of single-atom catalysts. This work proposes a controllable position regulation of active sites to improve atom utilization, which provides a new insight into the design of excellent Fenton-like catalysts with remarkable atom utilization efficiency.

Probing Basal and Prismatic Planes of Graphitic Materials for Metal Single Atom and Subnanometer Cluster Stabilization

Supported metal single atom catalysis is a dynamic research area in catalysis science combining the advantages of homogeneous and heterogeneous catalysis. Understanding the interactions between metal single atoms and the support constitutes a challenge facing the development of such catalysts, since these interactions are essential in optimizing the catalytic performance. For conventional carbon supports, two types of surfaces can contribute to single atom stabilization: the basal planes and the prismatic surface; both of which can be decorated by defects and surface oxygen groups. To date, most studies on carbon-supported single atom catalysts focused on nitrogen-doped carbons, which, unlike classic carbon materials, have a fairly well-defined chemical environment. Herein we report the synthesis, characterization and modeling of rhodium single atom catalysts supported on carbon materials presenting distinct concentrations of surface oxygen groups and basal/prismatic surface area. The influence of these parameters on the speciation of the Rh species, their coordination and ultimately on their catalytic performance in hydrogenation and hydroformylation reactions is analyzed. The results obtained show that catalysis itself is an interesting tool for the fine characterization of these materials, for which the detection of small quantities of metal clusters remains a challenge, even when combining several cutting-edge analytical methods.

Designing hard carbon microsphere structure via halogenation amination and oxidative polymerization reactions for sodium ion insertion mechanism investigation

Hard carbon as a negative electrode material for sodium-ion batteries (SIBs) has great commercial potential and has been widely studied. The sodium-ion intercalation in graphite domains and the filling of closed pores in the low voltage platform region still remain a subject of controversy. We have successfully constructed hard carbon materials with a pseudo-graphitic structure by using polymerizable p-phenylenediamine and dichloromethane as carbon sources. This was achieved by a halogenated amination reaction and oxidative polymerization. It was found that the capacity of hard carbon materials mainly originates from intercalation into graphite domains. The study found that the prepared hard carbon could store 339.33 mAh g-1 of sodium in a reversible way at a current density of 25 mA g-1, and it had an initial coulomb efficiency of 80.23%. It even maintained a reversible sodium storage capacity of 125.53 mAh g-1 at a high current density of 12.8 A g-1. Based on the analysis of hard carbon structure and electrochemical performance, it was shown that the materials conform with an "adsorption-intercalation" mechanism for sodium storage.

Designing Symmetric Gradient Honeycomb Structures with Carbon-Coated Iron-Based Composites for High-Efficiency Microwave Absorption

The impedance matching of absorbers is a vital factor affecting their microwave absorption (MA) properties. In this work, we controllably synthesized Material of Institute Lavoisier 88C (MIL-88C) with varying aspect ratios (AR) as a precursor by regulating oil bath conditions, followed by one-step thermal decomposition to obtain carbon-coated iron-based composites. Modifying the precursor MIL-88C (Fe) preparation conditions, such as the molar ratio between metal ions and organic ligands (M/O), oil bath temperature, and oil bath time, influenced the phases, graphitization degree, and AR of the derivatives, enabling low filler loading, achieving well-matched impedance, and ensuring outstanding MA properties. The MOF-derivatives 2 (MD2)/polyvinylidene Difluoride (PVDF), MD3/PVDF, and MD4/PVDF absorbers all exhibited excellent MA properties with optimal filler loadings below 20 wt% and as low as 5 wt%. The MD2/PVDF (5 wt%) achieved a maximum effective absorption bandwidth (EAB) of 5.52 GHz (1.90 mm). The MD3/PVDF (10 wt%) possessed a minimum reflection loss (RLmin) value of - 67.4 at 12.56 GHz (2.13 mm). A symmetric gradient honeycomb structure (SGHS) was constructed utilizing the high-frequency structure simulator (HFSS) to further extend the EAB, achieving an EAB of 14.6 GHz and a RLmin of - 59.0 dB. This research offers a viable inspiration to creating structures or materials with high-efficiency MA properties.

Purine-Doped g-C3N4-Modified Fabrics for Personal Protective Masks with Rapid and Sustained Antibacterial Activity

Protective masks are critical to impeding microorganism transmission but can propagate infection via pathogen buildup and face touching. To reduce this liability, we integrated electrospun photocatalytic graphitic carbon nitride (g-C3N4) nanoflakes into standard surgical masks to confer a self-sanitization capacity. By optimizing the purine/melamine precursor ratio during synthesis, we reduced the g-C3N4 band gap from 2.92 to 2.05 eV, eliciting a 4× increase in sterilizing hydrogen peroxide production under visible light. This narrower band gap enables robust photocatalytic generation of reactive oxygen species from environmental and breath humidity to swiftly eliminate accumulated microbes. Under ambient sunlight, the g-C3N4 nanocomposite mask layer achieved a 97% reduction in the bacterial viability during typical use. Because the optimized band gap also allows photocatalytic activity under shadowless lamp illumination, the self-cleaning functionality could mitigate infection risk from residual pathogens in routine hospital settings. Both g-C3N4 and polycaprolactone demonstrate favorable biocompatibility and biodegradability, making this approach preferable over current commercially available metal-based options. Given the abundance and low cost of these components, this scalable approach could expand global access to reusable self-sanitizing protective masks, serving as a sustainable public health preparedness measure against future pandemics, especially in resource-limited settings.

Hard Carbon Derived From Different Precursors for Sodium Storage

Due to the almost unlimited resource and acceptable performance, Sodium-ion batteries (SIBs) have been regarded as a promising alternative for lithium-ion batteries (LIBs) for grid-scale energy storage. As the key material of SIBs, hard carbon (HC) plays a decisive role in determining the batteries' performance. Nevertheless, the micro-structure of HCs is quite complex and the random organization of turbostratically stacked graphene layers, closed pores, and defects make the structure-performance relationship insufficiently revealed. On the other hand, the impending large-scale deployment of SIBs leads to producing HCs with low-cost and abundant precursors actively pursued. In this work, the recent progress of preparing HCs from different precursors including biomass, polymers, and fossil fuels is summarized with close attention to the influences of precursors on the structural evolution of HCs. After a brief introduction of the structural features of HCs, the recent understanding of the structure-performance relationship of HCs for sodium storage is summarized. Then, the main focus is concentrated on the progress of producing HCs from distinct precursors. After that, the pros and cons of HCs derived from different precursors are comprehensively compared to conclude the selection rules of precursors. Finally, the further directions of HCs are deeply discussed to end this review.

Hard carbon for sodium-ion batteries: progress, strategies and future perspective

Because of its abundant resources, low cost and high reversible specific capacity, hard carbon (HC) is considered as the most likely commercial anode material for sodium-ion batteries (SIBs). Therefore, reasonable design and effective strategies to regulate the structure of HCs play a crucial role in promoting the development of SIBs. Herein, the progress in the preparation approaches for HC anode materials is systematically overviewed, with a special focus on the comparison between traditional fabrication methods and advanced strategies emerged in recent years in terms of their influence on performance, including preparation efficiency, initial coulombic efficiency (ICE), specific capacity and rate capability. Furthermore, the advanced strategies are categorized into two groups: those exhibiting potential for large-scale production to replace traditional methods and those presenting guidelines for achieving high-performance HC anodes from top-level design. Finally, challenges and future development prospects to achieve high-performance HC anodes are also proposed. We believe that this review will provide beneficial guidance to actualize the truly rational design of advanced HC anodes, facilitating the industrialization of SIBs and assisting in formulating design rules for developing high-end advanced electrode materials for energy storage devices.

Ultrathin Two-dimensional Layered Composite Carbosilicates from in situ Unzipped Carbon Nanotubes and Exfoliated Bulk Silica

A key task in today's inorganic synthetic chemistry is to develop effective reactions, routes, and associated techniques aiming to create new functional materials with specifically desired multilevel structures and properties. Herein, we report an ultrathin two-dimensional layered composite of graphene ribbon and silicate via a simple and scalable one-pot reaction, which leads to the creation of a novel carbon-metal-silicate hybrid family: carbosilicate. The graphene ribbon is in situ formed by unzipping carbon nanotubes, while the ultrathin silicate is in situ obtained from bulk silica or commercial glass; transition metals (Fe or Ni) oxidized by water act as bridging agent, covalently bonding the two structures. The unprecedented structure combines the superior properties of the silicate and the nanocarbon, which triggers some specific novel properties. All processes during synthesis are complementary to each other. The associated synergistic chemistry could stimulate the discovery of a large class of more interesting, functionalized structures and materials.

Mesoporous carbon spheres with programmable interiors as efficient nanoreactors for H2O2 electrosynthesis

The nanoreactor holds great promise as it emulates the natural processes of living organisms to facilitate chemical reactions, offering immense potential in catalytic energy conversion owing to its unique structural functionality. Here, we propose the utilization of precisely engineered carbon spheres as building blocks, integrating micromechanics and controllable synthesis to explore their catalytic functionalities in two-electron oxygen reduction reactions. After conducting rigorous experiments and simulations, we present compelling evidence for the enhanced mass transfer and microenvironment modulation effects offered by these mesoporous hollow carbon spheres, particularly when possessing a suitably sized hollow architecture. Impressively, the pivotal achievement lies in the successful screening of a potent, selective, and durable two-electron oxygen reduction reaction catalyst for the direct synthesis of medical-grade hydrogen peroxide disinfectant. Serving as an exemplary demonstration of nanoreactor engineering in catalyst screening, this work highlights the immense potential of various well-designed carbon-based nanoreactors in extensive applications.

Directional manipulation of electron transfer in copper/nitrogen doped carbon by Schottky barrier for efficient anodic hydrazine oxidation and cathodic oxygen reduction

Development of bifunctional hydrazine oxidation and oxygen reduction electrocatalysts with high activity and stability is of great significance for the implementation of direct hydrazine fuel cells. Combining zero-dimensional metal nanoparticles with three-dimensional nitrogen-doped carbon nanosheets is an attractive strategy for balancing performance and cost. However, the precise construction of these composites remains a significant challenge, and thorough study of their interaction mechanisms is lacking. Herein, the CuNPs/CuSA-NPCF catalyst was constructed by anchoring copper nanoparticles on a three-dimensional nitrogen-doped porous carbon nanosheet framework through coordination of polyvinyl pyrrolidone and copper ions. The Schottky barrier of metal-semiconductor matched the Fermi level of the rectifying contact, thus enabling directional electron transfer. The resulting electron-deficient Cu nanoparticles surface exhibited Lewis acidity, which was beneficial to adsorption of hydrazine molecule. While the electron-enriched Cu-N4/carbon surface improved the adsorption of oxygen molecule, and accelerated electron supply from Cu-N4 active sites to various oxygen intermediates. The CuNPs/CuSA-NPCF Mott-Schottky catalyst exhibited excellent catalytic activity for hydrazine oxidation reaction and oxygen reduction reaction in an alkaline media. The directional manipulation of electron transfer in heterogeneous materials was an attractive universal synthesis method, providing new approach for the preparation of efficient and stable hydrazine fuel cell catalysts.

High-entropy oxychloride increasing the stability of Li-sulfur batteries

A novel lithiated high-entropy oxychloride Li0.5(Zn0.25Mg0.25Co0.25Cu0.25)0.5Fe2O3.5Cl0.5 (LiHEOFeCl) with spinel structure belonging to the cubic Fd3̄m space group is synthesized by a mechanochemical-thermal route. Cyclic voltammetry measurement of the pristine LiHEOFeCl sample confirms its excellent electrochemical stability and the initial charge capacity of 648 mA h g-1. The reduction of LiHEOFeCl starts at ca. 1.5 V vs. Li+/Li, which is outside the electrochemical window of the Li-S batteries (1.7/2.9 V). The addition of the LiHEOFeCl material to the composite of carbon with sulfur results in improved long-term electrochemical cycling stability and increased charge capacity of this cathode material in Li-S batteries. The carbon/LiHEOFeCl/sulfur cathode provides a charge capacity of 530 mA h g-1 after 100 galvanostatic cycles, which represents ca. 33% increase as compared to the charge capacity of the blank carbon/sulfur composite cathode after 100 cycles. This considerable effect of the LiHEOFeCl material is assigned to its excellent structural and electrochemical stability within the potential window of 1.7 V/2.9 V vs. Li+/Li. In this potential region, our LiHEOFeCl has no inherent electrochemical activity. Hence, it acts solely as an electrocatalyst accelerating the redox reactions of polysulfides. This can be beneficial for the performance of Li-S batteries, as evidenced by reference experiments with TiO2 (P90).

Characterization of solid and liquid carbonization products of polyvinyl chloride (PVC) and investigation of the PVC-derived adsorbent for the removal of organic compounds from water

The transformation of plastic wastes into value-added carbon materials is a promising strategy for the recycling of plastics. Commonly used polyvinyl chloride (PVC) plastics are converted into microporous carbonaceous materials using KOH as an activator via simultaneous carbonization and activation for the first time. The optimized spongy microporous carbon material has a surface area of 2093 m² g^-1 and a total pore volume of 1.12 cm³ g^-1, and aliphatic hydrocarbons and alcohols are yielded as the carbonization by-products. The PVC-derived carbon materials exhibit outstanding adsorption performance for removing tetracycline from water, and the maximum adsorption capacity reaches 1480 mg g^-1. The kinetic and isotherm patterns for tetracycline adsorption follow the pseudo-second-order and Freundlich models, respectively. Adsorption mechanism investigation indicates that pore filling and hydrogen bond interaction are mainly responsible for the adsorption. This study provides a facile and environmentally friendly approach for valorizing PVC into adsorbents for wastewater treatment.

Direct Observation of the Anisotropic Transport Behavior of Li+ in Graphite Anodes and Thermal Runaway Induced by the Interlayer Polarization

Graphite is one of the major anode materials for commercial lithium-ion batteries. Li+ transport in a single graphite granule along intra and interlayer modes is a crucial factor for the battery performance. However, direct evidence and visualized details of the Li+ transports are hardly provided. Here, we report the direct observation of the anisotropic transport behavior of Li+ and investigate the electro-chemo-structure evolution during the lithiation of graphite through both the intra and interlayer pathways via in situ transmission electron microscopy. The in situ experiments of nano batteries give two extreme conditions, in which thermal runaway induced by polarization only occurs along the interlayer, not along the intralayer. The high diffusion energy barrier induced large polarization when the interlayer Li+ transport became dominant. The energy of the polarization electric field would be instantaneously released like a short electric pulse, which generated a substantial amount of joule heat and created an extremely high temperature, causing the melting of the tungsten tip. We provide another possible fundamental mechanism of thermal failure in graphite-based Li-ion batteries and hope this insightful work would help the safety management of graphite-based lithium-ion batteries.

Functionalized Regulation of Metal Defects in ln2S3 of p-n Homojunctions

The introduction of metal vacancies into n-type semiconductors could efficiently construct intimate contact interface p-n homojunctions to accelerate the separation of photogenerated carriers. In this work, a cationic surfactant occupancy method was developed to synthesize an indium-vacancy (V_In)-enriched p-n amorphous/crystal homojunction of indium sulfide (A/C-IS) for sodium lignosulfonate (SL) degradation. The amount of V_In in the A/C-IS could be regulated by varying the content of added cetyltrimethylammonium bromide (CTAB). Meanwhile, the steric hindrance of CTAB produced mesopores and macropores, providing transfer channels for SL. The degradation rates of A/C-IS to SL were 8.3 and 20.9 times higher than those of crystalline In₂S₃ and commercial photocatalyst (P25), respectively. The presence of unsaturated dangling bonds formed by V_In reduced the formation energy of superoxide radicals (^•O₂^-). In addition, the inner electric field between the intimate contact interface p-n A/C-IS promoted the migration of electron-hole pairs. A reasonable degradation pathway of SL by A/C-IS was proposed based on the above mechanism. Moreover, the proposed method could also be applicable for the preparation of p-n homojunctions with metal vacancies from other sulfides.

Topologically Porous Heterostructures for Photo/Photothermal Catalysis of Clean Energy Conversion

As a straightforward way to fix solar energy, photo/photothermal catalysis with semiconductor provides a promising way to settle the energy shortage and environmental crisis in many fields, especially in clean energy conversion. Topologically porous heterostructures (TPHs), featured with well-defined pores and mainly composed by the derivatives of some precursors with specific morphology, are a major part of hierarchical materials in photo/photothermal catalysis and provide a versatile platform to construct efficient photocatalysts for their enhanced light absorption, accelerated charges transfer, improved stability, and promoted mass transportation. Therefore, a comprehensive and timely review on the advantages and recent applications of the TPHs is of great importance to forecast the potential applications and research trend in the future. This review initially demonstrates the advantages of TPHs in photo/photothermal catalysis. Then the universal classifications and design strategies of TPHs are emphasized. Besides, the applications and mechanisms of photo/photothermal catalysis in hydrogen evolution from water splitting and CO_x hydrogenation over TPHs are carefully reviewed and highlighted. Finally, the challenges and perspectives of TPHs in photo/photothermal catalysis are also critically discussed.

Waste Adsorbent-Derived Interconnected Hierarchical Attapulgite@Carbon/NiCo Layered Double Hydroxide Nanocomposites for Advanced Supercapacitors

The attapulgite@carbon/NiCo layered double hydroxide nanocomposites based on waste adsorbents are manufactured via simple and eco-friendly calcination and hydrothermal methods, by which they would be considerable electrode materials for advanced supercapacitors. To achieve sustainable development, the spent tetracycline-loaded attapulgite can act as a cost-effective available carbon source as well as a matrix material for carbon species and NiCo layered double hydroxide simultaneously. A controlled amount of attapulgite@carbon could be used to regulate the electrochemical properties of nanocomposites. The generated electrodes possess superior electrochemical properties with a specific capacitance of 2013.8 F g^-1 at 0.5 A g^-1, a retention rate of 87.7% at 5 A g^-1, and a cyclic stability of 64.9% for 4000 cycles at 5 A g^-1. Thus, the asymmetric supercapacitor device assembled with attapulgite@carbon/NiCo layered double hydroxide nanocomposites||active carbon shows a maximum capacitance of 231.3 F g^-1 at 0.5 A g^-1, with a preeminent energy density of 82.2 Wh kg^-1 when its power density is 4318 W kg^-1. This approach would contribute to the development of supercapacitors in an efficient and effective manner, as well as provide a feasible strategy for solving tetracycline pollution and recycling waste adsorbents to achieve sustainable development.