Graphitic Carbon Nitride (g‐C3N4)‐Derived N‐Rich Graphene with Tuneable Interlayer Distance as a High‐Rate Anode for Sodium‐Ion Batteries

Heteroatom‐doped carbon materials with expanded interlayer distance have been widely studied as anodes for sodium‐ion batteries (SIBs). However, it remains unexplored to further enlarge the interlayer spacing and reveal the influence of heteroatom doping on carbon nanostructures for developing more efficient SIB anode materials. Here, a series of N‐rich few‐layer graphene (N‐FLG) with tuneable interlayer distance ranging from 0.45 to 0.51 nm is successfully synthesized by annealing graphitic carbon nitride (g‐C₃N₄) under zinc catalysis and selected temperature (T = 700, 800, and 900 °C). More significantly, the correlation between N dopants and interlayer distance of resultant N‐FLG‐T highlights the effect of pyrrolic N on the enlargement of graphene interlayer spacing, due to its stronger electrostatic repulsion. As a consequence, N‐FLG‐800 achieves the optimal properties in terms of interlayer spacing, nitrogen configuration and electronic conductivity. When used as an anode for SIBs, N‐FLG‐800 shows remarkable Na⁺ storage performance with ultrahigh rate capability (56.6 mAh g^?1 at 40 A g^?1) and excellent long‐term stability (211.3 mAh g^?1 at 0.5 A g^?1 after 2000 cycles), demonstrating the effectiveness of material design.     

Tri‐s‐triazine‐Based Crystalline Carbon Nitride Nanosheets for an Improved Hydrogen Evolution

Tri‐s‐triazine‐based crystalline carbon nitride nanosheets (CCNNSs) have been successfully extracted via a conventional and cost‐effective sonication–centrifugation process. These CCNNSs possess a highly defined and unambiguous structure with minimal thickness, large aspect ratios, homogeneous tri‐s‐triazine‐based units, and high crystallinity. These tri‐s‐triazine‐based CCNNSs show significantly enhanced photocatalytic hydrogen generation activity under visible light than g‐C₃N₄, poly (triazine imide)/Li⁺ Cl^–, and bulk tri‐s‐triazine‐based crystalline carbon nitrides. A highly apparent quantum efficiency of 8.57% at 420 nm for hydrogen production from aqueous methanol feedstock can be achieved from tri‐s‐triazine‐based CCNNSs, exceeding most of the reported carbon nitride nanosheets. Benefiting from the inherent structure of 2D crystals, the ultrathin tri‐s‐triazine‐based CCNNSs provide a broad range of application prospects in the fields of bioimaging, and energy storage and conversion.     

Polymeric Photocatalysts Based on Graphitic Carbon Nitride

Semiconductor‐based photocatalysis is considered to be an attractive way for solving the worldwide energy shortage and environmental pollution issues. Since the pioneering work in 2009 on graphitic carbon nitride (g‐C₃N₄) for visible‐light photocatalytic water splitting, g‐C₃N₄‐based photocatalysis has become a very hot research topic. This review summarizes the recent progress regarding the design and preparation of g‐C₃N₄‐based photocatalysts, including the fabrication and nanostructure design of pristine g‐C₃N₄, bandgap engineering through atomic‐level doping and molecular‐level modification, and the preparation of g‐C₃N₄‐based semiconductor composites. Also, the photo­catalytic applications of g‐C₃N₄‐based photocatalysts in the fields of water splitting, CO₂ reduction, pollutant degradation, organic syntheses, and bacterial disinfection are reviewed, with emphasis on photocatalysis promoted by carbon materials, non‐noble‐metal cocatalysts, and Z‐scheme heterojunctions. Finally, the concluding remarks are presented and some perspectives regarding the future development of g‐C₃N₄‐based photocatalysts are highlighted.     

Single‐Crystalline,Metallic TiC Nanowires for Highly Robust and Wide‐Temperature Electrochemical Energy Storage

Customized electrode materials with good temperature adaptability and high‐rate capability are critical to the development of wide‐temperature power sources. Herein, high‐quality TiC nanowires are uniformly grown on flexible carbon cloth as free‐standing electric‐double‐layer supercapacitor electrode. The TiC nanowires, 20–40 nm wide and 3–6 µm long, are single‐crystalline and highly conductive that is close to typical metal. Symmetric supercapacitors are constructed with ionic liquid electrolyte and TiC nanowires electrodes as wide‐temperature and long‐cycle stable power source. Ultrastable high‐rate cycling life of TiC nanowire arrays electrodes is demonstrated with capacitance retention of 96.8% at 60 °C (≈440 F g^?1), 99% at 25 °C (≈400 F g^?1), and 98% at ?25 °C (≈240 F g^?1) after 50 000 cycles at 10 A g^?1. Moreover, due to high electrical conductivity, the TiC nanowire arrays show ultrafast energy release with a fast response time constant of ≈0.7 ms. The results demonstrate the viability of metal carbide nanostructures as wide‐temperature, robust electrode materials for high‐rate and ultrastable supercapacitors.     

Oxidized Quasi‐Carbon Nitride Quantum Dots Inhibit Ice Growth

Antifreeze proteins (AFPs), a type of high‐efficiency but expensive and often unstable biological antifreeze, have stimulated substantial interest in the search for synthetic mimics. However, only a few reported AFP mimics display thermal hysteresis, and general criteria for the design of AFP mimics remain unknown. Herein, oxidized quasi‐carbon nitride quantum dots (OQCNs) are synthesized through an up‐scalable bottom‐up approach. They exhibit thermal‐hysteresis activity, an ice‐crystal shaping effect, and activity on ice‐recrystallization inhibition. In the cryopreservation of sheep red blood cells, OQCNs improve cell recovery to more than twice that obtained by using a commercial cryoprotectant (hydroxyethyl starch) without the addition of any organic solvents. It is shown experimentally that OQCNs preferably bind onto the ice‐crystal surface, which leads to the inhibition of ice‐crystal growth due to the Kelvin effect. Further analysis reveals that the match of the distance between two neighboring tertiary N atoms on OQCNs with the repeated spacing of O atoms along the c‐axis on the primary prism plane of ice lattice is critical for OQCNs to bind preferentially on ice crystals. Here, the application of graphitic carbon nitride derivatives for cryopreservation is reported for the first time.     

Carbon materials for chemical capacitive energy storage

Carbon materials have attracted intense interests as electrode materials for electrochemical capacitors, because of their high surface area, electrical conductivity, chemical stability and low cost. Activated carbons produced by different activation processes from various precursors are the most widely used electrodes. Recently, with the rapid growth of nanotechnology, nanostructured electrode materials, such as carbon nanotubes and template-synthesized porous carbons have been developed. Their unique electrical properties and well controlled pore sizes and structures facilitate fast ion and electron transportation. In order to further improve the power and energy densities of the capacitors, carbon-based composites combining electrical double layer capacitors (EDLC)-capacitance and pseudo-capacitance have been explored. They show not only enhanced capacitance, but as well good cyclability. In this review, recent progresses on carbon-based electrode materials are summarized, including activated carbons, carbon nanotubes, and template-synthesized porous carbons, in particular mesoporous carbons. Their advantages and disadvantages as electrochemical capacitors are discussed. At the end of this review, the future trends of electrochemical capacitors with high energy and power are proposed.     

废茶叶基活性炭的制备及其电化学性能研究

以废茶叶的炭化料为前驱体,KOH为活化剂(碱炭比1∶1、2∶1、3∶1),在800℃下活化1h制备双电层电容器用活性炭电极材料。利用扫描电镜、低温N2吸附对活性炭的形貌、孔结构进行表征,采用恒流充放电、循环伏安和交流阻抗等测试方法评价其在3mol/L KOH电解液中的电化学性能。结果表明,3种活性炭比表面积、总孔容和中孔率最高分别达1 900m2/g、0.919 4cm3/g和35.7%;3种活性炭电极材料在0.055 6 A/g电流密度下的比电容分别为202F/g、255F/g、194F/g,电流密度增加到2.780A/g时,电容保持率分别为84.2%、67.1%、86.6%;等效串联电阻仅为0.10~0.12Ω;在碱碳比为2∶1时制备的活性炭电极材料在2.363A/g下比电容为148F/g,经1 000次循环充放电后,其质量比电容为147.7F/g,电容保持率高达99.3%。     

Tailoring Thickness of Conformal Conducting Polymer Decorated Aligned Carbon Nanotube Electrodes for Energy Storage

Aligned Carbon nanotubes (A‐CNT) based electrodes have emerged as high‐performance elements in electric energy storage and conversion devices. Morphological tailoring of conformal coatings of poly(ethylenedioxythiophene) (PEDOT) conductive polymer (CP) on the A‐CNT scaffold is demonstrated by controlling CP thickness at the nm scale. Results show that the CP nano‐films dominate the electrode capacitance in a supercapacitor application, contributing as much as 10x (pseudo)capacitance over the electric double layer of pristine A‐CNT due to volumetric vs. surface charge storage. Comparison to theoretical ion mobilities shows that the conformal CP films have active sites at ∼30% doping, indicating the CP quality is similar to thin films on flat substrates and that all these sites are accessed at all CP thickness values (up to 10 nm PEDOT thickness) and do not limit the rate of ion transport in and out of the CP film volume. Supercapacitor electrodes fabricated from these novel morphology‐controlled nanostructured composites provide a new route towards high‐performance next generation energy storage devices.     

Nitrogen‐Doped Carbon Encapsulated Mesoporous Vanadium Nitride Nanowires as Self‐Supported Electrodes for Flexible All‐Solid‐State Supercapacitors

Flexible 3D nanoarchitectures have received tremendous interest recently because of their potential applications in flexible/wearable energy storage devices. Herein, 3D intertwined nitrogen‐doped carbon encapsulated mesoporous vanadium nitride nanowires (MVN@NC NWs) are investigated as thin, lightweight, and self‐supported electrodes for flexible supercapacitors (SCs). The MVN NWs have abundant active sites accessible to charge storage, and the N‐doped carbon shell suppresses electrochemical dissolution of the inner MVN NWs in an alkaline electrolyte, leading to excellent capacitive properties. The flexible MVN@NC NWs film electrode delivers a high areal capacitance of 282 mF cm⁻² and exhibits excellent long‐term stability with 91.8% capacitance retention after 12 000 cycles in a KOH electrolyte. All‐solid‐state flexible SCs assembled by sandwiching two flexible MVN@NC NWs film electrodes with alkaline poly(vinyl alcohol) (PVA), sodium polyacrylate, and KOH gel electrolyte boast a high volumetric capacitance of 10.9 F cm⁻³, an energy density of 0.97 mWh cm⁻³, and a power density of 2.72 W cm⁻³ at a current density of 0.051 A cm⁻³ based on the entire cell. By virtue of the excellent mechanical flexibility, high capacitance, and large energy/power density, the self‐supported MVN@NC NWs paper‐like electrodes have large potential applications in portable and wearable flexible electronics.     

Cobalt‐Doped Nickel Phosphite for High Performance of Electrochemical Energy Storage

Compared to single metallic Ni or Co phosphides, bimetallic Ni–Co phosphides own ameliorative properties, such as high electrical conductivity, remarkable rate capability, upper specific capacity, and excellent cycle performance. Here, a simple one‐step solvothermal process is proposed for the synthesis of bouquet‐like cobalt‐doped nickel phosphite (Ni₁₁(HPO₃)₈(OH)₆), and the effect of the structure on the pseudocapacitive performance is investigated via a series of electrochemical measurements. It is found that when the cobalt content is low, the glycol/deionized water ratio is 1, and the reaction is under 200 °C for 20 h, the morphology of the sample is uniform and has the highest specific surface area. The cobalt‐doped Ni₁₁(HPO₃)₈(OH)₆ electrode presents a maximum specific capacitance of 714.8 F g^?1. More significantly, aqueous and solid‐state flexible electrochemical energy storage devices are successfully assembled. The aqueous device shows a high energy density of 15.48 mWh cm^?2 at the power density of 0.6 KW cm^?2. The solid‐state device shows a high energy density of 14.72 mWh cm^?2 at the power density of 0.6 KW cm^?2. These excellent performances confirm that the cobalt‐doped Ni₁₁(HPO₃)₈(OH)₆ are promising materials for applications in electrochemical energy storage devices.     

碳／陶复合导电陶瓷的研究

本文提出了复合式导电陶瓷的概念，并实际制备了ＳｉＯ２－Ａｌ２Ｏ３－Ｃ系列的碳／陶复全导电陶瓷，通过ＸＲＤ，ＳＥＭ，电阻率测定等实验研究了材料工艺，结构，性能之间的相互关系，着重研究了导电功能成功石墨的加入对材料烧吉和导电性能的影响，指出了石墨颗粒在材料基体内容的结构方式以及石墨的加入影响导电的规律，讨论了材料烧结和导电机理，并提出了普通复合式导电陶瓷的接触导电机理，材料性能优良，有良好的应用前景，     

Synergy of Dopants and Defects in Graphitic Carbon Nitride with Exceptionally Modulated Band Structures for Efficient Photocatalytic Oxygen Evolution

Electronic structure greatly determines the band structures and the charge carrier transport properties of semiconducting photocatalysts and consequently their photocatalytic activities. Here, by simply calcining the mixture of graphitic carbon nitride (g‐C₃N₄) and sodium borohydride in an inert atmosphere, boron dopants and nitrogen defects are simultaneously introduced into g‐C₃N₄. The resultant boron‐doped and nitrogen‐deficient g‐C₃N₄ exhibits excellent activity for photocatalytic oxygen evolution, with highest oxygen evolution rate reaching 561.2 µmol h^?1 g^?1, much higher than previously reported g‐C₃N₄. It is well evidenced that with conduction and valence band positions substantially and continuously tuned by the simultaneous introduction of boron dopants and nitrogen defects into g‐C₃N₄, the band structures are exceptionally modulated for both effective optical absorption in visible light and much increased driving force for water oxidation. Moreover, the engineered electronic structure creates abundant unsaturated sites and induces strong interlayer C–N interaction, leading to efficient electron excitation and accelerated charge transport. In the present work, a facile approach is successfully demonstrated to engineer the electronic structures and the band structures of g‐C₃N₄ with simultaneous introduction of dopants and defects for high‐performance photocatalytic oxygen evolution, which can provide informative principles for the design of efficient photocatalysis systems for solar energy conversion.     

a-C:N膜的制备及结构分析

采用射频溅射法在锗衬底上沉积无定形碳氮膜 (a- C:N) ,用 X射线光电子谱 (XPS)、傅立叶变换红外光谱 (FT- IR)和喇曼光谱 (RS)分析了膜的成分与结构。结果表明 ,氮是以化学键的形式存在于膜中 ,且有三种不同的 C- N键合状态。随着反应气体中氮气分压的增加 ,a- C:N膜中氮浓度增加 ,C≡N键的含量增加。     

Nitrogen-doped Carbon Nanospheres-Modified Graphitic Carbon Nitride with Outstanding Photocatalytic Activity

Metals and metal oxides are widely used as photo/electro-catalysts for environmental remediation.However,there are many issues related to these metal-based catalysts for practical applications,such as high cost and detrimental environmental impact due to metal leaching.Carbon-based catalysts have the potential to overcome these limitations.In this study,monodisperse nitrogen-doped carbon nanospheres(NCs)were synthesized and loaded onto graphitic carbon nitride(g-C3N4,GCN)via a facile hydrothermal method for photocatalytic removal of sulfachloropyridazine(SCP).The prepared metal-free GCN-NC exhibited remarkably enhanced efficiency in SCP degradation.The nitrogen content in NC critically influences the physicochemical properties and performances of the resultant hybrids.The optimum nitrogen doping concentration was identified at 6.0 wt%.The SCP removal rates can be improved by a factor of 4.7 and 3.2,under UV and visible lights,by the GCN-NC composite due to the enhanced charge mobility and visible light harvesting.The mechanism of the improved photocatalytic performance and band structure alternation were further investigated by density functional theory(DFT)calculations.The DFT results confirm the high capability of the GCN-NC hybrids to activate the electron–hole pairs by reducing the band gap energy and efficiently separating electron/hole pairs.Superoxide and hydroxyl radicals are subsequently produced,leading to the efficient SCP removal.     

碳纤维导电复合材料的电学性能研究

研究了FR－4溴化环氧树脂玻璃布和碳纤维导电纸层压复合面状发热板的电学性能,结果表明：溴化环氧树脂固化过程对其电性能产生影响,对于不同规格的导电纸,其电阻下降率不同。面状发热板的电阻在升温和降温过程中存在不同程度的偏离,呈现PTC或NTC效应,数次热循环后,可以使室温电阻保持恒定。发热板的电阻随通电时间的延长而逐渐下降并趋于稳定,通断电次数对基电阻影响不大,在长期通电使用下能保持其功能稳定性,发热板的功率密度与表面温度呈现良好的线性关系。