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An ultrasensitive enzyme-free glucose sensor was facilely prepared by electrodepositing three-dimensional dendritic Cu on a room temperature exfoliated graphite-derived film (RTEG-F). An excellent electrocatalytic performance was demonstrated for glucose by using Cu/RTEG-F as an electrode. In terms of the high conductivity of RTEG-F and the good catalytic activity of the dendritic Cu structures, the sensor demonstrates high sensitivities of 23.237 mA/mM/cm2, R2 = 0.990, and 10.098 mA/mM/cm2, R2 = 0.999, corresponding to the concentration of glucose ranging from 0.025 mM to 1.0 mM and 1.0 mM to 2.7 mM, respectively, and the detection limit is 0.68 μM. In addition, the Cu/RTEG-F electrode demonstrates excellent anti-interference to interfering species and a high stability. Our work provides a new idea for the preparation of high-performance electrochemical enzyme-free glucose sensor.

Exfoliated graphite (EG) blocks are prepared from the ultra-large flakes of graphite by intercalation of H2SO4 using a large amount of H2O2 at 5 °C and following exfoliation at 30 °C. By the exfoliation in a closed container, EG blocks with the bulk densities of 0.008~0.024 g/cm3 are successfully prepared. The resultant EG blocks have high sorption capacities for a diesel oil, up to 45 g/g. The EG blocks after oil sorption can get certain resilience for compressive stress with high reproducibility by compression-release cycles, which allows us to apply the compression-releasing for the oil sorption-desorption of the EG blocks. The performance of cyclic oil sorption-desorption by compression-releasing of EG block is compared with those of filtration and distillation. Since the resultant EG blocks had sufficient mechanical strength, the continuous removal of oil floating on the water surface is possible, exporting oil through a catheter inserted into the block and connected to a peristaltic pump. By warming up by Joule heating, even a crude oil having high viscosity can be continuously removed from the water with sufficient rate. The high hydrophobicity and lipophilicity of EG make selective removal of oil from water possible.

Ultrafine hierarchically porous carbon fibers (HPCFs) were produced by electrospinning from phenolic resin and Fe(acetylacetonate)3, carbonization under an NH3 atmosphere and HCl/water leaching to remove the Fe species. Their adsorption performance for ethanol and acetone and their pore structure were compared with fibers produced from polyacrylonitrile (PAN) and Fe(acetylacetonate)3 (HPCFs(PAN)), and phenolic resin without the Fe(acetylacetonate)3 addition (PCFs). Results indicate that HPCFs and HPCFs(PAN) are hierarchically porous with abundant micropores and mesopores while PCFs are dominantly microporous. The addition of Fe(acetylacetonate)3 promotes graphitization. The hierarchical pore structure increases the uptake of both ethanol and acetone vapors at high pressures by multilayer adsorption while the microporous structure contributes to the uptake at low pressures by monolayer adsorption. The highest ethanol and acetone adsorption uptakes were found for the HPCFs, and are 7.55 and 12.56 mmol g−1 at 25 °C, respectively. Superiority of phenolic resin to PAN as the carbon precursor is demonstrated. The freestanding characteristic of the ultrafine carbon fibers as a result of their electrospining is advantageous as an adsorbent for the removal of volatile organic compounds.

Ti3C2Tx MXene has drawn considerable attention as anode materials to store sodium ions because of the capability of accommodating the large sodium ions, enabling their intercalation without substantial structural change. However, the limited sodium-ion storage capacity of Ti3C2Tx hinders its real application in sodium-ion batteries (SIBs). To enhance its performance as anode materials in SIBs, here, we introduce nanopores into Ti3C2Tx sheets by sonication, and after which we assemble them with rGO and cellulose nanofibers into an elastic freestanding composite structure by mimicking the wasp nest. The wasp nest-like structure endows the resulting composite with more accessible surfaces of electrode materials to the electrolyte. Further, the nanopores on the Ti3C2Tx sheets and the TiO2 formed from the sonication provide more active sites for sodium storage. As a result, the resulting composite shows a high capacity of 280 mAh g−1 at 100 mA g−1 and remarkable cyclic life with a capacity retention of 84.8% after 1000 cycles at 1 A g−1.

Vanadium trioxide material have attracted enormous attention recently, owing to their high theoretical capacity for use as anodes in lithium ion batteries. However, the unstable structure of V2O3 limits its practical application. It is challenge to develop a simple, scalable and economical technique to produce 3D porous carbon-based V2O3 materials with high structure stability. In this work, a facile NaCl template-assisted freeze-drying strategy was used to produce 3D porous carbon-encapsulated V2O3 (3D porous V2O3@C) composites with highly crystalline architecture, uniformly carbon-encapsulated V2O3 nanoparticles and interconnected conductive carbon networks. The resultant 3D porous V2O3@C anode exhibits significantly enhanced rate performance (797 mAh/g at 0.1 A/g, 715 mAh/g at 0.3 A/g, 658 mAh/g at 0.5 A/g, 598 mAh/g at 1 A/g, 480 mAh/g at 3 A/g and 426 mAh/g at 5 A/g) and long-term cycling stability (506 mAh/g at 5A/g after 2000 cycles). The present work suggests a scalable preparation of the 3D porous carbon-based V2O3 materials, which may be extended to preparing other 3D porous materials for potential applications in energy storage, catalysis and sensors.

Historical architecture is of great significance to the continuation of urban historical context, and it is an important part of cultural heritage. The general survey and identification of historical buildings is the basis and support of the protection and utilization of historical buildings. However, the existing working methods and technical means are relatively backward, it can not reflect and record the value characteristics and basic information of historical buildings truly and completely. These backward means have led to the inefficiency of the general survey and identification of historical buildings, which has also led to the fact that the results of the general survey can not be digitized and difficult to refer to. This paper analyzes the problems existing in the traditional methods of general survey and identification of historical buildings, and constructs the basic technical support of the general survey and identification of historical buildings from the aspects of general survey and identification standard system, investigation and data processing tool system, operation guidance system and so on, which is based on the technical requirements and the secondary development of GIS, taking the general survey and identification of historical buildings in Beijing as an example. It is hoped that this paper can convey our thinking and research results to our professional colleagues. In addition, we look forward to the promotion and application of this method, so as to promote the protection and management of cultural heritage towards comprehensive data.

Historic cities, especially inhabited historic cities, are a special type of cultural heritage. Because of the expanding intension and extension of urban heritage, the rapid urbanization and the various stakeholders, the historic cities become much more complex nowadays. The need of GIS-based information systems for historic cities has never been greater. This paper introduces the research on the framework of the Smart Conservation Management System for the Historic City Fuzhou. It is an effort to explore an informatization way for historic cities. The needs of urban heritage itself, and the needs of different stakeholders should be respected. This system follows the principle of authenticity and integrity conservation, the coordination of conservation and sustainable development, the consideration of stakeholders, ease of use, extensibility, and security. The database should be fit for the construction of knowledge warehouse, be easy to collect and renew information. The module should be able to apply easily in everyday use situations, support smart decision making for the users. It is hoped that the research and the system will be referential for other historic cities.

Sulfur cathodes in lithium-sulfur batteries (LSBs) have received a boost in electrochemical performance through developing various sulfur hosts. However, it remains great challenges in achieving fast electron and ion conduction while accommodating the dramatic volume change and suppressing severe intermediate polysulfide dissolution under practically necessary ‘3H’ conditions (high areal sulfur loading, high electrode compactness and high sulfur content). Here a compact 3D interconnected sulfur cathode is reported to satisfy the above requirements. It is constructed by self-assembly of Zn,Co-bimetallic ZIF nanoparticles, following pyrolysis and subsequent melt-diffusion of high-content sulfur. Sulfur filled into an open porous 3D carbon network (3DCN) with abundant N, Co doping and graphitic carbon species and produced a thin sulfur-coating layer on the macroporous surface of 3DCN. Such smart architecture provides multidimensional electron and ion transport pathways and shortened mass and ion diffusion length. The close contact of sulfur species with carbon-based polar host provides facilitated physiochemical adsorption and conversion reaction of polysulfides. At high areal sulfur loading of 10.9 mg cm-2, high sulfur content of 74 wt% in the whole cathode and low electrolyte/sulfur ratio of 6 µL/mg, it delivers high gravimetric/volumetric/areal capacities of 945 mA h g-1/867 mA h cm-3/10.3 mA h cm-2 at 0.1 C (1.83 mA cm-2). At a high rate of 0.5 C (9.13 mA cm-2), it still presents a high capacity of 8.73 mA h cm-2 and maintains 6.35 mA h cm-2 after 200 cycles. Therefore this work provides an instructive paradigm of rational architecture design to fabricate sulfur cathodes for practically viable Li-S batteries.

Herein, hierarchical porous carbon derived from polyethylene waste (plastic bags etc.) has been synthesized by ball-milling and carbonization with a flame-retardant agent, basic magnesium carbonate pentahydrate (MCHP:4MgCO3·Mg(OH)2·5H2O). The presence of MCHP not only provides in-situ MgO template during pyrolysis, but also greatly enhances the thermal stability of polyethylene for carbonization. After subsequent NH3 activation, the polyethylene waste derived carbon (PE-HPC-900NH3) shows a high surface area and a unique property of meso-porosity, which contribute to the excellent capacitive performance. Remarkably, the obtained PE-HPC-900NH3 electrode displays a relatively high specific capacitance with excellent cycling stability (about 97.1% of capacitance retention after 10,000 cycles at 2 A g−1). A high energy density of 43 Wh kg−1 can be achieved for the PE-HPC-900NH3 symmetrical supercapacitor at an extremely wide voltage of 4 V in EMIMBF4 due to the high purity and low ratio of O/N. This work provides a promising approach to disposal of waste plastics and opens new applications in various energy fields.

Fiber supercapacitor (FSC) is a promising power source for wearable/stretchable electronics and high capacitive performance of FSCs is highly desirable for practice flexible applications. Here, we report a composite of manganese dioxide (MnO2) and activated carbon fibers (ACFs) with high MnO2 mass loading and microporous structure (abbreviated as MnO2@ACF), which is used as a fiber electrode to produce a FSC with a high capacitive performance and a good flexibility. The MnO2@ACF composite electrode in FSCs delivers an ultrahigh specific capacitance of 410 mF/cm2 at 0.1 mA/cm2, corresponding to a high energy density of 36 µWh/cm2 and high power density of 726 µW/cm2. Such high capacitive performance and simple fabrication method indicates that the MnO2@ACF composite is a very promising electrode material for flexible fiber supercapacitors.

A graphite ore with ultra-large flakes (ULFG) found in China (Wulate County, Inner Mongolia Autonomous Region, China), was first jaw-crushed and pneumatically separated to remove rocks, before being subjected to two froth-flotations and finally leached with NaOH and HCl to a purity of 99.9%. The purified ULFG was used to prepare exfoliated graphite by a combined chemical intercalation and rapid heating method and the latter was rolled into flexible graphite sheets of different densities. Results show that the beneficiation and purification methods preserve the graphite crystallites. The purified ULFG has a high degree of graphitization (99.9%). The volume of the ULFG-based exfoliated graphite is more than 400 mL/g, and some randomly selected individual exfoliated graphite particles are larger than 40 mm. A ULFG-based flexible graphite sheet with a density of 1.8 g/cm3 shows an excellent electrical conductivity of 2.78×105 S/m.

As rarely large flake graphite (9 mesh) was recently exploited in China, it was innovatively developed as the raw material to prepare a novel wound dressing based on large expanded graphite (EG) in this work. The EG worms were prepared in an easy oxidative intercalation and thermal expansion method. Afterward, chitosan was grafted onto the surface of EG by chemical modification, forming CS-EG worms. CS-EG sponge dressings were then obtained by pressing a number of CS-EG worms together by external force. Due to the porous structure and large specific surface area, the produced CS-EG sponges exhibited outstanding adsorption capacity for wound exudate. They could also promote blood coagulation by adsorbing the blood cells and proteins quickly and effectively, showing excellent hemostatic performance. The eminent performances and the simple preparation process ensure the great application potential of CS-EG as a dressing material. This is also the first time to report the application of the traditional carbon material, EG, to act as a dressing material after chemical modification.

Flexible and rechargeable Zn–air batteries, because of their high energy density, low cost, and environmental and human benignity, are one kind of the most attractive energy systems for future wear...

It is of vital importance to construct highly interconnected, macroporous photocatalyst to improve its efficiency and applicability in solar energy conversion and environment remediation. Graphitic-like C3N4 (g-C3N4), as an analogy to two-dimensional (2D) graphene, is highly identified as a visible-light-responsive polymeric semiconductor. Moreover, the feasibility of g-C3N4 in making porous structures has been well established. However, the preparation of macroporous g-C3N4 with abundant porous networks and exposure surface, still constitutes a difficulty. To solve it, we report a first facile preparation of bimodal macroporous g-C3N4 hybrids with abundant in-plane holes, which is simply enabled by in-situ modification through thermally treating the mixture of thiourea and SnCl4 (pore modifier) after rotary evaporation. For one hand, the formed in-plane macropores endow the g-C3N4 system with plentiful active sites and short, cross-plane diffusion channels that can greatly speed up mass transport and transfer. For another, the heterojunctions founded between g-C3N4 and SnO2 consolidate the electron transfer reaction to greatly reduce the recombination probability. As a consequence, the resulted macroporous g-C3N4/SnO2 nanohybrid had a high specific surface area (SSA) of 44.3 m2/g that was quite comparable to most nano/mesoporous g-C3N4 reported. The interconnected porous network also rendered a highly intensified light absorption by strengthening the light penetration. Together with the improved mass transport and electron transfer, the macroporous g-C3N4/SnO2 hybrid exhibited about 2.4-fold increment in the photoactivity compared with pure g-C3N4. Additionally, the recyclability of such hybrid could be guaranteed after eight successive uses.

Lithium ion capacitors (LICs), bridging the advantages of batteries and electrochemical capacitors, are regarded as one of the most promising energy storage devices. Nevertheless, it is always limited by the anodes that accompany with low capacity and poor rate performance. Here, we develop a versatile and scalable method including ball-milling and pyrolysis to synthesize exfoliated MoS2 supported by N-doped carbon matrix derived from chitosan, which is encapsulated by pitch-derived carbon shells (MoS2/CP). Because the carbon matrix with high nitrogen content can improve the electron conductivity, the robust carbon shells can suppress the volume expansion during cycles, and the sufficient exfoliation of lamellar MoS2 can reduce the ions transfer paths, the MoS2/CP electrode delivers high specific capacity (530 mA h g−1 at 100 mA g−1), remarkable rate capability (230 mA h g−1 at 10 A g−1) and superior cycle performance (73% retention after 250 cycles). Thereby, the LICs, composed of MoS2/CP as the anode and commercial activated carbon (21 KS) as the cathode, exhibit high power density of 35.81 kW kg−1 at 19.86 W h kg−1 and high energy density of 87.74 W h kg−1 at 0.253 kW kg−1.

Lithium-ion hybrid capacitors (LICs) are regarded as one of the most promising next generation energy storage devices. Commercial activated carbon materials with low cost and excellent cycling stability are widely used as cathode materials for LICs, however, their low energy density remains a significant challenge for the practical applications of LICs. Herein, Na0.76V6O15 nanobelts (NaVO) were prepared and combined with commercial activated carbon YP50D to form hybrid cathode materials. Credit to the synergism of its capacitive effect and diffusion-controlled faradaic effect, NaVO/C hybrid cathode displays both superior cyclability and enhanced capacity. LICs were assembled with the as-prepared NaVO/C hybrid cathode and artificial graphite anode which was pre-lithiated. Furthermore, 10-NaVO/C//AG LIC delivers a high energy density of 118.9 Wh kg&minus, 1 at a power density of 220.6 W kg&minus, 1 and retains 43.7 Wh kg&minus, 1 even at a high power density of 21,793.0 W kg&minus, 1. The LIC can also maintain long-term cycling stability with capacitance retention of approximately 70% after 5000 cycles at 1 A g&minus, 1. Accordingly, hybrid cathodes composed of commercial activated carbon and a small amount of high energy battery-type materials are expected to be a candidate for low-cost advanced LICs with both high energy density and power density.

Metal-organic framework (MOF)-derived nanoporous carbons (NPCs) and porous metal oxide nanostructures or nanocomposites have gathered considerable interest due to their potential use in supercapacitor (SCs) applications, owing to their precise control over porous architectures, pore volumes, and surface area. Bimetallic MOFs could provide rich redox reactions deriving from improved charge transfer between different metal ions, so their supercapacitor performance could be further greatly enhanced. In this study, "One-for-All" strategy is adopted to synthesize both positive and negative electrodes for hybrid asymmetric SCs (ASCs) from a single bimetallic MOF. The bimetallic Zn/Co-MOF with cuboid-like structures were synthesized by a simple method. The MOF-derived nanoporous carbons (NPC) were then obtained by post-heat treatment of the as-synthesized Zn/Co-MOF and rinsing with HCl, and bimetallic oxides (ZnCo2O4) were achieved by sintering the Zn/Co-MOF in air. The as-prepared MOF-derived NPC and bimetallic oxides were utilized as negative and positive materials to assemble hybrid ASCs with 6 M KOH as an electrolyte. Owing to the matchable voltage window and specific capacitance between the negative (NPC) and positive (ZnCo2O4), the as-assembled ASCs delivered high specific capacitance of 94.4 F/g (cell), excellent energy density of 28.6 Wh/kg at a power density of 100 W/kg, and high cycling stability of 87.2% after 5,000 charge-discharge cycles. This strategy is promising in producing high-energy-density electrode materials in supercapacitors.

Hierarchical porous hollow carbon nanospheres (HCNSs) were fabricated directly from raw biomass via a one-step method, in which HCNSs were obtained by thermal treatment of raw biomass in the presence of polytetrafluoroethylene (PTFE). The HCNSs possess coupling merits of uniformly distributed hollow spherical architectures, and high specific surface area, abundant accessible/open micropores and reasonable mesopores, the HCNS-based electrodes deliver high electrochemical capacitance. The formation mechanisms of pores and hollow core-shell structures were explored thoroughly, it is found that the key to the formation of hollow core-shell structure is the onset-pyrolysis temperature difference between raw biomass and PTFE. Moreover, the content of silica had significant effects on the textures of HCNSs, and HCNS with the largest SSA of 1984 m2/g was obtained. Accordingly, a possible mechanism of HCNSs formation was proposed here, where PTFE acted as the pore creation and nucleation agents and raw biomasses were the primary carbon precursors.

Aromatic polyimide (PI)-based graphite nanofibers were obtained from the graphitization of graphene oxide (GO)-doped electrospun PI nanofibers. GO improves the PI molecular orientation, crystalline structure and thermal conductivity of the resulting nanofibers. The degree of PI molecular orientation in the nanofibers is increased by the GO during fiber preparation. This improvement in molecular orientation produces an increase in the thermal conductivity of the graphite nanofibers, and the addition of only 0.1% GO has a significant effect. The GO not only affects the thermal conductivity, but improves the PI molecular orientation and its role as nucleation centers during graphitization. This approach and the resulting high thermal conductivity materials show great potential for practical applications.

A self-standing nitrogen/oxygen dual-doped carbon nanofiber matrix is prepared on the basis of polymer chain design and electrospinning followed by a one-step carbonization. The interlayer can subs...

Porous nitrogen and oxygen co-doped carbon microtubes (PCMTs) were prepared via carbonization followed by activation of plane tree fruit fluffs (PTFFs) and employed as high-performance supercapacitor electrode materials. The pore structures, surface chemistry and degree of graphitization of the final products can be facilely tailored by adjusting the activation temperature, which changed remarkably as the activation temperature increased from 650 to 900 °C. The PCMT-850 obtained by activating at 850 °C possessed despite the second largest specific surface area (1533 m2/g), but the highest mesopore ratio (9.13%), the maximal nitrogen content (2.20 at.%) and highest degree of graphitization as well as excellent electrical conductivity. The PCMT-850-based carbon electrode exhibited the highest charge storage capacity with a specific capacitance of 257.6 F/g at a current of 1 A/g and the lowest internal resistance in 6 M KOH. The high supercapacitor performance can be attributed to the combined effects of its pore structure, heteroatom doping effects and degree of crystallinity. The favorable capacitive performance render the waste biomass PTFFs serve as novel resources of nitrogen and oxygen co-doped carbon materials for high-performance supercapacitors.

A self-standing porous carbon nanofiber (PCNF) matrix with controllable shallow hierarchical mesoporous structure on ∼40 nm of the top layer and microporous network in the fiber bulk has been prepared by electrospinning technology coupled with Mg(NO3)2 treatment in a one-step carbonization without further treatment. By regulating the heating rate during carbonization, PCNF with high specific surface area of 1836 m2 g−1 have been obtained. Symmetric supercapacitor assembled with PCNF as electrodes in 1 mol L−1 LiPF6 organic electrolyte has a specific capacity of 140 F g−1 and an energy density of 30 Wh kg−1 at current density of 0.1 A g−1. And the lithium-ion capacitor (LIC) device can deliver a large energy density of 106 Wh kg−1 (at 242 W kg−1), a high power density of 30 kW kg−1 (at 53 Wh kg−1) and reasonably good cycling stability with capacity retention of 91% after 2000 cycles. In addition, the self-standing PCNF with high energy density and high power density presented in this work is highly desirable to apply to other electrochemical energy storage devices.

Hybrid supercapacitors (HSCs) are novel, promising devices having features of both batteries and supercapacitors. Herein, we report HSCs (Li-HSC and Na-HSC in a uniform system) based on an interlayer-expanded MoS2/rGO composite that show ultrahigh energy density and power density as well as superior cycle stability. The 3D network-structured interlayer-expanded MoS2/rGO nanocomposite (3D-IEMoS2@G) was synthesized and employed as the anode. Because the 3D architecture of the graphene skeleton frame delivered sufficient charges and the highly interlayer-expanded MoS2 achieved fast ion diffusion, the as-prepared composite exhibited excellent performance as the anode material for both LIBs and SIBs (1600 mAh g−1 at 100 mA g−1 for the LIB; 580 mAh g−1 at 100 mAh g−1 and 320 mAh g−1 at a high current density of 10 A g−1). When paired with nitrogen-doped hierarchically porous 3D graphene (N-3DG), the obtained Na-HSC surpassed Li-HSC in a uniform system, showing an excellent performance of 140 Wh kg−1 at 630 W kg−1, 43 Wh kg−1 at an ultrahigh power density of 103 kW kg−1 (charge finished within 1.5 s) and no distinct capacity attenuation after over 10000 cycles. Thus, a quantitative kinetic analysis was performed to understand the synergistic effect of the two electrodes and the resulting effect of ions in the hybrid supercapacitors and to further pave a general path for fabricating high-performance HSCs. An energy storage device that combines the advantages of batteries and capacitors has been developed by researchers in China. Batteries store energy electrochemically as charged ions, while supercapacitors store electrical charge electrostatically on a surface. This gives supercapacitors the advantage that they can be charged very quickly, and charged and discharged many times, but they can’t store as much energy as a battery of the same weight. Zheng-Hong Huang from Tsinghua University in Beijing and co-workers created a hybrid device that exhibited both ultra-high energy and power density along with excellent cycle stability. Their structure had an anode made from a composite of interlayer-expanded molybdenum disulfide and graphene oxide. The three-dimensional graphene skeleton supported the electrical charge, while the interlayer-expanded molybdenum disulfide enabled rapid diffusion of ions and provided sufficient energy storage sites. Sodium ion hybrid capacitors is fabricated by interlayer-expanded MoS2/rGO composite and it shows greater performance than lithium ion capacitor.

Electrochemical reduction of water is a renewable way to produce clean hydrogen energy. In order to overcome the high-cost and shortage of noble metals, transition metal compounds involving earth-abundant elements, such as MoS2 and WS2, have been proposed as novel catalysts for hydrogen evolution reaction (HER). Efforts have been made to increase the intrinsic catalytic activity of transition metal dichalcogenides (TMDCs), while alloying same- group elements has not been vastly investigated. Moreover, besides the catalytic activity, the design of free-standing catalytic electrodes is also critical for HER. In this work, we synthesize pyrolytic carbon film with MoxW1-xS2 nanoflakes embedded as a free-standing flexible electrodes for HER catalysis. The pyrolytic carbon acts as conductive and flexible matrix for TMDC alloys with controlled composition, resulting in remarkably enhanced HER activity. The highest HER activity was observed for Mo0.37W0.63S2/C samples with an overpotential of 0.137 V at geometric current densities of jgeo = 10 mA cm−2 and a Tafel slope of 53 mV dec−1. These results now provide low-cost viable alternatives for the design and construction of catalysts based on alloyed TMDCs.

Three-dimensional (3D) interconnected porous architectures are expected to perform well in photoelectrochemical (PEC) water splitting due to their high specific surface area as well as favourable porous properties and interconnections. In this work, we demonstrated the facile fabrication of 3D interconnected nanoporous N-doped TiO 2 (N-TiO 2 network) by annealing the anodized 3D interconnected nanoporous TiO 2 (TiO 2 network) in ammonia atmosphere. The obtained N-TiO 2 network exhibited broadened light absorption, and abundant, interconnected pores for improving charge separation, which was supported by the reduced charge transfer resistance. With these merits, a remarkably high photocurrent density at 1.23 V vs. reversible hydrogen electrode (RHE) was realized for the N-TiO 2 network without any co-catalysts or sacrificial reagents, and the photostability can be assured after long term illumination. In view of its simplicity and efficiency, this structure promises for perspective PEC applications.

A flexible asymmetric supercapacitor with high energy density was constructed by using a flexible substrate of carbonized silk-fabrics decorated with carbon nanotube, electroplating MnO2 nanosheets and dip-coating activated carbon powders as the positive and the negative electrodes, respectively. By controlling the electroplating time, the MnO2 nanosheets can be self-assembled to honeycomb structure and showed excellent electrochemical performance in 1 mol/L Na2SO4 electrolyte with SC950-EP30 performing the best. It exhibited a high specific capacitance (1110.85 F/g at a current density of 1 A/g based on the mass of MnO2) and superior rate capability (77.44% capacity retention from 1 A/g to 10 A/g). Thus, the optimal asymmetric device assembled with this material as positive electrode can deliver a maximum energy density of 43.84 Wh/kg and a maximum power density of 6.62 kW/kg.

Advanced flexible electronics have been attracting increasing attention nowadays. Herein, we fabricated an efficient flexible glucose sensor based on multi-walled carbon nanotubes coated carbonized silk fabric (MWCNTs/CSF) by Pt microsphere decoration. The MWCNTs/CSF was obtained by carbonization at 950 °C under an inert atmosphere, which showed good conductivity, flexibility and stability. After a decoration of Pt microspheres by electrodeposition, the resultant material showed a good sensitivity towards H2O2. Following with immobilizing with glucose oxidase (GOx), the resultant sensor showed a sensitivity of 288.86 μA mM−1 cm−2 with a good linear range from 0 to 5 mM. This method is considered to be an efficient way to fabricate flexible electrodes and wearable electronic devices.

Exploring anode materials with excellent rate performance and high initial coulombic efficiency (ICE) is crucial for lithium/sodium-ion batteries (LIBs/SIBs). However, it is still very challenging to achieve this goal in a cost-effective way, particularly for SIBs. Herein, graphite oxide, was treated in ammonia atmosphere for a balance between the oxygen- and nitrogen-contained functional groups and yielded nitrogen-doped expanded graphite oxide (NEGO). Electrochemical characterizations were systematically carried out in ether and ester-based electrolytes to shed light on the storage mechanism of NEGO in SIBs. The ICE of NEGO employed in ether-based electrolyte improves to 72.08% from that in ester-based electrolyte (24.73%). Moreover, the as-synthesized NEGO exhibits ∼125 mA h g−1 and ∼110 mA h g−1 capacities in ether and ester-based electrolytes, respectively, even under a record high current density (30 A g−1). Expanded surface area and nitrogen doping significantly increase the active sites and decrease the electrical resistivity from 140 Ω (EGO) to 40 Ω (NEGO) by removing excess oxygen. Moreover, small amounts of residual oxygen, particularly quinone and carboxyl, along with nitrogen occupied sites offer additional pseudocapacitance. Considering the advantages in scale-up and cost-effective production, NEGO is a promising low-cost anode material for SIBs. This study also provides strategies for the design of electrolyte for SIBs to realize practical applications in power-grid energy storage.

Electrospun carbon fiber films have high contact resistance at the fiber junctions, which causes poor cycling stability and limits their further improvement in energy storage performances. To eliminate the contact resistance of the film, we provide a new strategy to fuse the fiber junctions by introducing MoO2 in the fibers, which replaces the C–C interface by a more active C–MoO2–C interface at the fiber junction to promote mass transfer. MoO2 reacts with C matrix to generate Mo2C and form self-fused junctions during the carbonization process. Due to much lower charge transfer and sodium diffusion resistance, the C–Mo2C fiber film with self-fused junctions shows much better cyclability with capacity retention of 90% after 2000 cycles at a constant current density of 1 A g−1. Moreover, the Mo2C particles provide many electrochemically active sites, leading to additional improvement in sodium storage. The C–Mo2C fiber film has a capacity of 134 mA h g−1 at 1 A g−1 and a high capacity of 99 mA h g−1 even at 5 A g−1.

Although various anode materials have been reported, graphite is still a commercial anode material for lithium-ion batteries. In this study, nitrogen-doped carbon-coating graphite anode material with hollow structure is designed and fabricated through a facile and scalable process. This hollow structure constituted of graphite flakelets with disordered orientation inside can promote the penetration of electrolyte and shorten path of Li+ diffusion. The uniform N-doped carbon coating layer of NHG@C can significantly limit the side reaction between the organic electrolyte and superfine graphite inside and keep the electrode structure stability during charge and discharge. The obtained NHG@C anode material exhibits excellent rate capability in different current densities and displays a high reversible capacity of 304 ​mAh g−1 at a current density of 1A g−1 after 500 cycles. The excellent properties indicate that such a graphite-based anode material has a good prospect in the practical application of LIBs.

Porous and Ultrafine Nitrogen-doped carbon nanofibers (NCNFs) were successfully obtained from bacterial cellulose (BC) by carbonization/activation in NH3/N2 atmosphere at higher temperatures. Thanks to the ammonia treatment, the as-obtained NCNFs have nanoarchitectures constructed of one-dimensional (1-D) nanofiber with ultrafine fibers, hierarchically porous structures, abundant nitrogen functionalities leading to the basic and hydrophobic surface, which render them as excellent adsorbents for the adsorption removal of organic pollutants from aqueous solutions. Their adsorption performance for low-concentration 4-chlorophenol (4-CP) were investigated systematically under different conditions. In comparison with the carbon nanofibers (CNFs) without ammonia treatment and commercial activated carbon (CAC), NCNFs displayed greatly enhanced adsorption capacity, short equilibrium time and wide pH range. NCNF-1000 prepared at 1000 °C had adsorption capacity of 4-CP up to 604.1 mg/g for the initial low-concentration of 100 mg/L, which was superior to the previously reported adsorbents. Analyses of the equilibrium adsorption and kinetic data revealed that the adsorption process of 4-CP onto NCNFs were fitted well with the Liu isotherm and pseudo-second-order kinetic models. The thermodynamic parameters (ΔH°, ΔS°, ΔG°) for 4-CP adsorption onto NCNFs confirmed that the essence of 4-CP adsorption was exothermic, feasible and spontaneous. The possible adsorption mechanism of 4-CP on NCNFs was proposed. The excellent adsorption performance of NCNFs for 4-CP were mainly ascribed to their maximum effective surface area, short mass transfer path and hydrophobic surface, which resulted from their nanoarchitectures with many exposed, shallow and accessible pores and a great deal of nitrogen functionalities.

Developing high-performance and low-cost anode materials is crucial for the practical use of sodium-ion batteries (SIBs) at room-temperature. Porous carbon nanospheres with a uniform diameter for use as SIB anode materials were synthesized by the hydrothermal treatment of glucose to obtain the spheres, and subsequent carbonization and modification with KOH activation and N, S co-doping during or after the activation using thiourea as the N and S sources. Nanospheres doped with N and S after KOH activation have a high initial specific capacity of 527 mAh g−1 at a current density of 20 mA g−1 and an excellent cycling stability with a 95.2% capacity retention after 1000 cycles at a high current density of 500 mA g−1. The capacity retention rate is higher than that of most of the state-of-the-art anode materials for SIBs. This good performance is attributed to the abundant micro-pores, the enlarged interlayer spacing produced by the co-doping, and the high conductivity of the carbon nanospheres.

Developing high-performance noble metal-free and free-standing catalytic electrodes are crucial for overall water splitting. Here, nickel sulfide (Ni3S2) and nickel selenide (NiSe) are synthesized on nickel foam (NF) with a one-pot solvothermal method and directly used as free-standing electrodes for efficiently catalyzing hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline solution. In virtue of abundant active sites, the Ni3S2/NF and the NiSe/NF electrodes can deliver a current density of 10 mA cm−2 at only 123 mV, 137 mV for HER and 222 mV, 271 mV for OER. Both of the hierarchical Ni3S2/NF and NiSe/NF electrodes can serve as anodes and cathodes in electrocatalytic overall water-splitting and can achieve a current density of 10 mA cm−2 with an applied voltage of ∼1.59 V and 1.69 V, respectively. The performance of as-obtained Ni3S2/NF||Ni3S2/NF is even close to that of the noble metal-based Pt/C/NF||IrO2/NF system.

The sodium-ion battery (SIB) has been considered as one of the most important and promising candidates for large-scale storage of electrical energy. Developing cost-effective but high-performance anode materials is crucial for SIBs. Herein a hard carbon-based anode material is synthesized from polyurethane foam. In order to boost its performance, NaCl, one of the most abundant and low-cost salts in the ocean, is used to intercalate hard carbon. To the best of our knowledge, reports on NaCl intercalation in sodium ion battery anode materials are very scarce so far. After Na+ intercalation, the as-obtained sample delivers a capacity of over 210 mAh g−1 at 20 mA g−1. Moreover, a 90 mAh g−1 specific capacity with over 78% retention can be achieved after 1000 cycles at 1 A g−1 current density, which is 100% higher than that of untreated samples. The much enhanced performance can be attributed to a synergetic effect of both heteroatom doping and Na+ intercalation which can improve the electronic/ionic conductivity and enlarge the lattice spacing of the hard carbon as well. This work demonstrates that NaCl-intercalated nitrogen-rich hard carbons are very promising in their ability to serve as a kind of low-cost but efficient anode material for SIBs.

A photocatalytic CeO 2 @TiO 2 core–shell nanocomposite with enhanced photocatalytic performance was synthesized via a simple hydrothermal route assisted with the Stober method. The TiO 2 coating layer consisting of fine TiO 2 crystallites contributed most of the surface area of the CeO 2 @TiO 2 nanocomposite. The CeO 2 @TiO 2 nanocomposite exhibited a significantly narrower optical band gap than that of the pure TiO 2 . Photocatalytic studies revealed that the CeO 2 @TiO 2 core–shell nanocomposite displayed higher photocatalytic activity than both CeO 2 nanocubes and TiO 2 in degradation of the organic pollutant Rhodamine B. Such varieties in optical band gap and photocatalytic activity were assigned to the heterojunction interfaces formed in CeO 2 @TiO 2 , which could both promote photoinduced charge separation and suppress the recombination of photogenerated electrons and holes. During the process, the reversible oxidation-reduction in Ce(IV)/Ce(III) redox couples also promoted the efficient electron transfer.

Graphene nanoribbons (GNRs) with opened edges and less structural defects are embedded in polyacrylonitrile (PAN)-based carbon nanofibers (CNFs) by electrospinning followed by stabilization and carbonization. GNRs not only can be used as one-dimensional nanofillers, but also act as nanoplatelet template to promote the formation of graphitic carbon in PAN matrix. X-ray diffraction, Raman spectroscopy and N2 absorption are used to analyze the microstructure of GNR-reinforced CNFs. In situ tensile test using a micromechanical device inside a scanning electron microscope (SEM) is carried out to evaluate the mechanical performance of individual GNR-reinforced CNF. The tensile strength and elastic modulus of CNFs reinforced by 2 wt% GNRs with a diameter of ∼160 nm are 3.52 GPa and 70.07 GPa, respectively, which are higher than those of pristine PAN CNFs with similar size, i.e. 2.44 GPa and 28.97 GPa. The rough fracture surface for all GNR-reinforced CNFs suggests that the GNRs can dramatically toughen the fibers. A sword-in-sheath failure is observed in 4 wt% GNR reinforced CNFs, confirming that GNRs are entirely embedded and well aligned along the fiber axis. This study demonstrates the potential of GNRs as a promising reinforcement to improve the formation of graphitic carbon and mechanical performance of CNFs.

Achieving high-power lithium-ion hybrid electrochemical capacitor (Li-HEC) through facile and low-cost synthesis procedures is still quite challenging. In this work, starting from daily used food additives, nitrogen-doped hierarchical porous carbon (N-HPC) was prepared through facile pyrolysis of magnesium citrate and subsequent NH 3 treatment, and carbon-coated Fe 2 O 3 (Fe 2 O 3 @C) was synthesized by thermal decomposition of ferric citrate and following heat treatment in air, respectively. As-prepared N-HPC and Fe 2 O 3 @C were separately employed as cathode and anode materials to fabricate a high-power, which delivers a high energy density of 65 W h kg −1 at 368 W kg −1 , and 31 W h kg −1 at a high power density of 9.2 kW kg −1 . And it remains 84.1% capacity over 1000 galvanostatic charge-discharge cycles at 1 A g −1 .

The corrosion behaviour and mechanism of solid-state sintered silicon carbide ceramics in the mixed HF–HNO3 acid solution were investigated in this paper. The corrosion results of SiC in different corrosion medium demonstrated that the corrosion of ceramic was affected by the coefficient of HF and HNO3. In addition, the results of different corrosion time showed that the corrosion process can be divided into three stages: 0–6, 6–24, 24–96 h, which was also proved by the strength degradation of SiC after being corroded for different time. Because the relationship between mass loss and corrosion time was linear, the corrosion of first two stages was controlled by chemical reaction. Owing to the scattered data of mass loss in the third stage, the apparent activation is introduced to investigate the control mechanism. The corrosion results at different corrosion temperatures demonstrated that the corrosion mechanism was diffusion control in the third stage, and the apparent activation energy was 198.47 ± 13.9...

Efficient absorption in the S-band (2–4 GHz) has been a very challenging task for developing high-performance microwave absorption materials. Three-dimensional reduced graphene oxide (3D-rGO) powders were prepared by using a hydrothermal method and subsequent thermal treatment. It is found that as-prepared 3D-rGO could significantly enhance the electromagnetic wave attenuation in 2–4 GHz. When the content in the paraffin matrix is 4%, the 3D-rGO shows the strongest absorption in S-band, and the absorption will get stronger with the increase of coating thickness. When the thickness is 5 mm, the bandwidth of reflection loss less than −5 dB is in the range of 2.3 to 4.1 GHz, that is, it can almost cover the whole S-band. The excellent microwave absorption could be attributed to the honeycomb-like structures and the strong polarization of 3D-rGO powders. Considering the low density and good corrosion resistance, 3D-rGO powders may serve as an excellent component for the design of lightweight electromagnetic wave absorption coatings.

Due to the low density of nanostructured materials, it is still a big challenge to realize high volumetric performance instead of high specific gravimetric capacity with many state-of-the-art electrodes for compact electrochemical energy storage. Moreover, developing high-performance flexible and binder-free electrode materials is also crucial for their future applications in diverse fields, such as portable electronics and wearable devices. In this work, we designed and synthesized a Ni3V2O8/carbon cloth (CC) hierarchical structure as a flexible anode for sodium-ion batteries. Morphology-controllable growth of different Ni3V2O8/CC hierarchical structures is achieved by optimizing the synthesis parameters (e.g. the growth temperatures). The high mass loading (4 mg cm−2), ultra-high areal specific capacity (2.6 mA h cm−2 at a current density of 500 mA g−1), no addition of binders or other additives and good flexibility facilitate their application in sodium-ion batteries.

Carbon materials for electrodes of capacitive deionization (CDI) process are reviewed. Electrochemical cells are briefly explained by classifying into conventional, membrane and flow-electrode CDI cells. CDI performance of carbon materials, porous carbons, including activated carbons (ACs), activated carbon fibers (ACFs), templated nanoporous carbons, carbon aerogels, carbon nanotubes (CNTs), carbon nanofibers (CNFs) and graphenes, have been reviewed in detail. The feasibility of CDI techniques is then discussed on the basis of the experimental results reported.

Micro-mesoporous carbon nanofiber membranes with improved graphitic structure are produced by electrospinning, catalytic graphitization and NH3 treatment. Exceptionally ultrathin curved graphitic nanolayers and developed micro-mesoporous structure with narrow aperiodic mesopore size distribution (3–10 nm) are grown simultaneously in nano-scaled one-dimensional structure. Specific surface area is as high as 1326 m2 g−1. Mesopore volume with pore widths of 3–10 nm exhibiting highly linear dependency on the graphitization degree can be precisely tuned from 0.025 to 0.186 cm3 g−1 by adjusting heat-treatment temperature and transition metal content in the template-free synthesis, due to limitation of nano-scaled fiber diameter.

Lithium ion capacitors (LICs), bridging the advantages of batteries and electrochemical capacitors, are regarded as one of the most promising energy storage devices. Nevertheless, it is always limited by the anodes that accompany with low capacity and poor rate performance. Here, we develop a versatile and scalable method including ball-milling and pyrolysis to synthesize exfoliated MoS