A multihierarchical structure with (NH4)(Ni, Co)PO4·0.67H2O microplatelets and (Ni, Co)3(PO4)2·8H2O ultrathin nanopieces anchored on reduced graphene oxide (NCNP/RGO) is synthesized via a mild hydrothermal approach. This unique interface-rich structure is suitable for a high power energy storage device by providing efficient pathways for both electronic conduction and ionic transportation, which are effective ways to improve the electrochemical performance. Specifically, a specific capacity of 993 F g–1 is obtained in the three-electrode measurement, with ultrahigh capacity retention of 81.2% (807 F g–1) from 0.5 to 32 A g–1. The hybrid device constructed with the as-prepared NCNP/RGO as anode and a hierarchical porous carbon (HPC) as cathode offers a very superior energy density of 42.1 Wh kg–1 at a power density of 73 W kg–1, which remains 32 Wh kg–1 at 14 kW kg–1. Meanwhile, the as-prepared hybrid capacitor exhibits a remarkable cycling stability (96.5% capacitance retention after 10 000 cycles). The capacity contribution of capacitive behavior for the hybrid device is analyzed as 91.1% at 25 mV s–1.Keywords: High power; Hybrid energy storage; Multihierarchical; Phosphate;

•New 3D porous carbon nanosheets with few layers are prepared from biomass.•KOH plays an important role in evolution of such porous carbon materials.•Higher ORR activity is shown for N-doped carbon nanosheets than Pt/C in alkaline media.•Higher stability and immunity for methanol and CO poisoning are exhibited than Pt/C.Novel three dimensional (3D) porous carbon nanosheets with few layers are successfully prepared using intrinsically porous cellulose as carbon matrix only by means of calcination and KOH activation. Further, the N-doped 3D carbon nanosheets show high density of pyridinic N and extremely high specific surface area (1756 m2 g−1). As oxygen reduction catalyst, they possess an outperformed onset (E0 = −0.03 V) and half-wave (E1/2 = −0.17 V) potential compared with the platinum (Pt) electrocatalyst (E0 = −0.05 V, E1/2 = −0.2 V) in an alkaline system. In addition, excellent electrochemical stability as well as improved CO poisoning resistance and suppressed methanol crossover relative to Pt is also obtained. In an acid system, the catalyst also exhibits good activity and higher durability than Pt/C. Significantly, when used as a catalyst of the air electrode for Zn–air batteries, it demonstrates a higher peak power density of 208 mW cm−2 and a voltage plateau at the controlled discharge current density compared to the commercial Pt/C electrode. This simple and scalable approach provides a direct route to synthesize low cost and highly efficient electrocatalysts from biomass without addition of extra metal catalysts.Download high-res image (207KB)Download full-size image

Lithium–sulfur batteries (LSBs) possess many fold higher energy densities than conventional batteries; however, their establishment as a dominant niche in modern electronics and grid level storage energy techniques is critically impeded by their short cycling life, limited sulfur loading and severe polysulfide shuttling effect. Tremendous achievement has been made during the last decade in eliminating the aforementioned obstacles by employing various strategies to enhance their performance and make them promising alternative candidates for the present energy storage technology that shows great potential for next-generation high-energy systems. To promote breakthroughs in this exciting field, here this article will highlight the recent progress in the innovation of sulfur cathodes with an emphasis on the design of a new class of materials, and engineering of advanced nanostructures and novel cell configurations to enhance the electrochemical stability of LSBs. We also discuss future research directions and the remaining challenging issues in the concluding remarks that pave the way for further significant progress in this field.

In this work, we propose a one-step process to realize the in situ evolution of molybdenum carbide (Mo2C) nanoflakes into ordered mesoporous carbon with few-layered graphene walls (OMG) by chloridization and self-organization, and simultaneously the Cl-doping of OMG (OMG-Cl) by modulating chloridization and annealing processes is fulfilled. Benefiting from the improvement of electroconductivity induced by Cl-doping, together with large specific surface area (1882 cm2 g–1) and homogeneous pore structures, as anode of lithium ion batteries, OMG-Cl shows remarkable charge capacity of 1305 mA h g–1 at current rate of 50 mA g–1 and fast charge–discharge rate within dozens of seconds (a charge time of 46 s), as well as retains a charge capacity of 733 mA h g–1 at a current rate of 0.5 mA g–1 after 100 cycles. Furthermore, as a promising electrode material for supercapacitors, OMG-Cl holds the specific capacitances of 250 F g–1 in 1 M H2SO4 solution and 220 F g–1 at a current density of 0.5 A g–1 in 6 M KOH solution, which are ∼40% and 20% higher than those of undoped OMG electrode, respectively. The high capacitive performance of OMG-Cl material can be due to the additional fast Faradaic reactions induced from Cl-doping species.Keywords: chlorine-doped ordered mesoporous carbon; few-layered graphene wall; Li ion battery; molybdenum carbide; supercapacitor;

•A N,B-codoped carbon nanocage is reported for high efficiency multifunctional electrocatalyst.•DFT calculations reveal the catalytic compatibility of the N,B-codoping for ORR/OER/HER.•A primary zinc-air battery is assembled presenting a maximum power density of 320 mW cm−2.Nanocarbon materials recognized as effective and inexpensive catalysts for independent electrochemical reactions, are anticipated to possess a broader spectrum of multifunctionality toward oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER). A rational design of trifunctional nanocarbon catalyst requires balancing the heteroatoms-doping and defect-engineering to afford desired active centers and satisfied electric conductivity, which however is conceptually challenging while desires in-depth research both experimentally and theoretically. This work reports a N,B-codoped graphitic carbon nanocage (NB-CN) with graphitic yet defect-rich characteristic as a promising trifunctional electrocatalyst through a facile thermal pyrolysis assisted in-situ catalytic graphitization (TPCG) process. Density functional theory (DFT) calculations are conducted, for the first time, to demonstrate that the best performance for ORR/OER and HER can be originated from the configuration with B meta to a pyridinic-N, which presents a minimum theoretical overpotential of 0.34 V for ORR, 0.39 V for OER, and a lowest Gibbs free-energy (ΔGads) of 0.013 eV for HER. A primary zinc-air battery is assembled presenting a maximum power density of 320 mW cm−2 along with excellent operation durability, evidencing great potential in practical applications.The N,B-codoped defect-rich graphitic carbon nanocages (NB-CN) are prepared through a technique of in situ vapor deposition. The NB-CN exhibits efficient multifunctional catalytic activity for ORR, OER and HER, shows potential practical performances in the fields of metal-air battery, fuel cell and water splitting.Download high-res image (200KB)Download full-size image

Aqueous hybrid capacitors (HCs) suffer from sacrificed power density and long cycle life due to the insufficient electric conductivity and poor chemical stability of the battery-type electrode material. Herein, we report a novel NH4-Co-Ni phosphate with a stable hierarchical structure combining ultrathin nanopieces and single crystal microplatelets in one system, which allows for a synergistic integration of two microstructures with different length scales and different energy storage mechanisms. The microplatelets with a stable single crystal structure store charge through the intercalation of hydroxyl ions, while the ultrathin nanopieces store charge through surface redox reaction providing enhanced specific capacitance. Furthermore, the large single crystal can bridge the small nanopieces forming continuous electronic conduction paths as well as ionic conduction channels, and facilitate both electron and ion transportation in the hierarchical structure. The HC cell based on the as prepared material and a 3D hierarchical porous carbon delivers a high energy density of 29.6 Wh kg−1 at a high power density of 11 kW kg−1. Particularly, an ultralong cycle life along with 93.5% capacitance retention after 10000 charge–discharge cycles is achieved, which is outstanding among the state-of-the-art aqueous HC cells.

Carbon nanotubes (CNTs) are synthesized through a novel low cost self-vaporized chemical vapor deposition (SCVD) technique from an indecomposable solid carbon source for the first time. This method was manipulated to avoid the injection of flammable gasses, by producing gaseous carbon (e.g. CO) through an in situ catalyzed gasification of the intermediate product induced by KOH. Simultaneously, the as-produced gaseous carbons will deposit onto the pre-imbedded Ni nanocatalyst surface and form CNTs. The growth mechanism is discussed in detail by adjusting the KOH amount. The as-prepared CNTs are rich in oxygen and deficiencies, which endow them with abundant active sites for electrochemical applications. Superior supercapacitor performance is achieved with a specific capacitance 6 times higher than that of commercial CNTs. This technique represents a novel, convenient approach toward large scale production of CNTs directly from a solid carbon precursor, and would show promising applications in various industrial fields.

Nanolayered structures present significantly enhanced electrochemical performance by facilitating the surface-dependent electrochemical reaction processes for supercapacitors, which, however, causes capacitance fade upon cycling due to their poor chemical stability. In this work, we report a simple and effective approach to develop a stable, high performance electrode material by integrating 2D transition metal hydroxide and reduced graphene oxide sheets at nanometer scale. Specifically, a hybrid nanolayer of Ni–Co hydroxide @reduced graphene oxide (Ni,Co–OH/rGO) with an average thickness of 1.37 nm is synthesized through an easy one-pot hydrothermal method. Benefiting from the face to face contact model between Ni–Co hydroxide and rGO sheets, such unique structure presents superior specific capacitance and cycling performance as compared to the pure Ni–Co hydroxide nanolayers. An asymmetric supercapacitor based on Ni,Co–OH/rGO and three-dimensional (3D) hierarchical porous carbon is developed, exhibiting a high energy density of 56.1 Wh kg–1 along with remarkable cycling stability (80% retention after 17 000 cycles), which holds great promise for practical applications in energy storage devices.Keywords: cycling stability; nanolayer; Ni−Co hydroxide; supercapacitor; ultrathin

The emergence of atomically thick nanolayer materials, which feature a short ion diffusion channel and provide more exposed atoms in the electrochemical reactions, offers a promising occasion to optimize the performance of supercapacitors on the atomic level. In this work, a novel monolayer Ni–Co hydroxyl carbonate with an average thickness of 1.07 nm is synthesized via an ordinary one-pot hydrothermal route for the first time. This unique monolayer structure can efficiently rise up the exposed electroactive sites and facilitate the surface dependent electrochemical reaction processes, and thus results in outstanding specific capacitance of 2266 F g–1. Based on this material, an all-solid-state asymmetric supercapacitor is developed adopting alkaline PVA (poly(vinyl alcohol)) gel (PVA/KOH) as electrolyte, which performs remarkable cycling stability (no capacitance fade after 19 000 cycles) together with promising energy density of 50 Wh kg–1 (202 μWh cm–2) and high power density of 8.69 kW kg–1 (35.1 mW cm–2). This as-assembled all-solid-state asymmetric supercapacitor (AASC) holds great potential in the field of portable energy storage devices.Keywords: cycling stability; monolayer; Ni−Co hydroxyl carbonate; solid-state; supercapacitor

•A novel solution coating method was used to modify the commercial BSCF.•Electrical conductivity of modified BSCF with 5–10 wt% CoOx was enhanced by 5–27%.•Peak power density of anode-supported fuel cell was nearly enhanced by 100%.•A CoOx promoted ORR mechanism was proposed.•The applied modification method of perovskite has great potential in exploring new functional cathodes for advanced LTSOFCs.In order to improve the catalytic activity of commercial Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) for low-temperature solid oxide fuel cells (LTSOFC) (300–600 °C), CoOx has been used to modify the commercial BSCF through a solution coating approach. Phase and morphology of samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and energy-dispersive spectrometry (EDS), respectively. BSCF with 10 wt% CoOx exhibited an improved conductivity of 44 S/cm, and achieved a peak power density of 463 mW/cm2 at 550 °C for LTSOFC, which is a 100% enhancement than that with the BSCF cathode. The cathode oxygen reduction reaction (ORR) promoted by CoOx and enhanced device performance mechanism have been proposed. This work provides a new way for the exploitation of high effective cathode materials for LTSOFCs.

•An N-P-O co-doped 3D graphene is produced through a novel “cutting-thin” strategy.•This “cutting-thin” strategy is applicable to variable carbon sources.•The 3D graphene exhibits ultrahigh specific capacitance of 426 F g−1 (424 F cm−3).•The 3D graphene can be directly utilized as an excellent metal free ORR catalyst.Large scale production of three dimensional (3D) graphene materials with high density and low degree of defects stands for the main challenge hindering their practical applications. Herein, we report a universal and readily scalable strategy to produce an N-P-O co-doped free standing 3D graphene through a one-pot red phosphorus-assisted “cutting-thin” technique. The solid carbon precursor is gradually exfoliated through the slowly released gases (e.g. pH3, H2, CO2) and metallic K during the reaction, which allows the formation of dominant amount nanopores, and ensures the high density of the products. The as-produced graphene exhibits continuously 3D hierarchical porous (3D-HPG) structure with good quality (ID/IG=0.4, I2D/IG=0.65). Density functional theory (DFT) calculations indicate the N-P-O co-doping can significantly enhance the charge delocalization with benefited electrochemical activity. The 3D-HPG is directly utilized as the supercapacitor electrode and a metal free catalyst for oxygen reduction reaction (ORR), offering ultrahigh specific capacitance of 426 F g−1(424 F cm−3), as well as excellent catalytic performance. The assembled all-solid-state cell exhibits both high gravimetric (25.3 W h kg−1) and volumetric (25.2 W h L−1) energy density, which are among the highest values of the state-of-art carbon only supercapacitors. Remarkably, this “cutting-thin” strategy is applicable to variable carbon sources.An N-P-O co-doped free standing 3D graphene is synthesized through a one-pot red phosphorus-assisted “cutting-thin” technique. The material is directly utilized as the supercapacitor electrode and a metal free catalyst for oxygen reduction reaction (ORR), offering ultrahigh specific capacitance, as well as excellent catalytic performance. Remarkably, this “cutting-thin” strategy is applicable to various carbon sources.

In this study, three-dimensional (3D) hierarchical porous carbon with abundant functional groups is produced through a very simple low-cost carbonization of Artemia cyst shells. The unique hierarchical porous structure of this material, combining large numbers of micropores and macropores, as well as reasonable amount of mesopores, is proven favorable to capacitive behavior. The abundant oxygen functional groups from the natural carbon precursor contribute stable pseudocapacitance. As-prepared sample exhibits high specific capacitance (369 F g–1 in 1 M H2SO4 and 349 F g–1 in 6 M KOH), excellent cycling stability with capacitance retention of 100% over 10 000 cycles, and promising rate performance. This work not only describes a simple way to produce high-performance carbon electrode materials for practical application, but also inspires an idea for future structure design of porous carbon.Keywords: carbon; hierarchical porous; natural carbon source; oxygen-rich; supercapacitor

•PANI was coated on to hierarchical porous carbon through VDP method.•The PANI@HPC composite exhibited good electrochemical performance.•The cycling stability is superior as compared to literature.•Symmetric supercapacitor based on the composite displayed high energy density.In this work, a polyaniline coated hierarchical porous carbon (HPC) composite (PANI@HPC) is developed using a vapor deposition polymerization technique. The as synthesized composite is applied as the supercapacitor electrode material, and presents a high specific capacitance of 531 F g−1 at current density of 0.5 A g−1 and superior cycling stability of 96.1% (after 10,000 charge–discharge cycles at current density of 10 A g−1). This can be attributed to the maximized synergistic effect of PANI and HPC. Furthermore, an aqueous symmetric supercapacitor device based on PANI@HPC is fabricated, demonstrating a high specific energy of 17.3 Wh kg−1.

•NixCo(1−x)(OH)2 nanoflowers are synthesized by a template-free method•The formation mechanism of flower-like structure is demonstrated in detail•The NixCo(1−x)(OH)2 exhibit high performance as battery materials.•The NixCo(1−x)(OH)2 battery materials are used in high performance supercapacitor.In this work, various nickel cobalt double hydroxide nanoflowers with different Ni/Co ratios (denoted as NixCo(1−x)(OH)2), assembled by filmy nanoflakes, are prepared via a facile template-free hydrothermal process. The sizes of these nanoflowers are easily tuned by the Ni/Co ratio in the precursors. The formation mechanism of flower-like nickel cobalt hydroxide, based on the synergistic effect of ammonia complexation, Ni/Co ratios, precipitators and solvents in the template-free hydrothermal system, is demonstrated in detail. As the battery materials, the as prepared flower-like nickel cobalt double hydroxides exhibit excellent specific capacities and high rate performance. Ni0.28Co0.72(OH)2 displays the highest capacity of 206.7 mA h g−1 at 1 mV s−1 and 174.3 mA h g−1 at 1 A g−1, respectively. The capacity retention of Ni0.28Co0.72(OH)2 is 59.1% (from 206.7 to 122.2 mA h g−1) at the potential scan rate from 1 to 25 mV s−1. Due to the high rate performance corresponding to high power energy, Ni0.28Co0.72(OH)2 is used as positive material to assemble the hybrid device (asymmetric supercapacitor) with activated carbon as negative material. The as-prepared asymmetric supercapacitor exhibits 19.4 Wh kg−1 at 80.5 W kg−1, and even 20.6 Wh kg−1 at 3.93 kW kg−1.

In recent years, composite semiconductor photocatalytic materials have received significant attention as a novel type of materials and technical means. So in this work, CdS-modified TiO2 nanowires are fabricated on natural zeolite by simple sol-gel and hydrothermal synthesis method. This novel composite semiconductor photocatalytic material has almost solved the shortcomings of pure TiO2, such as easy cohesion, low utilization rate, and exceedingly weak photocatalytic activities under visible light. The degradation efficiency of methylene blue dye in water is near to 90% with CdS-modified TiO2 nanowires/zeolite composite materials after 60 min under visible light, which indicated its huge potential application in wastewater treatment.

Highly ordered AgInS2-modified ZnO nanoarrays were fabricated via a low-cost hydrothermal chemical method, and their application as all-solid-state solar cells was also tested. A sensitizer and a buffer layer were developed around the surface of ZnO nanotubes in the preparation process, and this method is easily be manipulated to produce uniform structure. In this structure, the ZnO served as direct electron transport path, the ZnS as the buffer layer, and the ternary sensitizer AgInS2 as absorber and outer shell. The novel all-solid-state hybrid solar cells (ITO/ZnO/ZnS/AgInS2/P3HT/Pt) showed improved short-circuit current density (Jsc) of 7.5 mA/cm2, open-circuit voltage (Voc) of 512 mV, giving rise to a power conversion efficiency of 2.11%, which is the relatively highest value ever reported for ZnO-based all-solid-state hybrid solar cells. This better result is attributed to the improved absorption spectrum, high speed of photoinduced charge transmission velocity, and appropriate gradient energy gap structure, which implies a promising application in all-solid-state solar cells.Keywords: AgInS2; all-solid-state; buffer layer; highly ordered; solar cell

•ZnO/SrTiO3 nanomaterials by a chemical conversion hydrothermal synthesis method.•The expected samples can be used for photoelectrochemical water splitting.•High photocurrent due to the improved absorption spectrum and appropriate nanostructure.The ZnO/SrTiO3 nanomaterials were fabricated by a chemical conversion hydrothermal method in order to utilize the high electron transfer rate of one-dimensional ZnO nanorods and photocatalytic activity of SrTiO3. The technological parameters, such as TiO2 sol concentration, TiO2 sol dipping cycle, Sr(NO3)2 concentration and reaction temperature, were investigated in the synthetic process and the reaction mechanism of the ZnO/SrTiO3 nanomaterials was proposed. A photocurrent density of 7.53 mA/cm2 was obtained for the as-prepared ZnO/SrTiO3 photocatalyst, attributed to its improved absorption spectrum and appropriate nanostructure, which indicates a potential application in photoelectrochemical water splitting.

•Hierarchical porous ZnO synthesis through template method.•The pore structure of as-prepared ZnO is highly ordered.•High photocurrent of the ZnO film was obtained due to the hierarchical porous structure.In this work, a novel hierarchical porous ZnO is successfully synthesized through a sol–gel method, in which a kind of biological material is used as hard template, block copolymer Pluronic F127 as soft template. The phase and morphology of the products are characterized by X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), and transmission electron microscope (TEM). The results show that the as-prepared ZnO with a hierarchical porous architecture is assembled by multiple-layered porous nanosheets, of which the pore structure is highly ordered. The photocatalytic activity of the as-prepared ZnO is evaluated by photodegradation reaction of methylene blue. The photoelectrochemical (PEC) property of the hierarchical porous ZnO film is also investigated in this work.

•Hierarchical porous metal oxide composite is successfully synthesized.•Symmetrical electrode for LTSOFC.•Semiconductor for single component fuel cell.•Single component fuel cell presents higher performance than LTSOFC.In this work, hierarchically porous composite metal oxide LiNiCuZn-oxide (LNCZO) was successfully synthesized through a sol–gel method with a bio-Artemia cyst shell (AS) as a hard template. The phase and morphology of the products were characterized by X-ray diffraction analysis (XRD), scanning electron microscopy (SEM). The as-synthesized material was used as symmetrical electrodes, anode and cathode, for the SDC-LiNaCO3 (LNSDC) electrolyte based low temperature solid oxide fuel cell (LTSOFCs), achieving a maximum power density of 132 mW cm−2 at 550 °C. Besides, a single-component fuel cell device was also demonstrated using a mixture of as-prepared LNCZO and ionic conductor LNSDC, and a corresponding peak power output of 155 mW cm−2 was obtained, suggesting that the hierarchically porous product has high prospective in the single-component fuel cell.

Novel hierarchical porous TiO2 is successfully synthesized through a sol–gel method, using a natural cyst shell as a hard template. The morphology characterization shows that the as-prepared TiO2 with a hierarchical porous architecture is assembled by multiple-layered porous nanosheets. The degradation of methylene blue dye in water can rapidly reach 96% with as-prepared TiO2 after 50 min, showing an improved photocatalytic efficiency of 13% as compared to commercial TiO2.

•Hierarchical porous NiO is synthesized through the biotemplate assisted method.•The potential application as a supercapacitor electrode is tested.•A ~93% capacitance retention is achieved from 0.3 to 10 A g−1.•A ~96 % capacitance retention after 2000 charge/discharge cycles is achieved.•This work inspires an idea for future structure design of other metal oxides.A novel 3D hierarchical porous nickel oxide (NiO) was fabricated by a facile biotemplate assisted method. Physicochemical characterizations indicate that the as prepared hierarchical porous NiO is assembled by multiple-layered porous nanosheets, of which the pore structure is highly ordered. The electrochemical performance of the as prepared hierarchical porous NiO was carried out in 6 M KOH, exhibited relatively high specific capacitance value of 493 F g−1 at a current density of 0.3 A g−1, good rate performance (~93% capacity retention from 0.3 A g−1 to 10 A g−1), as well as good cycling stability (~96% retention upon 2000 charge/discharge cycles at 10 A g−1).

•A simple approach was developed to synthesize Sn doped Mn3O4/C nanocomposite.•The potential application as supercapacitor electrode was tested.•The as-synthesized nanocomposite shows excellent rate capability and cycling stability.•A ~93% capacitance retention after 10,000 charge/discharge cycles was achieved.Sn-doped Mn3O4/C nanocomposite was synthesized using Pluronics P123 (EO20PO70EO20) as both structure-directing agent and carbon source. The phase and morphology was characterized with X-ray diffraction (XRD), X-ray spectroscopy (EDS), Field-emission scanning electron microscope (FESEM) and transmission electron microscope (TEM). The electrochemical performance of the sample was tested in 6 M KOH A high specific capacitance of 216 F g−1 was achieved at current density of 5 A g−1, and 93% capacitance retention remained after 10,000 charge/discharge cycles.

•LiNiCuZn oxide with hierarchical porous structure was synthesized.•The potential application in SOFC is tested.•An artemia cyst shell was applied as the natural biotemplate.Low temperature, 300–600 °C solid oxide fuel cell (LTSOFC) is one of the hot areas in recent fuel cell development. In order to develop high performance LTSOFCs, compatible electrodes are highly demanded. In this work, a lithium transition metal oxide electrode material with hierarchical porous structure was synthesized. The phase structure was analysed by XRD and microstructure was studied by SEM. The as-synthesized material was constructed to devices using the SDC (samarium doped ceria)-carbonate nanocomposite (NSDC) as the electrolyte to test the OCV (open circuit voltage), which indicates good catalytic performance for H2 at 600 °C.

Carbide derived carbons (CDCs) are porous carbons produced by extraction metals from metal carbides. In this paper, nanoporous carbon with large surface area of above 1000 m2/g has been prepared by thermo-chemical etching of titanium carbide (TiC) in chlorine atmosphere. An improved design of accurate control on the reaction time with high yield percentage above 98% is reported. Transmission electron microscope (TEM) and X-ray diffraction (XRD) analysis showed the existence of ordered graphite phase in this mostly amorphous titanium carbide derived carbon (TiC-CDC), and the degree of ordering increased with chlorination temperature. Raman spectra study demonstrated that the TiC-CDC consisted of both D-band and G band of graphitic carbon, and the ratio of the integrated intensities ID/IG decreased with chlorination temperature. T-plot nitrogen sorption measurements proved the co-existence of micropores (<2 nm) and mesopores (2–50 nm), while the highest specific surface area was achieved from sample synthesized at 400 °C. Cyclic voltammetry measurements on the TiC-CDC did not show any major Faradic reactions within the experimental voltage range. A specific capacitance of 138.3 F/g was achieved from sample synthesized at 400 °C. The specific capacitance increased with increasing the amount of microporous area.

Carbon nanotubes (CNTs) are synthesized through a novel low cost self-vaporized chemical vapor deposition (SCVD) technique from an indecomposable solid carbon source for the first time. This method was manipulated to avoid the injection of flammable gasses, by producing gaseous carbon (e.g. CO) through an in situ catalyzed gasification of the intermediate product induced by KOH. Simultaneously, the as-produced gaseous carbons will deposit onto the pre-imbedded Ni nanocatalyst surface and form CNTs. The growth mechanism is discussed in detail by adjusting the KOH amount. The as-prepared CNTs are rich in oxygen and deficiencies, which endow them with abundant active sites for electrochemical applications. Superior supercapacitor performance is achieved with a specific capacitance 6 times higher than that of commercial CNTs. This technique represents a novel, convenient approach toward large scale production of CNTs directly from a solid carbon precursor, and would show promising applications in various industrial fields.

Lithium–sulfur batteries (LSBs) possess many fold higher energy densities than conventional batteries; however, their establishment as a dominant niche in modern electronics and grid level storage energy techniques is critically impeded by their short cycling life, limited sulfur loading and severe polysulfide shuttling effect. Tremendous achievement has been made during the last decade in eliminating the aforementioned obstacles by employing various strategies to enhance their performance and make them promising alternative candidates for the present energy storage technology that shows great potential for next-generation high-energy systems. To promote breakthroughs in this exciting field, here this article will highlight the recent progress in the innovation of sulfur cathodes with an emphasis on the design of a new class of materials, and engineering of advanced nanostructures and novel cell configurations to enhance the electrochemical stability of LSBs. We also discuss future research directions and the remaining challenging issues in the concluding remarks that pave the way for further significant progress in this field.