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Germanium-based ternary oxides have aroused wide attention as an anode for high-performance lithium-ion batteries (LIBs). Nevertheless, they usually suffer a large volume expansion and rapid capacity fading during lithiation/delithiation cycles. To address this issue, herein, Zn2GeO4/RGO composites are synthesized with Zn2GeO4 hollow rods in-situ grown on reduced graphene oxide (RGO) sheets. The Zn2GeO4 hollow rods can be facilely adjusted from nano- to micro-size. The lithium storage performances of the composites strongly depend on the size of Zn2GeO4 hollow rods and the content of RGO. The optimized Zn2GeO4/RGO composite exhibits a pseudocapacitance-dominated Li+ storage performance, with a large reversible capacity of 1005 mAh g-1 after 100 cycles at 0.5 A g-1, an excellent rate capability (515 mAh g-1 at a high rate of 5 A g-1) and a good long cycling stability of 500 cycles with a low capacity loss of 0.05% per cycle at 1 A g-1. The outstanding electrochemical performance can be attributed to the unique composition and microstructure of the material as well as the synergistic effect of the conductive RGO sheets and the hollow Zn2GeO4 nanostructure. This work provides a promising anode for high-performance LIBs and a useful inspiration for further improving the Ge-based ternary oxide anodes.

Elastic polyion hydrogels (EPIHs) as pressure sensors require to be microstructurally modified or micropatterned to improve the sensitivity of the parallel-plate sensing configurations. In this work, we designed a novel lignocellulose/EPIH composite microstructure that featured three unique characteristics including the loosening of the polyion chains, the introduction of complex porous channels and the reduction of the compressive modulus of the system for the purpose of piezoresistive sensitivity improvement. This lignocellulose/EPIH displayed hierarchical porous networks involving huger stiffer pores in lignocellulose (hindering the excessive intertwining of polyanion chains) and resultant smaller softer pores in polyanions, leading to high compressibility (80% strain), a high energy dissipation ratio (65%), and low Young's modulus (104 KPa) below 40% strain. Ultimately, the hybrid hydrogel possessed an increased conductivity change rate when compressing at low pressures (C20/C0 = 1.24) because of the soft, porous structure and the introduction of rGO nanosheets as ion repositories. Using this material, a soft tactile sensor with high sensitivity (9.71 MPa−1 within 22 KPa) was demonstrated to reconstruct and simulate the waves of a series of force signals, showing promising applications in the fields of recreation and sports for human–machine interfaces with relatively broad force ranges.

Herein, we demonstrate an advanced cathode of nitrogen-doped carbon dots (NCDs) anchored NiO/Co3O4 ultrathin nanosheets for hybrid supercapacitors by a facile hydrothermal-calcination route. Owing to the well defined thin-plate structure and ternary composition, the optimized NiO/Co3O4/NCDs nanosheets demonstrate a high specific capacity of 976.3 C g−1 (1775 F g−1) at 1 A g−1, and a splendid cycling stability of approximately 95.7% retention over 10,000 continuous cycles (15 A g−1). In addition, a hybrid supercapacitor is constructed by using NiO/Co3O4/NCDs nanosheets as cathode and reduced graphene oxide (RGO) supported NCDs composites as anode. The obtained NiO/Co3O4/NCDs//RGO/NCDs hybrid supercapacitor delivers a maximum energy density of 41.6 Wh kg−1, together with outstanding cycling stability (no decay after 10,000 cycles at 10 A g−1). Therefore, the ultrathin sheet-like structured NiO/Co3O4/NCDs cathode presents a great potential for supercapacitor application.

The development of high-performance anode materials is critical for next-generation asymmetric supercapacitor devices. Herein, an advanced anode of bismuth oxide/nitrogen-doped carbon dots (Bi2O3/NCDs) hollow and porous hierarchitecture was successfully developed by a facile two-step strategy. It is revealed that the presence of NCDs can not only induce the assembly of Bi2O3 porous nanosheets to hollow microspheres, but also remarkably improve the specific capacitances of them. Attributing to the intriguing properties of NCDs and the unique structure of Bi2O3/NCDs composites, the Bi2O3/NCDs hierarchitectures deliver an enhanced specific capacitance of approximately 1046 F g−1 at a current density of 1 A g−1. In particularly, an asymmetric supercapacitor was constructed by using the Bi2O3/NCDs hierarchical microspheres as anode and Ni(OH)2/NCDs nanosheets as cathode, which exhibits an ultrahigh energy density of about 79.9 Wh kg−1 at 770.9 W kg−1. These results indicate that the Bi2O3/NCDs hollow and porous hierarchitectures hold great potential as novel anode materials for energy storage.

Three-dimensional graphitic carbon materials with controllable composition and hierarchically porous structure are promising electrode materials for supercapacitors. In this work, a modified phase inversion method combined with a calcination process was developed to prepare three-dimensional graphene networks embedded with nitrogen-doped carbon nanoparticles. When used as electrode for supercapacitors, the as-prepared material delivered a high capacitance of 431.9 F g−1 at 0.1 A g−1 and 156.8 F g−1 at 20 A g−1, as well as a stable cyclic behavior with no capacitance decay after 5000 cycles. Such a remakable capacitive performance was attributed to its hierarchically porous structure and proper nitrogen doping content (9.68 ± 0.24 at%), which facilitated the migration of electrolyte ions and provided abundant redox active sites for the faradic reactions. The synthetic strategy may be exploited for the rational design and synthesis of new carbon materials with controlled doping level and three-dimensional porous structure.

Taking inspiration from skeletal muscle with highly oriented myofibers, we developed a tough wood aerogel/poly(ionic liquid) (WA/PIL) hydrogel directly from wood via delignification, impregnation and gelation for the formation of a tactile sensor of electric double-layer capacitive configuration. The WA/PIL hydrogels integrated the representative properties of both wood and ionic liquids, being a promising candidate for both polyelectrolyte and separator materials. The influences of the wood texture and cross-linker (Bis) content on the mechanical and sensing performances of the hydrogels were investigated. The results showed that the tangential hydrogel slice with a 1.0 mol% Bis content (tan 1.0) displayed the most significant improvement in compressive stress (1.65 MPa) and deformation (73.3%) at fracture, suggesting the best compressibility. Electrodes also played a significant role in the sensitivity and stability of the sensor devices. While tan 1.0 with reduced graphene oxide (rGO) electrodes displayed the largest sensitivities (1.13–19.70 MPa−1), tan 1.0 with Ni foams possessed much more stable ionic signals within the whole stress range with sensitivities of 0.33–9.67 MPa−1. Due to the wide-stress-range responsiveness of our hydrogel sensor from gentle finger contact to vigorous hitting modes, it will find promising applications in various human–machine interfaces in the fields of electronics, recreation, sports, etc.

Vapor generation by means of harvesting solar energy is an energy-saving, environmentally friendly and efficient method to achieve seawater desalination and water purification. However, solar vapor generation is subjected to poor utilization efficiency of solar energy or it depends on expensive solar absorption materials and complex processes. In this work, inspired by tree transpiration in nature, a novel wood-based vapor generator composed of wood substrates with 3D microchannels and a candle soot decoration surface was designed and developed. Profiting from the simultaneous optimization of the candle soot-decorated wood (CS-wood) properties (hydrophilic wood substrates with microchannels for water transportation and escape, low heat conduction value, and a black CS decoration surface with high solar absorbing abilities), the as-fabricated CS-wood vapor generation material achieved a relatively high net evaporation rate value of 0.950 kg m−2 h−1 when being illuminated at one sun. This bilayer wood-based vapor generator exhibited good capacities of desalination (seawater) and purification (lake water). Such wood-based material as a high-performance, cost-efficient and scalable vapor generator can be a potential candidate for the production of clean water to alleviate the global clean water shortage crisis via the effective utilization of green energy.

Designing of cost-effective electrocatalysts for efficient oxygen evolution reaction (OER) is highly desired for the practical production of clean hydrogen energy. Herein, reduced graphene oxide (RGO) supported N-doped porous carbon-coated NiFe alloy composite (NiFe@NC/RGO) was synthesized via a facile pyrolysis route. The introduction of RGO effectively protects the active NiFe component from agglomeration and largely promotes charge transfer. Meanwhile, the formation of porous N-doped carbon shell provides sufficient contact between active species and electrolyte, thus exposing plenty of accessible active sites. Specifically, the optimized NiFe@NC/RGO composite shows superior electrocatalytic performance, delivering an overpotential as low as 223 mV at current density of 10 mA cm−2, and a small Tafel slope of 48.7 mV dec−1 in 1 M KOH solution, which outperforms commercial precious metal oxide catalysts such as RuO2 and a vast majority of electrocatalysts reported so far. Long-term cycling test demonstrates that the overpotential at current density of 10 mA cm−2 has almost no change after 1000 cycles at a scan rate of 50 mV s−1, indicating its quite good stability. The low-cost and high-performance electrocatalyst developed in this work shows great potential for practical hydrogen production from electrolysis of water.

Germanium (Ge), as an anode material for lithium-ion batteries (LIBs), has received considerable attention because of its high theoretical capacity and excellent electrochemical performance. However, Ge anode usually undergoes large volume expansion during lithium insertion/extraction, resulting in severe structural pulverization and fast capacity fading. Here, we report an efficient cationic polymer-assisted in-situ reduction method for the preparation of highly uniform Ge/RGO composites (RGO = reduced graphene oxide) using GeO2, instead of expensive and toxic GeXn (X = Cl, Br and I), as Ge source. In this protocol, GeO32− anions are well adsorbed on cationic polymer-modified graphene oxide sheets by electrostatic interaction, followed by in-situ reduction, which results in the growth of ultrafine Ge nanoparticles (ca. 5 nm) on RGO sheets to form highly uniform sandwich-like structure. Benefiting from the tiny size of Ge nanoparticles and the well-conductive RGO sheets, the Ge/RGO anodes exhibit a high reversible capacity of 960 mAh g−1 after 100 cycles at 0.2 A g−1, an excellent rate capability of 631 mAh g−1 at 5 A g−1, and 705 mAh g−1 after 350 cycles at 1 A g−1 (with the capacity fading of only 0.07% per cycle based on the initial discharge capacity of 940 mAh g−1). More impressively, by coupling with LiFePO4 cathode, the full battery also shows a good electrochemical performance in terms of specific capacity and cycling stability. The simple, low-cost and environmental friendly synthesis strategy together with the outstanding lithium-storage performance of Ge/RGO composites affords a promising anode material for next-generation LIBs.

The fabrication of non-precious-metal and highly active electrocatalytic materials to drive oxygen evolution reaction (OER) at low overpotential from earth-abundant elements by a low-cost and easy method is extremely important for many advanced energy technologies. Herein, a non-noble-metal catalyst with FeNi@nitrogen-doped graphene dispersed on a nitrogen-doped carbon matrix (named FeNi@NGE/NC) is synthesized by a facile one-pot pyrolysis process. In this composite, FeNi alloy nanoparticles encapsulated with few-layer nitrogen-doped graphene are uniformly anchored on a nitrogen-doped carbon matrix. The FeNi@NGE/NC composite exhibits outstanding electrocatalytic performance for OER with a low overpotential of 275 mV at 10 mA cm–2, a small Tafel slope of 41.2 mV dec–1, and high stability in 1 M KOH solution. Even at the low concentration of basic solution (0.1 M KOH), it still displays good activity for OER with an overpotential of 372 mV at 10 mA cm–2. The outstanding OER performance of the FeNi@NGE/NC co...

The exploitation of hybrid supercapacitors with excellent electrochemical properties is of great significance for energy storage systems. Herein, a three-dimensional hierarchical flower-like architecture of nickel phosphide (Ni2P) decorated with nitrogen-doped carbon quantum dots (N-CQDs) and cobalt oxide (Co3O4) is constructed by an effective two-step hydrothermal strategy followed by in situ phosphorization process. Introducing N-CQDs with superior electrochemical characteristics can not only induce the formation of N-CQDs deposited nickel hydroxide (Ni(OH)2) flower-like architecture but also significantly enhance the electrochemical features of Ni(OH)2 nanosheets. After combination with Co3O4 nanoparticles and phosphorization treatment, an advanced cathode of Ni2P/Co3O4/N-CQDs with enriched surface phosphate ions is obtained, which possesses an ultra-high capacity of 1044 C g-1 (2088 F g-1) at 1 A g-1 with a splendid rate capacity of 876 C g-1 (1752 F g-1) at 20 A g-1. Moreover, a device assembled by Ni2P/Co3O4/N-CQDs hierarchical flower-like architecture and p-phenylenediamine functionalized reduced graphene oxide (PPD/rGO) nanosheets depicts a commendable energy density of 53.5 Wh kg-1 at 772.9 W kg-1. This work provides a novel hierarchical multi-component electrode material with decent electrochemical capacities for hybrid supercapacitors, which has a broad prospect in energy storage devices.

The exploration of advanced electrode materials with outstanding electrochemical properties is of considerable importance for hybrid supercapacitors but challenging. In this paper, an effective two-step solvothermal route is demonstrated to synthesize nitrogen-doped carbon dots (NCDs) decorated cobalt-doped nickel sulfide (Co-NiS) flower-like hierarchitectures. Because of the modification with NCDs and doping by cobalt atoms, the resulting Co-NiS/NCDs hierarchitectures exhibit an ultrahigh specific capacity up to 1240 C g−1 (2480 F g−1) at 1 A g−1 and a remarkable rate capability of 790.8 C g−1 (1581.6 F g−1) even at 20 A g−1 when used as advanced electrodes for supercapacitors. More significantly, coupling with ap-phenylenediamine (PPD) modified reduced graphene oxide (rGO) anode, a hybrid supercapacitor device is successfully constructed, which possesses an impressive energy density of 71.6 W h kg−1 at 712.0 W kg−1 and a decent cyclic stability with 78.3% retention after 12 000 cycles at 5 A g−1. The dual improvement strategy may provide insight to rational engineering of novel electrode materials with multi-components for high-performance hybrid supercapacitors.

Developing highly efficient, low-cost and stable electrocatalysts for oxygen evolution reaction (OER) is momentous to achieve the conversion and storage of sustainable energy. Herein, the CoFe(OH) x / GO composites with accordion-like CoFe(OH) x nanosheets clusters dispersed on graphene oxide (GO) sheets are prepared via a template-assisted route. It is found that the OER performance of the CoFe(OH) x / GO composites strongly depends on the content of GO and the mole ratio of Co/Fe. The optimized CoFe(OH) x / GO composites exhibit remarkably enhanced OER electrocatalytic activity in 1 M KOH with a low overpotential of 294 mV at 10 mA cm -2 and a small Tafel slope of 63.4 mV dec -1 , which are far superior to the corresponding Co(OH) 2 / GO and bare CoFe(OH) x . The enhanced electrocatalytic activity can be ascribed to the regulated electronic structure surrounding the active metal sites by introducing Fe, the improved conductivity by GO for faster charge transfer, and the accordion-like hierarchical structure with increased accessible active sites. This work demonstrates a comprehensive strategy to improve the electrocatalytic performance of transition metal hydroxide based OER catalysts.

With the ever-increasing demands for energy resources, the exploration of high energy density hybrid supercapacitors is urgently required. Herein, an effective hydrothermal strategy is demonstrated to construct advanced cathode of nickel carbonate hydroxide (NCH) ultrathin nanosheets anchored nitrogen-doped carbon quantum dots (NCQDs) for hybrid supercapacitors. It is revealed that the NCQDs are evenly deposited on the surface of NCH nanosheets, which provide abundant active sites for NCH nanosheets and endow them improved electrochemical characteristics. The NCH/NCQDs nanosheets deliver a decent electrochemical capacity of 727C g−1 at 1 A g−1 with ameliorative rate capability and cyclic stability. In addition, a hybrid supercapacitor device with an impressive energy density (49.1 Wh kg−1 at 700.3 W kg−1) and stable cycling property (87.5% after 8000 cycles) is fabricated by employing NCH/NCQDs nanosheets and p-phenylenediamine functionalized reduced graphene oxide (PRGO) as cathode and anode. These results indicate the great potential of NCH/NCQDs nanosheets for renewable energy storage.

In this study, a new ternary AgBiO3/GO/NCDs composite (GO = graphene oxide, NCDs = nitrogen-doped carbon dots) has been successfully prepared through in-situ growth of flower-like AgBiO3 on GO/NCDs complex support. The AgBiO3/GO/NCDs composite exhibits significantly enhanced degradation activities towards organic pollutants of rhodamine B, phenol and tetracycline. Especially, the refractory tetracycline (20 mg L−1) can be completely removed within 6.0 min with a dosage of 30 mg of AgBiO3/GO/NCDs under the assistance of peroxymonosulfate (PMS, 0.2 mM). It is revealed that GO in the composite can facilitate the quick and efficient electron transfer and improve the generation of reactive oxygen species during the degradation process, while the NCDs may play double roles as both the electron-acceptor and the reactive site. Besides, the electrons can be captured by PMS to produce plenty of sulfate radicals (SO4 −) with very strong oxidation ability. All these factors collaboratively promote the degradation efficiency of AgBiO3/GO/NCDs towards organic pollutants. The excellent degradation activities of AgBiO3/GO/NCDs endow it with potential application in wastewater purification.

Oxygen evolution catalysts can effectively reduce the high overpotentials of oxidation evolution reaction. Here, we demonstrate that metallic Ag can improve the electrocatalytic performance of Fe-Co-S/N-doped carbon composites, which was prepared by a calcination route. Ag was loaded on the composite by a simple dipping method. With appropriate amount of Ag loading, the over potential to achieve current density of 10 mA cm−2 can make a decrease of 37 mV in 1 M KOH, while the Tafel slope almost doesn't change. It is demonstrated that loading of Ag not only improves the activity of catalytic site, but also cause a higher electrochemically-active surface area. The optimized OER catalyst was then covered on a hematite photoanode. The appropriate loading mass of the catalyst on hematite photoanode was investigated. It was found that the catalyst can improve the photocurrent density of 7 times enhancement at potential of 1.23 V vs RHE. This study demonstrates a surface decoration route to improve the catalytic activity, which would also be extended to other highly efficient catalysts for OER.

The development of simple and cost-effective synthesis methods for electrocatalysts of hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR) is critical to renewable energy technologies. Herein, we report an interesting bifunctional HER and ORR electrocatalyst of Fe/Fe3C@N-doped-carbon porous hierarchical polyhedrons (Fe/Fe3C@N-C) by a simple metal-organic framework precursor route. The Fe/Fe3C@N-C polyhedrons consisting of Fe and Fe3C nanocrystals enveloped by N-doped carbon shells and accompanying with some carbon nanotubes on the surface were prepared by thermal annealing of Zn3[Fe(CN)6]2·xH2O polyhedral particles in nitrogen atmosphere. This material exhibits a large specific surface area of 182.5 m2 g−1 and excellent ferromagnetic property. Electrochemical tests indicate that the Fe/Fe3C@N-C hybrid has apparent HER activity with a relatively low overpotential of 236 mV at the current density of 10 mA cm−2 and a small Tafel slope of 59.6 mV decade-1. Meanwhile, this material exhibits excellent catalytic activity toward ORR with an onset potential (0.936 V vs. RHE) and half-wave potential (0.804 V vs. RHE) in 0.1 M KOH, which is comparable to commercial 20 wt% Pt/C (0.975 V and 0.820 V), and shows even better stability than the Pt/C. This work provides a new insight to developing multi-functional materials for renewable energy application.

The sluggish oxygen evolution kinetics involved in water splitting and various metal-air batteries makes the effective and inexpensive electrocatalysts be highly desirable for oxygen evolution reaction (OER). Herein, an effective and facile two-step route is developed to construct Fe3O4@NiSx composite loaded on reduced graphene oxide (rGO). The morphology and microstructure of the composites were characterized by different characterization techniques. The obtained composites show amounts of heterointerfaces. The shift of binding energy in X-ray photoelectron spectrum demonstrates the existence of interfacial charge transfer effect between Fe3O4 and NiSx. The optimized Fe3O4@NiSx/rGO sample exhibits excellent electrocatalytic performance toward OER in alkaline media, showing 10 mA·cm−2 at η = 330 mV, lower Tafel slope (35.5 mV·dec−1), and good durability, demonstrating a great perspective. The excellent OER performance can be ascribed to the synergetic effect between Fe and Ni species. It is believed that the heterointerfaces between Fe3O4 and NiSx perform as active centers for OER.

This study aimed at developing supercapacitor electrode materials from textile industry waste, thereby mediating waste disposal problem through reuse. Through a simple two-step process, nitrogen-doped hierarchically porous carbons (NHPC) derived from sericin, a waste protein, were synthesized and used for electrochemical capacitors for the first time. The as-prepared NHPC with a specific surface area of 2723 m2 g−1 and a pore volume of 1.42 cm3 g−1 exhibited a high specific capacitance of 287 F g−1 at the current density of 0.5 A g−1, which was comparable or even higher than that of numerous porous carbon materials reported previously. With this electrode, about 93% of the initial capacitance (221 F g−1/5 A g−1) was retained after 10,000 cycles, demonstrating a good cyclic stability. Moreover, the specific capacitance of sericin-derived NHPC is also better than that of fibroin-derived porous carbon. This work not only developed an effective way to prepare high-performance supercapacitor electrode materials from the waste protein, but also provided a strategy for its disposal issue and contributed to the environmental improvement.

FeCo-based materials are promising candidates as efficient, affordable, and sustainable electrocatalysts for oxygen evolution reaction (OER). Herein, a composite based on FeSe2@CoSe2 particles supported on reduced graphene oxide (rGO) was successfully prepared as an OER catalyst. In the catalyst, the CoSe2 phase was located on the FeSe2 surface, forming a large number of exposed heterointerfaces with acidic iron sites because of strong charge interaction between CoSe2 and FeSe2. It is believed that the exposed heterointerfaces act as catalytic active sites for OER via a two-site mechanism, manifesting an overpotential as low as 260 mV to reach the current density of 10 mA cm–2 in 1 M KOH and excellent stability for at least 6 h, which is superior to those of CoSe2/rGO, FeSe2/rGO, as well as most of the FeNi- and FeCo-based electrocatalysts reported in recent literatures. It was demonstrated that the most optimal composite electrocatalysts release more Fe species into the electrolyte during the OER process...

Background: Balance training may be beneficial for patients with osteoporosis, although current results are inconclusive. The aim of this systematic review and meta-analysis was to explore the effect of balance training on falls in patients with osteoporosis. Methods: PubMed, Embase, Web of Science, EBSCO, and Cochrane Library databases were systematically searched. Randomized controlled trials (RCTs) assessing the effect of balance training vs usual activities on falls in patients with osteoporosis were included. Two investigators independently searched articles, extracted data, and assessed the quality of included studies. The primary outcome was fall frequency. This meta-analysis was performed using the fixed- or random-effect model when appropriate. Results: Six RCTs were included in the systematic review and 3 in the meta-analyses. Compared with control groups, a balance training intervention was found to significantly reduce the frequency of falls (risk ratio = 0.63; 95% confidence interval (95% CI) 0.42–0.95; p = 0.03) in patients with osteoporosis, but demonstrated no remarkable influence on the results of the Berg Balance Scale (mean difference –3.66; 95% CI –12.04–4.72; p = 0.39) and Timed Up and Go test (mean difference –1.79; 95% CI –6.05–2.47; p = 0.41). Conclusion: Balance training may significantly reduce the frequency of falls in patients with osteoporosis.

Graphene has received much attention to develop efficient photocatalysts on account of its unique two-dimensional network structure, excellent chemical stability as well as interesting functionalities. Herein, a two-phase self-assembly strategy was applied to prepare graphene oxide (GO)-FePO 4 nanocomposites. The resulting products were characterized by XRD, TEM, EDS, IR and UV–vis spectroscopy. The GO-FePO 4 materials can act as Fenton-like catalysts and display improved photocatalytic activities compared to pure FePO 4 in the degradation of methylene blue under simulated sunlight irradiation. The proposed strategy can be extended to produce graphene-based nanocomposites with various functionalities for the environment protection and energy development.

The construction of battery-type cathodes with glorious electrochemical features is of great significance for hybrid supercapacitors. Herein, an effective one-step calcination strategy is demonstrated for the fabrication of nickel sulfide and cobalt sulfide nanoparticles deposited on ultrathin carbon two-dimensional nanosheets (Ni3S2/Co9S8/C) by employing sodium sulfate (Na2SO4) as the sulfur source and template. Benefiting from the remarkable combination of multiple functional components and the ultrathin two-dimensional architecture, the constructed Ni3S2/Co9S8/C cathode features with a commendable capacity of 1160 C g−1 (2320 F g−1) at 1 A g−1 and a decent cyclic capability at 10 A g−1 (91.3% after 10,000 cycles). In addition, the manufactured hybrid supercapacitor with Ni3S2/Co9S8/C cathode and p-phenylenediamine modified graphene (PMG) anode achieves a maximum energy density of 69.6 Wh kg−1 at 970.5 W kg−1 and an appropriate cyclic capability of 82.6% after 20,000 cycles. These fascinating results reveal the great potential of Ni3S2/Co9S8/C ultrathin nanosheets for practical application.

Compounds of transition metal tripolyphosphate are a kind of stable complexes due to the strong coordination interaction between transition metal ions and the tripolyphosphate groups. Herein Fe/Co tripolyphosphate was loaded on carbon nanotube surface through a simple wet-impregnation method. This strategy enables the effective loading of Fe/Co tripolyphosphate on carbon nanotube surface with tunable Fe/Co molar ratios. The obtained composite can be in situ activated during electrochemical test process. When employed as OER catalyst, it shows a lower overpotential (254 mV for 10 mA cm−2) and faster kinetics (Tafel slope of 36.3 mV dec−1). It was found that the Fe/Co tripolyphosphate on carbon nanotubes was transferred into small-sized oxyhydroxide particles embedded in amorphous matrix acting as catalytic active species. This study provides a low-cost, simple but effective way for the synthesis of favorable pre-catalysts for oxygen evolution.

Designing nanostructured metal oxides (MOs) is a particularly effective approach to enhance their lithium storage properties. However, it is difficult to synthesize MOs with various nanostructures by a facile strategy. Herein, based on the Kirkendall effect, the yolk-shell, hollow, and hierarchical Fe0.8Mn1.2O3 sub-micropolyhedrons are produced by briefly adjusting the calcination temperature of the precursor. Moreover, hollow and hierarchical Fe0.8Mn1.2O3 sub-microcubes can also be synthesized by further aging the precursor and then using the same strategy. Furthermore, the formation mechanism for the above-mentioned nanostructures is carefully studied. Among all prepared Fe0.8Mn1.2O3 nanostructures, the hierarchical sub-micropolyhedrons exhibit the best lithium-ion storage performance. It can deliver an excellent discharge capacity of 1114.3 mAh g−1 after 100 cycles at 200 mA g−1 and superior rate properties (1268.8, 864.1, 698.9, 556.3, and 397.6 mAh g−1 at 0.2, 1, 2, 4, and 8 A g−1, respectively).

Supercapacitors with superior performance and long cycling ability are attractive for the next-generation energy storage devices. Herein, an unique hybrid of nickel hydroxide carbonate nanobelts densely and strongly anchored on reduced graphene oxide nanosheets (HC/RGO) has been designed and synthesized through a facile hydrothermal approach. The as-prepared HC/RGO composites display a nearly two-dimensional architecture. Electrochemical investigation shows that the HC/RGO composite electrode has a maximum specific capacitance of 1662.4 F/g (3.5 F/cm2) at 1.0 A/g with excellent rate capability (64.7% capacitance retention when increasing the current density from 1.0 to 10.0 A/g) and good cyclic stability. The outstanding electrochemical property of HC/RGO composite electrode is possibly attributed to the intrinsic nature of Ni2(OH)2(CO3), the conductive RGO support, and the ultrathin thickness of Ni2(OH)2(CO3) nanounits which can accelerate the electron transport and facilitate the redox reactions. This hydroxycarbonate-based hybrids with excellent electrochemical performance provide an new avenue for designing high-performance supercapacitor electrodes.

In this paper, an all solid Z-scheme Ag3PO4/GO/NCD photocatalyst has been prepared through anchoring nitrogen-doped carbon dots (NCDs) on the Ag3PO4/GO (GO = graphene oxide) composite. The Ag3PO4/GO/NCD photocatalyst exhibits excellent photocatalytic activity for the degradation of organic pollutants, methylene blue (MB), rhodamine B (RhB) and phenol, under visible-light irradiation. The pollutants MB (10 mg L−1), RhB (10 mg L−1) and phenol (50 mg L−1) could be efficiently degraded within 2.5 min, 5 min and 120 min, respectively, which are much better than that over Ag3PO4 and Ag3PO4/GO, indicating that the introduction of NCDs can further improve the photocatalytic activity of Ag3PO4/GO. Moreover, after four photocatalytic cycles, the photocatalytic activity of Ag3PO4/GO/NCDs shows only a slight decrease, demonstrating high photocatalytic stability. It is revealed that GO in the photocatalyst acts as a semiconductor and forms a Z-scheme heterojunction with Ag3PO4, while NCDs improve the oxygen activation, enhance the light harvesting capacity and serve as the reaction sites during the photocatalytic process. This study highlights the potential application of highly efficient NCD-modified photocatalysts in waste water purification.

Three-dimensional (3D) graphene aerogel and its composite with interconnected pores have aroused continuous interests in energy storage field owning to its large surface area and hierarchical pore structure. Herein, we reported the preparation of 3D nitrogen-doped graphene/polyaniline (N-GE/PANI) composite foam for supercapacitive material with greatly improved electrochemical performance. The 3D porous structure can allow the penetration and diffusion of electrolyte, the incorporation of nitrogen doping can enhance the wettability of the active material and the number of active sites with electrolyte, and both the N-GE and PANI can ensure the high electrical conductivity of total electrode. Moreover, the synergistic effect between N-GE and PANI materials also play an important role on the electrochemical performance of electrode. Therefore, the as-prepared composite foam could deliver a high specific capacitance of 528 F g −1 at 0.1 A g −1 and a high cyclic stability with 95.9% capacitance retention after 5000 charge-discharge cycles. This study provides a new idea on improving the energy storage capacity of supercapacitors by using 3D graphene-based psedocapacitive electrode materials.

In this work, an excellent ternary visible-light all solid Z-scheme photocatalytic heterojunction of g-C3N4/GO/AgBr has been prepared by the attachment of graphene oxide (GO) to the surface of g-C3N4, followed by in-situ growth of AgBr nanoparticles on GO sheets. The g-C3N4/GO/AgBr heterojunction exhibits excellent photocatalytic efficiency for RhB degradation, which is about 17.5, 7.9, 3.5, 4.0 and 2.2 times as high as that of P25, g-C3N4, AgBr, g-C3N4/GO and g-C3N4/AgBr heterojunction, indicating the introduction of GO into the system largely improved the capability of the photocatalysis since GO acted as the charge transmission bridge between g-C3N4 and AgBr. Moreover, the photocatalytic performance of g-C3N4/GO/AgBr just showed a slight decrease after 4 degradation cycles, demonstrating a high stability of the g-C3N4/GO/AgBr photocatalyst. The photocatalytic mechanism investigation indicated that O2− and h+ are the major active species in the photocatalytic process. It is expected that the GO-inserted Z-scheme photocatalytic heterojunction could be applied to practical pollutant degradation.

Designing highly efficient and stable electrocatalysts for hydrogen evolution reaction (HER) is critical to the large-scale application of clean hydrogen energy. Herein, NiFe@N-doped graphene microtube (NiFe-NGMT) composites have been synthesized by a facile metal organic framework (MOF) precursor route, and employed as an effective electrocatalyst for HER. The NiFe-NGMT composites, which consist of NiFe alloy particles enveloped in N-doped graphene microtubes with a diameter of 1–2 μm, were synthesized by thermal annealing a MOF precursor of nickel nitroprussides (NiFe(CN)5NO·2H2O) in nitrogen atmosphere. By adjusting the pyrolysis temperature, the diameter of the tubular graphene can be tuned to 50–200 nm. The obtained NiFe-NGMT composites exhibit excellent catalytic activity for HER with a low overpotential (70.5 mV) and a small Tafel slope (63.4 mV per decade), which afford the materials promising application for splitting water to generate hydrogen.

ZIF-67 derived CoP-decorated nitrogen-doped porous carbon (CoP-NPC) polyhedra anchored on reduced graphene oxide (RGO) sheets have been successfully prepared through an efficient pyrolysis–phosphidation–assembly strategy. The resulting CoP-NPC/RGO composite as an electrode for supercapacitors shows an enhanced electrochemical performance with high capacitances of 466.6 F g−1 at 1 A g−1 and 252 F g−1 at 20 A g−1, as well as 94.7% of capacitance retention after 10 000 cycles in 1 M H2SO4 solution. Moreover, the symmetrical two-electrode device assembled from CoP-NPC/RGO electrodes delivers a high energy density of 12 W h kg−1 at a power density of 500 W kg−1 and excellent long-term cycling stability (93% of the initial capacitance after 10 000 cycles at 10 A g−1). This superior electrochemical performance of CoP-NPC/RGO can be ascribed to its 3D interconnected porous structure and the synergistic effect between CoP and the nitrogen-doped carbon matrix. The unique architecture of the composites can effectively enhance the electrochemical performance by shortening the diffusion distance of electrolyte ions and improving the electrical conductivity and the contact area between active materials and the electrolyte. The excellent electrochemical performances make CoP-NPC/RGO a promising electrode material for high-performance supercapacitors.

Transition metal oxides (TMOs) are promising anode materials for next-generation lithium-ion batteries (LIBs). Nevertheless, their poor electronic and ionic conductivity as well as huge volume change leads to low capacity release and rapid capacity decay. Herein, a reduced graphene oxide (rGO)-encapsulated TMOs strategy is developed to address the above problems. The Co3 O4 -CoFe2 O4 @rGO composites with rGO sheets-encapsulated Co3 O4 -CoFe2 O4 microcubes are successfully constructed through a simple metal-organic frameworks precursor route, in which Co[Fe(CN)5 NO] microcubes are in situ coated by graphene oxide sheets, followed by a two-step calcination process. As anode material of LIBs, Co3 O4 -CoFe2 O4 @rGO exhibits remarkable reversible capacity (1393 mAh g-1 at 0.2 A g-1 after 300 cycles), outstanding long-term cycling stability (701 mAh g-1 at 2.0 A g-1 after 500 cycles), and excellent rate capability (420 mAh g-1 at 4.0 A g-1 ). The superior lithium storage performance can be attributed to the unique double-buffer structure, in which the outer flexible rGO shells can prevent the structure collapse of the electrode and improve its conductivity, while the hierarchical porous cores of Co3 O4 -CoFe2 O4 microcubes can buffer the volume expansion. This work provides a general and straightforward strategy for the construction of novel rGO-encapsulated bimetal oxides for energy storage and conversion application.

High-volume capacity electrode materials are the key to the development and application of lithium-ion batteries in electric vehicles and small consumer electronics. Here, through simply calcination the W-based metal-organic frameworks, a novel Fe2WO6 hierarchical porous octahedra with oxygen vacancies are successfully constructed. Oxygen vacancies can enhance the conductivity of the material, provide more Li+ storage sites, while the hierarchical porous structure effectively buffers the volume expansion and promotes the diffusion of the electrolyte. Besides, by introducing the heavy element W, the compact density of Fe2WO6 is as high as 2.9 g cm−3. Thus, an ultrahigh volumetric capacity of 4785 mAh cm−3 (0.2 A g−1), and superior rate capability of 2323 mAh cm−3 (4.0 A g−1) could be achieved by Fe2WO6 anode, which is the best performance of W-based anode so far. Furthermore, the mechanism of the significant increment in capacity is also investigated. The new findings indicate that the phase transition and structural rearrangement of the Fe2WO6 electrode, along with the enhanced reversible formation and decomposition of the polymer/gel-like film, collectively result in the capacity evolution during cycling. Remarkably, the introduction of oxygen vacancies and high density makes hierarchical porous Fe2WO6 a promising anode for high volumetric lithium storage.

Fiber-shaped supercapacitors (FSSCs) have attracted increasing attention for wearable electronics. Herein, an asymmetrical fiber-shaped supercapacitor, AFSSCs-ICS, with an innovative encapsulated core-sheath architecture has been successfully constructed for the first time. The sword-scabbard inspired AFSSCs-ICS was fabricated by simply inserting a ‘sword’ positive electrode, PPy-MWCNTs-silk, into one tubular graphene ‘scabbard’ negative electrode with H2SO4/PVA gel as electrolyte. Notably, our newly designed PPy-MWCNTs-silk electrode had an ultrahigh length specific capacitance of 15.3 mF cm−1 (corresponding to high areal or volumetric capacitance of 676.9 mF cm−2 or 376.3 F cm−3), representing one of the highest levels among the fabric yarn derived electrodes, while the hollow graphene tube depicted a superior linear capacitance of 19.1 mF cm−1, which could match well with that of the PPy-MWCNTs-silk electrode. Benefiting from the innovative yet rational structure, and ideally balanced charges, the AFSSCs-ICS had an extended operating potential of 1.6 V, and an outstanding length specific capacitance of 2.3 mF cm−1 with a very admirable energy density of 0.8 μWh cm−1, dramatically surpassing numerous reported FSSCs. Moreover, the AFSSCs-ICS device also afforded superb electrochemical and mechanical stabilities with retentions of 81% after 3000 charging-discharging cycles and 95–105% under bending degrees from 0 to 150°. This study may pave a new way for constructing coaxial fiber-shaped energy source unit for next-generation wearable and portable miniaturized electronics.

Structural data from the supercooled Zr55Cu35Al10 ternary alloy liquid were collected in-situ in the temperature range from 1172 K to 953 K during continuous cooling using the high-energy synchrotron X-ray Advanced Photon Source. The lowest-r peaks of the pair distribution functions (PDFs) sharpened, becoming higher and narrower, with decreasing temperature. The experimental data are in good agreement with the results of ab-initio molecular dynamics (AIMD) simulations. Quantitative analyses of the simulated structures (clusters, interconnecting zones and free volume) in the supercooled liquid were made based on the tight-bond cluster model. The significance of Al additions on the increase in glass forming ability (GFA) was estimated from the simulated structures and their electronic structure analysis.

Graphene oxide (GO)–AgIO4 nanocomposites with excellent photocatalytic performance have been prepared through a facile ion-exchange method. The as-prepared samples are characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy. The GO–AgIO4 nanocomposites exhibit an enhanced photocatalytic activity in the degradation of organic pollutants as compared to bare AgIO4. It is revealed that the introduction of GO can relieve the agglomeration of AgIO4 particles, enhance the light absorption of the materials, and promote the separation of photoexcited electron–hole pairs. In addition, the possible transfer and separation behaviors of the charge carriers and the photocatalytic mechanism are discussed in detail. The excellent photocatalytic performance makes the GO–AgIO4 nanocomposites a promising photocatalyst for organic pollutant treatment.

In this work, cuprous oxide (Cu2O) hollow cubes were synthesized on reduced graphene oxide (RGO) nanosheets by a facile one-pot refluxing approach. The as-prepared Cu2O/RGO nanocomposites were characterized by X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy. It was revealed that Cu2O with a well-defined hollow cubic morphology is homogeneously dispersed on the surface of RGO nanosheets. The electrocatalytic properties of Cu2O/RGO nanocomposites for glucose oxidation were investigated by cyclic voltammetry and chronoamperometry. It was found that the constructed glucose sensor has a wide linear range of 0.01–9.0 mM (R2 = 0.996) with a high sensitivity of 813.713 μA cm−2 mM−1 and a low detection limit of 0.44 μM based on signal/noise = 3. Compared to bare Cu2O and previously reported Cu2O-based glucose sensors, the as-prepared Cu2O/RGO nanocomposite glucose sensor showed remarkably enhanced electrocatalytic activity. In addition, the electrode also exhibited an excellent anti-interference ability. The excellent electrocatalytic performance together with simple and low-cost preparation makes Cu2O/RGO nanocomposites attractive for glucose sensor application.

In this study, a facile refluxing approach has been developed to load Mn 3 O 4 nanocrystals onto reduced graphene oxide (RGO) sheets. The microstructure and morphology of the resulting Mn 3 O 4 /RGO nanocomposites were systematically investigated by X-ray diffraction (XRD), Raman spectroscopy and transmission electron microscopy (TEM). The results reveal that Mn 3 O 4 nanocrystals with particle size of several nanometers were uniformly dispersed on the surface of RGO sheets. The electrochemical properties of the resulting Mn 3 O 4 /RGO nanocomposites were investigated by using them as electrode materials for a supercapacitor. It is found that the Mn 3 O 4 /RGO nanocomposites exhibit enhanced specific capacitance and long-term stability. The enhanced capacitive performance can be attributed to the synergistic effect among Mn 3 O 4 and RGO. The facile synthesis and the enhanced capacitive performance demonstrate the promising application of the Mn 3 O 4 /RGO nanocomposites as supercapacitor electrode materials.

In this work, a series of zeolitic imidazolate framework (ZIF-8)/graphene oxide (GO) supported Pt or Pd nanoparticles (NPs) with different loading amounts were obtained via a simple liquid impregnation of ZIF-8/GO with metal salt solution followed by a reduction treatment. Powder X-ray diffraction, Fourier transform infrared spectra, scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, inductively coupled plasma-emission spectroscopy, and nitrogen adsorption-desorption measurements were employed to investigate the physical and chemical properties of as-prepared samples. The Pt and Pd particles in the corresponding composites have average diameters of about 4.5 and 4.6 nm, respectively. All metal-doped ZIF-8/GO composites maintained the host framework of pure ZIF-8, although their specific surface areas were significantly reduced. The introduction of metal catalysts into the ZIF-8/GO matrix does not favor the hydrogen adsorption performance at 77 K due to the physisorption mechanism. In contrast, the adsorption isotherms at 298 exhibited dramatically improved storage capacities, by factors of 3.8–11.8 (Pt-doped ZIF-8/GO) and 7.9–12.6 (Pd-doped ZIF-8/GO) times over pristine ZIF-8 at the hydrogen pressure of 860 mmHg. This enhancement is mainly attributed to the spillover mechanism by metal catalysts into the ZIF-8/GO support. More importantly, the effect of catalysts dispersion and content on the level of hydrogen storage was also explored, which showed that the composites with the most homogeneous metal distribution and moderate loading amount would display the highest hydrogen adsorption performance.

Cobalt sulfide materials have attracted enormous interest as low-cost alternatives to noble-metal catalysts capable of catalyzing both oxygen reduction and oxygen evolution reactions. Although recent advances have been achieved in the development of various cobalt sulfide composites to expedite their oxygen reduction reaction properties, to improve their poor oxygen evolution reaction (OER) activity is still challenging, which significantly limits their utilization. Here, the synthesis of Fe3O4-decorated Co9S8 nanoparticles in situ grown on a reduced graphene oxide surface (Fe3O4@Co9S8/rGO) and the use of it as a remarkably active and stable OER catalyst are first reported. Loading of Fe3O4 on cobalt sulfide induces the formation of pure phase Co9S8 and highly improves the catalytic activity for OER. The composite exhibits superior OER performance with a small overpotential of 0.34 V at the current density of 10 mA cm−2 and high stability. It is believed that the electron transfer trend from Fe species to Co9S8 promotes the breaking of the Co–O bond in the stable configuration (Co–O–O superoxo group), attributing to the excellent catalytic activity. This development offers a new and effective cobalt sulfide-based oxygen evolution electrocatalysts to replace the expensive commercial catalysts such as RuO2 or IrO2.

Based on pair distribution function studies, a structural parameter, derived from the number of cluster connecting bonds and the coordination number, and energy analysis have been introduced to describe different kinds of local clusters in the liquids and glasses. By applying these analyses to a widely studied Zr–Cu–Al base alloy system, we found that Zr-, Cu- and Al-centered first shell clusters showed different structural evolution and energy distributions during cooling. In terms of their structure and energy states, it is confirmed that the Al-centered first shell clusters play dominant role in the appearance of glass transition prior to the crystallization.

Highly uniform Ag/ZnO/ZnFe 2 O 4 ternary composites with porous and hollow nanostructures are synthesized using Ag-loaded Prussian blue analogue Zn 3 Fe(CN) 6 · x H 2 O (Ag-ZnPBA) as the precursor via a facile calcination process. The cubic morphology of the precursor is well inherited after the calcination process. The microstructures of the ternary composites can be tuned from porous to hollow interiors by simply changing the heating modes. The loading amount of Ag in the composites can be adjusted by controlling the initial adsorption amount of Ag + ions on the metal-organic framework of ZnPBA. The as-synthesized ternary Ag/ZnO/ZnFe 2 O 4 shows significantly enhanced photocatalytic activity towards the degradation of organic dye as compared to the binary counterpart of ZnO/ZnFe 2 O 4 , demonstrating the important role of Ag for the photocatalytic process. It seems that the combination of the three components of Ag, ZnO, ZnFe 2 O 4 can form type-II band alignment and Schottky barrier, which would inhibit the recombination of photo-generated electrons and holes. Moreover, benefited from the excellent magnetic property of ZnFe 2 O 4 , the composite photocatalysts can be easily recovered from reaction systems by a magnet. This work presents a facile and effective route for the construction of uniform multi-component nanocomposites with intriguing structures and multiple functions.

Two-dimensional (2D) nanosheets possess the very essential features of nanomaterials, including quantum-confinement effects and unconventional reactivity, and are of special interest for a variety of promising applications. Here we report a facile chemical transformation strategy to prepare porous ZnS nanosheets via the organic-inorganic hybrid ZnS(butylamine) nanosheet-like precursor prepared from zinc diethyldithiocarbamate. The hybrid ZnS(butylamine) precursor show unique nanosheet-like structure composed by ZnS nanocluster region and non-crystalline region. The ZnS nanoclusters with crystallized state show the same crystal orientation in the nanosheets. A simple calcination process in nitrogen can induce the transformation of ZnS(butylamine) hybrid precursor to porous ZnS nanosheets. Different calcination temperature will cause the formation of porous ZnS nanosheets with different microstructure. In addition, the photoelectrochemical properties of the ZnS-based products including ZnS(butylamine) and porous ZnS nanosheets were investigated. This organic-inorganic hybrid precursor strategy to porous sulfides would also be suitable for fabricating other metal chalcogenides.

Textile-based supercapacitors having intrinsically mechanical flexibility are regarded as hopeful power sources for wearable electronics. Herein, four PANI/graphene/textile electrodes are successfully synthesized using a simple ‘dipping and drying’ procedure followed by in-situ polymerization of aniline. The effects of the acidic dopants on the morphological, structural and capacitive characteristics of the resultant electrodes are systematically investigated. The PANI/graphene/textile-HCl (PANI/G/T-HCl) depicts a maximum areal specific capacitance of 1601 mF cm−2 at the current density of 1 mA cm−2, which is apparently higher than numerous textile-electrodes reported so far, and an attractive cycling stability with a capacitance retention more than 75% after 10,000 cycles at 10 mA cm−2. The constructed all-solid-state supercapacitor device affords an outstanding energy density of 755 mWh m−2 at a power density of 1448 mW m−2. The capacitive performance of this device remains stable under bending degrees from 0 to 180° and exhibits a high capacity retention of 77% over 600 bending cycles, verifying a superior mechanical flexibility and capacitive stability with extensive prospects for practical applications.

Tin (Sn)-based anodic materials have attracted tremendous attention in lithium-ion batteries (LIBs) owing to their high theoretical capacity and low potential (0.5 V versus Li/Li+). However, Sn-based anodic materials usually suffer from serious structural collapse and large volume expansion. To overcome this obstacle, herein, a dual-buffer structure of tin-cobalt (Sn-Co) alloy-based nanocomposite was designed through thermal annealing of a cyanometallic framework. The inactive Co acts as robust framework to buffer the volume expansion of Sn-Co alloy nanoparticles, and the reduced graphene oxide (rGO) matrix can reduce the aggregation of Sn-Co nanoparticles as well as alleviate the structure collapse of electrode during long-term cycling. As LIBs anodes, the Sn-Co/rGO composites exhibit a high reversible capacity (1055 mAh g−1 at 0.2 A g−1 after 250 cycles), good rate capability (320 mAh g−1 at 5 A g−1), and outstanding long-term cycling performance (720 mAh g−1 at 1 A g−1 after 600 cycles). When coupled with LiFePO4, the full battery can also display high electrochemical performance in terms of discharge capacity and cyclic stability.

Al-based glassy alloys (metallic glasses) have been of great scientific and technological interest as a high specific strength and high corrosion resistant materials. However, the low glass-forming ability (GFA) is still a choke point that greatly influences the applications. In order to further comprehend the glass formation mechanism and investigate the possibility of enhancing the GFA, it is important to obtain the definite information on the atomic scale glassy structures in correlation with properties and to study the composition dependence of crystallization and properties of Al-based metallic glasses. The purpose of this paper is to summarize the structure characteristics and crystallization behavior in conjunction with alloy component in Al-based metallic glasses and to investigate the possibility of synthesizing an Al-based bulk metallic glass with better engineering performances. This may assist to learn the structural features systematically and understand the development and current status for Al-based metallic glasses.

Inspired by the naturally occurring silk, in this work, a novel parallel-like fiber-shaped supercapacitor (PFSS) was developed by using two silk-derived fiber electrodes. The ternary electrode, PANI@F-MWCNT@silk, was prepared by decorating raw silk yarn with 13 wt% of carboxyl-functionalized multi-walled carbon nanotube (F-MWCNT) and 16 wt% of polyaniline (PANI), which were utilized as a conductive interlayer and a pseudocapacitive wrapping layer, respectively. In a three-electrode configuration, the PANI@F-MWCNT@silk showed a large area-normalized capacitance of 95.5 mF cm−2, and an ultrahigh volumetric capacitance of 63.7 F cm−3 at 0.1 mA (0.1 mA = 5.3 mA cm−2 and 3.5 A cm−3), which were obviously higher than numerous polyester fiber electrodes, and also comparable to or even better than many metal wire electrodes reported so far. The symmetric parallel-like all-solid-state supercapacitor device based on PANI@F-MWCNT@silk demonstrated an attractive capacitive performance with a high energy density of 1.22 mWh m−2 at a power density of 127 mW m−2. Moreover, benefiting from the extraordinary mechanical properties of silk, this ternary electrode exhibited a very large elongation of 33% with a high tensile strength of 225 MPa, and the silk-inspired PFSS could maintain more than 80% of its initial capacitance under an applied strain of 20%, suggesting a superb capacitive stability against deformations. Notably, the proposed fibrous substrate, which has abundantly existed in nature, may open up a new strategy to develop high-efficiency fiber-shaped power storage devices for wearable electronics.

Owing to their unique electronic properties and capability to host diverse functional groups on the surface, carbon dots (CDs) have attracted increasing attention in energy storage field. Herein, ultrathin nitrogen-doped carbon dots (NCDs) decorated nickel hydroxide (Ni(OH)2) nanosheets were fabricated by a facile hydrothermal approach, where NCDs play an important role as a structure-directing agent in tuning the size and thickness of the Ni(OH)2. With the merits of the battery-type faradaic behavior of Ni(OH)2 and high electronic properties of NCDs, the achieved Ni(OH)2/NCDs ultrathin nanosheets show a specific capacitance of about 1711.2 F g−1 at a current density of 1 A g−1, which is twice more than that of pristine Ni(OH)2. A hybrid supercapacitor device was constructed using Ni(OH)2/NCDs ultrathin nanosheets as the positive electrode and three-dimensional graphene (3DGE) as the negative electrode, respectively, which presents high energy density of 23.8–34.6 Wh kg−1 at power density of 700–7000 W kg−1. The enhanced electrochemical properties of Ni(OH)2/NCDs nanocomposite hold potential for future high-performance energy storage applications.

Herein, Co nanoparticles with high dispersivity were grown in situ on reduced graphene oxide (RGO) nanosheets by an environmentally friendly and facile one-step strategy. The as-synthesized products were characterized by X-ray powder diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The magnetic and catalytic properties of the RGO/Co nanocomposites were systematically investigated. The results reveal that the RGO/Co nanocomposites have room-temperature ferromagnetic characteristics with Co particle size below single domain size. In addition, these RGO/Co nanocomposites also exhibit excellent catalytic activities toward the reduction of 4-nitrophenol by NaBH4 and enhanced electrocatalytic properties for the oxidation of glucose. It is believed that this eco-friendly and facile route can be extended to synthesize other metal nanostructures on RGO nanosheets with various functions, and provides a new opportunity for the application of graphene/metal nanocomposites.