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Rechargeable aluminum-ion batteries have attracted great attention due to the high theoretical volumetric capacity, good safety and abundant sources. Although tremendous efforts have been concentrated on exploring novel electrode materials for aluminum-ion batteries, the electrochemical mechanism still need to be further investigated. In this work, we found that even without employing any initial anode materials, the aluminum-ion batteries assembled with graphite cathode, AlCl3/ion liquid based electrolyte and various anodic current collectors still can be stably charged/discharged. A variety of carbon or metal based materials can be utilized as anodic current collectors in the initial-anode-free aluminum-ion batteries; however, their anti-corrosion capabilities against Cl− ions do greatly affect the battery performances. The electrochemical mechanism of initial-anode-free aluminum-ion batteries were comprehensively investigated by a series of in-situ and ex-situ spectroscopic and microscopic methods, revealing the reversible Al metal plating/stripping processes on the anodic current collectors during the charge-discharge cycles. We hope this work may provide new insights into the key component design and mechanism study of initial-anode-free multivalent secondary batteries.

Solar-powered CO2 conversion represents a promising green and sustainable approach for achieving a carbon-neutral economy. However, the rational design of a wide-spectrum sunlight-driven catalysis system for effective CO2 reduction is an ongoing challenge. Herein, we report the preparation of a rhodium/aluminum (Rh/Al) nanoantenna photothermal catalyst that can utilize a broad range of sunlight (from ultraviolet to the near-infrared region) for highly efficient CO2 methanation, achieving a high CH4 selectivity of nearly 100% and an unprecedented CH4 productivity of 550 mmol·g-1·h-1 under concentrated simulated solar irradiation (11.3 W·cm-2). Detailed control experiment results verified that the CO2 methanation process was facilitated by the localized surface plasmonic resonance and nanoantenna effects of the Rh/Al nanostructure under light irradiation. In operando temperature-programmed Fourier transform infrared spectroscopy confirmed that CO2 methanation on the Rh/Al nanoantenna catalyst was a multistep reaction with CO as a key intermediate. The design of a wide-spectrum solar-driven photothermal catalyst provides a feasible strategy for boosting CO2-to-fuel conversion.

Nanozyme is a collection of nanomaterials with enzyme-like activity but exhibits higher environmental tolerance and long-term stability than their natural counterparts. Improving the catalytic activity and expanding the category of nanozymes are prerequisites to complement or even supersede natural enzymes. Specifically, a powerful hydrolytic nanozyme is demanded to degrade the unsustainable substance which natural enzymes hardly achieve. However, the development of hydrolytic nanozymes is still hindered by diverse hydrolytic substrates and following complicated mechanisms. Here, we apply two strategies which are informed by data to screen and predict catalytic active sites of MOF (metal–organic framework) based hydrolytic nanozymes. One is to increase the intrinsic activity by finely tuned Lewis acidity of the metal clusters. The other is to adjust the volume density of the active sites by shortening the length of ligands. Finally, we construct a Ce-FMA-MOF-based hydrolytic nanozyme with robust cleavage ability towards phosphate bonds, amide bonds, glycosidic bonds whose energy ascend in order; and even their mixture, biofilms. This work provides a rational methodology to design hydrolytic nanozyme, enriches the diversity of nanozymes, and potentially sheds a light on the evolution of enzyme engineering in the future.

Rechargeable aluminum-ion batteries (RAIBs) have attracted increasing attention owing to their high theoretical volumetric capacity, high resource abundance, and good safety performance. However, the existing RAIB systems usually exhibit relatively low specific capacities limited by the cathode materials. In this study, we developed a one-step chemical vapor deposition method to prepare single-crystal orthogonal Nb2O5 nanotubes for serving as high-performance electrode materials for RAIBs, showing a high reversible capability of 556 mA h g-1 at 25 mA g-1 and good thermal endurability at elevated temperatures (50 °C). A combination of a series of detailed ex situ structural characterization studies verified the reversible intercalation/deintercalation of chloroaluminate anions (AlCl4-) into/from the (001) planes of monocrystalline Nb2O5 nanotubes. It also revealed that the nanoarchitecture of Nb2O5 nanotubes with thin tube walls, hollow inner space and a short ion transport distance is conducive to the rapid kinetics of the insertion/extraction process. This work provides a promising route to design high-performance electrode materials based on transition metal compounds for RAIBs via the rational modulation of their structure and morphology.

Lithium–sulfur (Li–S) batteries with high theoretical energy density have caught enormous attention for electrochemical power source applications. However, the development of Li–S batteries is hindered by the electrochemical performance decay that resulted from low electrical conductivity of sulfur and serious shuttling effect of intermediate polysulfides. Moreover, the areal capacity is usually restricted by the low areal sulfur loadings (1.0–3.0 mg cm–2). When the areal sulfur loading increases to a practically accepted level above 3.0–5.0 mg cm–2, the areal capacity and cycling life tend to become inferior. Herein, we report an effective polysulfide mediator composed of nitrogen-doped carbon nanotube (N-CNT) forest planted on cobalt nanoflowers (N-CNTs/Co-NFs). The abundant pores in N-CNTs/Co-NFs can allow a high sulfur content (78 wt %) and block the dissolution/diffusion of polysulfides via physical confinement, and the Co nanoparticles and nitrogen heteroatoms (4.3 at. %) can enhance the polysulfide...

Sodium-ion batteries (SIBs) have been considered as one of the promising alternatives for lithium-ion batteries, owning to the abundant reserve and low cost of sodium-related salts. However, SIBs usually suffer from the sluggish kinetics of Na+ and the serious volume expansion of anode materials, which inevitably restrict the performance of SIBs. Herein, electroconductive wrinkled anatase-phase black titanium oxide nanosheets with rich oxygen vacancies (OVs-TiO2-x) was found to have an ultrafast Na+ insertion and extraction kinetics as anode material in SIBs. The wrinkled structure can significantly reduce the Na+ diffusion length, and the conductive networks formed by wrinkled OVs-TiO2-x can boost the electron transfer during Na+ insertion and extraction processes. With the rapid Na+ insertion/extraction ability, wrinkled OVs-TiO2-x delivers excellent sodium storage performance with high reversible capacity, ultra-high rate capability with the capacity reaches 91 mAh g−1 even at 20,000 mA g−1, and ultra-long cycling stability. These properties demonstrated the great potential of wrinkled OVs-TiO2-x to serve as a realistic choice of anode materials in SIBs.

Hybrid lithium-ion capacitors (HLICs) have drawn great attention as promising energy devices, because they can integrate the high energy density of lithium ion batteries and the high power density of supercapacitors, and their low cost and long cycling-life are well suited to large-scale energy storage. However, the development of HLICs is usually limited by the kinetics mismatch between the battery-type anode and capacitor-type cathode. In this study, hierarchical Co3ZnC nanoparticle encapsulated mesoporous nitrogen-doped carbon nanopolyhedra (Co3ZnC@NC) synthesized by one-step pyrolysis of bimetallic-organic-frameworks are used as anode material for HLICs, exhibit high lithium storage capacity and excellent rate performance. Moreover, heteroatom-doped microporous carbon (MPC) derived from nature-abundant biomass (pine needles) are employed as cathode material, demonstrating good rate capability and long cycle stability. As a result, the as-prepared Co3ZnC@NC||MPC HLICs deliver high energy densities (up to 141.4 Wh kg−1), high power densities (up to 10.3 kW kg−1) and long cycle life within the wide operating voltage range (1.0–4.5 V). These encouraging results of the HLICs bridge the gap between supercapacitors and batteries, and show great potential in next-generation energy storage devices.

In the development of lithium-sulfur (Li-S) batteries, various approaches have been adopted to enhance the electronic conductivity of the sulfur cathode and alleviate the shuttle effect of polysulfides; however, the strategies providing efficient solutions are still limited. To further improve the electrochemical performance of Li-S batteries, in this work we propose a new strategy involving the incorporation of a three-dimensional functional spongy framework as polysulfide reservoir layer, with strong absorbability and electrocatalytic activity towards sulfur species. The spongy framework has a hierarchical architecture composed of highly conductive Ni foam/graphene/carbon nanotubes/MnO2 nanoflakes (NGCM). The strongly interconnected Ni foam, graphene, and carbon nanotubes of the NGCM sponge facilitate electron transfer during discharge/charge processes; moreover, the superlyophilic properties of the NGCM sponge ensure good wettability and interface contact with the Li-S electrolyte, and the porous MnO2 nanoflakes provide strong chemisorptive and electrocatalytic effects on polysulfides (as confirmed theoretically and experimentally). The NGCM sponge, serving as a polysulfide reservoir layer attached on a conventional sulfur-mixed carbon nanotubes (S/CNTs) cathode, can provide improved reversible capacity, rate capability (593 mAh·g–1 at 3.0 C), and cycling stability. In addition, the self-discharge rate is greatly reduced, owing to the efficient conservation of polysulfides in the NGCM spongy framework.

An efficient self-standing hydrogen evolution electrode was prepared by in situ growth of stacked ultrathin TiO2/MoS2 heterolayers on carbon paper (CP@TiO2@MoS2). Owing to the high overall conductivity, large electrochemical surface area and abundant active sites, this novel electrode exhibits an excellent performance for hydrogen evolution reaction (HER). Remarkably, the composite electrode shows a low Tafel slope of 41.7 mV/dec, and an ultrahigh cathodic current density of 550 mA/cm2 at a very low overpotential of 0.25 V. This work presents a new universal strategy for the construction of effective, durable, scalable, and inexpensive electrodes that can be extended to other electrocatalytic systems.

Overall water splitting driven by a sustainable solar energy source has been recognized as a promising route to produce clean and renewable hydrogen fuel. However, its practical application is restricted by the low energy conversion efficiency and poor stability of photocatalysts. Herein, we report the realization of highly efficient overall water splitting promoted by bifunctional bimetallic phosphide (Ni0.5Co0.5P) nanowire arrays vertically grown on carbon paper (Ni0.5Co0.5P/CP) and driven by highly stable all-inorganic perovskite solar cells (PSCs). The Ni0.5Co0.5P/CP electrocatalysts can provide abundant active sites, high electrical conductivity, and good contact interface with the electrolyte, thus showing remarkable activity and great durability for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The electrolyzer assembled with both the Ni0.5Co0.5P/CP anode and cathode can afford a current density of 10 mA cm−2 at only 1.61 V and allow consecutive water splitting. The all-inorganic PSCs based on a CsPb0.9Sn0.1IBr2 light absorber and a nanocarbon electrode exhibit remarkable stability. When driven by all-inorganic PSCs, the electrolyzer delivers a high overall energy conversion efficiency (3.12%) and good long-term durability.

As emerging 2D materials, arsenene and arsenic materials have attracted rising interest in the past few years. The diverse crystalline phases, exotic electrical characteristics, and widespread applications of 2D arsenene and arsenic bring them great research value and utilization potential. Herein, the recent progress of 2D arsenene and arsenic is reviewed in terms of fundamental properties, preparation, and applications. The fundamental properties of 2D arsenene and arsenic, including the crystal phases, environmental stability, and electrical structure, from theoretical to experimental reports are first summarized. Then, the experimental processes for preparing 2D arsenene and arsenic, along with their respective advantages and disadvantages, are introduced including epitaxial growth, mechanical exfoliation, and liquid-phase exfoliation. Moreover, applications of 2D arsenene and arsenic are discussed, suggesting a wide range of applications of 2D arsenene and arsenic in field-effect transistors, sensors, catalysts, biological applications, and so on. Finally, some perspectives about the challenges and opportunities of promising 2D arsenene and arsenic are provided. This review provides a helpful guidance and stimulates more focus on future explorations and developments of 2D arsenene and arsenic.

Rechargeable silicon anode lithium ion batteries (SLIBs) have attracted tremendous attention because of their merits, including a high theoretical capacity, low working potential, and abundant natural sources. The past decade has witnessed significant developments in terms of extending the lifespan and maintaining high capacities of SLIBs. However, the detrimental issue of low initial Coulombic efficiency (ICE) toward SLIBs is causing more and more attention in recent years because ICE value is a core index in full battery design that profoundly determines the utilization of active materials and the weight of an assembled battery. Herein, a comprehensive review is presented of recent advances in solutions for improving ICE of SLIBs. From design perspectives, the strategies for boosting ICE of silicon anodes are systematically categorized into several aspects covering structure regulation, prelithiation, interfacial design, binder design, and electrolyte additives. The merits and challenges of various approaches are highlighted and discussed in detail, which provides valuable insights into the rational design and development of state-of-the-art techniques to deal with the deteriorative issue of low ICE of SLIBs. Furthermore, conclusions and future promising research prospects for lifting ICE of SLIBs are proposed at the end of the review.

Sodium-ion batteries (SIBs) are being increasingly studied due to their cost-effectiveness, high energy density and abundant resources. However, because of scanty interlayer spacing, commercial graphite-based materials that are currently used in lithium-ion batteries (LIBs) are not compatible for SIB anodes. Herein, we design a very convenient template strategy to synthesize spongy-like N, S-codoped ultrathin layered carbon assembly (NSLCA) with high N (9.5%) and S (1.7%) contents as an advanced anode material for SIBs. A petroleum-derived sulfur- containing pitch is chosen as the carbon skeleton, thus simplifying the preparation steps and reducing the costs. With the help of nanoporous MgO templates, the ultrathin layered carbon assembly can be facilely prepared. In addition, benefitting from the synergistic effects of codoped abundant N and S, as well as its unique assembly structures, the NSLCA anode exhibits outstanding sodium storage performance, with an especially superior rate performance (256 mA h g−1 at a current density of 3 A g−1) and a long lifespan (charge–discharge for as many as 2000 cycles with no capacity decay). This study provides a feasible and convenient strategy for the convenient and batch production of a spongy-like N, S-codoped carboneous material towards the construction of high-performance and cost-effectiveness SIBs.

Lithium−sulfur (Li−S) batteries are promising to replace current commercial Li−ion batteries due to the high energy density. Despite this, the poor cyclic stability induced by the shuttle effect of electrolyte-soluble intermediate polysulfides is one of the great obstacles for the application of Li−S batteries. To overcome this issue, here we report a self-template synthesis of metallic and polar Co 9 S 8 nanocrystals inlaid carbon (Co 9 S 8 /C) hollow nanopolyhedra as an efficient sulfur host material. The Co 9 S 8 /C hollow nanopolyhedra with large inner space can ensure the loading mass of sulfur and buffer the volume expansion of Li 2 S x species during cycling; while the metallic and polar Co 9 S 8 /C shell offers synergetic spatial confinement and chemical binding to immobilize polysulfides and prevent the shutting effect. The Co 9 S 8 /C-S composite cathode exhibits high capacity and long cycle life with a low capacity decay of 0.041% per cycle over 1000 cycles at 2.0 C. When the areal sulfur content is as high as 3.0 mg cm –2 , the Co 9 S 8 /C-S cathode still maintains high cycling stability.

Recently, Ni–based layered double hydroxide (LDH) materials have attracted growing interest owing to the remarkable performance for oxygen evolution reaction (OER). Here we demonstrate the preparation of ultrathin Ni3FeAlx trinary LDH nanosheets with higher activity and stability than NiFe–LDH nanosheets for OER. The enhancement was derived from Al substitution, which increased the concentration of Ni3+ active sites on the catalyst surface. Besides, low-coordinated Ni and Fe atoms and defects were formed by partial etching/dissolution of Al3+ in alkaline solution, which further increased the activity towards OER. To improve the conductivity, Ni3FeAlx–LDH (x=0, 0.91, 1.27 or 2.73) nanosheets were also in-situ grown on three-dimensional-networked nickel foam. The binder-free Ni3FeAlx–LDH/Ni foam electrodes exhibited further improved catalytic performance compared to the electrodes made of powdery Ni3FeAlx–LDHs and nafion binder. The best OER performance was presented by Ni3FeAl0.91–LDH/Ni foam, showing a Tafel slope of 57 mV/dec, a low overpotential (304 mV) at the current density of 20 mA/cm2, and a current density of 235 mA/cm2 at 1.60 V (vs. RHE). Furthermore, the Ni3FeAl0.91–LDHs/Ni foam electrode showed excellent long-term stability, maintaining a stable overpotential of 320 mV at 20 mA/cm2 after testing for 18 h.

Particulate matter (PM) pollution has become a serious environmental problem, especially in developing countries, owing to its severe threat to human health. Particularly, airborne PM 2.5 (mean aerodynamic diameter ≤2.5 µm) particles are extremely harmful, because the tiny particles can enter human respiratory system and even penetrate into circulatory system. Herein, we propose an effective strategy to recycle PM 2.5 carbon nanoparticles generated by diesel vehicle engine for the applications of clean energy. After thermal treatment and purification, the PM 2.5 derived carbon nanoparticles show a diameter distribution between 25 and 40 nm, mesoporous characteristics (with an average pore size of ~3.3 nm), and homogeneous nitrogen incorporation (with N content of ~1.1 at%). The PM 2.5 derived N-doped mesoporous carbon nanoparticles were used as an advanced electrode material in supercapacitors, exhibiting excellent specific capacity and superb stability over long-term cycling. Moreover, the recycled PM 2.5 carbon nanoparticles show attractive electrocatalytic properties for oxygen reduction reaction, presenting high onset potential and good immunity to methanol crossover. We expect this research can provide inspiration for air pollution control and sustainable energy utilization.

Although silver nanoparticles are considered as promising antibacterial agents because of their antibacterial activity, the acute cytotoxicity of Ag+ released from Ag nanoparticles restricts their potential practical applications. Herein, porous Ag@Au nanoplates, which could balance the Ag+ release and the toxicity of Ag naoparticles, were fabricated by stepwise seed-mediated growth and oxidation. Laser irradiation further boosted their antimicrobial activity, and significantly accelerated the curing rate of wound. Comparing with Ag nanoplates, the irradiated porous Ag@Au nanoplates showed the similar antibiotic ability against S. aureus strains and lower cytotoxicity in vitro. When the porous Ag@Au nanoplates were applied to treat S. aureus-infected wound, they had the best curing effect. Thus, these porous Ag@Au nanoplates could act as promising antibacterial agents for wound healing applications.

Here, we report a hierarchical Co3ZnC/carbon nanotube-inserted nitrogen-doped carbon concave-polyhedrons synthesized by direct pyrolysis of bimetallic zeolitic imidazolate framework precursors under a flow of Ar/H2 and subsequent calcination for both high-performance rechargeable Li-ion and Na-ion batteries. In this structure, Co3ZnC nanoparticles were homogeneously distributed in in situ growth carbon nanotube-inserted nitrogen-doped carbon concave-polyhedrons. Such a hierarchical structure offers a synergistic effect to withstand the volume variation and inhibit the aggregation of Co3ZnC nanoparticles during long-term cycles. Meanwhile, the nitrogen-doped carbon and carbon nanotubes in the hierarchical Co3ZnC/carbon composite offer fast electron transportation to achieve excellent rate capability. As anode of Li-ion batteries, the electrode delivered a high reversible capacity (∼800 mA h/g at 0.5 A/g), outstanding high-rate capacity (408 mA h/g at 5.0 A/g), and long-term cycling performance (585 mA h/g ...

Herein, we report a unique thermal synthesis method to prepare a novel two-dimensional (2D) hybrid nanostructure consisting of ultrathin and tiny-sized molybdenum disulfide nanoplatelets homogeneously inlaid in graphene sheets (MoS2/G) with excellent electrocatalytic performance for HER. In this process, molybdenum oleate served as the source of both molybdenum and carbon, while crystalline sodium sulfate (Na2SO4) served as both reaction template and sulfur source. The remarkable integration of MoS2 and graphene in a well-assembled 2D hybrid architecture provided large electrochemically active surface area and a huge number of active sites and also exhibited extraordinary collective properties for electron transport and H+ trapping. The MoS2/G inlaid nanosheets deliver ultrahigh catalytic activity toward HER among the existing electrocatalysts with similar compositions, presenting a low onset overpotential approaching 30 mV, a current density of 10 mA/cm2 at ∼110 mV, and a Tafel slope as small as 67.4 mV/...

Considerable efforts have been devoted on the design and fabrication of non-platinum electrocatalysts with high performance and low cost for hydrogen evolution reaction (HER). However, the catalytic activity of existing electrocatalysts usually subjects to the limited amount of exposed active sites. Herein, we propose that self-assembled ultrathin NiCo2S4 nanoflakes grown on nickel foam (NiCo2S4/Ni foam) can serve as excellent electrocatalyst for HER in alkaline solution with high activity and stability. The NiCo2S4/Ni foam electrodes were prepared by the complete sulfidation of networked ultrathin NiCo-layered double hydroxide nanoflakes grown on Ni foam (NiCo-LDH/Ni foam). The advantages of this unique architecture are that the ultrathin and porous NiCo2S4 nanoflakes can provide a huge number of exposed active sites, the highly-conductive Ni foam can promote the transfer of electrons, and the three-dimensional-networked structure can facilitate the diffusion and penetration of electrolyte. Electrochemical measurements reveal that NiCo2S4/Ni foam electrodes exhibit greatly improved performance than NiCo-LDH/Ni foam for HER in alkaline solution with low onset overpotential (17 mV), small Tafel slope (84.5 mV/dec) and excellent long-duration cycling stability (maintaining an onset overpotential of ~20 mV and an overpotential of 155 mV at 50 mA/cm2 after testing for 100,000 s). In addition, the highly-flexible NiCo2S4/Ni foam electrodes show no obvious catalytic degradation after bending for 200 times, confirming the high flexibility and robustness under severe conditions.

Although transition metal oxides have attracted considerable attention for their high energy density as anode materials of lithium-ion batteries, they suffer from large volume expansion during lithiation process, which usually causes fast capacity degradation. Herein, we report a rational design and facile preparation strategy of copper oxide encapsulated mesoporous carbon multi-yolk-shell octahedra, in which multiple CuO nanoparticles are well-confined in the compartments of micro-scale octahedral carbon scaffolds. The advantages of the novel multi-yolk-shell design are that the three-dimensional carbon scaffolds can buffer the volume change and prevent aggregation of CuO nanoparticles during the charge/discharge cycles, provide pathways for electron transport and Li + diffusion, and restrict the thin solid-electrolyte interphase layer to the outer surface of carbon shells. The results demonstrate how the electrochemical properties of anodes can be significantly improved by the multi-yolk-shell nanostructures with greatly enhanced structural stability and electrochemical actuation. Moreover, the micrometer-size CuO@C octahedra reduce the relative quality of SEI, resulting in high Coulombic efficiency and long cycling stability. In Li-ion cells, the CuO@C multi-yolk-shell octahedra anodes deliver a highly-reversible capacity of 598 mA h g −1 at 250 mA g −1 , excellent rate capacity of 365 mA h g −1 at 3000 mA g −1 and exhibit long-term cyclability with a capacity of 512 mA h g −1 after 300 cycles at 500 mA g −1 .

To alleviate the capacity degradation of conventional anode materials caused by serious volume expansion and particle aggregation for lithium-ion batteries (LIBs), considerable attention has been devoted to the rational design and synthesis of novel anode architectures. Herein, we report an effective fabrication strategy to implant well-distributed carbide nanoparticles into spherical porous carbon frameworks to form pitaya-like microspheres. Benefiting from their unique components and architecture features, the as-synthesized pitaya-like microspheres can effectively buffer the volume change and prevent aggregation of Co3ZnC nanoparticles during the charge/discharge processes of LIBs. The porous carbon framework provides an unhindered pathway for electron transport and Li+ diffusion and restricts the thin solid-electrolyte interphase (SEI) layer to the outer surface of carbon outer-shells. In LIBs, the anodes deliver a high capacity of 608 mA h g−1 at 100 mA g−1 after 300 charge/discharge cycles and ultrahigh cyclic stability and rate performance with a capacity of 423 mA h g−1 even after 1150 consecutive cycles at 1000 mA g−1.

The development of flexible lithium-sulfur (Li-S) batteries with high energy density and long cycling life are very appealing for the emerging flexible, portable, and wearable electronics. However, the progress on flexible Li-S batteries was limited by the poor flexibility and serious performance decay of existing sulfur composite cathodes. Herein, we report a freestanding and highly flexible sulfur host that can simultaneously meet the flexibility, stability, and capacity requirements of flexible Li-S batteries. The host consists of a crisscrossed network of carbon nanotubes reinforced CoS nanostraws (CNTs/CoS-NSs). The CNTs/CoS-NSs with large inner space and high conductivity enable high loading and efficient utilization of sulfur. The strong capillarity effect and chemisorption of CNTs/CoS-NSs to sulfur species were verified, which can efficiently suppress the shuttle effect and promote the redox kinetics of polysulfides. The sulfur-encapsulated CNTs/CoS-NSs (S@CNTs/CoS-NSs) cathode in Li-S batteries exhibits superior performance, including high discharge capacity, rate capability (1045 mAh g

Selenium (Se) has great promise to serve as cathode material for rechargeable batteries because of its good conductivity and high theoretical volumetric energy density comparable to sulfur. Herein, we report the preparation of mesoporous nitrogen-doped carbon scaffolds (NCSs) to restrain selenium for advanced lithium-selenium (Li-Se) batteries. The NCSs synthesized by a bottom-up solution-phase method have graphene-like laminar structure and well-distributed mesopores. The unique architecture of NCSs can severe as conductive framework for encapsulating selenium and polyselenides, and provide sufficient pathways to facilitate ion transport. Furthermore, the laminar and porous NCSs can effectively buffer the volume variation during charge/discharge processes. The integrated composite of Se-NCSs has a high Se content and can ensure the complete electrochemical reactions of Se and Li species. When used for Li-Se batteries, the cathodes based on Se-NCSs exhibit high capacity, remarkable cyclability, and excellent rate performance.

Here we report an effective bottom-up solution-phase process for the preparation of nitrogen-doped porous carbon scaffolds (NPCSs), which can be employed as high-performance anode materials for both lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). The as-obtained NPCSs show favorable features for electrochemical energy storage such as high specific surface area, appropriate pore size distribution (3.9 nm in average), large pore volume (1.36 cm3 g-1), nanosheet-like morphology, a certain degree of graphitization, enlarged interlayer distance (0.38 nm), high content of nitrogen (∼5.6 at%) and abundant electrochemically-active sites. Such a unique architecture provides efficient Li+/Na+ reservoirs, and also possesses smooth electron transport pathways and electrolyte access. For LIBs, the anodes based on NPCSs deliver a high reversible capacity of 1275 mA h g-1 after 250 cycles at 0.5 C (1 C = 372 mA g-1), and outstanding cycling stabilities with a capacity of 518 mA h g-1 after 500 cycles at 5 C and 310 mA h g-1 after 1500 cycles even at 10 C. For SIBs, the anodes based on NPCSs display a reversible capacity of 257 mA h g-1 at 50 mA g-1, and superior long-term cycling performance with a capacity of 191 mA h g-1 after 1000 cycles at 200 mA g-1.

The design of electrochemically active materials with appropriate structures and compositions is very important for applications in energy conversion and storage devices. Herein, we demonstrate an effective strategy to prepare microporous heteroatom-doped carbon frameworks derived from naturally-abundant pine needles. The preparation procedure is based on the carbonization of pine needles, followed by KOH activation at a temperature range of 700–1000 °C. The resultant nitrogen-doped carbon consists of abundant micropores and an ultrahigh specific surface area (up to 2433 m2 g−1), leading to high performances in electrocatalytic hydrogen evolution reaction (HER) and supercapacitors. Specifically, when the pine needle-derived carbon (activated at 800 °C) serves as a HER electrocatalyst, it exhibits a low onset potential (∼4 mV), a small Tafel slope (∼45.9 mV dec−1) and a remarkable stability over long-term cycling. When evaluated as an electrode material for supercapacitors, the pine needle-derived carbon (activated at 900 °C) demonstrates high specific capacitance (236 F g−1 at 0.1 A g−1), remarkable rate capability (183 F g−1 at even 20 A g−1) and good long-term stability. Notably, the specific capacitance at 2.0 A g−1 increased from ∼205 to ∼227 F g−1 after cycling for 5000 times, owing to the further activation and wetting of the electrodes. This novel and low-cost biomass-derived carbon material is very promising for many applications, especially in electrocatalytic water splitting and supercapacitors.

Rechargeable magnesium batteries have attracted increasing attention due to the high theoretical volumetric capacities, dendrite formation-free characteristic and low cost of Mg metal anodes. However, the development of magnesium batteries is seriously hindered by the lack of capable cathode materials with long cycling life and fast solid-state diffusion kinetics for highly-polarized divalent Mg2+ ions. Herein, vanadium tetrasulfide (VS4 ) with special one-dimensional atomic-chain structure is reported to be able to serve as a favorable cathode material for high-performance magnesium batteries. Through a surfactant-assisted solution-phase process, sea-urchin-like VS4 nanodendrites are controllably prepared. Benefiting from the chain-like crystalline structure of VS4 , the S22- dimers in the VS4 nanodendrites provide abundant sites for Mg2+ insertion. Moreover, the VS4 atomic-chains bonded by weak van der Waals forces are beneficial to the diffusion kinetics of Mg2+ ions inside the open channels of VS4 . Through a series of systematic ex situ characterizations and density functional theory calculations, the magnesiation/demagnesiation mechanism of VS4 are elucidated. The VS4 nanodendrites present remarkable performance for Mg2+ storage among existing cathode materials, exhibiting a remarkable initial discharge capacity of 251 mAh g-1 at 100 mA g-1 and an impressive long-term cyclability at large current density of 500 mA g-1 (74 mAh g-1 after 800 cycles).

In order to understand the effects of metal ions on the structural stability of proteins, urea-induced unfolding transition of bovine serum albumin (BSA) in the presence of different kinds of metal ions (Zn2+, Ca2+, Cd2+ and Co2+) are characterized by far-UV circular dichroism (CD) and fluorescence spectra. Under neutral condition, there is a significant deviation of the unfolding transition curves of free protein by fluorescence and CD spectra. However, the unfolding curves of fluorescence and CD spectra turn to be coincident in the presence of Ca2+ or Cd2+ ions, indicating that the tertiary and secondary structures of BSA unfold simultaneously, i.e. a cooperative two-state behavior, while the deviation of them is enhanced in the presence of Zn2+ or Co2+ ions, suggesting that the unfolding remains a three-state behavior. Our results provide evidence that the metal ions alter the urea-induced unfolding pathway of BSA. Furthermore, the change of free energy (ΔG), the midpoint of chemical denaturation (Cm) and the solvent-exposed surface (m) during the urea-induced unfolding process have also been obtained to characterize the effects of metal ions on the conformational stability of BSA.

The interchain contraction and association of polystyrene in semidilute solution near the Θ temperature are studies using NET. The results reveal that during a drop of temperature, polystyrene chains pass through different states: a smooth change of conformation at temperatures above the Θ temperature, an accelerated contraction and association, aggregation of polymer chains, and then further continuous contraction below the Θ temperature. A pronounced hysteresis is observed during repeated heating. A viscosity study of the same solution was compared with the NET results. It indicates that NET can effectively be used to study conformational changes like contraction and association of polymer chains in a semidilute solution.

In this work, the difference between pH-induced isomerization and urea-induced unfolding, and the urea- and thermal-induced unfolding processes in different isomeric forms of Bovine serum albumin (BSA) are studied experimentally. Our results show that urea-induced unfolding is a two-step, three-state transition in both the N-form and the B-form, but a single-step, two-state transition in both the E-form and the F-form. At the same time, thermal-induced unfolding shows a two-state transition in all isomeric forms, but the cooperativity of unfolding is different.

Here, novel multifunctional electronic skins (E-skins) based on aligned few-walled carbon nanotube (AFWCNT) polymer composites with a piezoresistive functioning mechanism different from the mostly investigated theory of “tunneling current channels” in randomly dispersed CNT polymer composites are demonstrated. The high performances of as-prepared E-skins originate from the anisotropic conductivity of AFWCNT array embedded in flexible composite and the distinct variation of “tube-to-tube” interfacial resistance responsive to bending or stretching. The polymer/AFWCNT-based flexion-sensitive E-skins exhibit high precision and linearity, together with low power consumption (

We investigated the effects of solvents on the intrinsic propensity of peptide backbone conformations based on molecular dynamics simulations. The results show that compared with pure water, aqueous urea decreases the helix propensity. In comparison, methanol decreases the polyproline II (PPII) propensity. Such a solvent dependence of the intrinsic propensity of the backbone conformation is correlated with the solvent dependence of the hydration of the backbone groups and the formation probability of the local intrapeptide hydrogen bonds. Aqueous urea which has low ability to stabilize the local intrapeptide hydrogen bonds disfavors the helical conformation. Whereas, methanol which has low ability to hydrate the backbone groups disfavors the polyproline II conformation. In addition, the solvent effects can be further modulated by the side chains of the peptides. The solvent effects of the intrinsic propensity of peptide backbone conformations observed in this work suggest that changing the intrinsic propensity of the protein backbone conformations can partly contribute to the solvent-induced protein structure and dynamics variations. These results will be useful in understanding the solvent dependence of the conformational distributions of the unfolded proteins or peptides (or intrinsically disordered proteins) in which the global tertiary interactions are less important than that in the well-folded proteins.

Effects of hydrophobic and electrostatic interactions on the self-assembling process of the ionic-complementary peptide EMK16-II are investigated by atomic force microscopy imaging, circular dichroism spectra, light scattering, and chromatography. It is found that the hydrophobicity of the peptide promotes the aggregation in pure water even at a very low concentration, resulting in a much lower critical aggregation concentration than that of another peptide, EAK16-II. The effect of anions in solution with different valences on electrostatic interactions is also important. Monovalent anions (Cl− and Ac−) with a proper concentration can facilitate the formation of peptide fibrils, with Cl− of smaller size being more effective than Ac− of larger size. However, only small amounts of fibrils, but plenty of large amorphous aggregates, are found when the peptide solution is incubated with multivalent anions, such as SO, C6H5O, and HPO. More importantly, by gel filtration chromatography, the citrate anion, which induces a similar effect on the self-assembling process of EMK16-II as that of SO and HPO, can interact with two or more positively charged residues of the peptide and reside in the amorphous aggregates. This implies a “salt bridge” effect of multivalent anions on the peptide self-assembling process, which can interpret a previous puzzle why divalent cations inhibit the formation of ordered nanofibrils of the ionic-complementary peptides. Thus, our results clarify the important effects of hydrophobic and electrostatic interactions on the self-assembling process of the ionic-complementary peptides. These are greatly helpful for us to understand the mechanism of peptides' self-assembling process and protein folding and aggregation. © 2009 Wiley Periodicals, Inc. Biopolymers 93: 318–329, 2010. This article was originally published online as an acceptedpreprint. The “Published Online” date corresponds to the preprintversion. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com

The diphenylalanine (FF) motif has been widely used in the design of peptides that are capable of forming various ordered structures, such as nanotubes, nanospheres and hydrogels. In these assemblies, FF based peptides adopt an antiparallel structure and are stabilized by π — π stacking among the phenyl groups. Here we show that assembly of FF-based peptides can be controlled by their geometric restrictions. Using tripeptide FFY (L-Phe-L-Phe-L-Tyr) as an example, we demonstrate that photo-crosslinking of C-terminal tyrosine can impose a geometric restriction to the formation of an antiparallel structure, leading to a structural change of the assemblies from nanosphere to amorphous. This finding is confirmed using far-UV circular dichroism, Fourier transform infrared spectroscopy and atomic force microscopy. Based on such a mechanism, we are able to control the gel-sol transition of Fmoc-FFY using the geometric restriction induced by photo-crosslinking of C-terminal tyrosine groups. We believe that geometric restriction should be considered as an important factor in the design of peptide-based materials. It can also be implemented as a useful strategy for the construction of environment-responsive "smart" materials.