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Mixed multiple oxidation states CoMoO4 nanowires (electrocatalysts) with tunable intrinsic oxygen vacancies were fabricated. CoMoO4 with proper oxygen vacancy can be employed to construct a Li-air battery with a high capacity and stable cyclability. This is possible because CoMoO4 contains surface oxygen vacancies, which result in the unit of CoMo bond, that is important for electrocatalysts used in Li-air batteries. Both the experimental and theoretical results demonstrate that the surface oxygen vacancies containing CoMoO4 nanowires have a higher electrocatalytic activity. This shows that the highly efficient electrocatalysts used for Li-air batteries were designed to modify the redox properties of the mixed metal oxide in the catalytic active sites. This successful material design led to an improved strategy for high oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) activities based on the fast formation and extinction of ORR products.

Lithium oxygen (Li-O2) batteries have shown great potential as new energy-storage devices due to the high theoretical energy density. However, there are still substantial problems to be solved before practical application, including large overpotential, low energy efficiency, and poor cycle life. Herein, we have successfully synthesized a RuO2-Co3O4 nanohybrid with a rich oxygen vacancy and large specific surface area. The Li-O2 batteries based on the RuO2-Co3O4 nanohybrid shown obviously reduced overpotential and improved circulatory property, which can cycle stably for more than 100 cycles at a current density of 200 mA g-1. Experimental results and density function theory calculation prove that the introduction of RuO2 can increase oxygen vacancy concentration of Co3O4 and accelerate the charge transfer. Meanwhile, the hollow and porous structure leads to a large specific surface area about 104.5 m2 g-1, exposing more active sites. Due to the synergistic effect, the catalyst of the RuO2-Co3O4 nanohybrid can significantly reduce the adsorption energy of the LiO2 intermediate, thereby reducing the overpotential effectively.

Reasonably regulating electronic coupling to promote charge transfer and exciton separation has been regarded a promising approach in catalysis. The material engineering of van der Waals heterojunction (vdWsH) based on two-dimensional (2D) materials would be a potential way to optimize the as-prepared extrinsic physicochemical characteristics. However, it was still an almost uncultivated land waiting for exploration in catalysis. Herein, we introduced the inert h-boron nitride (h-BN) in non-metal reduced graphene oxide (GN) catalysts and constructed BN-GN vdWsH. The theoretical calculation demonstrated that the h-BN can effectively modify the electronic properties of graphene. With the introduction of h-BN, the BN-GN vdWsH can obviously enhance the catalytic activity of Li-CO2 battery. The existence of BN-GN vdWsH can reduce the overpotential more than 700 mV compared with reduced graphene oxide during the CO2 reduction reaction (CO2RR) and CO2 evolution reaction (CO2ER), and it extended cyclic stability more than three times, which was one of the most outstanding non-metallic catalysts. The reasonable structure design made it work as a high efficient electrocatalyst, which shed light on the development for functional treatment of catalytic materials.

Due to the limited energy densities, which could be achieved by lithium-ion cells, Li-O2 batteries, which could provide a promising super energy storage medium, attract much attention nowadays. For its high activity, high storage and low cost, Mn-based oxides have shown versatile application in various batteries. To enhance the cyclability of Li-O2 batteries, here, we synthesized a kind of α-MnO2 nanowires as a bifunctional catalyst for Li-O2 batteries. The particular structure of α-MnO2 reduces the mass transfer resistance of the battery, and the MnO2 nanowires were ion exchanged by saturated lithium sulfate solution so as to further improve the performance of the catalyst. The exchanged α-MnO2 catalyst showed a high discharge specific capacity(6243 mA·h/g at a current density of 200 mA/g) and significantly improved the cyclability up to the 55th cycle(200 mA/g with capacity of 1000 mA·h/g). The results show that the Li ion exchange method is a promising strategy for improving the performance of MnO2 catalyst for Li-O2 batteries.

NiFe layered double hydroxides (LDHs) have been denoted as benchmark non-noble-metal electrocatalysts for the oxygen evolution reaction (OER). However, for laminates of NiFe LDHs, the edge sites are active, but the basal plane is inert, leading to underutilization as catalysts for the OER. Herein, for the first time, light and electron-deficient Li ions are intercalated into the basal plane of NiFe LDHs. The results of theoretical calculations and experiments both showed that electrons would be transferred from near Ni2+ to the surroundings of Li+ , resulting in electron-deficient properties of the Ni sites, which would function as "electron-hungry" sites, to enhance surface adsorption of electron-rich oxygen-containing groups, which would enhance the effective activity for the OER. As demonstrated by the catalytic performance, the Li-NiFe LDH electrodes showed an ultralow overpotential of only 298 mV at 50 mA cm-2 , which was lower than that of 347 mV for initial NiFe LDHs and lower than that of 373 mV for RuO2 . Reasonable intercalation adjustment effectively activates laminated Ni2+ sites and constructs the electron-deficient structure to enhance its electrocatalytic activity, which sheds light on the functional treatment of catalytic materials.

The topological structure of carbon materials for lithium storage performance is an active issue in energy resources. However, the low specific capacity of carbon materials limits their application in the rapidly developing market, although they have the highest marginal value. Herein, we develop a facile method for scaled-up production of materials with atomically dispersed metal sites anchored on nitrogen-enriched carbon nanosheets (M–N–C), including nickel, iron and manganese metal sites. This is the first time that low-cost atomically dispersed M–N–C has been used to enhance Li storage performance. The anchoring of the atomically dispersed metal sites effectively improves the extent of carbonization and optimizes the electronic structure, which enhances the conductivity and accelerates the adsorption kinetics for Li+; this results in high capacity and superior rate performance. In the case of Mn–N–C, it presents an ultrahigh specific capacity of 500 mA h g−1 at 1 A g−1 after 1000 cycles. The atomically dispersed materials also demonstrate satisfactory rate performance, with an extremely high specific capacity of 328 mA h g−1 at 10 A g−1; this is greatly superior to that of N-doped carbon nanosheets (

Two-dimensional MXene, a significant member of the two-dimensional family, has attracted much interest in physics, energy evolution, environmental science, and nanomedicine. However, the acute toxi...

We develop a facile method to prepare a hierarchical mesoporous nanocomposite of manganese carbodiimide nanoparticles modified with N-doping carbon materials (MnNCN/NC). The nanocomposite is endowe...

Li–oxygen batteries (LOBs) have drawn widespread attention in the past decades. Herein, bifunctional hybrid catalysts based on perovskite La0.5Sr0.5CoO3−δ with Ti3C2Tx MXene nanosheets have been pr...

The development of highly effective, universal, and economical electrocatalysts for hydrogen evolution reaction (HER) via structure modulations remains a great challenge. Herein, we propose a novel solidoid nitridation reduction method to synthesize α-MoC1–x quantum dots encapsulated in nitrogen-doped carbon (α-MoC1–x/NC) with a shape like “frog eggs”. Carbon nitride was first prepared by pyrolysis of urea and then mixed with ammonium molybdate tetrahydrate under a temperature-programmed reduction. With the assistance of nitrogen release during thermal treatment, N doping and an ultrathin porous structure were obtained. Benefiting from the strong interaction of α-MoC1–x quantum dots and nitrogen-doped carbon, the α-MoC1–x/NC delivered an outstanding performance toward HER at all pH values. Here, 118 mV, a lower overpotential, is needed to reach 10 mA cm–2 in alkaline solution, and the current density of α-MoC1–x grew much faster than the commercial Pt/C with increased potential. And, this can keep steadil...

Defect engineering is an important approach to enhancing the catalytic activity of a material, but there have been few reported controllable experiments due to the lack of systematic and comprehensive understanding of the effects of defects. For nanocarbon catalysts, it is still a challenge to prepare both atom-doped and defect-engineered catalysts with the desired more effective active centers, which requires an in-depth understanding of both experiment and theory. Herein, a topological rich-vacancy-defect nitrogen-doped nanocarbon (TRNC) material is constructed in situ via a simple magnesiothermic technology. It exhibits remarkable oxygen catalytic performance, which can be compared to the best metal-free bifunctional carbon electrocatalysts reported, even better than that of commercial noble-metal RuO2. Combined with density functional theory (DFT) calculations, the carbon vacancy defects with edge nitrogen doping as intrinsic active sites were found to exhibit excellent oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) activity. When used practically as a catalyst in Li–O2 batteries, with a capacity restriction of 500 mA h g−1, it displays a long cycling and high rate durability of over 300 cycles at 200 mA g−1. This excellent performance arises from the three-dimensional topological rich-vacancy-defect nitrogen-doped nanocarbon. The effects of vacancy sites and nitrogen doping were probed via first-principles simulations to clarify the catalytic mechanisms which contribute to this superior performance.

NiFe layered double hydroxides (NiFe-LDHs) have been regarded as significant electrocatalysts for the oxygen evolution reaction (OER). However, their overpotential must still be further reduced to enable commercial applications. Herein, a promising and highly effective "hydroxyl ions hungry" electrode structure was prepared for the first time via a two-step hydrothermal reaction procedure to enhance the surface adsorption kinetics to obtain an ultralow overpotential. The electrode exhibits OER activity with ultralow overpotentials of 203 mV and 293 mV at the current densities of 10 mA cm-2 and 100 mA cm-2, respectively, in 1.0 M KOH. These results reveal an important way to improve the catalytic performance in an alkaline medium.

The development of high-performance, low-cost, and long-lasting electrocatalysts for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is urgently needed for effective electrochemical water splitting. In the present study, an engineering process was employed to prepare "Lewis base-hungry" amorphous-crystalline nickel borate-nickel sulfide (Ni3(BO3)2-Ni3S2) heterostructures, which exhibited unprecedentedly high electrocatalytic activity toward both OER and HER in alkaline media. The optimal Ni3(BO3)2-Ni3S2/nickel foam (Ni3(BO3)2-Ni3S2/NF) electrode displayed an ultralow overpotential of only -92 and +217 mV to reach the current density of 10 mA cm-2 for HER and OER, respectively. When the Ni3(BO3)2-Ni3S2/NF electrode was used as both the anode and cathode for overall water splitting, a low cell voltage of 1.49 V was needed to achieve the current density of 10 mA cm-2, which was superior to the performance of most noble metal-free electrocatalysts. Results from density functional theory calculations showed that the Lewis base-hungry sites in the heterostructures effectively enhanced the chemisorption of hydrogen and oxygen intermediates, a critical step in HER and OER electrocatalysis. Results from this study highlight the significance of rational design and engineering of heterostructured materials for the development of high-efficiency electrocatalysts.

An amorphous boron oxide layer has been deposited in situ on the NiCo-LDH (layered double hydroxide) nanosheet arrays via the simple chemical vapor deposition. The overpotential of the NiCo-LDHs@B2O3/carbon paper (NiCo-LDHs@B2O3/CP) electrode is only 213 mV at the current density of 10 mA cm–2 in 1 M KOH, which is 123 mV less than that of NiCo-LDHs/CP and slightly better than noble metal catalyst RuO2/CP (230 mV). What’s more, at 50 mA cm–2 in 1.0 M KOH, the overpotential of NiCo-LDHs@B2O3/CP is still kept at a low value of 320 mV much better than that of NiCo-LDHs/CP (441 mV) and RuO2/CP (373 mV). Importantly, it showed long-term electrochemical stability. The introduction of amorphous boron oxide layers can be promoted to form a borate interface, and it can effectively enhance reactivity of active species. The boron oxide shell on the surface of LDHs can protect active species stability to enhance cycling stability. This work may inspire the development of low-cost and efficient OER electrocatalysts for...

Metal-oxygen batteries, especially Li-oxygen batteries (LOBs), have attracted tremendous research attentions in the past decades. It is necessary to design novel cost-effective catalysts in the development of high performance rechargeable LOBs. Herein, we prepare the atom-layered two-dimensional (2D) β -Co(OH) 2 nanosheets (AL- β -Co(OH) 2 ) via phase transition of layered α- Co(OH) 2 nanosheets ( α- Co(OH) 2 ) in a mild wet chemical process. The thickness of AL- β- Co(OH) 2 is less than 1.5 nm. It is the first time of using atom-layered β -Co(OH) 2 in the system of LOBs and this material shows outstanding catalytic performance. The AL- β -Co(OH) 2 nanosheets as electrocatalysts in LOBs can better reduce the over-potential, enhance the specific capacity and improve cycling capability. It demonstrates a high initial capacity 11841 mAh g −1 at a current density of 100 mA g −1 . It displays long cycle stability more than 70 cycles with a capacity restriction of 1000 mAh g −1 . These results suggest that this strategy for designing oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) catalysts via exfoliation of materials to atom-layered level could be a promising way to improve the performance of LOBs.

Due to the increasing demand for energy, improving the current density of fuel cells is an urgent issue. Here we report a bifunctional electrocatalyst for fuel cells involving methanol or formic acid oxidation. A nanocomposite consisting of 7.2 nm NiPt nanocrystals, which are grown in situ on graphene nanosheets (NiPt/GN), has been prepared via a solution thermal decomposition method. The NiPt/GN nanocatalyst presents specific activities as high as 41.1 mA cm-2 and 42.9 mA cm-2 for methanol oxidation and formic acid oxidation, respectively, outperforming most reported catalysts. Moreover, it retains 76.3% of this activity after 900 cycles of methanol oxidation. Additionally, in comparison with general NiPt nanoparticles, the NiPt/GN nanocatalyst shows higher electrocatalytic activity in methanol and formic acid oxidation. All these results indicate that ultrathin NiPt nanocrystals grown in situ on graphene nanosheet substrates can significantly improve performance as a bifunctional electrocatalyst.

Herein, hierarchical dendrite-like Pt crystals with a distinct morphology were synthesized via a facile one-pot method without any templates. Formation of this hierarchical structure is dependent on the reaction duration. Interestingly, different hierarchical structures show different catalytic activities. After a 12 hour reaction, tertiary structures of Pt are formed, which can act as outstanding catalysts in the hydrogen evolution reaction (HER). The onset potential of this dendrite-like Pt catalyst for the HER in a 0.5 M H2SO4 solution is 15 mV, which outperforms that of commercial Pt/C (30 mV). Moreover, it shows significantly improved stability for HER as the polarization curve after 10 000 cycles retains a similar performance as in the initial test; this results in a loss of only 2.6% of its initial current density at an overpotential of 0.05 V. The distinct hierarchical dendrite-like structures are maintained after cycling and current–time tests, which can be responsible for the excellent performance of this catalyst.

MOFs present potential application in electrocatalysis. The structure-activity of the Ni-MOFs with different morphologies, nanowires, neurons, and urchins is systemically investigated. The Ni-MOFs were controllably synthesized via the facile solvothermal method. Among them, the Ni-MOF nanowires are endowed with the highest electrocatalytic activity due to the unique structure, more exposed active sites, lower charge transfer resistance, and the fast and direct electron transfer in 1D structures. The typical morphology of the Ni-MOF nanowires is ca. 10 nm in diameter and several micrometers in length. When employed as an electrocatalyst in urea oxidation reaction, it exhibits a lower overpotential than and superior stability to the Ni-MOFs with other morphologies. Ni-MOF nanowires require a potential of ∼0.80 V (vs Ag/AgCl) to obtain 160 mA cm-2. In addition, after continuous electrocatalyzing for 3600 s at 0.40 V (vs Ag/AgCl), the current density retention of Ni-MOF nanowires could still reach more than 60% (>12 mA cm-2), which demonstrates Ni-MOF nanowires as promising electrocatalysts for urea oxidation.

A novel two-phase approach towards the corrosion of PtNi10 nanoctahedra has been developed. In this strategy, the active component of Ni in oil-soluble PtNi10 nanoctahedra which resided in the upper toluene phase, suffered from etching and was then transferred into a lower aqueous phase with coordination by ethylenediaminetetraacetate (EDTA). Due to the existence of the phase-transfer interface promoted by EDTA, the corrosion reaction proceeded at an accelerated rate under the mild conditions. Specifically, the resultant products of octahedral Pt4Ni nanoframes were successfully fabricated for the first time, and PtNi4 porous octahedra could be obtained when the dosage of EDTA-2Na was reduced. After a systematic study of this two-phase system, a “synergetic corrosion” mechanism is proposed to account for the formation of octahedral Pt4Ni nanoframes, involving contributions from many species (i.e., O2, H2O, H+, OAm, and EDTA4−). As a result of the fascinating three-dimensional geometry of Pt4Ni nanoframes and PtNi4 porous octahedra, both of the corroded nanocrystals showed superior activity over the pristine PtNi10 nanoctahedra for ethanol electrooxidation in alkaline media and hydrogenation of nitrobenzene.

Lithium/sulfur (Li/S) cells have a theoretical specific energy five times higher than that of lithium-ion (Li-ion) cells (2600 vs. ~500 Wh kg−1). The conventional Li/S cells that use an organic liquid electrolyte are short-lived with low coulombic efficiency due to the polysulfide shuttle. We herein design carbon-coated NanoLi2S (NanoLi2S@carbon) composites, which consist of Li2S nanoparticles as the core and a carbon coating as the shell. The carbon shell prevents the NanoLi2S core from directly contacting the liquid electrolyte, which improves the performance of Li/S cells to provide longer cycle life and high sulfur utilization. The cyclability of Li/S cells is further enhanced by mixing the core–shell NanoLi2S@carbon composites with graphene oxide, which chemically immobilizes polysulfides in the cathode through their functional groups. The resulting Li/S cell shows an initial specific discharge capacity of 1263 mAh g−1 (normalized to sulfur) at the C/10 rate and a capacity retention of 65.4% after 200 cycles. The capacity decay mechanism during cycling is also characterized in detail using near edge X-ray absorption fine structure (NEXAFS) spectra.

Nickel sulfide (NiS) materials with a different 1D structure are successfully synthesized by strictly controlling the reaction time and temperature, using dodecanethiol as both solvent and sulfur source. The formation of the NiS nanomaterials results from a “dispersion–decomposition” mechanism. Remarkably, 1D NiS electrode materials show super specific capacitance and stability.

To improve the dielectric performance of polyvinylidene fluoride (PVDF), blend films based on PVDF and aromatic polythiourea (ArPTU) were prepared by the solution casting method. The blend films have higher dielectric constant (9.2) and lower loss at low fields (0.02 at 1 kHz) than a pure PVDF film (8.4, 0.05 at 1 kHz). More importantly, the blend films can also inhibit the early polarization saturation at low fields and result in the significant enhancement of the dielectric strength and increase in the energy density and reduction of loss at high fields. For the PVDF/ArPTU(90/10) film, the maximum operating electric field is about 700 MV m−1 and the released energy density can be up to 10.8 J cm−3 with an efficiency of above 83%. The X-ray diffraction data and atomic force microscopy images show that these blend films exhibit clear structural changes with an increasing percentage of ArPTU. It is proven that the increase of the β phase content and decrease of the crystalline grains in blend films are helpful to reduce the dielectric loss and enhance the dielectric strength.

Lithium iron phosphate (LiFePO4) is a potential high efficiency cathode material for lithium ion batteries, but the low electronic conductivity and single diffusion channel for lithium ions require good particle size and shape control during the synthesis of this material. In this paper, six LiFePO4 nanocrystals with different size and shape have been successfully synthesized in ethylene glycol. The addition sequence Fe-PO4-Li helps to form LiFePO4 nanocrystals with mostly {010} faces exposed, and increasing the amount of LiOH leads to a decrease in particle size. The electrochemical performance of the six distinct LiFePO4 particles show that the most promising LiFePO4 nanocrystals either have predominant {010} face exposure or high specific area, with little iron(II) oxidation.

By using a novel coating approach based on the reaction between MC(2)O(4)·xH(2)O and Ti(OC(4)H(9))(4), a series of nanoscale Li(2)TiO(3)-coated LiMO(2) nanobelts with varied Ni, Co, and Mn contents was prepared for the first time. The complete, thin Li(2)TiO(3) coating layer strongly adheres to the host material and has a 3D diffusion path for Li(+) ions. It is doped with Ni(2+) and Co(3+) ions in addition to Ti(4+) in LiMO(2), both of which were found to favor Li(+)-ion transfer at the interface. As a result, the coated nanobelts show improved rate, cycling, and thermal capabilities when used as the cathode for Li-ion battery.

[020]-oriented tin sulfide nanobelts with a length/thickness ratio of 100 have been synthesized by a facile hydrothermal method without any surfactants, and the nanobelts have shown good strain-accommodating properties as well as good electrochemical performance as the anode for Li-ion batteries. The formation of the nanobelts results from a precipitation-dissolution-transformation mechanism, and the [020] oriented growth can be ascribed to the {010} facet family having the lowest atomic density. In particular, SnS shows clear Li-Sn alloying/de-alloying reversible reactions in the potential range 0.1–1.0 V. Based on galvanostatic measurements and electrochemical impedance spectroscopy, SnS nanobelts have shown impressive rate performance. The post-cycled SnS nanobelts were completely transformed into metallic tin, and preserved the one-dimensional structure due to their flexibility which accommodates the large volumetric expansion. Open image in new window

Shape-dependent nanocatalysis: Monodisperse cubic, rhombic dodecahedral, and octadecahedral Cu(2) O nanocrystals (NCs) were selectively synthesized. Cu(2) O octadecahedra exhibited the best activity upon recycling, though etched on nanoframes, in the ligand-free oxidative arylation of phenylacetylene. Rhombic dodecahedra had moderate activity and optimal stability, whereas cubes suffered significant loss of activity during recycling.

Here we report the synthesis and electrochemical performance of 40 nm near-uniform lithium titanate (Li4Ti5O12) single crystals. The cubic spinel Li4Ti5O12 nanocrystals are transformed without size changes at 400 °C from cubic NaCl type (Li0.4H0.6)2TiO3 nanocrystals that are prepared from hydrothermal synthesized α-Li2TiO3. The prepared Li4Ti5O12 nanocrystals show reduced charge-transfer impedance and exhibit favorable performance under high current charging/discharging due to the reduced Li+ ion diffusion path.

We report a facile process for the controllable synthesis of the Mn3O4 nanocrystals with different sizes and shapes, which includes dots, rods, and wires in the presence of the surfactants dodecanol and oleylamine. It is notable that the uniform-sized nanocrystals were achieved under mild experimental conditions and the common inorganic salt, such as manganese(II) nitrate, was adopted as the precursor. Furthermore, the as-prepared monodisperse nanocrystals, as ideal building blocks, can be rationally assembled into three-dimensional (3D) Mn3O4 colloidal spheres, using a facile ultrasonication strategy. In particular, the 3D colloidal spheres can be successfully converted to LiMn2O4 nanocrystals, which show distinct electrochemical performance, mainly depending on their crystallinity and size.

A three-phase composite with multi-walled carbon nanotubes (MWNTs) and BaTiO 3 particles embedded into polyvinylidene fluoride was prepared by using a simple blending and hot-molding technique. The dielectric measurement results show that the effective dielectric constant of the composite is slightly dependence on the frequency below 1 MHz but increases rapidly with the MWNTs concentration when the concentration is very close to the percolation threshold. The temperature has a little effect on the variation of the dielectric behavior. The percolation theory is used to explain the experimental results.

The dielectric behavior of two kinds of Li and Ti co-doped NiO (LTNO)/polyvinylidene fluoride (PVDF) composite was studied at various different frequencies and temperatures. The effective dielectric constant of the percolative composite at 100 Hz is very high, i.e., e eff ≈600, which is 60 times higher than that of the PVDF. The results also show that there is a remarkable difference in the dielectric constant of the composites with different LTNO fillers. Boundary layer capacitor effect and percolation theory can be used to explain the experimental results.

Uniform tetrapod-like zinc oxide (T-ZnO) nanorods were produced in bulk quantity by oxidation of Zn powders. Field-emission scanning electron microscope and transmission electron microscopy investigations showed that T-ZnO nanorods were high-quality nanocrystals. The length of legs of T-ZnO nanorods was 2–3 μm and the edge size of centering nucleus was 70–150 nm. The growth of T-ZnO nanorods was controlled by a vapor–solid (VS) mechanism. UV emission peak at ∼380 nm and green emission peak at ∼495 nm were observed at room temperature, which was assigned to the near band-edge emission and the deep-level emission, respectively.

Large over-potentials during battery operation remain a big obstacle for aprotic Li–O2 batteries. Herein, a nanocomposite of about 4 nm cobalt monoxide nanocrystals grown in situ on reduced graphene oxide substrates (CoO/RGO) has been synthesized via a thermal decomposition method. The CoO/RGO cathode delivers a high initial capacity of 14 450 mAh g−1 at a current density of 200 mA g−1. Simultaneously it displays little capacity fading after 32 cycles with a capacity restriction of 1000 mAh g−1. Additionally, compared with Ketjenblack and general CoO nanoparticles, ultrathin CoO nanoparticle-decorated RGO electrode materials with a delaminated structure display an observable reduction of over-potential in Li–O2 batteries. These results demonstrate that the introduction of RGO improves the performance of CoO, which is a promising strategy for optimizing the design of electrocatalysts for aprotic rechargeable Li–O2 batteries.

A simple in situ reduction approach was used to obtain Pt3Ni/reduced graphene oxide (rGO) with dominant {111} facets. The catalytic activity of Pt-Ni/rGO toward methanol electro-oxidation was studied by performing cyclic voltammetry. The Pt3Ni/rGO nanocatalysts exhibited improved catalytic activity and durability.

The title nanotubes are hydrothermally prepared from a mixture of KMnO4, NH4H2PO4, Bu4NOH, and H2O (autoclave, 180 °C, 48 h).

A simple one-step route for preparing α-MnO(2) nanotubes is reported. The α-MnO(2) nanotubes exhibit a high surface area of 226 m(2) g(-1) and reversible capacity of 512 mA h g(-1) at a high current density of 800 mA g(-1) after 300 cycles, as well as cycling stability when measured as an anode in lithium batteries.

A three-phase percolative composite with a ferroelectric phase (BaTiO3) and metallic inclusions (Ni) embedded into polyvinylidene fluoride matrix was prepared by using a simple blending and hot-molding technique. Effective medium approximations and percolation theory were employed in order to design and describe the dielectric behavior of such three-phase composites. Our experimental results showed that the static dielectric constant of such a three-phase composite can reach above 800 when the Ni concentration is close to its percolation threshold. Such composites have a potential to become capacitors and can be easily fabricated into various shapes due to its flexibility.

Ba0.6Sr0.4TiO3 (BST) nanofibers prepared via electrospinning and modified by dopamine are used as dielectric fillers in polyvinylidene fluoride (PVDF)-based composites. With 4.4 vol. % of BST nanofibers, the extractable energy density of the BST/PVDF composites is more than doubled as compared with pure PVDF matrix. Such significant enhancement is attributed to the combined effect of both surface modification by dopamine and large aspect ratio of the BST nanofibers. Paraelectric or anti-ferroelectric fillers of large aspect ratio may serve as a general strategy for enhanced electric energy density in polymer composites.

The converse magnetoelectric (ME) effect was investigated in bi-layered Ni/Pb(Zr0.52Ti0.48)O3 (PZT) thin films grown on Si substrates, with different thicknesses of Ni thin layers. By using an AC-mode magneto-optical Kerr effect method, it was revealed that the electric-voltage induced magnetization variation was dependent on the thickness of the Ni thin layer. The results showed that the Ni/PZT bilayered films with thick (about 40 nm) Ni films presented a dominative strain mediated ME coupling, whereas an interface-charge and strain co-mediated ME coupling might coexist in the Ni/PZT bilayered films with decreasing thickness (e.g., about 10 nm) of Ni films.

Uniform lithium iron phosphate nanoplates with a thickness of 30 nm, width of 100 nm, and length of 200 nm are synthesized by a solvothermal method. Electrochemical measurements show that the nanoplates exhibit low polarization and reach a discharge capacity of 165 mAh g−1 at 0.1 C, 140 mAh g−1 at 5 C.

BiFeO3 films with different thicknesses and crystallographic orientations were grown on LaNiO3-buffered Si substrates via a modified chemical route. Remarkable size effect in ferroelectric behavior was observed with thicker films exhibiting a larger polarization value, due to combined depolarization effect and microstructure of the BiFeO3 films. High resolution transmission electron micrograph revealed a complex strain state in the BiFeO3 films, and the net magnetic moment induced by the canting of the antiparallel spins was arranged in disorder in thicker films, presenting a spin-glass state; while in the thinner BiFeO3 films, the disorder spins turned to be orderly arranged to induce a ferromagnetic behavior. Thus there exists a competition between ferroelectric and magnetic behaviors as film thickness changes. Furthermore, magnetoelectric coupling was observed in the BiFeO3 films with a magnetic-field-induced electrical voltage of around 3.5 μV/Oe.

Multiferroic bilayered thin films consisting of Pb(Zr0.52Ti0.48)O3 (PZT) and CoFe2O4 (CFO) layers of different relative thicknesses were prepared on a general Pt/Ti/SiO2/Si substrate via a simple solution processing. The influence of the thickness fraction on their properties including ferroelectric, ferromagnetic, and magnetoelectric properties in the PZT-CFO bilayered thin films was investigated. Our results showed that the thickness fractions (or relative thicknesses) of the layers have a significant effect not only on the magnetic and electric properties of the bilayered films but also on their magnetoelectric response. The bilayered thin films with the intermediate thickness fraction of around 0.6 exhibited a maximum magnetoelectric effect.