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Metal–organic framework (MOF) is a promising electrochromic material due to its high specific surface area and tunable pore size, which can benefit the fast transportation of ion/charge. Here, a simple solvothermal deposition method for fabrication of Ni-MOF 74 electrochromic films on ITO is developed. It is found that the reaction temperature has played an important role in the morphology and electrochromic performance of as-prepared Ni-MOF 74 film. The film prepared at the optimized temperature exhibits the best electrochromic performance with a rapid switching speed (the coloration/bleaching time = 24.5/23.5 s). In addition, the optimized film displays a high optical contrast of 44.4% at 550 nm and can be stably switched for 650 cycles with

Single-atom catalysts provide an effective approach to reduce the amount of precious metals meanwhile maintain their catalytic activity. However, the sluggish activity of the catalysts for alkaline water dissociation has hampered advances in highly efficient hydrogen production. Herein, we develop a single-atom platinum immobilized NiO/Ni heterostructure (PtSA-NiO/Ni) as an alkaline hydrogen evolution catalyst. It is found that Pt single atom coupled with NiO/Ni heterostructure enables the tunable binding abilities of hydroxyl ions (OH*) and hydrogen (H*), which efficiently tailors the water dissociation energy and promotes the H* conversion for accelerating alkaline hydrogen evolution reaction. A further enhancement is achieved by constructing PtSA-NiO/Ni nanosheets on Ag nanowires to form a hierarchical three-dimensional morphology. Consequently, the fabricated PtSA-NiO/Ni catalyst displays high alkaline hydrogen evolution performances with a quite high mass activity of 20.6 A mg−1 for Pt at the overpotential of 100 mV, significantly outperforming the reported catalysts., While H2 evolution from water may represent a renewable energy source, there is a strong need to improve catalytic efficiencies while maximizing materials utilization. Here, authors examine single-atom Pt on nickel-based heterostructures as highly active electrocatalysts for alkaline H2 evolution.

Catalytically active metals atomically dispersed on supports presents the ultimate atom utilization efficiency and cost‐effective pathway for electrocatalyst design. Optimizing the coordination nature of metal atoms represents the advanced strategy for enhancing the catalytic activity and the selectivity of single‐atom catalysts (SACs). Here, we designed a transition‐metal based sulfide‐Ni3S2 with abundant exposed Ni vacancies created by the interaction between chloride ions and the functional groups on the surface of Ni3S2 for the anchoring of atomically dispersed Pt (PtSA‐Ni3S2). The theoretical calculation reveals that unique Pt‐Ni3S2 support interaction increases the d orbital electron occupation at the Fermi level and leads to a shift‐down of the d ‐band center, which energetically enhances H2O adsorption and provides the optimum H binding sites. Introducing Pt into Ni position in Ni3S2 system can efficiently enhance electronic field distribution and construct a metallic‐state feature on the Pt sites by the orbital hybridization between S‐3p and Pt‐5d for improved reaction kinetics. Finally, the fabricated PtSA‐Ni3S2 SAC is supported by Ag nanowires network to construct a seamless conductive three‐dimensional (3D) nanostructure (PtSA‐Ni3S2@Ag NWs), and the developed catalyst shows an extremely great mass activity of 7.6 A mg−1 with 27‐time higher than the commercial Pt/C HER catalyst., A transition‐metal sulfide‐Ni3S2, with abundant exposed Ni vacancies in the outside layers, to anchor and modulate atomically dispersed Pt as the durable catalyst (PtSA‐Ni3S2) for efficiently electrocatalytic hydrogen evolution.

Transition metal selenides (TMSs) have been considering as a kind of promising alternative anode materials for the application of sodium ion batteries due to their high electrical conductivity and high capacity. Here, hollow NiCoSe2 microspheres was prepared via an easy hydrothermal method, followed by the dopamine derived N-doped carbon coated which formed the hollow NiCoSe2@C composite. As-prepared hollow NiCoSe2@C composite has been first used as a new anode material for sodium ion batteries (SIBs). Our selenides displays a quite good electrochemical sodium storage performance. For example, the reversible capacity of as-prepared hollow NiCoSe2@C composite electrode can be maintained at 464.7 mAh g−1 at a current density of 100 mA g−1 after 200 cycles. Moreover, the rate performance of the hollow NiCoSe2@C composite is outstanding. The reversible capacities of 425.3, 420.8, 403.2, 394.7, 378.7, 367.8 and 337.5 mAh g−1 can be achieved at the current densities of 100, 200, 500, 1000, 2000, 3000 and 5000 mA g−1, respectively. Meanwhile, hollow NiCoSe2@C composite electrode exhibits a high discharge capacity of 338 mAh g−1 at a relatively high current density of 0.5 A g−1 after 250 cycles. In addition, the kinetic analysis of electrochemical Na + storage properties of the hollow NiCoSe2@C composite demonstrates that the extrinsic pseudo capacitive behaviour contributes significantly to excellent rate performance and good long-term cycling life. This method can be used to modify the morphologies and structures of the other TMSs for the development of new anode materials as anode materials in the application of sodium ion batteries.

Sodium ion batteries (SIBs) are deemed as the potential alternative for lithium ion batteries (LIBs) in the application of large-scale energy storage and conversion. The favorable anode materials play an important role for high-performance SIBs. Sn4P3 has been considered as one of the promising anode materials for sodium ion batteries due to the combination of high electrical conductivity from Sn and high specific capacity from P. In this work, Sn4P3/graphene aerogel (Sn4P3-GA) composite is prepared via a rapid low-temperature phosphidation reaction from SnO2-GA composite. The structural and morphological characterizations demonstrate that the Sn4P3 nanoparticles with an average size of 8 nm are uniformly and tightly embedded on the surface of 3D GA. The unique 3D network structure as well as the synergistic effect between graphene nanosheets and Sn4P3 nanoparticles would endow the as-prepared Sn4P3-GA composite with good electrochemical sodium storage performance. It delivers the high initial discharge capacity of 1180 mAh g−1 at 0.1 A g−1 and good cycle stability (657 mAh g−1 at 0.1 A g−1 after 100 cycles). Meanwhile, the Sn4P3-GA composite exhibits high-rate capacity of 462 and 403 mAh g−1 at a current density of 1 and 2 A g−1, respectively. Moreover, the contribution of the pseudocapacitance capacity can explicate the origin of good rate capability of the Sn4P3-GA composite. This work demonstrates the great potential of Sn4P3-GA composite as an alternative anode material for the low-cost and high-performance sodium ion batteries.

SnO2 is considered as one of the most promising alternative anode materials for lithium ion batteries (LIBs) and sodium ion batteries (SIBs) due to high specific capacity, low discharge voltage plateau and environmental friendliness. In this work, 1D ultrafine SnO2 nanorods anchored on 3D graphene aerogel (SnO2 NRs/GA) composite is prepared through a simple reduction-induced self-assembly method in the solution of graphene oxide (GO), Vitamin C and SnO2 nanoparticles. Vitamin C plays an important role in the reduction of GO. The structural and morphological characterizations demonstrate that 1D ultrafine SnO2 nanorods are uniformly and tightly anchored on the surface of 3D graphene nanosheet aerogels. The unique 3D network structure as well as the synergistic effect between 3D graphene nanoshhet and 1D SnO2 nanorods endows the as-prepared SnO2 NRs/GA composite with the good electrochemical lithium/sodium storage performance. It delivers the high initial discharge capacity (1713 mA h g−1 at 0.1 A g−1 for LIBs and 539 mA h g−1 at 0.05 A g−1 for SIBs) and good cycle stability (869 mA h g−1 at 0.1 A g−1 after 50 cycles for LIBs and 232 mA h g−1 at 0.05 A g−1 after 100 cycles for SIBs). Moreover, the SnO2 NRs/GA composite exhibits excellent cycle stability for SIBs with a high reversible capacity of 96 mA h g−1 at as high as 1 A g−1 for 500 cycles. This work provides a simple method to fabricate the electro-active materials-graphene aerogel composites for high-performance LIBs and SIBs.

Flower-like Fe3O4/graphene aerogel (Fe3O4/GA) composite was prepared by water-bath vitamin C reduction self-assembly process followed by a heat treatment under N2 atmosphere. The morphological and structural results demonstrate that 3D flower-like Fe3O4 particles are homogenously embedded into the 3D conductive network of graphene nanosheet aerogels. Based on this unique structure, flower-like Fe3O4/GA composite exhibits a high reversible capacity of 797 mAh g−1 at 0.2 A g−1, and good rate capacity of 551 mAh g−1 at 3.2 A g−1 as well as excellent cycling performance with a stable capacity of ~1138 mAh g−1 after 100 cycles at 0.2 A g−1 compared with bare flower-like Fe3O4 electrode. Our work demonstrates this self-assembly approach can be used to prepare other electroactive metal oxides/graphene composite for the application of lithium ion batteries.

Lithium-sulfur batteries (LSBs) have become one of the most promising candidates for next-generation energy storage systems owing to their high theoretical energy density, environmental friendliness, and cost effectiveness. However, real-word applications are seriously restricted by an undesirable shuttle effect and Li dendrite formation. In essence, uncontrollable anion transport is a key factor that causes both polysulfide shuttling and dendrite formation, which creates the possibility of simultaneously addressing the two critical issues in LSBs. An effective strategy to control anion transport is the construction of cation-selective separators. Significant progress has been achieved in the inhibition of the shuttle effect, whereas addressing the problem of Li dendrite formation by utilizing a cation-selective separator is still under way. From this viewpoint, this Review analyzes critical issues with regard to the shuttle effect and Li dendrite formation caused by uncontrollable anion transport, based on which roles and advantages of cation-selective separators toward high-performance LSBs are presented. According to the separator-construction principle, the latest advances and progress in cation-selective separators in inhibiting the shuttle effect and Li dendrite formation are reviewed in detail. Finally, some challenges and prospects are proposed for the future development of cation-selective separators. This Review is anticipated to provide a new perspective for simultaneously addressing the two critical issues in LSBs.

The electro-catalytic performance of the bi-functional catalysts at the air cathode for the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) plays a significant role for the development of rechargeable zinc air batteries (ZABs). To obtain the high-performance electrocatalysts, a series of porous Co3O4 samples derived from zeolitic imidazolate framework-67 (ZIF-67) are prepared by one-step annealing process at different temperature (350, 450, and 550 °C) under air atmosphere. Compared with the commercial Co3O4, the optimized sample Co3O4 prepared at 450 °C (CO3O4/C-450) exhibits the lowest overpotential of 1.68 V and the highest half-wave potential of − 0.56 V because the porosity of as-prepared Co3O4 provides abundant reactive sites. Moreover, the high discharge potential of 1.33 V and long cycle life of more than 100 h at 20 mA cm−2 are achieved in ZABs with CO3O4/C-450 electrocatalyst, which are attributed to the better stability provided by the carbon coating.

Designing a simple method to prepare a binder- and carbon-free catalyst with a highly efficient and stable hydrogen evolution electro-catalytic performance in the alkaline media is necessary and urgent. Herein, we develop a low-temperature hydrothermal nitridation and crystal transformation process for the preparation of nitrogen-doped Ni(OH)2 nanobelts decorated on 3D Ni foam (N-Ni(OH)2/NF), where the precursor of amorphous Ni(OH)2/3D Ni foam is fabricated by a simple electrodeposition process. The hydrogen evolution process of our N-Ni(OH)2/NF electrode is studied by using a classical three-electrode electrochemical measurement in the alkaline media. The as-prepared N-Ni(OH)2/NF electrode exhibits a small onset overpotential of 178 mV at 100 mA·cm−2 along with the superior electro-catalytic durability and stability after 10,000 cycles and 24-h continuous operation. The good electrocatalytic hydrogen evolution performance of the N-Ni(OH)2/NF electrode may be attributed to the absence of inactive materials (conducting carbon and binder), the high electrochemical active sites with a double-layer capacitance (Cdl) of 9.33 mF·cm−2, the doping effect of nitrogen atom into Ni(OH)2 crystalline, and the crystal transformation of Ni(OH)2. More importantly, this strategy may be used to modify other transition metal oxides/hydroxides/sulfides/phosphides/selenides for the improved electrocatalytic hydrogen evolution performance.

Transition metal phosphides have attracted increasing attention as anode materials for sodium-ion batteries (SIBs). Cobalt phosphide (CoP) has been deemed as prospective anode materials owing to its high theoretical capacity. Nevertheless, the defects of cobalt phosphides are evident. Low conductivity, the non-negligible volume expansion and aggregation of particles during sodiation/desodiation process result in poor cycling performance and rapid capacity decay, which greatly limit their applications. Herein, we designed a hollow-nanotube structure of sulfur-doped cobalt phosphide (S-CoP) nanoparticles coated by nitrogen-doped porous carbon (S-CoP@NPC), which can be successfully synthesized via an ordinary hydrothermal process followed by the low-temperature phosphorization/sulfuration treatment. The doping of sulfur element provides more active sites, meanwhile, the carbon coating largely helps to avoid the agglomeration of nanoparticles, alleviate volume expansion and improve the conductivity of materials. The S-CoP@NPC composite presents stable cycling performance, showing a discharge specific capacity of 230 mAh g−1 over 370 cycles at 0.2 A g−1. In addition, it also exhibits good rate capability with a discharge specific capacity of 143 mAh g−1 at 5 A g−1, even when the current density returns to 0.2 A g−1, the discharge specific capacity can recover 213 mAh g−1. Furthermore, the kinetic analysis of S-CoP@NPC composite explains that the excellent cycling and rate performance benefit from the extrinsic pseudocapacitive behavior.

Fe3O4 nanoparticle/graphene aerogel (Fe3O4/GA) composite is fabricated by a simple one-step liquid phase precipitation method without further heat-treatment. The reduction of graphene oxide, deposition of Fe3O4 nanoparticle and formation of 3D graphene nanosheet network can happen simultaneously during preparation process, guaranteeing the uniform distribution of Fe3O4 nanoparticles on the surface of graphene nanosheets. The influence of the graphene amount in the Fe3O4/GA composites on electrochemical performance is investigated. The as-prepared Fe3O4/GA composite with a graphene content of 25% displays good electrochemical lithium storage performance (a high reversible capacity of 985 mAh g−1 at a current density of 0.1 A g−1 after 100 cycles) and good rate capability (434 mAh g−1 at the current density as high as 2 A g−1). Moreover, the contribution of the pseudocapacitance capacity can explicate the origin of good rate capability of the Fe3O4/GA composite. This work demonstrates the great potential of Fe3O4/GA composite as an alternative anode material for the low-cost and high-performance lithium ion batteries.

Sn4P3 is one of the most promising anode materials for sodium ion batteries (SIBs) owning to the alloying reaction of P and Sn with Na to form Na3P and Na15Sn4, which is beneficial to achieve a high specific capacity, especially for the high volumetric capacity (6650 mAh cm−3). However, the high capacities generate large volume changes, which pulverize the anode material, resulting in poor cycling stability. This restricts its practical applications for SIBs. Here, the dopamine-derived N-doped carbon encapsulating hollow Sn4P3 microspheres (hollow Sn4P3@C) composites are prepared by an in-situ self-polymerization of dopamine on the surface of hollow SnO2 microspheres followed by a carbonization process and a low temperature phosphorization using NaH2PO2 as P source. The results of the structural and morphological characterization can be demonstrated that as-prepared hollow Sn4P3@C composites are constructed by hollow Sn4P3 microspheres with the ultrathin N-doped carbon coating. The as-prepared samples are tested as the anode materials for SIBs. Compared with bared hollow Sn4P3 microspheres, hollow Sn4P3@C composites exhibit better electrochemical sodium storage performance. As a result, hollow Sn4P3@C composites deliver the first discharge and charge specific capacities of 840 and 587 mAh g−1 with a high initial coulombic efficiency of 70% at a current density of 0.2 A g−1. Moreover, hollow Sn4P3@C composites display superior rate capabilities of 555, 438, 339, 239, 157 and 92 mAh g−1 at 0.2 A g−1, 0.5 A g−1, 1 A g−1, 2 A g−1, 5 A g−1 and 10 A g−1, respectively. Meanwhile, hollow Sn4P3@C composites show a high discharge capacity of 372 mAh g−1 at 0.2 A g−1 after long 200 cycles. A detailed electrochemical kinetic analysis indicates that energy storage for Na+ in Sn4P3 is due to a pseudocapacitive mechanism. The good electrochemical sodium storage performance of as-prepared hollow Sn4P3@C composites may be attributed to the introduction of N-doped carbon coating and unique hollow structure. Therefore, our work provides a new structure model for the development of new anode materials for SIBs.

Fe3O4 nanowires/graphene aerogel composite is prepared for the first time via a simple two-step method, including a hydrothermal and self-assembly water-bath l -ascorbic acid reduction process. Structural and morphological characterizations confirm that the ultralong Fe3O4 nanowires are embedded into the networks of graphene nanosheets. When exploited as an anode material for lithium ion batteries, Fe3O4 nanowires/graphene aerogel composite exhibits good rate capability (557 mAh g−1 at a current density 2000 mA g−1) and excellent cycling performance (900 mAh g−1 at a current density of 200 mA g−1 after 100 cycles) together with good rate performance. This work offers a simple and large-scale preparation process for Fe3O4 nanowires/graphene aerogel composite as an advanced anode material for lithium ion batteries.

Utilized as an oxygen reduction reaction (ORR) catalyst for magnesium-air battery, multi-walled carbon nanotubes (MWCNTs) supported PdSn bimetallic catalyst was synthesized by a facile borohydride reduction method. Heat-treatment was applied to improve the catalytic activity and stability by tailoring the alloying content and surface components of the catalyst. Results illustrated that the 24 h heat-treated PdSn/MWCNTs exhibited best alkaline ORR performance with low over-potential, high diffusion-limited current density and superior stability. A magnesium-air battery employing the 24 h heat-treated PdSn/MWCNTs as cathodic catalyst showed higher discharging power density and enhanced durability compared with those employing the unheated sample and commercial Pd/C catalyst.

The development of effective and high capacitive electrode materials for supercapacitor applications is highly desired. CoP nanowires are prepared by hydrothermal-oxidation-phosphidation method. As a novel electrode material for supercapacitors operating in alkaline aqueous electrolyte, the CoP nanowire electrode exhibits relatively high specific capacitance of 558 F g−1 at a current density of 1 A g−1, maintains a stable cycling life with 98% of the initial capacitance after continuous 5000 cycles. Furthermore, the CoP nanowire electrode can reach up to a high energy density of 23.4 W h Kg−1 at a power density of 274 W Kg−1. Moreover, it is found that as-prepared CoP nanowire electrode delivers substantially enhanced specific capacitance and rate performance compared with the Co3O4 nanowire electrode. These results demonstrate that the CoP nanowires could be an attractive electrode material for high-performance supercapacitor applications.

CoO has been considered as a novel anode material for lithium storage due to its high theoretical capacity. Herein, mesoporous 3D CoO/nitrogen-doped graphene aerogel (CoO/NGA) is constructed by a facile solvothermal approach followed by subsequent annealing. The NGA is prepared by using dimethylmethanamide (DMF) as a reducing agent and nitrogen source. Ultrafine CoO nanocrystals are homogeneously distributed and tightly anchored on the 3D macroscopic NGA frameworks. The 3D NGA can not only effectively restrain the agglomeration of CoO nanocrystal but also accelerate ion and electron transport through 3D networks. Benefiting from the combine of the two characteristics, the unique CoO/NGA anode exhibits an outstanding cycling stability, showing a specific capacity of 896 mAh g−1 at 200 mA g−1 after 200 cycles.

Efficient catalyst with low overpotential and small Tafel slope for oxygen evolution reaction is the key factor to improve overall efficiency of Zn-air battery. In the present study, a novel hybrid catalyst with polyaniline and amorphous iron-cobalt-binary oxide supporting on multiwalled carbon nanotubes is prepared via a simple in situ method by mixing Fe3+, Co2+, aniline and multiwalled carbon nanotubes together followed by subsequent borohydride reduction with citrate as protective stabilizer. The optimal sample exhibits remarkable activity for oxygen evolution reaction in 0.1 M KOH solution, accompanied by a low overpotential of 440 mV at a current density of 10 mA cm−2, and a small Tafel slope of 55 mV dec−1. Such catalyst can endow rechargeable Zn-air battery with a high peak power density of 287.4 mW cm−2 and long-term cycling performance over 100 h with high efficiency and stability, demonstrating its promising feasibility as highly active electrocatalyst for rechargeable metal-air batteries.

In this study, mesoporous NiCoP microflowers are fabricated by a simple direct low-temperature phosphorization of the hydrothermal-prepared Ni0.5Co0.5(OH)2 microflower precursors. The resultant NiCoP material possesses a unique three-dimensional flower-like architecture with high specifc surface area (56.6 m2 g−1) and large pore volume (0.432 cm3 g−1). Utilized as the supercapacitor electrodes, mesoporous NiCoP microflowers outperform the monometallic phosphides (CoxP and Ni2P microflowers) with excellent charge-discharge rate properties (e.g., specific capacity of 1153 and 715 F g−1 at 1 and 30 A g−1, respectively) and superior cycling performance. The specific capacitance of 883 F g−1 can remain stable at 20 A g−1 after 7000 cycles. More importantly, as-prepared NiCoP microflower electrode is able to deliver high energy densities of 48.4 Wh kg−1 and 30 Wh kg−1 at the power densities of 275 W kg−1 and 8.2 kW kg−1, respectively. The enhanced pseudocapacitive performance is mainly attributed to the mesoporous microflower structure and the synergistic combination of different metal elements (Ni and Co) for electrochemical reactions.

In this paper, MOF-derived N-doped porous carbon anchoring Sn4P3 (Sn4P3@NPC) composite is prepared via a low-temperature phosphidation reaction with SnO2@NPC composite as the precursor. The as-prepared Sn4P3@NPC composite exhibit a high stable capacity of 319 mAh g−1 at 0.1 A g−1 after 100 cycles and improved rate performance (the capacities of 365, 322, 260, 204, and 146 mAh g−1 at 0.1, 0.2, 0.5, 1, and 2 A g−1, respectively) for sodium ion batteries. The good electrochemical sodium storage performance of the Sn4P3@NPC composite anodes can be ascribed to the synergistic effect between porous N-doped carbon and high-active Sn4P3 nanoparticles.

Flower-like MoS2 supported on three-dimensional graphene aerogel (MoS2/GA) composite has been prepared by a facile hydrothermal method followed by subsequent heat-treatment process. Each of MoS2 microflowers is surrounded by the three-dimensional graphene nanosheets. The MoS2/GA composite is applied as an anode material of sodium-ion batteries (SIBs) and it exhibits high initial discharge/charge capacities of 562.7 and 460 mAh g−1 at a current density of 0.1 A g−1 and good cycling performance (348.6 mAh g−1 after 30 cycles at 0.1 A g−1). The good Na+ storage properties of the MoS2/GA composite could be attributed to the unique structure which flower-like MoS2 are homogeneously and tightly decorated on the surface of three-dimensional graphene aerogel. Our results demonstrate that as-prepared MoS2/GA composite has a great potential prospect as anodes for SIBs.

For wide application of metal-air batteries, the key factor is the development of catalysts for air cathodes. In the present study, PdCo/C bimetallic nanocatalysts are prepared by a facile borohydride reduction method. To improve the activity and stability, the catalysts are heat-treated at 200 °C in H2/Ar atmosphere from 4 h to 24 h. The optimal heat-treatment time is found to be 8 h, at which the highest activity for both oxygen reduction reaction and oxygen evolution reaction is obtained. With the 8 h heat-treated PdCo/C catalyst, the rechargeable zinc-air battery exhibits a high power density of 180 mW cm−2 and retains stability for more than 50 h at a discharge-charge current density of 10 mA cm−2, while the magnesium-air battery obtains a power density of more than 200 mW cm−2 and remains stable within 8 h at a discharge current density of 65 mA cm−2.

The development of bifunctional electrochemically-active materials for both hydrogen evolution reaction (HER) and supercapacitors enables the possibility to integrate energy storage and production into one single system. Here, we report a novel bifunctional mesoporous Ni2P nanobelt-like architecture prepared via the hydrothermal synthesis of Ni(SO4)0.3(OH)1.4 nanobelt precursor and subsequent low temperature phosphorization process under Ar atmosphere. Composed of numerous cross-linked Ni2P nanoparticles, the as-obtained Ni2P nanobelts exhibit a two dimensional leaf-like morphology, allowing remarkable enhancement of mesoporosity as well as active surface area. The HER electrocatalytic test in acid medium show a current density of 16 mA cm−2 at an overpotential of 187 mV, Tafel slope of 62 mV dec−1 and long-term durability. Investigation of this Ni2P nanobelts as supercapacitor materials in 2M KOH electrolyte display a high specific capacity ranging from 1074 F g−1 at 0.625 A g−1 to 554 F g−1 at 25 A g−1, and notable cycling life with 86.7% retention after 3000 cycles at 10 A g−1. With the simplicity of the synthetic routine and the outstanding performance as both HER catalysts and supercapacitors, the Ni2P nanobelts provide promising potential for energy devices.

Insufficient lithium resource reserves will severely limit the development prospects of lithium-ion batteries. As the next generation of secondary batteries, sodium-ion batteries have attracted widespread attention. In recent years, people have used synergistic bimetal oxides instead of single metal oxides as anode materials for sodium ion batteries, but its electrochemical performance is still not ideal. Therefore, we synthesized cubic SnO2-Co3O4 hybrids by oxidizing CoSn(OH)6 precursor, and then prepared SnO2-CoO@Gr composites by a simple hydrothermal method. The SnO2-CoO@Gr-2 composite material with the graphene content of 9.6% as an anode material for sodium-ion batteries shows an initial discharge capacity of 598.9 mAh g−1 at a current density of 0.1 A g−1, and still has a reversible capacity of 302.8 mAh g−1 after 200 cycles. The introduction of graphene not only greatly restrains volume expansion of material during the cycle, but also effectively improves the conductivity of the composite material, which provides a great direction for preparing high-performance sodium ion battery anode materials.

Unlike full-thickness cartilage defects (FCD), partial-thickness cartilage defects (PCD) may still have residual healthy cartilage tissue, and therefore, the conventional clinical treatments such as microfracture and autologous chondrocyte implantation (ACI) are so traumatic that they may not be the suitable therapies for PCD. Although intra-articular injection of mesenchymal stem cells (MSCs) is a minimally invasive treatment, its therapeutic efficacy is markedly limited due to anoikis caused by failure of cell colonization in the injured area. By modifying a functional polypeptide on the MSC plasma membrane and exploiting the high expression of transglutaminase 2 (TGase2) in the regions of injured cartilage, we achieved targeted recognition and capture of modified MSCs by injured articular chondrocytes (ACs). In the in vitro co-culture model, MSCs improved the function of injured ACs and enhanced the chondrogenic differentiation potential of MSCs. Results of in vitro study also revealed that the activation of the AKT/mTOR signaling pathway may play an important role in the treatment of injured ACs by MSCs. Further, membrane-modified MSCs exhibited a better therapeutic effect than wide-type MSCs in a rabbit model of PCD. Thus, this unique cell membrane modification strategy provides a new cell-based therapeutic approach for the early treatment of articular cartilage defects and other joint diseases.

The fast development of supercapacitors inspires a growing interest in inexpensive super-capacitive electrode material with high performance. Herein, we develop a Rone step method for preparing Cu3P nanocrystals by direct low-temperature phosphorization treatment of commercial copper powder. As a super-capacitive electrode material, for the first time, Cu3P nanocrystals exhibit outstanding electrochemical rate performance (318.5 F g−1 at 400 mV s−1; 169.2 F g−1 at 50 A g−1) and excellent cycling stability with no loss of specific capacitance at 10 A g−1 for 10,000 cycles. The presented synthesis method opens up a facile and large-scale approach to explore high-performance and low-cost Cu3P electrodes for supercapacitors.

ZnFe2O4-graphene aerogels (ZnFe2O4/GAs) composites are prepared by two-step method (hydrothermal-calcination). Highly-purified ZnFe2O4 nanoparticles are dispersed uniformly on three-dimensional (3D) GAs substrate. The mass loading of ZnFe2O4 in ZnFe2O4/GAs composites is 89.3%. Compared with pure ZnFe2O4 sample, the ZnFe2O4/GAs composites exhibit much higher irreversible capacity of 1449.4 mAh g−1 and enhanced cycling stability (1049 mAh g−1 at 100 mA g−1 after 100 cycles). The improved electrochemical performance of the ZnFe2O4/GAs composites could be attributed from the synergetic effect between 3D conductive GAs and nanostructured ZnFe2O4.

Three-dimensional fabricated Fe3O4 quantum dots/graphene aerogel materials (Fe3O4 QDs/GA) were obtained from a facile hydrothermal strategy, followed by a subsequently heat treatment process. The Fe3O4 QDs (2–5 nm) are anchored tightly and dispersed uniformly on the surface of three-dimensional GA. The as-prepared anode materials exhibit a high reversible capacity of 1078 mAh g−1 at a current density of 100 mA g−1 after 70 cycles in lithium-ion batteries (LIBs) system. Moreover, the rate capacity still remains 536 mAh g−1 at 1000 mA g−1. The enhanced electrochemical performance is attributed to that the GA not only acts as a three-dimensional electronic conductive matrix for the fast transportation of Li+ and electrons, but also provides with double protection against the aggregation and pulverization of Fe3O4 QDs during cycling. Apparently, the synergistic effects of the three-dimensional GA and the quantum dots are fully utilized. Therefore, the Fe3O4 QDs/GA composites are promising materials as advanced anode materials for LIBs.

A three-dimensional SnO2 quantum dots/graphene aerogel (SnO2 QDs/GA) composite was prepared using a facile and scalable strategy without adding any surfactant and reducing agent .This as-prepared nanocomposite, with zero-dimensional SnO2 QDs (2–5 nm) anchoring and dispersing on the surface of three-dimensional graphene aerogel, exhibits better properties as anode material for sodium ion batteries than bare SnO2 for its higher reversible capacity (319 mAh g−1 at 50 mA g−1 after 50 cycles) and stability (rate capacity still remains 150 mAh g−1 at 800 mA g−1). Such three-dimensional graphene aerogel could not only act as an electronic conductive matrix for the fast transportation of sodium ion and electrons, but also provide double protection against the aggregation and volume changes of SnO2 QDs during cycling.

In this work, a scalable approach of preparing Co3O4/Co@N–C composite derived from metal organic frameworks (MOFs) is developed. After consecutive carbonization and oxidation of MOFs at different calcination temperatures, a series of nanocomposite consisting of Co3O4, conductive Co nanoparticles, and Nitrogen doped (N-doped) mesoporous carbon are obtained via in-situ polymerization strategy. When employed as anode materials for lithium-ion batteries (LIBs), the Crystalline-Co3O4/Co@N–C-700 (Cry-Co3O4/Co@N–C-700) electrode has shown high reversible specific capacity of 896.5 mAh g−1 at 0.1 A g−1, excellent rate capability of 376.2 mAh g−1 at a large current density of 2 A g−1, and robust long-term capacity retention rate of 96.0% at 0.2 A g−1 after 50 cycles. Such superior lithium storage performance could be attributed to the unique porous structure which composed of well-dispersed Co3O4 and conductive Co nanoparticles together with N-doped carbon skeleton. The unique structure can effectively improve the conductivity and act as a buffer medium to alleviate the volume change, which shows potential application for new energy storage materials.

Traditional metal selenide was used as sodium ion battery anode on account of its high specific capacity and large layer spacing. Here, ZnSe/rGO composites are synthesized through a facile one-step hydrothermal method using relatively environmentally friendly raw materials. The obtained ZnSe nanoparticles with a diameter of about 50 nm, which evenly distributed on the three-dimensional graphene sheet. Electrochemical test results show improved performance, under a current density of 100 mA g−1, the capacity can still remain 276.6 mA h g−1 after 100 cycles. For rate performance, when the current density are under 0.1, 0.2, 0.5, 1, 2, 5 and 10 A g−1, the capacity can remain 411.6, 385.9, 340.1, 293.9, 239.4, 179.2 and 119.4 mA h g−1, respectively. Furthermore, under a large current density of 500 mA g−1, it can remain a reversible capacity of 119.4 mA h g−1. In addition, the calculation of pseudocapacitance shows that it is helpful to achieve pleasing rate capability and long cyclic stability. As a result of its high specific surface area and enhanced electronic conductivity, an improved performance can be obtain, furthermore can well alleviate the volume expansion of the composite.

Targeted cell delivery to lesion sites via minimally invasive approach remains an unmet need in regenerative medicine to endow controlled cell distribution and minimized side-effects. Current cell modification approaches to improve cell delivery tend to have adverse effects on cellular phenotype and functionality. Here, we rationally developed a facile and mild cell modification and targeted delivery strategy leveraging endogenous tissue transglutaminase (TGase) expressed on the surface of MSCs (Mesenchymal Stem Cells) and inflammatory endothelial cells (ECs). Cell modification by functional peptides was accomplished simply via TGase catalyzed cross-linking with naturally-expressed MSCs membrane proteins (e.g. Annexin II), without detectable disturbance of cellular viability and functionality. The modified functional peptides could facilitate adhesion of MSCs to inflammatory ECs (with up-regulated TGase expression compared with normal ECs) in vitro, as demonstrated by a one-fold increase of the MSC-EC adhesion force measured by atomic force microscopy (AFM) and by targeted delivery of modified MSC to inflammatory ECs in a flow chamber assay. When transplanted in vivo, modified MSCs demonstrated a dramatic increase in targeted efficiency to inflammatory endothelium compared with non-modified MSCs in both mice ear inflammation and acute/chronic liver injury models. The cell membrane modification strategy and targeted cell delivery mechanism described here can be readily extended for empowering cell engineering and cell therapy with multifaceted functionalities to combat refractory diseases.

Mesoporous MnCo2O4 microflowers constructed by sheets have been successfully synthesized via a solvothermal route using polymer polyvinyl pyrrolidone (PVP, K30) as a capping agent. Herein, we find concentration of PVP in the reaction mixture plays a key role for controllable structures and morphologies of mesoporous MnCo2O4 microflowers. When tested as anode materials for lithium ion batteries, the MnCo2O4 microflowers exhibit initial discharge and charge capacities of 1465.1 and 1001.2 mA h g−1 at the current density of 100 mA g−1. Moreover, the as-obtained MnCo2O4 microflowers show enhanced rate capability and good cycling stability.

The porous micro-/nanostructured Co3O4 microellipsoids are successfully fabricated through a urea-assisted solvothermal route using polyvinylpyrrolidone (PVP) as the capping reagent followed by thermal treatment in air. The porous characterization has been performed to confirm that porous Co3O4 micro-/nanostructures are composed of numerous primary nanocrystallines. The specific surface area and pore size of the Co3O4 microellipsoids are around ⿼24.2 m2 g⿿1 and 13.5 nm, respectively. The obtained porous Co3O4 microellipsoids demonstrate the high initial discharge capacity of ⿼1314 mAh g⿿1 with a Columbic efficiency of 79.2% at a current density of 50 mA g⿿1 in the potential range of 0.01⿿3.0 V. More impressively, a significantly improved reversible capacity of ⿼1192 mAh g⿿1 is retained at 100 mA g⿿1 after 50 discharge-charge cycles. Excellent rate capabilities (⿼920 mAh g⿿1 at 200 mA g⿿1 and ⿼630 mAh g⿿1 at 600 mA g⿿1) are observed for the porous microellipsoid-like structure. It should be noted that the unique porous micro-/nanostructured microellipsoids play an important role in the enhanced electrochemical lithium storage performance. Therefore, the porous micro-/nanostructured Co3O4 microellipsoids should be suitable as an anode material for lithium ion batteries.

Transition metal selenide (TMS) is recognized as a prospective alternative anode material for the sodium ion battery application because of its high conductivity and high theoretical capacity. Herein, a simple hydrothermal method was used to prepare the ZIF-8 cubes and then followed by a selenization process to fabricate ZnSe nanoparticles decorated with hollow N-doped carbon (ZnSe/HNC) nanocubes. Our selenides exhibit good electrochemical sodium storage properties. It delivers a high initial discharge and charge capacities of 526.9 and 319.5 mAh g−1 at a current density of 100 mA g−1. The reversible capacity of as-prepared ZnSe/HNC nanocube electrode can be maintained at 335.7 mAh g−1 after 50 cycles at the current density of 100 mA g−1. As for rate capacity, the high reversible capacities of ZnSe/HNC nanocube electrode are 323.6, 306.9, 290.2, 262.0, 202.4, 173.6 and 115.4 mAh g−1 at different current densities of 100, 200, 500, 1000, 2000, 3000, 5000 mA g−1, respectively. In addition, the stability of the ZnSe/HNC nanocube electrode at high current density was also obtained. It can release a high and stable capacity of 251.1 mAh g−1 after 500 cycles at a current density of 500 mA g−1. The electrochemical sodium storage process and the reaction mechanism of the ZnSe/HNC nanocube electrode were confirmed by Ex-situ XRD study. Meanwhile, kinetic analysis of the electrochemical Na+ storage characteristics of the ZnSe/HNC nanocube demonstrates that the behavior of the external pseudocapacitor significantly contributes to good rate performance and good long cycle life. The good sodium storage performance of our ZnSe/HNC nanocube anode material can be attributed to the confinement of charge and discharge products for as-prepared ZnSe/HNC nanocube electrode material and the alleviation of volume change effect for our electrode material during cyclic process. This method can be used to adjust other TMS morphologies and structures to develop a new kind of anode materials for sodium ion battery applications.

Bimetallic selenide (ZnSe / CoSe) was embedded in N-doped carbon rhombic dodecahedron and used as a sodium ion battery (SIB) anode. Metal organic framework (MOF) precursors (ZIF-8 / 67) form hollow structures (denoted as ZnSe/CoSe@NPC)through in situ pyrolysis and selenization processes at specific temperatures. Our selenides have very good electrochemical sodium storage properties. After 200circulation, the capacity of the as-prepared ZnSe/CoSe@NPC nanocomposite electrode was maintained at 417.6 mAh g−1 at 0.1 A g−1. Regarding rate capacity, the capacities of ZnSe/CoSe@NPC nanocomposite electrode are of 460.8, 415.6, 359.9, 346.3, 318.0, 274.1 and 236.4 mAh g−1 at different current densities of 0.1, 0.2, 0.5, 1, 2, 5 and 10 A g−1, respectively. The stability of the ZnSe/CoSe@NPC nanocomposite electrode at high current density is also obtained, and after 900 cycles at a high current density of 1 A g−1, the electrode can maintain a stable reversible capacity of 303.9 mAh g−1. Besides, kinetic analysis of the electrochemical Na+ storage behaviour of the ZnSe/CoSe@NPC nanocomposite shows that the external pseudocapacitor results in excellent rate performance and excellent long-cycle stability. This study proposes a new strategy for synthesizing multi-component hollow structures for the manufacture of intended energy storage devices.

Fiber supercapacitors (FSCs) are attractive energy storage devices for wearable and portable electronics. However, it still remains a great challenge to achieve high volumetric specific capacitance without sacrificing the rate capability of FSC. Here, we demonstrate a novel hierarchically nanostructured hybrid fiber with thin polyaniline (PANI) layer anchored on the highly-conductive poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) hydrogel framework as electrodes for FSCs. The hybrid fiber was prepared via hydrothermal assembly of a commercial PEDOT:PSS dispersion followed by acid treatment and in-situ chemical polymerization of aniline. The incorporation of highly-electroactive PANI boosts the whole capacitance of hybrid fiber; the robust PEDOT hydrogel framework provides abundant ions diffusion channels and rapid electron transfer pathways, improving the utilization efficiency and the kinetics of pseudocapacitance reaction of PANI. Attributed to the synergistic effect, the PEDOT/PANI hybrid fiber in FSC exhibits high volumetric/areal specific capacitance (554.1 F cm−3 or 740.0 mF cm−2 at 5 A cm−3), excellent rate performance and good electrochemical stability. The flexible FSC device delivers a high volumetric energy density of 11.9 mWh cm−3 at 981.4 mW cm−3 and areal energy density of 15.8 μWh cm−2 at 1310.5 μW cm−2, outperforming most of the reported counterparts. The well-designed PEDOT/PANI hybrid fiber based FSC hold a great potential for powering the next-generation wearable and portable electronics.