Search

Sodium-ion batteries (SIBs) have aroused great attention because of the low cost and environmental benignity of sodium resources. However, practical applications of SIBs are plagued by the sluggish kinetics of sodium ions with large size in the host structure, which results in poor rate performance and rapid capacity decline. Herein, a self-templated approach was developed to synthesize MoS2 /Cu2 Se nanosheets with improved interfacial electron- and ion-transfer kinetics. The MoS2 /Cu2 Se nanosheets provided superior sodium storage performance, delivering 139 mAh g-1 at a high current density of 100 A g-1 and 222 mAh g-1 after 14000 cycles (at 20 A g-1 ). The outstanding electrochemical performance was attributed to the synergetic engineering of interface and structure, which could enhance the electrochemical kinetics and gave excellent mechanical properties to deal with the volume expansion phenomenon. Combined with a high-voltage cathode, the full battery demonstrated a high energy density of 152 Wh kg-1 at a power density of 420 W kg-1 , which opens a new avenue for the development of high-performance SIBs.

The development of metal–organic frameworks (MOFs) as high-efficiency electrocatalysts for water splitting has attracted special attention due to their unique structural features including high porosity, large surface areas, high concentrations of active sites, uniform pore sizes and shapes, etc. Most of the related reports focus on the in situ generation of high-efficiency electrocatalysts by annealed MOFs. However, the pyrolysis process usually destroys the porous structure of MOFs and reduces the number of active sites due to the absence of organic ligands and agglomeration of metal centers. In this work, we prepared unique NiCo-MOF hollow nanospheres (NiCo-MOF HNSs) by a solvothermal method and further fabricated Fe-doped NiCo-MOF HNSs (Fe@NiCo-MOF HNSs) by a simple impregnation-drying method. Significant enhancement of electrocatalytic activity of Fe@NiCo-MOF HNSs was witnessed because of the doped Fe. Compared with the parent NiCo-MOF HNSs, the optimized Fe@NiCo-MOF HNSs exhibited a lower overpotential of 244 mV at 10 mA·cm−2 with a smaller Tafel slope of 48.61 mV·dec−1, which was lowered by ca. 90 mV due to the influence of Fe doping on the electronic structure of the active centers of Ni and Co. The above materials also displayed excellent stability without obvious activity decay for at least 16 hours. These findings present a new entry in the design and fabrication of high-efficiency MOF-based electrocatalysts for energy conversion.

Pristine metal-organic frameworks (MOFs) have received much attention in recent years due to their high specific surface areas, large porosity, excellent pore size distributions, flexible structure, and remarkable catalytic properties. The design of functional MOFs that can function as efficient HER and OER catalysts is significant in solving the energy crisis but remains a big challenge. Tri-metallic metal-organic frameworks show a good application prospect in water oxidation. In this review, we are going to focus on the latest progress and future trends in the development of pristine trimetallic MOFs with respect to the OER. The synergistic effect between multi-metal active sites is effective at improving the intrinsic activity of MOFs toward the OER. By summarizing the synthesis method of tri-metallic MOFs and observing their performance toward the oxygen evolution reaction, we hope that this review will trigger new developments in coordination chemistry, electrochemistry, nanomaterials and energy materials.

As an important two-dimensional material, layered double hydroxides (LDHs) show considerable potential in electrocatalytic reactions. However, the great thickness of the bulk LDH materials significantly limits their catalytic activity. In this work, we report ultrathin NiFe-LDH nanosheets with sulfate interlayer anions (Ni6Fe2(SO4)(OH)16·7H2O) (U-LDH(SO42−)), which can be synthesized in gram-scale by a simple solvothermal method. The U-LDH(SO42−) shows excellent stability and great electrocatalytic performance in OER with a current density of 10 mA cm−2 at a low overpotential of 212 mV and a small Tafel slope of 65.2 mV dec−1, exhibiting its great potential for a highly efficient OER electrocatalyst.

Cuboidal [Ni4O4] clusters supported by a pyridine alkoxide ligand have been developed. One of these clusters was selected as a precursor for carbon-hosted Ni nanoparticles (NiNPs/C) which were efficient catalysts for the conversion of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) at room temperature.

The development of bifunctional non-noble metal electrocatalysts demonstrating high activity and stability for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is of great significance for renewable and clean energy. In this work, we report hierarchically structured integrated Fe-MoS2/Ni3S2/NF (NF = nickel foam) materials prepared by a facile in situ solvothermal method, and among them, the Fe-doped MoS2 was assembled into spine-like nanorods. The optimized electrocatalyst (denoted as Fe-MoS2/Ni3S2/NF-2) demonstrated excellent activity and durability for performing the HER and OER in an alkaline electrolyte (pH = 14) with low overpotentials of 130.6 mV and 256 mV (vs. RHE) at a current density of 10 mA cm-2, as well as no significant loss in catalytic performance even after 2000 cyclic voltammetry (CV) cycles. An outstanding durability of 180 h could be achieved for OER. The overall water splitting made up of the two-electrode system with Fe-MoS2/Ni3S2/NF-2 as both the anode and the cathode required a voltage of only 1.61 V to drive a current density of 10 mA cm-2 along with an outstanding long-term stability of 20 h, displaying its great potential for application in water splitting. The effective construction of multi-component synergistic structures shows a good pathway for high-performance electrocatalysis and energy storage.

Ultrathin metal-organic framework (MOF) nanosheets (NSs) offer potential for many applications, but the synthetic strategies are largely limited to top-down, low-yield exfoliation methods. Herein, Ni-M-MOF (M=Fe, Al, Co, Mn, Zn, and Cd) NSs are reported with a thickness of only several atomic layers, prepared by a large-scale, bottom-up solvothermal method. The solvent mixture of N,N-dimethylacetamide and water plays key role in controlling the formation of these two-dimensional MOF NSs. The MOF NSs can be directly used as efficient electrocatalysts for the oxygen evolution reaction, in which the Ni-Fe-MOF NSs deliver a current density of 10 mA cm-2 at a low overpotential of 221 mV with a small Tafel slope of 56.0 mV dec-1 , and exhibit excellent stability for at least 20 h without obvious activity decay. Density functional theory calculations on the energy barriers for OER occurring at different metal sites confirm that Fe is the active site for OER at Ni-Fe-MOF NSs.

In this work, we fabricate new yolk–shell Pd@ZIF-8 (ZIF = zeolitic imidazolate framework) nanoparticles (NPs) through reactions of the preformed core–shell Pd@ZnO NPs with 2-methylimidazole under mild conditions. In this method, ZnO is used as the self-template and the Zn2+ source for the formation of the ZIF-8 shell. The morphology, composition and structure of the as-prepared yolk–shell nanomaterial are characterized by scanning electron microscopy, transmission electron microscopy, high resolution transmission electron microscopy, powder X-ray diffraction, energy dispersive X-ray spectroscopy, and inductively coupled plasma atomic emission spectroscopy. The formation of this well-defined yolk–shell nanostructure is highly dependent on the solvent system and reaction time. This nanomaterial can be employed as an excellent heterogeneous catalyst for the liquid-phase hydrogenation of olefins with high size-selectivity at room temperature, which is mainly due to the inherent porous structure of the outer ZIF-8 shell along with the enclosed Pd NPs. The nanocatalyst system can be recycled at least three times without any evident loss of the catalytic efficiency.

We report the synthesis of unique Au–Pd bimetallic alloy nanoparticles (NPs) supported on a hollow Cu2O–CuO core–shell heterostructure via the galvanic replacement method, which represents the first example of Au–Pd alloy nanoparticles immobilized on hollow Cu2O@CuO nanocubes. The morphological evolution can be controlled by the reaction time. The morphology, composition, and structure of the as-prepared Cu2O@CuO/(Au–Pd) material are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), elemental analysis (EDS) and inductively coupled plasma atomic emission spectroscopy (ICP-AES). The size of the Au–Pd bimetallic NPs deposited onto the Cu2O@CuO nanocubes is ca. 15 nm. These bimetallic NPs showed a high catalytic activity towards the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) in water at room temperature. Significantly, the strong synergistic effect between Au and Pd, and the high specific surface area of Cu2O@CuO enhance the catalytic efficiency. The catalytic system can be reused for several cycles without any obvious decay of the catalytic efficiency.

Using Li2O-B2O3-SiO2 (LBS) glass and LiF as a liquid phase sintering additive, the effects of it on the microstructure and properties of 16CaO-9Li2O-12Sm2O3-63TiO2（CLST）ceramics were investigated. The results indicated that the compound sintering aids of LBS glass and LiF reduced the sintering temperature of CLST from 1300 °C to 950°C. Compared with the sample doped single LBS glass, the optimum dielectric properties, Kr=81, Tanδ=0.0073 could be obtained when the CLST ceramic samples doped 3 wt% LBS glass and 0.25 wt% LiF were sintered at 950°C for 3 h.

The Bi1.5ZnNb1.5O7 ( -BZN) ceramics were prepared by combining conventional solid synthesis (CS) and hydrothermal method (HTM). The emphasis was placed on the effects of doping nanopowder synthesized by HTM on the properties of -BZN ceramics. The results show that there is no effect of doping nanopowder on the sintering temperature and phase of -BZN ceramics. Therefore, with the increase of doping nanopowder, the density of ceramics decreases. Doped 10 wt% nanopowder, the ceramic sample sintered at 1000°C exhibits a well-crystalline phase and more excellent dielectric properties than others. At 1MHz, the observed value is about 148 and tan value is less than 3.365×10-4.

The effects of ZnO-Bi2O3-B2O3-SiO2(ZBBS) glass addition on the sintering behavior, crystalline phase, microstructure and dielectric properties of 16CaO-9Li2O-12Sm2O3-63TiO2(CLST) ceramics were investigated. The results show that ZBBS glass can effectively decrease the sintering temperature of CLST ceramics to 1 000 °C by liquid phase sintering. With the increase of ZBBS content, the second phase，Sm2Ti2O7 is found and increase, which causes the dielectric constant and dielectric loss of CLST decrease. The temperature coefficient of the resonance frequency shifts to positive. The optimum dielectric properties of r = 71, Tan = 0.006, TCF= 5×10-6/°C were obtained in 10wt% LBS glass-doped CLST ceramics sintered at 1 000 °C for 3 h.