By using zeolitic imidazolate framework of ZIF-67 as the precursor, the hollow porous Co9S8 (H–Co9S8) nanocages are synthesized via the sulfidation reaction and thermal treatment processes. The ...ordinary solid Co9S8 (S–Co9S8) particles are prepared by hydrothermal method. To improve the conductivity and activity of the Co9S8 materials, H–Co9S8 + MWCNTs and S–Co9S8 + MWCNTs composites are fabricated by ball milling. The electrochemical hydrogen storage properties of H–Co9S8 and H–Co9S8 + MWCNTs electrodes are tested via a three-electrode system for the first time. Ultimately, the H–Co9S8 nanocages with hollow porous structure show higher discharge capacity of 667.1 mAh/g than the S–Co9S8 particles. The electrochemical performance enhanced after doping with MWCNTs. H–Co9S8 + MWCNTs displays the highest discharge capacity of 683.5 mAh/g. Additionally, the preferable high-rate dischargeability, corrosion resistance, and improved kinetic properties are also achieved for H–Co9S8 + MWCNTs. H–Co9S8 with a unique hollow structure and large specific surface area can offer sufficient electrochemical active sites to anchor hydrogen, meanwhile, MWCNTs with excellent electrical conductivity can further provide fast channels for charge transfer and improve the electrocatalytic activity of Co9S8 electrode during the charging/discharging processes.
Display omitted
•The hollow porous Co9S8 nanocages were prepared by hydrothermal using ZIF-67 as the precursor.•Composites of Co9S8 doping with MWCNTs were fabricated via ball-milling.•The unique hollow porous structure of H–Co9S8 could accelerate the hydrogen diffusion.•The capacity, stability, HRD and kinetic performance were enhanced after MWCNTs loading.
•Carbon nanoparticles derived from 3-hydroxybenzoic acid were achieved.•Lanthanide was incorporated into the nanosystem.•An “off-on” change was discovered in the presence of GSH.
Selective ...determination of targets in live cells and the real-time detection of active species will be highly valuable in biological field. Integration of 3-hydroxybenzoic acid and europium ions under hydrothermal conditions would lead to the formation of regular carbon nanoparticles with the size of 10–20 nm. This novel nanostructure possessed striking blue luminescence and no effective lanthanide signals were detected. In the presence of glutathione (GSH), the europium incorporated nanoparticles showed intensive red luminescence and an “off-on” change was observed. It has been accepted that GSH acts as an antioxidant to protect cell via entrapping free radicals and it controls oxidative stress within living systems. The abnormal levels of GSH will be closely related to a variety of diseases. Therefore, the bio-distribution and in vitro detection of GSH were investigated in this study. The biocompatibility and cytotoxicity of the europium incorporated nanoparticles were also evaluated by MTT assay and flow cytometry. This new system will be essential to monitor the concentration of important biological compounds in living organisms.
•Ni-Mo2C was introduced as adsorption-conversion material for Li-S battery.•Ni effectively promote the adsorption and catalytic conversion of Mo2C to polysulfide.•Ni-Mo2C with a superior performance ...was selected by composition regulation.
How to design the components of the cathode carrier is very important for the adsorption and catalysis of polysulfide conversion. Herein, Ni-Mo2C codoped hollow carbon nanospheres were prepared by two-step solvent synthesis and subsequent heat treatment. Ni as a supplementary material, it can effectively solve the problems of few electrochemical active sites and poor catalytic effect of lithium polysulfide (LPS) of Mo2C carbon nanospheres, and the optimal ratio of Ni to Mo2C was explored. Through the comparison of electrochemical tests, the Ni-Mo2C carbon nanospheres of optimal proportion shows high discharge specific capacity (0.2 C, 1101.3 mAh·g − 1) and excellent rate performance (2 C, 692.9 mAh·g − 1), which shows the best catalytic and adsorption effect on LPS. In addition, the optimal proportion of Ni-Mo2C carbon nanospheres has the highest lithium ion diffusion coefficient, which can accelerate the transport of Li+ and the kinetics of electrochemical reaction.
•La2O2S was introduced into lithium-sulfur battery as adsorption-conversion material.•La2O2S-c, La2O3-C and La2S3-C composites were prepared at a lower temperature.•Synergy of adsorption and Gibbs ...free energy ensure high capacity and reversibility.
How to solve the shuttle effect of soluble lithium polysulfide (LiPS) and the reversible conversion of solid LixS is an important challenge to realize the practical application of lithium sulfide battery (LSB), and the selection, preparation and design of adsorption-conversion materials have always been an important topic in the research of LSB. In this work, based on the adsorption sites of LiPS and the transport path of lithium ion, we propose that metal sulfur oxides containing both metal-O and metal-S bonds in their molecular structure may be ideal adsorption-conversion materials. Therefore, La2O2S as an air stable metal sulfur oxides is selected as the target material. With La-BTC nanorod as the precursor, by adjusting the heat treatment temperature and the use of sulfur source, we achieved the preparation of La2O2S-C composite under relative low heat treatment conditions. Through DFT theoretical calculation, XPS and electrochemical test of button simulation batteries, we find that compared with La2O3 and La2S3, La2O2S has moderate adsorption energy and the largest Gibbs free energy, which is more suitable for the adsorption-conversion material of lithium sulfur battery. The button cell with La2O2S-C/PP retained a capacity of 664 mAh g−1 after 300 cycles at the discharge current of 1C.
A facile saturated solution synthesis method is used to obtain the porous polyaniline (P-PANI). The materials exhibit unique sea urchin-like morphology and special porous structure. Ti49Zr26Ni25 ...quasicrystal is fabricated via mechanical alloying followed by annealing treatment. Different amounts of P-PANI are coated on the surface of hydrogen storage alloy by ball milling. For comparison, Ti49Zr26Ni25 alloy doped with conventional PANI (C-PANI) is also prepared. The electrochemical characterizations of the composites are conducted in the standard tri-electrode system. Ultimately, the P-PANI coated Ti49Zr26Ni25 electrode shows preferable performance compared with the C-PANI modified alloy (230.6 mAh/g) and original alloy (209.3 mAh/g). As the additive content of P-PANI is 6 wt%, a maximum discharge capacity of 258.7 mAh/g is obtained. Furthermore, the cycle stability and high-rate dischargeability of the electrodes are also enhanced. The P-PANI materials with distinctive morphology and unique porous structure can not only improve the electrocatalytic activity of polyaniline but also increase the specific surface area of Ti49Zr26Ni25 alloy. The P-PANI can further facilitate the hydrogen diffusion, expedite the charge transfer in/on the alloy and improve the corrosion resistance, thus enhancing the electrochemical performance and reaction kinetics of the hydrogen storage alloys.
•A facile saturated solution synthesis method is used to prepare porous polyaniline.•Ti49Zr26Ni25 alloy coated with sea urchin-like porous polyaniline is fabricated.•The Cmax, cycle stability and kinetic properties of composite electrodes are improved.•The porous structure may be advantageous to the hydrogen diffusion and charge transfer.
Ti49Zr26Ni25 quasicrystal alloy is prepared via mechanical alloying and subsequent annealing. ZIF-8 derived porous carbon (ZIF-8-C) is obtained through thermal treatment of zinc-based MOF ZIF-8. The ...solvothermal method is used to fabricate the ZIF-8 derived carbon/MoS2 (C/MoS2) composite. Then, the C/MoS2 hexahedral particles are coated on the Ti49Zr26Ni25 surface by ball-milling. For comparison, the Ti49Zr26Ni25 + ZIF-8-C and Ti49Zr26Ni25 + MoS2 composites are also prepared. The C/MoS2 modified Ti49Zr26Ni25 displays higher hydrogen storage capacity of 279.1 mAh/g than separate ZIF-8-C or MoS2 coated alloy and original Ti49Zr26Ni25. The superior properties may be due to the synergistic effect between high conductive flexible ZIF-8-C porous carbon and active MoS2. The preferable oxidation/corrosion resistance and cyclic stability are also realized. Moreover, Ti49Zr26Ni25 + C/MoS2 electrode exhibits higher exchange current density I0, limiting current density IL, hydrogen diffusion coefficient D and lower charge-transfer resistance Rct. The distinctive structural feature of C/MoS2 can serve a rapid passageway and accelerate the hydrogen diffusion, thus further improving the kinetic properties and electrochemical activity of Ti49Zr26Ni25 alloy electrode.
•A facile solvothermal method is used to prepare ZIF-8 derived carbon/MoS2 composite.•Ti49Zr26Ni25 quasicrystal alloy coated with C/MoS2 is obtained via ball milling.•The hydrogen storage capacity, HRD and kinetics performance of electrodes are improved.•The synergistic effect of MoS2 and ZIF-8-C is advantageous to the hydrogen diffusion.
Thermal treatment of zinc-based MOF (ZIF-8) is conducted to prepare ZIF-8 derived porous carbon (ZIF-8-C). ZIF-8-C/NiS hexahedral composites with different C/Ni mole ratios (C@NiS-2, C@NiS-4 and ...C@NiS-6) are synthesized by solvothermal method. Co–P hydrogen storage material is prepared via mechanical alloying. Then, composites of Co–P coated with NiS, ZIF-8-C and C@NiS are obtained by ball-milling. Eventually, C@NiS-4 coated Co–P electrode exhibits higher discharge capacity of 624.8 mAh/g than separate NiS or ZIF-8-C modified Co–P and original Co–P electrodes. The HRD, corrosion resistance and kinetics properties of Co–P are also improved after C@NiS-4 loading. The enhanced kinetics performance and electrochemical activities of Co–P + C@NiS-4 may be due to the synergistic effect between flexible porous carbon ZIF-8-C and active NiS nanosheets, which can further accelerate the hydrogen diffusion during the charging/discharging processes.
•ZIF-8 derived porous carbon/NiS hexahedral composite is prepared by solvothermal method.•C@NiS particles with different C/Ni mole ratios are coated on Co–P material by ball-milling.•The discharge capacity, HRD and kinetic properties of composite electrodes are enhanced.•The synergistic effect of ZIF-8-C and NiS can accelerate the hydrogen diffusion.
Urea oxidation reaction (UOR) is considered an ideal water splitting reaction with the potential to replace oxygen evolution reaction (OER), as it lowers the anodic potential and utilizes urea as a ...renewable and abundant resource. However, creating stable, effective bifunctional catalysts is still challenging. In this work, we report a novel bifunctional catalyst of core-shell structure Ni-500 Nano-particle. The carbon coating not only offers numerous active sites and facilitates rapid charge transfer but also shields the nickel core from corrosion. Moreover, By replenishing the urea concentration, the current density can be recovered and sustained for 50 h with only an 8 % decrease. It is significantly less than pure water electrolysis that the urea-assisted water electrolyzer with Ni-500 as both cathode and anode achieves cell-voltage of 1.55 V at 100 mA cm−2. This work demonstrates the potential of Ni-500 as a inexpensive and effective catalyst for urea-based hydrogen production, and offers new perspectives into the design and optimization for core-shell structure electrocatalyst.
Display omitted
•A core-shell structured nanoparticle catalyst was synthesized using a simple step-by-step annealing method.•The urea-assisted water electrolyzer using Ni 500 as both anode and cathode achieve a cell voltage of 1.55 V at 100 mA cm−2•Carbon shell protects nickel core from corrosion, while providing a large number of active sites.•Control the structure and composition of materials by adjusting the annealing temperature.
Li-O
2
batteries with extremely high specific energy density have been regarded as a kind of promising successor to current Li-ion batteries. However, the high charge overpotential for the ...decomposition of Li
2
O
2
discharge product reduces the energy efficiency and triggers a series of side reactions that cause the Li-O
2
batteries to have a limited lifetime. Herein, Co-doped C
3
N
4
(Co-C
3
N
4
) photocatalysts were designed by an
in situ
thermal evaporation method to take advantage of the photo-assisted charging technology to conquer the shortcomings of Li-O
2
batteries encountered in the charge process. Different from the commonly used photocatalysts, the Co-C
3
N
4
photocatalysts perform well no matter with and without illumination, owing to the Co doping induced conductivity and electrocatalytic ability enhancement. This makes the Co-C
3
N
4
reduce the charge and discharge overpotentials and improve the cycling performance of Li-O
2
batteries (from 20 to 106 cycles) without illumination. While introducing illumination, the performance can be further improved: Charge voltage reduces to 3.3 V, and the energy efficiency increases to 84.84%, indicating that the Co-C
3
N
4
could behave as a suitable photocathode for Li-O
2
batteries. Besides, the low charge voltage and the continuous illumination together weaken the corrosion of the Li anode, making the long-term high-efficiency operation of Li-O
2
batteries no longer just extravagant hope.
