Junke Hou

Facile Synthesis of Novel Networked Ultralong Cobalt Sulfide Nanotubes and Its Application in Supercapacitors

Ultralong cobalt sulfide (CoS(1.097)) nanotube networks are synthesized by a simple one-step solvothermal method without any surfactant or template. A possible formation mechanism for the growth processes is proposed. Owing to the hollow structure and large specific area, the novel CoS(1.097) materials present outstanding electrochemical properties. Electrochemical measurements for supercapacitors show that the as-prepared ultralong CoS(1.097) nanotube networks exhibit high specific capacity, good capacity retention, and excellent Coulombic efficiency.

Solvent-mediated directionally self-assembling MoS2 nanosheets into a novel worm-like structure and its application in sodium batteries

Ultralong worm-like MoS2 nanostructures were assembled with a solvent-mediated solvothermal process by controlling the composition ratio of the miscible precursors in solution. The formation mechanism of worm-like MoS2 nanostructures was proposed and the as-prepared materials as anodes in sodium ion batteries delivered a good discharge–charge capacity, superior cycling stability and excellent coulombic efficiency. This work provides an efficient and economic approach to tailor the nanostructure of layered transition metal oxides and transition-metal dichalcogenides simply by controlling the chemical composition and physical properties in a solvothermal process.

Na3.12Fe2.44(P2O7)2/multi-walled carbon nanotube composite as a cathode material for sodium-ion batteries

Na3.12Fe2.44(P2O7)2/multi-walled carbon nanotube (MWCNT) composite was fabricated by a solid state reaction and was further used to fabricate a cathode for sodium-ion batteries. The electrochemical behaviors were thoroughly investigated in assembled non-aqueous Na3.12Fe2.44(P2O7)2/MWCNT//Na cells, showing higher specific capacity (over 100 mA h g−1 at a rate of 0.15C) and better stable cycle performance than those of the pristine Na3.12Fe2.44(P2O7)2-based one. It is noted that with increased charge–discharge cycles, the specific capacity of Na3.12Fe2.44(P2O7)2/MWCNT gets close to the theoretical capacity (ca. 117.4 mA h g−1). These good performances could be attributed to the incorporated MWCNTs, which improve the conductivity for lower charge transfer resistance and shorten the diffusion length for faster Na+ diffusion to access the reaction sites. Through systematic studies of EIS at different states of charge and discharge, it is discovered that Rct decreases with the increase of voltage and reaches a minimum value at redox sites, but Re and DNa+ show the opposite trend. Moreover, a full cell test using a carbon black negative electrode also demonstrates good capacity retention up to 50 cycles and a reversible capacity of 145 mA h g−1 with the average operation voltage of 2.8 V.

Facile preparation of semimetallic MoP2 as a novel visible light driven photocatalyst with high photocatalytic activity

The production of clean and renewable H2 by photocatalytic water splitting has attracted much attention due to the increasing energy crisis. In this work, semimetallic MoP2 nanoparticles are discovered as a new photocatalyst to efficiently degenerate methyl orange and produce H2 from water under visible light irradiation. MoP2 nanoparticles were prepared using a solid-state reaction route via a vacuum encapsulation technique followed by acid washing. Both first-principle band-structure calculations and experimental measurements reveal typical semimetallic characteristics for MoP2. The obtained MoP2 nanoparticles display superior photocatalytic performances for the degradation of methyl orange with a good stability and the reduction of water assisted by sacrificial elemental Pt under visible light. The detection of hydroxyl radicals in the solution in the presence of MoP2 with fluorescence spectroscopy confirmed its photodegradable activities. The present study points out a new direction for developing semimetallic photocatalysts for H2 production through water splitting.

High performance mesoporous C@Se composite cathodes derived from Ni-based MOFs for Li–Se batteries

A mesoporous carbon matrix derived from MOF-Ni prepared via a hydrothermal method was used for encapsulating selenium as a cathode material for Li–Se batteries. Thermogravimetric analysis and energy-dispersive X-ray analysis confirm that selenium is highly homogeneously distributed in the composite with a mass loading up to 48%. It exhibits an initial discharge capacity of 599.7 mA h g−1 and retains 417 mA h g−1 with a high coulombic efficiency of 99.9% after 100 cycles at a high rate of 3C, of which the excellent electrochemical performance is mainly attributed to the high conductivity and the hollow structure of the carbon matrix.

A selenium-confined porous carbon cathode from silk cocoons for Li–Se battery applications

A composite of selenium (Se) and a rich porous carbon material (PCM) with mesopores from silk cocoons is explored as a cathode for lithium–selenium (Li–Se) batteries for the first time. Elemental selenium is homogeneously dispersed inside the mesopores of the PCM by a melt-diffusion method based on several analyses. The synthetic PCM/Se composite can effectively suppress the dissolution of the active material and maintain mechanical stability. In the case of Li–Se batteries, it delivers a reversible capacity of more than 230 mA h g−1 after 510 cycles at 2C. The remarkable electrochemical performance may benefit from the favorable conductivity and the porous structure of the carbon material as the host matrix.

Synthesis of novel book-like K0.23V2O5 crystals and their electrochemical behavior in lithium batteries

A novel book-like K0.23V2O5 crystal is obtained by a simple hydrothermal method and is explored as a cathode material for Li-ion batteries for the first time. It exhibits a high reversible capacity (of ca. 244 mA h g(-1) at a current density of 50 mA g(-1)), along with a good rate capability (80 mA h g(-1) at a current density of 1800 mA g(-1)) and a good capacity retention (185.3 mA h g(-1) after 100 cycles).

NaTi3FeO8: a novel anode material for sodium-ion batteries

A novel NaTi3FeO8 material is explored as an anode for sodium-ion batteries for the first time. It delivers a reversible discharge capacity of 170.7 mA h g−1 at 20 mA g−1 in a sodium half cell, exhibiting good capacity retention at a cut-off voltage of 0.01–3 V.

Na0.56Ti1.72Fe0.28O4: a novel anode material for Na-ion batteries

A novel Na0.56Ti1.72Fe0.28O4 material is explored as an anode in Na-ion batteries for the first time. It delivers a reversible discharge capacity of 210.3 mA h g−1 at 20 mA g−1 in Na-ion batteries, exhibiting good capacity retention at a cut-off voltage of 0.01–3 V.

Exploration of Na(2.65)Ti(3.35)Fe(0.65)O9 as anode materials for Na-ion batteries.

Na(2.65)Ti(3.35)Fe(0.65)O9 rods were prepared by a simple solid-state route and coated with carbon to enhance their electronic conductivity. For the first time, Na(2.65)Ti(3.35)Fe(0.65)O9 was explored as an anode material for Na-ion batteries to deliver a discharge capacity of 137.5 mA h g(-1) at a current rate of 40 mA g(-1). The charge/discharge capacity of a carbon-coated sample increased by 46.3% to achieve 201.1 mA h g(-1).