Bin Du,Xingming Huang,Anzhe Wang,Yiran Liu,Yuan Cheng
Ceramic powders with low oxygen content are highly demanded in monolithic ceramics. In this work, a series of medium-/high-entropy ceramic (HEC) particles, including (Zr 0.25 Ta 0.25 Nb 0.25 Ti 0.25 )C, (Zr 0.2 Ta 0.2 Nb 0.2 Ti 0.2 W 0.2 )C, (Zr 1/6 Ta 1/6 Nb 1/6 Ti 1/6 W 1/6 Hf 1/6 )C (Zr 1/7 Ta 1/7 Nb 1/7 Ti 1/7 W 1/7 Hf 1/7 V 1/7 )C, and (Zr 1/8 Ta 1/8 Nb 1/8 Ti 1/8 W 1/8 Hf 1/8 V 1/8 Mo 1/8 )C, were successfully fabricated by the polymer-derived ceramic (PDC) route. The structure evolutions of the precursor demonstrated that HEC particles obtained at 1800 °C possessed a single phase and rock-salt structure. All the samples had the similar microstructures (hillock structure) and a low oxygen impurity content (less than 2.00 wt%). The results also demonstrated that the as-obtained HEC particles had a disordered distribution of elements from nanoscale to microscale. This work proved a new method to fabricate the HEC powders with low oxygen impurity content and the HEC precursors for further obtaining the nanofibers or ceramic matrix composites .
Two-dimensional transition-metal dichalcogenides, such as tungsten disulfide (WS 2 ), have been actively studied as suitable candidates for anode materials used in lithium ion batteries recently, due to their remarkable ion intercalation properties. However, the difficulties in the synthesis of phase-pure WS 2 , restacking between WS 2 nanosheets, low electronic conductivity and brittle nature of WS 2 severely limit its Li-ion batteries application. Here, we adopt a one-pot method for synthesizing of WS 2 /reduced Graphene Oxide (rGO) composite to improve the battery performance dramatically. The WS 2 /rGO anode shows a stable discharge capacity of 431.2 mAh/g, at a current density of 0.1 A/g after 100 cycles, while the capacity of bare WS 2 is only 65.5 mAh/g under the same condition. The added graphene oxide is reduced to rGO in reaction process and constitute stable composite with WS 2 , not only avoiding the restacking between WS 2 nanosheets and improving the conductive properties, but also promoting the reduction of WO 3 effectively. Our work may provide a possible route to avoid oxygen impurities in transition metal dichalcogenides .
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