Xutang Qing

One-step construction of graphene–polypyrrole hydrogels and their superior electrochemical performance

Graphene–polypyrrole (GPPy) composites with 3-dimensional macrostructure were prepared by a one-step self-assembly process, in which the continuous oxidation-reduction reaction of pyrrole monomers and graphite oxide in the existence of Cu2+ finally resulted in the formation of macroporous hydrogels. The as-prepared hydrogel exhibited a high specific capacitance of 498 and 295 F g−1 respectively at the scan rate of 5 mV s−1 and the discharge current density of 1 A g−1. Furthermore, a specific capacitance of 240 F g−1 could be achieved even if at a high current density of 10 A g−1, and maintained 80% of the capacitance value after charge–discharge for 5000 cycles. Such excellent capacitive properties in rate stability and cycling stability endow the GPPy hydrogels with great potential applications in high-performance energy storage devices. Besides, this study also provides new insights into the design and synthesis of graphene-based materials.

P/N/O co-doped carbonaceous material based supercapacitor with voltage up to 1.9 V in aqueous electrolyte

Phosphorus, nitrogen and oxygen co-doped carbonaceous materials (PNODC) were facilely prepared by pyrolyzing phosphorus, nitrogen and oxygen-rich phytic acid doped polyanilines. ICP analysis and elemental analysis demonstrate that the maximum phosphorus content of the as-prepared PNODC reaches 6.02 wt% with the total heteroatom (phosphorus, nitrogen and oxygen) content up to 32.76 wt%. The symmetric supercapacitor built from PNODC could be operated at a very high working voltage of 1.9 V. A maximum energy density of 21.8 W h kg−1 is achieved at a power density of 238 W kg−1 and a voltage load of 1.9 V. The excellent electrochemical performance can be attributed to the high heteroatom content, the synergetic effect of phosphorus and nitrogen/oxygen co-doping and the protection of abundant heteroatom functionalities on the surface of the carbon electrodes.

Sequential Polymer Precipitation of Core–Shell Microstructured Composites with Giant Permittivity

Polymeric core-shell microstructures have been constructed through a new method, namely sequential precipitation, which is intrinsically a self-assembly and phase separation process. High-quality poly(vinyldene fluoride)-polycarbonate-lithium perchlorate composite films with spherical core-shell microstructures have been prepared and determined to consist of conducting cores and insulating shells. Because of the percolation effect, the resulting materials present a dielectric constant as high as 10(4) -10(7) at the threshold.