Kuiyong Chen

Fluorescent organic–inorganic hybrid polyphosphazene microspheres for the trace detection of nitroaromatic explosives

Highly cross-linked, intrinsically fluorescent organic–inorganic hybrid polymer microspheres bearing primary amine groups on the surface have been successfully prepared through a one-pot polycondensation of hexachlorocyclotriphosphazene with benzidine. Just by the single-step introduction of plentiful π-conjugated benzidine units in the structure, the resulting microspheres easily obtain both the luminescence and abundant active amino groups, with no need for more modification. Thus further using the microspheres as fluorescence-based nitroaromatic sensor, 2,4,6-trinitrotoluene, 2,4-dinitrotoluene, and picric acid can be effectively and sensitively detected. Because the nitroaromatic analytes can be effectively enriched on the surface of the microspheres by the charge-transfer complexing interaction between electron-deficient aromatic rings and electron-rich amino groups, which facilitates the electron transfer and energy transfer from microspheres to nitroaromatics, and finally leads to a significant and sensitive fluorescence quenching response. Moreover, the microspheres also exhibit remarkable thermal stability, photobleaching stability, and solvent resistance and dispersion ability in various solvents including both aqueous and organic media, owing to the highly cross-linked and organic–inorganic hybrid structure.

Enhancement of the electrocapacitive performance of manganese dioxide by introducing a microporous carbon spheres network

An amorphous MnO(2)·nH(2)O/microporous carbon spheres (α-MnO(2)·nH(2)O/MCS) composite electrode material is prepared by a chemical co-precipitation method. It is observed that the amorphous MnO(2) particles are deposited on the surface of the MCS, which form a network with a uniquely developed three-dimensional open porous system containing macropores, mesopores and micropores. The electrochemical measurements reveal that the composite electrode material presents a much more stable and reversible capacitance behavior compared to the pure α-MnO(2)·nH(2)O in 1 M of Na(2)SO(4) electrolyte. The composite containing 25 wt% MCS exhibits optimal specific capacitance of 218.2 F g(-1) at 2 mV s(-1), and is still as high as 112.4 F g(-1) at 100 mV s(-1), while a drastic reduction from 197.0 F g(-1) at 2 mV s(-1) to only 40.7 F g(-1) at 100 mV s(-1) occurs for the pure α-MnO(2)·nH(2)O. The composite also shows a rather high electrode-specific capacitance of 3.13 F cm(-2) and a long cycle life. The remarkable enhancement in the electrochemical performance is mainly attributed to the microporous structure of the MCS contributing to the deposition of MnO(2) particles on the surface of the MCS, and the uniquely developed porous network of the composite facilitating the rapid transport of the electrolyte. These factors result in the high electrochemical utilization of MnO(2), a great reduction of the equivalent series resistance, and hence the relatively high and stable electrochemical behavior.

Hybrids based on transition metal phosphide (Mn2P, Co2P, Ni2P) nanoparticles and heteroatom-doped carbon nanotubes for efficient oxygen reduction reaction

Hybrids based on transition metal phosphide (Mn2P, Co2P, Ni2P) nanoparticles and heteroatom-doped carbon nanotubes were facilely synthesized, and used as efficient oxygen reduction reaction (ORR) catalysts in alkaline solution. Transition metal phosphide nanoparticles formed core/shell structures with graphitic carbon, and the nanoparticles (core) can significantly influence the ORR catalytic activity of the carbon shell. Hybrids based on Co2P and Mn2P decorated heteroatom-doped carbon exhibit excellent ORR catalytic activity with regards to dominant 4e− process, low over potential, excellent methanol tolerance and durability. In contrast, Ni2P decorated heteroatom-doped carbon shows inferior ORR catalytic activity. The variation of ORR performance mainly derives from the collective effect of the electronegativity and binding energy shift of the transition metals, which would result in a different surface electronic structure of the heteroatom-doped carbon. Low electronegativity and low binding energy shift of the transition metals would lead to strong electron-donating ability of the transition metal phosphide nanoparticles, resulting in the enhanced ORR catalytic activity of the hybrid materials. This work is significant for development of advanced ORR catalysts based on heteroatom-doped carbon via rational design of the structure of hybrid materials.

Study on the Organic–Inorganic Hybrid Polyphosphazene Nanotube as a Flame Retardant for Polypropylene

Hybrid polyphosphazene nanotubes (HPPN) were synthesized via a facile one-pot polymerization in an ultrasonic bath at room temperature. The thermal properties of HPPN were investigated by thermogravimetric analysis, which showed that HPPN had good thermal stability and excellent char performance. The char yield of HPPN could reach 70% even at a high temperature of 800°C. HPPN were incorporated into polypropylene (PP) as a flame retardant by a Haake Rheometer system. The HPPN had good compatibility with PP and dispersed well in it. The combustion behaviors of the blends were evaluated by the UL-94 test on a CZF-3 horizontal and vertical burning tester and a V-0 rating was achieved for the blends.

Heteroatom-enhanced the formation of mesoporous carbon microspheres with high surface area as supercapacitor electrode materials

A novel supercapacitor electrode material based on heteroatom (N, O, P) doped mesoporous carbon microspheres (HMCMSs) was produced via a carbonization of highly cross-linked polyphosphazene microspheres (PMSs), with N, O, P acting as high efficient pore-forming agent. PMSs were synthesized through the polymerization reaction between melamine (MA) and hexachlorocyclotriphosphazene (HCCP). The high level of heteroatom atom of PMSs effectively afforde HMCMSs with high specific surface area (1854.1m2 /g), united mesopore structure (pore width ~3nm), as well as high supercapacitor performance. HMCMSs based electrodes exhibited highest specific capacitance of 274 F/g in 6 M KOH aqueous electrolyte at a current density of 0.2 A/g, and excellent cycling durability which had 98.4% capacitance retained even after 2000 cycles. These animative consequences of HMCMSs based electrodes show them great potential in developing highperformance supercapacitors for actual application.