An electrochemical investigation of rutile TiO2 microspheres anchored by nanoneedle clusters for sodium storage.

Rutile TiO2 microspheres anchored by nanoneedle clusters, as a new class of anode materials, are successfully employed for sodium-ion batteries and manifested good energy storage behavior. The initial discharge capacity of 308.8 mA h g(-1) is obtained and a high reversible capacity of 121.8 mA h g(-1) is maintained after 200 cycles at a current density of 0.1 C, exhibiting a high capacity retention of 83.1%. All these merits are not only ascribed to the rutile TiO2 crystal structure, but also thanks to the porous morphology of hundreds of nanoneedle clusters in favor of sodium diffusion and accommodating the strain during the sodiation and desodiation processes. Therefore, it is highly expected that rutile TiO2, as a feasible electrochemical sodium storage material, can be a new promising candidate as an anode for sodium-ion batteries.

Zirconia-coated graphite adsorption bar micro-extraction combined with ETV-ICP-MS for the determination of trace amounts of Cd, Hg and Pb in environmental and biological samples.

In this work, a new and simple micro-extraction method termed graphite adsorption bar micro-extraction was developed, for the first time, for electrothermal vaporization inductively coupled plasma mass spectrometry (ETV-ICP-MS) determination of trace Cd, Hg and Pb. In this method, the graphite bar was first coated with zirconia and then inserted into the sample solution for extraction. The graphite bar enriched with the analytes was inserted directly into a graphite tube, and subsequently analyzed by ETV-ICP-MS according to an established temperature program. The experimental parameters, which had influence on the extraction and vaporization, were systematically investigated and the optimal experimental conditions were established. Under the optimized conditions, the detection limits of the method were 0.05, 0.42 and 0.06 pg/ml for Cd, Hg and Pb and the relative standard deviations (RSDs) for 11 replicates at the 0.1 ng/ml level were 7.4, 8.2 and 7.7%, respectively. The proposed method was successfully applied to the determination of trace Cd, Hg and Pb in environmental and biological samples. The results of the experiments indicate that the method has a high enrichment factor and sample utilization efficiency. Furthermore, the method is fast and environment-friendly.

Mesoporous CoO nanocubes @ continuous 3D porous carbon skeleton of rose-based electrode for high-performance supercapacitor.

Supercapacitors have attracted lots of attentions for energy storage because of their outstanding electrochemical properties, and various kinds of carbon materials have been used to improve the performance. In this work, we innovatively elevate a natural rose-based continuous 3D porous carbon skeleton. The as-prepared carbon skeleton is graphited to some extent and possesses hierarchical interconnected 3D porous structures, providing a high electrical conductive and electrolyte easy-infiltrated substrate for the fabrication of ideal monolithic composite electrodes. Then, we utilized it as scaffold to prepare mesoporous CoO nanocubes @ continuous 3D porous carbon skeleton of rose composite-based electrode for supercapacitor via hydrothermal approach. The obtained material exhibits a noticeable pseudocapacitive performance with a brilliant capacitance of 1672 F/g at 1 A/g and as high as 521 F/g at 40 A/g. It also should be noted that ∼82% of the capacitance was maintained after 3000 cycles at 5 A/g, and only 40% capacitance loss after 1500 cycles at a relatively high current density of 10 A/g.

Composite of macroporous carbon with honeycomb-like structure from mollusc shell and NiCo(2)O(4) nanowires for high-performance supercapacitor.

Novel biological carbon materials with highly ordered microstructure and large pore volume have caused great interest due to their multifunctional properties. Herein, we report the preparation of an interconnected porous carbon material by carbonizing the organic matrix of mollusc shell. The obtained three-dimensional carbon skeleton consists of hexangular and tightly arranged channels, which endow it with efficient electrolyte penetration and fast electron transfer, enable the mollusc shell based macroporous carbon material (MSBPC) to be an excellent conductive scaffold for supercapacitor electrodes. By growing NiCo2O4 nanowires on the obtained MSBPC, NiCo2O4/MSBPC composites were synthesized. When used on supercapacitor electrode, it exhibited anomalously high specific capacitance (∼1696 F/g), excellent rate performance (with the capacity retention of 58.6% at 15 A/g) and outstanding cycling stability (88% retention after 2000 cycles). Furthermore, an all-solid-state symmetric supercapacitor was also assembled based on this NiCo2O4/MSBPC electrode and showed good electrochemical performance with an energy density of 8.47 Wh/kg at 1 A/g, good stability over 10000 cycles. And we believe that more potential applications beyond energy storage can be developed based on this MSBPC.

Speciation of dissolved iron(II) and iron(III) in environmental water samples by gallic acid-modified nanometer-sized alumina micro-column separation and ICP-MS determination.

A method has been developed for the speciation of trace dissolved Fe(II) and Fe(III) in water by coupling gallic acid (GA) modified nanometer-sized alumina micro-column separation with inductively coupled plasma mass spectrometry (ICP-MS). The separation of Fe(II) and Fe(III) was achieved based on the obvious difference in reaction kinetics between Fe(II) and Fe(III) with GA. Fe(III) was selectively retained on the micro-column at pH 5.5-6.5, while Fe(II) could not be retained by the micro-column at the whole tested pH range of 1.0-6.5, and passed through the micro-column. The Fe(II) can be determined by ICP-MS directly without preconcentration/separation procedure, while Fe(III) retained on the micro-column was then eluted with 1.0 mL of 1 mol L(-1) HCl and determined by ICP-MS. The parameters affecting the separation of Fe(II) and Fe(III) were investigated systematically and the optimum separation conditions were established. Under the optimized conditions, the detection limits of 0.48 microg L(-1) and 0.24 microg L(-1) with relative standard deviation of 5.6% and 4.3%(C= 5 microg L(-1), n= 7) for Fe(II) and Fe(III) were found, respectively. No obvious effect on the speciation of Fe(II) and Fe(III) was found with the change of the ratio of Fe(II) and Fe(III) from 0 ratio 10 to 10 ratio 0. The proposed method was applied for the determination of trace Fe(II) and Fe(III) in environmental water and the recoveries for spiked samples were found to be in the range of 97-105%.