A 3D structured composite was designed to improve the conductivity and to ease the volume problems of Si anode during cycling for lithium-ions batteries. An in situ method via a controllable gelation process was explored to fabricate the 3D composite of a multilayer carbon matrix toughened by cross-linked carbon nanotubes (CNTs) and decorated with conductive Cu agents. Structurally, a bifunctional carbon shell was formed on the surface of Si to improve the conductivity but alleviate side reactions. Cu particles as conducting agents decorated in the carbon matrix are also used to further improve the conductivity. The volume issue of Si particles can be effectively released via toughening the carbon matrix through the multilayered structure and cross-linked CNTs. Moreover, the carbon matrix might prevent silicon particles from agglomeration. Consequently, the Si@C@Cu composite is expected to exhibit benign electrochemical performances with a commendable capacity of 1500 mAh g–1 (900 cycles, 1 A g–1) and a high rate performance (1035 mAh g–1, 4 A g–1). The DLi + ranging from 10–11 to 10–9 cm–2 s–1 of the Si@C@Cu anode is obtained via the GITT test, which is higher than most reported data.

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A method is described for the sequential determination of Sb(III) and Sb(V) using Osteryoung square wave cathodic stripping voltammetry. It employs an in-situ plated bismuth-film on edge-plane graphite substrate as the working electrode. Selective electro-deposition of Sb(III)/Sb(V) is accomplished by applying a potential of-500 mV vs Ag/AgCl, this followed by reduction to stibine at a more negative potential in the stripping step. Stripping was carried out by applying a square wave waveform between-500 and-1400 mV to the antimony deposited. The stripping peak current at-1150 mV is proportional to the concentration of Sb(III)/Sb(V). The calibration plots for Sb(III) were linear up to 12.0 µg L-1 depending on the time of deposition. The calibration plots for Sb(V) were linear up to 7.0 µg L-1 , also depending on the time of deposition. The relative standard deviation in the determination of 0.1 µg L-1 of Sb(III) is 4.0% (n = 5), and the limit of detection is as low as 2 ng L-1. In case of 0.1 µg L-1 Sb(V), the relative standard deviation is 3.0% (n = 5) and the detection limit also is 2 ng L-1. The method was applied to the analysis of river water and of sea water samples.