Electrode materials with hollow micro/nanostructures and high electrical conductivity are important for achieving high-power supercapacitors, especially those with super-fast charging/discharging. TiN, which can be easily obtained from TiO2, is regarded as a high-power supercapacitor material. Here, we report that a nanoscale Kirkendall effect is triggered by surface branches on TiO2 nanowires, which then transform into hollow TiN nanotrees during a thermal nitridation process. The surface branches play a key role in accelerating the initial reaction, which forms a uniform, continuous surface TiN layer and induces the Kirkendall effect via surface diffusion. The hollow TiN nanotrees have a high surface area, porous structure, and high electrical conductivity. The constructed symmetric supercapacitors exhibit high areal and volumetric energy density, super-fast charge/discharge ability, and good capacitance retention up to 350 000 cycles. This work provides a new method to synthesize hollow TiN nanostructures and demonstrates their advantages in achieving high-power energy storage devices.
Shanliang Song,Chuanxi Wang,Yue Zhao,Tantan Hu,Xinxin Zhou,Tianxin Zhao,Minghui Yang,Quan Lin
A dual-emission ratiometric fluorescent sensing film for metal ion detection is designed. This dual-emission film is successfully prepared from chitosan, graphitic carbon nitride (g-C 3 N 4 ), and gold nanoclusters (Au NCs). Here, it is shown that the g-C 3 N 4 not only serves as the fluorescence emission source, but also enhances the mechanical and thermal stability of the film. Meanwhile, the Au NCs are adsorbed on the surface of chitosan film by the electrostatic interaction. The as-prepared dual-emission film can selectively detect Cu 2+ , leading to the quench of red fluorescence of Au NCs, whereas the blue fluorescence from g-C 3 N 4 persists. The ratio of the two fluorescence intensities depends on the Cu 2+ concentration and the fluorescence color changes from orange red to yellow, cyan, and finally to blue with increasing Cu 2+ concentration. Thus, the as-prepared dual-emission film can be worked as ratiometric sensing paper for Cu 2+ detection. Furthermore, the film shows high sensitivity and selectivity, with low limit of detection (LOD) (10 ppb). It is observed that this novel gold-cluster-based dual-emission ratiometric fluorescent sensing paper is an easy and convenient way for detecting metal ions. It is believed that this research work have created another avenue for the detection of metal ions in the environment.
危险品化学品经营许可证（带存储）