Rechargeable Mg batteries are an advantageous energy-storage technology with low cost and high safety, but the design of high-performance cathode materials is currently the major difficulty. Herein, a new cathode material of Cu 3 VSe 4 is fabricated with a comprehensive consideration of the chemical and electronic structures. The intermediate band semiconductor Cu 3 VSe 4 has a cubic crystal structure containing interlaced 3D tunnels. The V and Se atoms form chemical bonds with high covalent proportions and facilitate the charge delocalization via the V‒Se bonds. Because of these features, Cu 3 VSe 4 provides a high capacity of 251 mAh g ‒1 with co-redox of Cu, V, and Se elements and an outstanding rate performance of 44 mAh g ‒1 at 15 A g ‒1 . Prominently, a high mass load of 3.0 mg cm ‒2 is achieved without obvious rate capability decay, which is quite favorable to pair with the high-capacity Mg metal anode in practical application. The mechanism investigation and theoretical computation demonstrate that Cu 3 VSe 4 undergoes first a Mg-intercalation and then a displacement reaction, during which the crystal structure is maintained, assisting the reaction reversibility and cycling stability. These findings reveal a rational design principle of rechargeable Mg battery cathodes based on a comprehensive consideration of chemical and electronic structures.
Chunlan Liu,Ziqiang Zhang,Yong Wei,Puxi Ren,Yixiong Tang,Chao Guo,Zhihai Liu
Balance of selenium content is of great significance to human health, and there is a need for rapid and sensitive detection of selenium ion concentrations in the human body and food. This article proposes a highly sensitive fiber surface plasmon resonance (SPR) sensor for selenium ion concentration detection. By fabricating a fiber U-shaped ring composite structure and modifying Cu3VSe4 material, the sensitivity of the fiber SPR sensor is improved to 6826.82 nm/RIU. Using 2,4-diamino-6phenyl-1,3,5-triazine to modify the surface of the sensor to achieve specific detection of selenium ion concentration. The experiment results indicate that the detection sensitivity of the sensor is 1.858 nm/(lg(pg/ml)) with range of 100 pg/ml to 1 μg/ml, and the LOD is 124.06 pg/ml. The highly sensitive SPR sensor proposed in this article, without labeling, can achieve high sensitivity and rapid detection of selenium ions, providing a new approach for trace element content detection.
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