Regulation on electronic structure of VN-based materials for enhanced supercapacitor performances
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摘要: 从改变VN材料固有本征特性的角度出发，提出了一种利用电子结构调控来改善VN材料电化学性能的方法。通过利用Fe元素的掺杂，调控材料的电子结构状态，达到调控其电化学性能的目的；通过XRD、HRTEM、XPS等方法表征Fe元素掺杂前后对VN基材料微观形貌和电子结构的影响；结合DFT计算结果表明：Fe元素的电子调控改变了VN材料的电子/离子输运能力，使得所制备的Fe-VN材料表现出优异的超电容性能；当电流密度为1 A/g时，其比容量为343.75 F/g，同时，经过1000次循环充放电后，仍能保持85%的初始容量。Abstract: In this paper, a method to improve the electrochemical performances of VN-based materials by electronic structure regulation is proposed. By Fe doping, the electronic structure of VN-based materials was modified for better electrochemical performances. XRD, HRTEM, XPS and other methods were used to characterize the effect of Fe on the microstructure and electronic structure of VN-based materials. Combined with the DFT calculation, it shows that the electron/ion transport capacity of VN-based materials is changed by introduction of Fe element, which endows the as-prepared Fe-VN material with excellent supercapacitor performances. The specific capacity is 343.75 F/g at a current density of 1 A/g, and 85% of the initial capacity can be retained after 1000 charge-discharge cycles.
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Key words:
- VN-based materials /
- electronic structure /
- doping /
- Fe /
- supercapacitor
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图 1 VN（a）与Fe-VN（b）的晶体结构模型，XRD（c）和Raman（d）表征
Figure 1. The crystal structure of (a) VN and (b) Fe-VN. (c) XRD and (d) Raman spectra
图 2 VN（a）与Fe-VN（b）的HRTEM表征及Fe-VN的EDS（c）和Mapping（d）表征
Figure 2. The HRTEM images of (a) V and (b) Fe-VN. (c) EDS and (d) mapping of Fe-VN
图 3 VN与Fe-VN的电化学性能测试
(a) CV; (b) GCD; (c) EIS; (d) 循环寿命
Figure 3. The electrochemical performances of VN and Fe-VN
图 4 VN与Fe-VN的XPS表征及分峰拟合
(a) 全谱曲线; (b) Fe 2p; (c) V 2p; (d) N 2p
Figure 4. The XPS spectra of VN and Fe-VN
图 5 Fe-VN（a, c）和VN（b, d）的差分电荷密度分布对比及相应晶体结构
Figure 5. The differential charge density distribution and crystal structures of (a, c) Fe-VN and (b, d) VN
图 6 VN和Fe-VN的接触角性能测试及（200）晶面对OH−的吸附能计算
Figure 6. (a) Contact angle tests and (b, c) adsorption energy of (200) lattice plane of VN and Fe-VN
表 1 VN和Fe-VN的（200）晶面对OH−的吸附能
Table 1. The adsorption energy of (200) lattice plane for OH−
材料 吸附能/eV (200)+OH− (200) OH− Eads Fe-VN −16083.98 −15620.10 −447.78 −15.12 VN −18262.59 −17801.28 −447.78 −13.53 
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