Chao Yue Zhang,Guo Wen Sun,Zu De Shi,Qian Yu Liu,Jiang Long Pan,Yan Chun Wang,Hao Zhao,Geng Zhi Sun,Xiu Ping Gao,Xiao Jun Pan,Jin Yuan Zhou
Atom-intercalated transition metal disulfides (TMDs) have attached much attention mainly due to their highly improved conductivity. But it is few reported that the atom intercalation can enable the TMDs have unexpected catalytic properties, caused by the unit-cell deformation in them. In this work, a type of V 0.25 -intercalated VS 2 (V 5 S 8 ) nanoflakes was designed via a direct vulcanization method combining Kirkendall heat diffusion effect, and used as the promotor for lithium-sulfur batteries (LSBs). The V 5 S 8 possesses a NiAs crystal structure, in which V atoms occupy the interlayer spacing between VS 2 monolayers, which will unavoidably cause the unit-cell deformation. As expected, the CNF@V 5 S 8 /S cathodes show a specific capacity of 1260 mAh g −1 at 0.2 C, and can keep 73.65% of the capacity with charge/discharge rate increasing 10 times; while the CNF@VS 2 /S ones can only retain 54.0% of the initial capacity. Moreover, the CNF@V 5 S 8 /S cathodes show an ultralow decay rate of only 0.0312% per cycle for 1500 cycles at 5 C. Furthermore, the catalysis effect of V 5 S 8 on the conversion of lithium polysulfide (Li 2 S n , n = 1, 2, 4, 6 and 8) and S 8 clusters were systematically discusses. Besides, the V 5 S 8 can further enable LSBs achieve a high areal capacity (8.2 mAh cm −2 with sulfur loading of 7.8 mg cm −2 ) and a high dynamic flexible stability at bending angle between 0 and 180 °.
A novel and highly active vanadium self-intercalated C/V 1.11 S 2 nanosheets with abundant active sites are fabricated by a simple hydrothermal-calcinations method. The structures and morphology of C/V 1.11 S 2 nanosheets were characterized by XRD, SEM, XPS and TEM. Particularly, PVP (polyvinylpyrrolidone) was used as surfactant to control the morphology of vanadium sulfide and carbon source to reduce the vanadium sulfide into vanadium self-intercalated V 1.11 S 2 phase with rich active sites. The C/V 1.11 S 2 nanosheets showed an excellent electrocatalytic activity for hydrogen evolution reaction, including a low onset potential of 15 mV vs. RHE (reversible hydrogen electrode), small Tafel slope of 51 mV dec −1 , as well as extraordinary catalytic stability. The first-principle calculations further confirmed that the V 1.11 S 2 has a much lower Gibbs free energy for hydrogen adsorption (ΔG H ) than that of VS 2 . The enhanced HER performance can be contributed to the unique vanadium self-intercalated structures, nanostructured morphology and rich sulfur defects of the obtained C/V 1.11 S 2 nanosheets. We believe that the C/V 1.11 S 2 can be used as electrocatalyst in chemical engineering industry and our method provides guidance on the fabrication of other defective transition-metal dichalcogenides to improve their catalytic performances.
危险品化学品经营许可证（带存储）