High energy density and low-cost lithium-sulfur batteries have been considered as one of the most promising candidates for next-generation energy storage systems.However,the intrinsic problems of the sulfur cathode se...High energy density and low-cost lithium-sulfur batteries have been considered as one of the most promising candidates for next-generation energy storage systems.However,the intrinsic problems of the sulfur cathode severely restrict their further practical application.Here,a unique double-shell architecture composed of hollow carbon spheres@interlayer-expanded and sulfur-enriched MoS2+x nanocoating composite has been developed as an efficient sulfur host.A uniform precursor coating derived from heteropolyanions-induced polymerization of pyrrole leads to space confinement effect during the in-situ sulfurization process,which generates the interlayer-expanded and sulfur-enriched MoS2+x nanosheets on amorphous carbon hollow spheres.This new sulfur host possesses multifarious merits including sufficient voids for loading sulfur active materials,high electronic conductivity,and fast lithium-ion diffusive pathways.In addition,additional active edge sites of MoS2+x accompanied by the nitrogen-doped carbon species endow the sulfur host with immobilizing and catalyzing effects on the soluble polysulfide species,dramatically accelerating their conversion kinetics and re-utilization.The detailed defect-induced interface catalytic reaction mechanism is firstly proposed.As expected,the delicately-designed sulfur host exhibits an outstanding initial discharge capacity of 1,249 mAh·g^−1 at 0.2 C and a desirable rate performance(593 mAh·g^−1 at 5.0 C),implying its great prospects in achieving superior electrochemical performances for advanced lithium sulfur batteries.展开更多
Herein, we report a bottom-up solvothermal route to synthesize a flexible, highly efficient MoS2@SWNT electrocatalyst for hydrogen evolution reactions （HER）. Characterization revealed that branchqike MoS2 nanosheets...Herein, we report a bottom-up solvothermal route to synthesize a flexible, highly efficient MoS2@SWNT electrocatalyst for hydrogen evolution reactions （HER）. Characterization revealed that branchqike MoS2 nanosheets containing sulfur- rich sites were in situ uniformly dispersed on free-standing single-walled carbon nanotube （SWNT） film, which could expose more unsaturated sulfur atoms, allowing excellent electrical contact with active sites. The flexible catalyst exhibited excellent HER performance with a low overpotential （-150 mV at 10 ma/cm2） and small Tafel slope （4l mV/dec）. To further explain the improved performance, the local electronic structure was investigated by X-ray absorption near-edge structure （XANES） analysis, proving the presence of unsaturated sulfur atoms and strong electronic coupling between MoS2 and SWNT. This study provides an in-situ synthetic route to create new multifunctional flexible hybridized catalysts and useful insights into the relationships electronic structure, and properties among the catalyst microstructure,展开更多
There has been growing research interest in the use of molybdenum disulfide in the fields of optoelectronics and energy harvesting devices, by virtue of its indirect-to-direct band gap tunability. However, obtaining l...There has been growing research interest in the use of molybdenum disulfide in the fields of optoelectronics and energy harvesting devices, by virtue of its indirect-to-direct band gap tunability. However, obtaining large area thin films of MoS2 for future device applications still remains a challenge. In the present study, the amounts of the precursors （S and MOO3） were varied systematically in order to optimize the growth of highly crystalline and large area MoS2 layers by the chemical vapor deposition method. Careful control of the amounts of precursors was found to the key factor in the synthesis of large area highly crystalline flakes. The thickness of the layers was confirmed by Raman spectroscopy and atomic force microscopy. The optical properties and chemical composition were studied by photoluminescence （PL） and X-ray photoelectron spectroscopy. The emergence of strong direct excitonic emissions at 1.82 eV （A-exciton, with a normalized PL intensity of -55 × 10^3） and 1.98 eV （B-exciton, with a normalized PL intensity of -5 × 10^3） of the sample at room temperature clearly indicates the high luminescence quantum efficiency. The mobility of the films was found to be 0.09 cm^2/（V.s） at room temperature. This study provides a method for the controlled synthesis of high-quality two-dimensional （2D） transition metal dichalcogenide materials, useful for applications in nanodevices, optoelectronics and solar energv conversion.展开更多
Nanocomposites of iron disulfide（FeS2） and molybdenum disulfide（MoS2） with nanosheets structure were successfully grown on the flexible titanium foils through a facile one-step hydrothermal process, and then worke...Nanocomposites of iron disulfide（FeS2） and molybdenum disulfide（MoS2） with nanosheets structure were successfully grown on the flexible titanium foils through a facile one-step hydrothermal process, and then worked as counter electrodes（CEs） in the dye-sensitized solar cells（DSSCs）. X-ray diffraction, scanning electron microscopy,transmission electron microscopy, and energy dispersive spectrometer were employed to characterize the microstructure and composition of the FeS2/MoS2. Cyclic voltammogram reveals that the catalytic activity of FeS2/MoS2 CE is higher than that of FeS2, MoS2, and platinum（Pt） CEs towards triiodide/iodide（I3^–/I^–） redox electrolyte, owing to the superior carrier transfer properties of vertical array structure and abundant catalytic active sites of FeS2/MoS2 nanosheets.Moreover, the FeS2/MoS2 CE maintains its activity after 500 cycles, exhibiting excellent electrochemical stability. Furthermore, the power conversion efficiency（PCE） of FeS2/MoS2 CE reaches 8.67%, which is higher than that of the FeS2（7.20%）,MoS2（7.38%） and Pt（8.16%） CEs.展开更多
基金The paper was financially supported by the National Natural Science Foundation of China （No. 50741003）, Anhui Provincial Natural Science Foundation （No, 070414181） and key project of Science and Technology of Ministry of Education of China （No. 107066）.
基金The work was financially supported by the National Natural Science Foundation of China(Nos.51672146 and 21805157)the Natural Science Foundation of Shandong Province(No.ZR2018BEM011).
文摘High energy density and low-cost lithium-sulfur batteries have been considered as one of the most promising candidates for next-generation energy storage systems.However,the intrinsic problems of the sulfur cathode severely restrict their further practical application.Here,a unique double-shell architecture composed of hollow carbon spheres@interlayer-expanded and sulfur-enriched MoS2+x nanocoating composite has been developed as an efficient sulfur host.A uniform precursor coating derived from heteropolyanions-induced polymerization of pyrrole leads to space confinement effect during the in-situ sulfurization process,which generates the interlayer-expanded and sulfur-enriched MoS2+x nanosheets on amorphous carbon hollow spheres.This new sulfur host possesses multifarious merits including sufficient voids for loading sulfur active materials,high electronic conductivity,and fast lithium-ion diffusive pathways.In addition,additional active edge sites of MoS2+x accompanied by the nitrogen-doped carbon species endow the sulfur host with immobilizing and catalyzing effects on the soluble polysulfide species,dramatically accelerating their conversion kinetics and re-utilization.The detailed defect-induced interface catalytic reaction mechanism is firstly proposed.As expected,the delicately-designed sulfur host exhibits an outstanding initial discharge capacity of 1,249 mAh·g^−1 at 0.2 C and a desirable rate performance(593 mAh·g^−1 at 5.0 C),implying its great prospects in achieving superior electrochemical performances for advanced lithium sulfur batteries.
基金We acknowledge the financial support of the National Basic Research Program of China （No. 2014CB848900）, the National Natural Science Foundation of China （Nos. U1232131, U1532112, 11375198, and 11574280）, the Fundamental Research Funds for the Central Universities （No. WK2310000053）, User with Potential from CAS Hefei Science Center （No. 2015HSC-UP020） and Key Laboratory of Advanced Energy Materials Chemistry （Ministry of Education） Nankai University. L. S. thanks the recruitment program of global experts, the CAS Hundred Talent Program. We also thank the Shanghai synchrotron Radiation Facility （14W1, SSRF）, the Beijing Synchrotron Radiation Facility （1W1B and soft-X-ray endstation, BSRF） and the Hefei Synchrotron Radiation Facility （MCD and Photoemission Endstations, NSRL） for help in characterizations.
文摘Herein, we report a bottom-up solvothermal route to synthesize a flexible, highly efficient MoS2@SWNT electrocatalyst for hydrogen evolution reactions （HER）. Characterization revealed that branchqike MoS2 nanosheets containing sulfur- rich sites were in situ uniformly dispersed on free-standing single-walled carbon nanotube （SWNT） film, which could expose more unsaturated sulfur atoms, allowing excellent electrical contact with active sites. The flexible catalyst exhibited excellent HER performance with a low overpotential （-150 mV at 10 ma/cm2） and small Tafel slope （4l mV/dec）. To further explain the improved performance, the local electronic structure was investigated by X-ray absorption near-edge structure （XANES） analysis, proving the presence of unsaturated sulfur atoms and strong electronic coupling between MoS2 and SWNT. This study provides an in-situ synthetic route to create new multifunctional flexible hybridized catalysts and useful insights into the relationships electronic structure, and properties among the catalyst microstructure,
文摘There has been growing research interest in the use of molybdenum disulfide in the fields of optoelectronics and energy harvesting devices, by virtue of its indirect-to-direct band gap tunability. However, obtaining large area thin films of MoS2 for future device applications still remains a challenge. In the present study, the amounts of the precursors （S and MOO3） were varied systematically in order to optimize the growth of highly crystalline and large area MoS2 layers by the chemical vapor deposition method. Careful control of the amounts of precursors was found to the key factor in the synthesis of large area highly crystalline flakes. The thickness of the layers was confirmed by Raman spectroscopy and atomic force microscopy. The optical properties and chemical composition were studied by photoluminescence （PL） and X-ray photoelectron spectroscopy. The emergence of strong direct excitonic emissions at 1.82 eV （A-exciton, with a normalized PL intensity of -55 × 10^3） and 1.98 eV （B-exciton, with a normalized PL intensity of -5 × 10^3） of the sample at room temperature clearly indicates the high luminescence quantum efficiency. The mobility of the films was found to be 0.09 cm^2/（V.s） at room temperature. This study provides a method for the controlled synthesis of high-quality two-dimensional （2D） transition metal dichalcogenide materials, useful for applications in nanodevices, optoelectronics and solar energv conversion.
基金financially supported by the National Natural Science Foundation of China (61504076, 21574076, and U1510121)National Natural Science Foundation of Shanxi Province (2015021129 and 2014011016-1)+1 种基金Fund of Fujian Key Laboratory of Photoelectric Functional Materials (FJPFM-201502)Ministry of Science and Technology Taiwan (MOST 106-2923-E-036-002-MY3 and MOST 106-2221-E-036-018)
文摘Nanocomposites of iron disulfide（FeS2） and molybdenum disulfide（MoS2） with nanosheets structure were successfully grown on the flexible titanium foils through a facile one-step hydrothermal process, and then worked as counter electrodes（CEs） in the dye-sensitized solar cells（DSSCs）. X-ray diffraction, scanning electron microscopy,transmission electron microscopy, and energy dispersive spectrometer were employed to characterize the microstructure and composition of the FeS2/MoS2. Cyclic voltammogram reveals that the catalytic activity of FeS2/MoS2 CE is higher than that of FeS2, MoS2, and platinum（Pt） CEs towards triiodide/iodide（I3^–/I^–） redox electrolyte, owing to the superior carrier transfer properties of vertical array structure and abundant catalytic active sites of FeS2/MoS2 nanosheets.Moreover, the FeS2/MoS2 CE maintains its activity after 500 cycles, exhibiting excellent electrochemical stability. Furthermore, the power conversion efficiency（PCE） of FeS2/MoS2 CE reaches 8.67%, which is higher than that of the FeS2（7.20%）,MoS2（7.38%） and Pt（8.16%） CEs.
