As promising energy storage systems,lithium-sulfur(Li-S)batteries have attracted significant attention because of their ultra-high energy densities.However,Li-S battery suffers problems related to the complex phase co...As promising energy storage systems,lithium-sulfur(Li-S)batteries have attracted significant attention because of their ultra-high energy densities.However,Li-S battery suffers problems related to the complex phase conversion that occurs during the charge-discharge process,particularly the deposition of solid Li2S from the liquid-phase polysulfides,which greatly limits its practical application.In this paper,edge-rich MoS2/C hollow microspheres(Edg-MoS2/C HMs)were designed and used to functionalize separator for Li-S battery,resulting in the uniform deposition of Li2S.The microspheres were fabricated through the facile hydrothermal treatment of MoO3-aniline nanowires and a subsequent carbonization process.The obtained Edg-MoS2/C HMs have a strong chemical absorption capability and high density of Li2S binding sites,and exhibit excellent electrocatalytic performance and can effectively hinder the polysulfide shuttle effect and guide the uniform nucleation and growth of Li2S.Furthermore,we demonstrate that the Edg-MoS2/C HMs can effectively regulate the deposition of Li2S and significantly improve the reversibility of the phase conversion of the active sulfur species,especially at high sulfur loadings and high C-rates.As a result,a cell containing a separator functionalized with Edg-MoS2/C HMs exhibited an initial discharge capacity of 935 mAh g-1 at 1.0 C and maintained a capacity of 494 mAh g-1 after 1000 cycles with a sulfur loading of 1.7 mg cm-2.Impressively,at a high sulfur loading of 6.1 mg cm-2 and high rate of 0.5 C,the cell still delivered a high reversible discharge capacity of 478 mAh g-1 after 300 cycles.This work provides fresh insights into energy storage systems related to complex phase conversions.展开更多
MoS2/C composites are considered to have great application potential in sodium-ion batteries(SIBs).It is a challenging and meaningful subject that developing high-performance anode materials via combining MoS2 and car...MoS2/C composites are considered to have great application potential in sodium-ion batteries(SIBs).It is a challenging and meaningful subject that developing high-performance anode materials via combining MoS2 and carbon effectively to give free rein to their advantages in sodium ion storage.In this work,a novel MoS2-C material was designed by using cellulose nanocrystals(CNCs)as low-cost and green carbon source.3 D hierarchical microspheres(200-250 nm)constructed by ultrathin MoS2-C nanosheets were synthesized by synchronizing the pre-carbonization of CNCs with the formation of MoS2 in hydrothermal reaction and subsequent pyrolysis process.It is found that the ultrathin MoS2-C nanosheets were composed of CNCs-derived short-range ordered carbon and few-layered MoS2.Benefiting from the unique structure and robust combination of MoS2 and CNCs-derived carbon,the ultrathin MoS2-C nanosheets composite was proved to have excellent cycling stability and superior rate performance in sodium-ion half-cell test and have high first reversible specific capacity of 397.9 m Ah/g in full-cell test.This work provides a significant and effective pathway to prepare MoS2-C materials with excellent electrochemical performance for the application in large-scale energy storage systems.展开更多
Herein,N-Ti3C2@CNT microspheres are successfully synthesized by the simple spray drying method.In the preparation process,HCl-treated melamine(HTM)is selected as the sources of carbon and nitrogen.It not only realizes...Herein,N-Ti3C2@CNT microspheres are successfully synthesized by the simple spray drying method.In the preparation process,HCl-treated melamine(HTM)is selected as the sources of carbon and nitrogen.It not only realizes in situ growth of CNTs on the surface of MXene nanosheets with the catalysis of Ni,but also introduces efficient N-doping in both MXene and CNTs.Within the microsphere,MXene nanosheets interconnect with CNTs to form porous and conductive network.In addition,N-doped MXene and CNTs can provide strong chemical immobilization for polysulfides and effectively entrap them within the porous microspheres.Above-mentioned merits enable N-Ti3C2@CNT microspheres to be ideal sulfur host.When used in lithium–sulfur(Li–S)battery,the N-Ti3C2@CNT microspheres/S cathode delivers initial specific capacity of 927 mAh g−1 at 1 C and retains high capacity of 775 mAh g−1 after 1000 cycles with extremely low fading rate(FR)of 0.016%per cycle.Furthermore,the cathode still shows high cycling stability at high C-rate of 4 C(capacity of 647 mAh g−1 after 650 cycles,FR 0.027%)and high sulfur loading of 3 and 6 mg cm−2 for Li–S batteries.展开更多
以钼酸钠(Na_2MoO_4·2H_2O)、硫脲(NH_2CSNH_2)、CTAB为原料,利用水热法合成了MoS_2/C球状纳米花复合材料。通过XRD、SEM、TEM、TG等分析测试方法,研究了不同CTAB添加量对MoS_2/C复合材料的微观结构、表面形貌的影响规律,结果显示...以钼酸钠(Na_2MoO_4·2H_2O)、硫脲(NH_2CSNH_2)、CTAB为原料,利用水热法合成了MoS_2/C球状纳米花复合材料。通过XRD、SEM、TEM、TG等分析测试方法,研究了不同CTAB添加量对MoS_2/C复合材料的微观结构、表面形貌的影响规律,结果显示,有部分无定形碳嵌入了MoS_2层间,并抑制了MoS_2(002)面的堆积。电化学测试表明:与纯MoS_2相比,MoS_2/C复合材料具有更好的电化学性能,当加入0.025 g CTAB时首次放电比容量达到730 m Ah/g,在100 m A/g的电流密度下经过100次循环比容量稳定在415 m Ah/g。在此基础上讨论了MoS_2/C球状纳米花复合材料的可能生长机理以及对材料电化学性能的影响规律。展开更多
Self-powered devices are widely used in the detection and sensing fields.Asymmetric metal contacts provide an effective way to obtain self-powered devices.Finding two stable metallic electrode materials with large wor...Self-powered devices are widely used in the detection and sensing fields.Asymmetric metal contacts provide an effective way to obtain self-powered devices.Finding two stable metallic electrode materials with large work function differences is the key to obtain highly efficient asymmetric metal contacts structures.However,common metal electrode materials have similar and high work functions,making it difficult to form an asymmetric contacts structure with a large work function difference.Herein,Mo2C crystals with low work function(3.8 eV) was obtained by chemical vapor deposition(CVD) method.The large work function difference between Mo2C and Au allowed us to synthesize an efficient Mo2C/MoS2/Au photodetector with asymmetric metal contact structure,which enables light detection without external electric power.We believe that this novel device provides a new direcfor the design of miniature self-powered photodetectors.These results also highlight the great potential of ultrathin Mo2C prepared by CVD in heterojunction device applications.展开更多
MoS_2-decorated C_3N_4(C_3N_4/MoS_2) nanosheets hybrid photocatalysts were prepared by a simple sonication-impregnation method. Face-to-face lamellar heterojunctions were well established between two dimension(2D) C_3...MoS_2-decorated C_3N_4(C_3N_4/MoS_2) nanosheets hybrid photocatalysts were prepared by a simple sonication-impregnation method. Face-to-face lamellar heterojunctions were well established between two dimension(2D) C_3N_4 and MoS_2 nanosheets. The effects of MoS_2 content on the light absorption, charge transfer and photocatalytic activity of the hybrid samples were investigated. Characterization results show that MoS_2 nanosheets are well anchored on the face of C_3N_4 nanosheets and the composites have well dispersed layered morphology. After loading with MoS_2, the light absorption of composites was much improved, especially in visible-light region. The photocatalytic activities of C_3N_4/MoS_2 samples were evaluated based on the H_2 evolution under visible light irradiation(λ > 400 nm). When the loading amount of MoS_2 was increased to 5 wt%, the highest H_2 evolution rate(274 μmol·g^(-1)·h^(-1)) was obtained. Compared with samples obtained from direct impregnation method, sonication pretreatment is favorable for the formation of 2D layered heterojuctions and thus improve the photocatalytic activity. Slightly deactivation of C_3N_4/MoS_2 composites could be observed when recycled due to the mild photocorrosion of MoS_2. Based on the band alignments of C_3N_4 and MoS_2, a possible photocatalytic mechanism was discussed, where MoS_2 could efficiently promote the separation of the photogenerated carriers of C_3N_4.展开更多
基金financially supported by National Natural Science Foundation of China (No. 51672083)Program of Shanghai Academic/Technology Research Leader (18XD1401400)+3 种基金Basic Research Program of Shanghai (17JC1404702)Leading talents in Shanghai in 2018The 111 project (B14018)the Fundamental Research Funds for the Central Universities (222201718002)
文摘As promising energy storage systems,lithium-sulfur(Li-S)batteries have attracted significant attention because of their ultra-high energy densities.However,Li-S battery suffers problems related to the complex phase conversion that occurs during the charge-discharge process,particularly the deposition of solid Li2S from the liquid-phase polysulfides,which greatly limits its practical application.In this paper,edge-rich MoS2/C hollow microspheres(Edg-MoS2/C HMs)were designed and used to functionalize separator for Li-S battery,resulting in the uniform deposition of Li2S.The microspheres were fabricated through the facile hydrothermal treatment of MoO3-aniline nanowires and a subsequent carbonization process.The obtained Edg-MoS2/C HMs have a strong chemical absorption capability and high density of Li2S binding sites,and exhibit excellent electrocatalytic performance and can effectively hinder the polysulfide shuttle effect and guide the uniform nucleation and growth of Li2S.Furthermore,we demonstrate that the Edg-MoS2/C HMs can effectively regulate the deposition of Li2S and significantly improve the reversibility of the phase conversion of the active sulfur species,especially at high sulfur loadings and high C-rates.As a result,a cell containing a separator functionalized with Edg-MoS2/C HMs exhibited an initial discharge capacity of 935 mAh g-1 at 1.0 C and maintained a capacity of 494 mAh g-1 after 1000 cycles with a sulfur loading of 1.7 mg cm-2.Impressively,at a high sulfur loading of 6.1 mg cm-2 and high rate of 0.5 C,the cell still delivered a high reversible discharge capacity of 478 mAh g-1 after 300 cycles.This work provides fresh insights into energy storage systems related to complex phase conversions.
基金supported by the National Natural Science Foundation of China(Grant No.51974114,51672075,and 21908049)Natural Science Foundation of Hunan Province and the Fundamental Research Funds for the Central Universities。
文摘MoS2/C composites are considered to have great application potential in sodium-ion batteries(SIBs).It is a challenging and meaningful subject that developing high-performance anode materials via combining MoS2 and carbon effectively to give free rein to their advantages in sodium ion storage.In this work,a novel MoS2-C material was designed by using cellulose nanocrystals(CNCs)as low-cost and green carbon source.3 D hierarchical microspheres(200-250 nm)constructed by ultrathin MoS2-C nanosheets were synthesized by synchronizing the pre-carbonization of CNCs with the formation of MoS2 in hydrothermal reaction and subsequent pyrolysis process.It is found that the ultrathin MoS2-C nanosheets were composed of CNCs-derived short-range ordered carbon and few-layered MoS2.Benefiting from the unique structure and robust combination of MoS2 and CNCs-derived carbon,the ultrathin MoS2-C nanosheets composite was proved to have excellent cycling stability and superior rate performance in sodium-ion half-cell test and have high first reversible specific capacity of 397.9 m Ah/g in full-cell test.This work provides a significant and effective pathway to prepare MoS2-C materials with excellent electrochemical performance for the application in large-scale energy storage systems.
文摘Herein,N-Ti3C2@CNT microspheres are successfully synthesized by the simple spray drying method.In the preparation process,HCl-treated melamine(HTM)is selected as the sources of carbon and nitrogen.It not only realizes in situ growth of CNTs on the surface of MXene nanosheets with the catalysis of Ni,but also introduces efficient N-doping in both MXene and CNTs.Within the microsphere,MXene nanosheets interconnect with CNTs to form porous and conductive network.In addition,N-doped MXene and CNTs can provide strong chemical immobilization for polysulfides and effectively entrap them within the porous microspheres.Above-mentioned merits enable N-Ti3C2@CNT microspheres to be ideal sulfur host.When used in lithium–sulfur(Li–S)battery,the N-Ti3C2@CNT microspheres/S cathode delivers initial specific capacity of 927 mAh g−1 at 1 C and retains high capacity of 775 mAh g−1 after 1000 cycles with extremely low fading rate(FR)of 0.016%per cycle.Furthermore,the cathode still shows high cycling stability at high C-rate of 4 C(capacity of 647 mAh g−1 after 650 cycles,FR 0.027%)and high sulfur loading of 3 and 6 mg cm−2 for Li–S batteries.
文摘以钼酸钠(Na_2MoO_4·2H_2O)、硫脲(NH_2CSNH_2)、CTAB为原料,利用水热法合成了MoS_2/C球状纳米花复合材料。通过XRD、SEM、TEM、TG等分析测试方法,研究了不同CTAB添加量对MoS_2/C复合材料的微观结构、表面形貌的影响规律,结果显示,有部分无定形碳嵌入了MoS_2层间,并抑制了MoS_2(002)面的堆积。电化学测试表明:与纯MoS_2相比,MoS_2/C复合材料具有更好的电化学性能,当加入0.025 g CTAB时首次放电比容量达到730 m Ah/g,在100 m A/g的电流密度下经过100次循环比容量稳定在415 m Ah/g。在此基础上讨论了MoS_2/C球状纳米花复合材料的可能生长机理以及对材料电化学性能的影响规律。
基金supported by the National Natural Science Foundation of China(11674113,U1765105)the support of experimental facilities in WNLO of HUSTAnalysis and Testing Center of HUST for support
文摘Self-powered devices are widely used in the detection and sensing fields.Asymmetric metal contacts provide an effective way to obtain self-powered devices.Finding two stable metallic electrode materials with large work function differences is the key to obtain highly efficient asymmetric metal contacts structures.However,common metal electrode materials have similar and high work functions,making it difficult to form an asymmetric contacts structure with a large work function difference.Herein,Mo2C crystals with low work function(3.8 eV) was obtained by chemical vapor deposition(CVD) method.The large work function difference between Mo2C and Au allowed us to synthesize an efficient Mo2C/MoS2/Au photodetector with asymmetric metal contact structure,which enables light detection without external electric power.We believe that this novel device provides a new direcfor the design of miniature self-powered photodetectors.These results also highlight the great potential of ultrathin Mo2C prepared by CVD in heterojunction device applications.
基金Funded by the National Natural Science Foundation of China(No.21503096)
文摘MoS_2-decorated C_3N_4(C_3N_4/MoS_2) nanosheets hybrid photocatalysts were prepared by a simple sonication-impregnation method. Face-to-face lamellar heterojunctions were well established between two dimension(2D) C_3N_4 and MoS_2 nanosheets. The effects of MoS_2 content on the light absorption, charge transfer and photocatalytic activity of the hybrid samples were investigated. Characterization results show that MoS_2 nanosheets are well anchored on the face of C_3N_4 nanosheets and the composites have well dispersed layered morphology. After loading with MoS_2, the light absorption of composites was much improved, especially in visible-light region. The photocatalytic activities of C_3N_4/MoS_2 samples were evaluated based on the H_2 evolution under visible light irradiation(λ > 400 nm). When the loading amount of MoS_2 was increased to 5 wt%, the highest H_2 evolution rate(274 μmol·g^(-1)·h^(-1)) was obtained. Compared with samples obtained from direct impregnation method, sonication pretreatment is favorable for the formation of 2D layered heterojuctions and thus improve the photocatalytic activity. Slightly deactivation of C_3N_4/MoS_2 composites could be observed when recycled due to the mild photocorrosion of MoS_2. Based on the band alignments of C_3N_4 and MoS_2, a possible photocatalytic mechanism was discussed, where MoS_2 could efficiently promote the separation of the photogenerated carriers of C_3N_4.
