The mixture of graphene oxide （GO） and dye molecules may provide some new applications due to unique electronic, optical, and structural properties. Methylene blue （MB）, a typ- ical anionic dye, can attach on GO v...The mixture of graphene oxide （GO） and dye molecules may provide some new applications due to unique electronic, optical, and structural properties. Methylene blue （MB）, a typ- ical anionic dye, can attach on GO via π-π stacking and electrostatic interaction, and the molecule removal process on GO has been observed. However, it remains unclear about the ultrafast carrier dynamics and the internal energy transfer pathways of the system which is composed of GO and MB. We have employed ultrafast optical pump-probe spectroscopy to investigate the excited dynamics of the GO-MB system dispersed in water by exciting the samples at 400 nm pump pulse. The pristine MB and GO dynamics are also analyzed in tandem for a direct comparison. Utilizing the global analysis to fit the measured signal via a sequential model, five lifetimes are acquired：（0.61±0.01） ps, （3.52±0.04） ps, （14.1±0.3） ps, （84±2） ps, and （3.66±0.08） ns. The ultrafast dynamics corresponding to these lifetimes was analyzed and the new relaxation processes were found in the GO-MB system, compared with the pristine MB. The results reveal that the functionalization of GO can alter the known decay pathways of MB via the energy transfer from GO to MB in system, the increased intermediate state, and the promoted energy transfer from triplet state MB to ground state oxygen molecules dissolved in aqueous sample.展开更多
Unique MoS_(2)‐SnS_(2)heterogeneous nanoplates have successfully in‐situ grown on poly(3‐(1‐vinylimidazolium‐3‐yl)propane‐1‐sulfonate)functionalized polypyrrole/graphene oxide(PVIPS/PPy/GO).PVIPS can attract h...Unique MoS_(2)‐SnS_(2)heterogeneous nanoplates have successfully in‐situ grown on poly(3‐(1‐vinylimidazolium‐3‐yl)propane‐1‐sulfonate)functionalized polypyrrole/graphene oxide(PVIPS/PPy/GO).PVIPS can attract heptamolybdate ion(Mo7O246−)and Sn^(4+)as the precursors by the ion‐exchange,resulting in the simultaneous growth of 1T’‐MoS2 and the berndtite‐2T‐type hexagonal SnS_(2)by the interfacial induced effect of PVIPS.The obtained MoS_(2)‐SnS_(2)/PVIPS/PPy/GO can serve as electrocatalysts,exhibiting good NRR performance by the synergistic effect.The semi‐conducting SnS_(2)would limit the surface electron accessibility for suppressing HER process of 1T’‐MoS_(2),while metallic 1T’‐MoS_(2)might efficiently improve the NRR electroactivity of SnS_(2)by the creation of Mo‐Sn‐Sn trimer catalytic sites.Otherwise,the irreversible crystal phase transition has taken place during the NRR process.Partial 1T’‐MoS_(2)and SnS_(2)have electrochemically reacted with N_(2),and irreversibly converted into Mo^(2)N and SnxNz due to the formation of Mo−N and Sn−N bonding,meanwhile,partial SnS_(2) has been irreversibly evolved into SnS due to the reduction by the power source in the electrochemical system.It would put forward a new design idea for optimizing the preparation method and electrocatalytic activity of transition metal dichalcogenides.展开更多
Flexible lithium-sulfur(Li-S)batteries are considered one of the most promising candidates for highenergy-density storage devices in wearable electronics.However,the safety problem severely restricts the practical app...Flexible lithium-sulfur(Li-S)batteries are considered one of the most promising candidates for highenergy-density storage devices in wearable electronics.However,the safety problem severely restricts the practical application of Li-S batteries because of the possible occurrence of thermal runaway caused by battery short circuits and combustible components,particularly under bending conditions.The development of advanced separators that can suppress lithium dendrite growth and are incombustible is the key to improving the safety of flexible Li-S batteries.In this work,a nonflammable multifunctional Janus separator with self-extinguishing capability,high thermal stability,high thermal conductivity,good electrolyte infiltration,uniform lithium deposition,and efficient polysulfide shuttling inhibition,is proposed.The separator is composed of polyacrylonitrile(PAN)fiber and decabromodiphenyl ethane(DBDPE)membrane as well as functional layers of boron nitride(BN)for suppressing lithium dendrite growth and reduced graphene oxide(rGO)for accelerating the sulfur convention kinetics.As a result,the Li-S battery with a sulfur mass loading of2.7 mg cm^(-2) delivers a specific capacity of 916.8 mA h g^(-1) after100 cycles at 0.1 C and maintains a stable performance during intermittent thermal shock.Moreover,the Li-S pouch cell with a sulfur mass loading of 8 mg exhibits a high capacity of6.3 mA h under bending conditions.展开更多
基金This work was supported by the National Natural Basic Research Program of China （No.2013CB922200）,the National Natural Science Foundation of China （No.11674128, No.11474129, and No.11504129）, Jilin Province Scientific and Technological Development Program, China （No.20170101063JC）, the Thirteenth Five- Year Scientific and Technological Research Project of the Education Department of Jilin Province, China （No.n00）.
文摘The mixture of graphene oxide （GO） and dye molecules may provide some new applications due to unique electronic, optical, and structural properties. Methylene blue （MB）, a typ- ical anionic dye, can attach on GO via π-π stacking and electrostatic interaction, and the molecule removal process on GO has been observed. However, it remains unclear about the ultrafast carrier dynamics and the internal energy transfer pathways of the system which is composed of GO and MB. We have employed ultrafast optical pump-probe spectroscopy to investigate the excited dynamics of the GO-MB system dispersed in water by exciting the samples at 400 nm pump pulse. The pristine MB and GO dynamics are also analyzed in tandem for a direct comparison. Utilizing the global analysis to fit the measured signal via a sequential model, five lifetimes are acquired：（0.61±0.01） ps, （3.52±0.04） ps, （14.1±0.3） ps, （84±2） ps, and （3.66±0.08） ns. The ultrafast dynamics corresponding to these lifetimes was analyzed and the new relaxation processes were found in the GO-MB system, compared with the pristine MB. The results reveal that the functionalization of GO can alter the known decay pathways of MB via the energy transfer from GO to MB in system, the increased intermediate state, and the promoted energy transfer from triplet state MB to ground state oxygen molecules dissolved in aqueous sample.
文摘Unique MoS_(2)‐SnS_(2)heterogeneous nanoplates have successfully in‐situ grown on poly(3‐(1‐vinylimidazolium‐3‐yl)propane‐1‐sulfonate)functionalized polypyrrole/graphene oxide(PVIPS/PPy/GO).PVIPS can attract heptamolybdate ion(Mo7O246−)and Sn^(4+)as the precursors by the ion‐exchange,resulting in the simultaneous growth of 1T’‐MoS2 and the berndtite‐2T‐type hexagonal SnS_(2)by the interfacial induced effect of PVIPS.The obtained MoS_(2)‐SnS_(2)/PVIPS/PPy/GO can serve as electrocatalysts,exhibiting good NRR performance by the synergistic effect.The semi‐conducting SnS_(2)would limit the surface electron accessibility for suppressing HER process of 1T’‐MoS_(2),while metallic 1T’‐MoS_(2)might efficiently improve the NRR electroactivity of SnS_(2)by the creation of Mo‐Sn‐Sn trimer catalytic sites.Otherwise,the irreversible crystal phase transition has taken place during the NRR process.Partial 1T’‐MoS_(2)and SnS_(2)have electrochemically reacted with N_(2),and irreversibly converted into Mo^(2)N and SnxNz due to the formation of Mo−N and Sn−N bonding,meanwhile,partial SnS_(2) has been irreversibly evolved into SnS due to the reduction by the power source in the electrochemical system.It would put forward a new design idea for optimizing the preparation method and electrocatalytic activity of transition metal dichalcogenides.
基金support from the National Natural Science Foundation of China(52072205)the National Key Research and Development Program of China(2019YFA0705700,2021YFB2500200)+1 种基金Shenzhen Stabilization Support Program(WDZC20200824091903001)the Start-up Funds of Tsinghua Shenzhen International Graduate School。
文摘Flexible lithium-sulfur(Li-S)batteries are considered one of the most promising candidates for highenergy-density storage devices in wearable electronics.However,the safety problem severely restricts the practical application of Li-S batteries because of the possible occurrence of thermal runaway caused by battery short circuits and combustible components,particularly under bending conditions.The development of advanced separators that can suppress lithium dendrite growth and are incombustible is the key to improving the safety of flexible Li-S batteries.In this work,a nonflammable multifunctional Janus separator with self-extinguishing capability,high thermal stability,high thermal conductivity,good electrolyte infiltration,uniform lithium deposition,and efficient polysulfide shuttling inhibition,is proposed.The separator is composed of polyacrylonitrile(PAN)fiber and decabromodiphenyl ethane(DBDPE)membrane as well as functional layers of boron nitride(BN)for suppressing lithium dendrite growth and reduced graphene oxide(rGO)for accelerating the sulfur convention kinetics.As a result,the Li-S battery with a sulfur mass loading of2.7 mg cm^(-2) delivers a specific capacity of 916.8 mA h g^(-1) after100 cycles at 0.1 C and maintains a stable performance during intermittent thermal shock.Moreover,the Li-S pouch cell with a sulfur mass loading of 8 mg exhibits a high capacity of6.3 mA h under bending conditions.
