Smart proton conductive metal-organic framework(MOF) membranes with dynamic remote control over proton conduction show high potential for use in advanced applications, such as sensors and bioprocesses. Here, we report...Smart proton conductive metal-organic framework(MOF) membranes with dynamic remote control over proton conduction show high potential for use in advanced applications, such as sensors and bioprocesses. Here, we report a photoswitchable proton conductive ZIF-8 membrane by coencapsulating polystyrene sulfonate and graphene quantum dots into a ZIF-8 matrix(GQDs-PSS@ZIF-8) via a solidconfined conversion process. The proton conductivity of the GQDs-PSS@ZIF-8 membrane is 6.3 times higher than that of pristine ZIF-8 and can be reversibly switched by light due to photoluminescence quenching and the photothermal conversion effect, which converts light into heat. The local increase in temperature allows water molecules to escape from the porous channels, which cuts off the proton transport pathways and results in a decrease in proton conductivity. The proton conductivity is restored when the light is off owing to regaining water molecules, which act as proton carriers, from the surroundings. The GQDs-PSS@ZIF-8 membrane responds efficiently to light and exhibits an ON/OFF ratio of 12.8. This photogated proton conduction in MOFs has potential for the development and application of MOF-based protonic solids in advanced photoelectric devices.展开更多
Thermoelectric materials(TMs)can uniquely convert waste heat into electricity,which provides a potential solution for the global energy crisis that is increasingly severe.Bulk Cu2Se,with ionic conductivity of Cu ions,...Thermoelectric materials(TMs)can uniquely convert waste heat into electricity,which provides a potential solution for the global energy crisis that is increasingly severe.Bulk Cu2Se,with ionic conductivity of Cu ions,exhibits a significant enhancement of its thermoelectric figure of merit z T by a factor of^3 near its structural transition around 400 K.Here,we show a systematic study of the electronic structure of Cu2Se and its temperature evolution using high-resolution angle-resolved photoemission spectroscopy.Upon heating across the structural transition,the electronic states near the corner of the Brillouin zone gradually disappear,while the bands near the centre of Brillouin zone shift abruptly towards high binding energies and develop an energy gap.Interestingly,the observed band reconstruction well reproduces the temperature evolution of the Seebeck coefficient of Cu2 Se,providing an electronic origin for the drastic enhancement of the thermoelectric performance near 400 K.The current results not only bridge among structural phase transition,electronic structures and thermoelectric properties in a condensed matter system,but also provide valuable insights into the search and design of new generation of thermoelectric materials.展开更多
基金supported by the National Natural Science Foundation of China (21875212)the Key Program of National Natural Science Foundation (51632008)+2 种基金the Major R&D Plan of Zhejiang Natural Science Foundation (LD18E020001)the National Key Research and Development Program (2016YFA0200204)the Fundamental Research Funds for the Central Universities。
文摘Smart proton conductive metal-organic framework(MOF) membranes with dynamic remote control over proton conduction show high potential for use in advanced applications, such as sensors and bioprocesses. Here, we report a photoswitchable proton conductive ZIF-8 membrane by coencapsulating polystyrene sulfonate and graphene quantum dots into a ZIF-8 matrix(GQDs-PSS@ZIF-8) via a solidconfined conversion process. The proton conductivity of the GQDs-PSS@ZIF-8 membrane is 6.3 times higher than that of pristine ZIF-8 and can be reversibly switched by light due to photoluminescence quenching and the photothermal conversion effect, which converts light into heat. The local increase in temperature allows water molecules to escape from the porous channels, which cuts off the proton transport pathways and results in a decrease in proton conductivity. The proton conductivity is restored when the light is off owing to regaining water molecules, which act as proton carriers, from the surroundings. The GQDs-PSS@ZIF-8 membrane responds efficiently to light and exhibits an ON/OFF ratio of 12.8. This photogated proton conduction in MOFs has potential for the development and application of MOF-based protonic solids in advanced photoelectric devices.
基金the National Natural Science Foundation of China(11774190,11674229,11634009 and 11874264)the National Key R&D Program of China(2017YFA0304600,2017YFA0305400 and 2017YFA0402900)+2 种基金EPSRC Platform Grant(EP/M020517/1)the support from the Natural Science Foundation of Shanghai(17ZR1443300)the support from Tsinghua University Initiative Scientific Research Program。
文摘Thermoelectric materials(TMs)can uniquely convert waste heat into electricity,which provides a potential solution for the global energy crisis that is increasingly severe.Bulk Cu2Se,with ionic conductivity of Cu ions,exhibits a significant enhancement of its thermoelectric figure of merit z T by a factor of^3 near its structural transition around 400 K.Here,we show a systematic study of the electronic structure of Cu2Se and its temperature evolution using high-resolution angle-resolved photoemission spectroscopy.Upon heating across the structural transition,the electronic states near the corner of the Brillouin zone gradually disappear,while the bands near the centre of Brillouin zone shift abruptly towards high binding energies and develop an energy gap.Interestingly,the observed band reconstruction well reproduces the temperature evolution of the Seebeck coefficient of Cu2 Se,providing an electronic origin for the drastic enhancement of the thermoelectric performance near 400 K.The current results not only bridge among structural phase transition,electronic structures and thermoelectric properties in a condensed matter system,but also provide valuable insights into the search and design of new generation of thermoelectric materials.
