Integration of fast electrochemical double-layer capacitance and large pseudocapacitance is a practical way to improve the overall capability of supercapacitor,yet remains challenging.Herein,an effective cyanogel synt...Integration of fast electrochemical double-layer capacitance and large pseudocapacitance is a practical way to improve the overall capability of supercapacitor,yet remains challenging.Herein,an effective cyanogel synthetic strategy was demonstrated to prepare ultrathin Ni(OH)2 nanosheets coupling with conductive reduced graphene oxide(rGO)(rGO-Ni(OH)2)at ambient condition.Ultrathin Ni(OH)2 nanosheet with 3–4 layers of edge-sharing octahedral MO6 maximally exposes the active surface of Faradic reaction and promotes the ion diffusion,while the conductive rGO sheet boosts the electron transport during the reaction.Even at 30 A g−1,the optimal sample can deliver a specific capacitance of 1119.52 F g−1,and maintain 82.3%after 2000 cycles,demonstrating much higher electrochemical capability than bare Ni(OH)2 nanosheets.A maximum specific energy of 44.3 W h kg^−1(148.5 W kg^−1)is obtained,when assembled in a two-electrode system rGO-Ni(OH)2//rGO.This study provides an insight into efficient construction of two dimensional hybrid electrodes with high performance for the new-generation energy storage system.展开更多
The molecular coating on the surface of microvascular endothelium has been identified as a barrier to transvascular exchange of solutes. With a thickness of hundreds of nanometers, this endothelial surface layer （ESL...The molecular coating on the surface of microvascular endothelium has been identified as a barrier to transvascular exchange of solutes. With a thickness of hundreds of nanometers, this endothelial surface layer （ESL） has been treated as a porous do- main within which fluid shear stresses are dissipated and transmitted to the solid matrix to initiate mechanotransduction events. The present study aims to examine the effects of the ESL thickness and permeability on the transmission of shear stress throughout the ESL. Our results indicate that fluid shear stresses rapidly decrease to insignificant levels within a thin transition layer near the outer boundary of the ESL with a thickness on the order of ten nanometers. The thickness of the transition zone between free fluid and the porous layer was found to be proportional to the square root of the Darcy permeability. As the per- meability is reduced ten-fold, the interfacial fluid and solid matrix shear stress gradients increase exponentially two-fold. While the interracial fluid shear stress is positively related to the ESL thickness, the transmitted matrix stress is reduced by about 50% as the ESL thickness is decreased from 500 to 100 nm, which may occur under pathological conditions. Thus, thickness and permeability of the ESL are two main factors that determine flow features and the apportionment of shear stress- es between the fluid and solid phases of the ESL. These results may shed light on the mechanisms of force transmission through the ESL and the pathological events caused by alterations in thickness and permeability of the ESL.展开更多
The rapid development of perovskite solar cells(PSCs) has stimulated great interest in the fabrication of colorful PSCs to meet the needs of aesthetic purposes in varied applications including building integrated phot...The rapid development of perovskite solar cells(PSCs) has stimulated great interest in the fabrication of colorful PSCs to meet the needs of aesthetic purposes in varied applications including building integrated photovoltaics and wearable electronics. However, it remains challenging to prepare high-efficiency PSCs with attractive colors using perovskites with broad optical absorption and large absorption coefficients. Here we show that high-efficiency PSCs exhibiting distinct structural colors can be readily fabricated by employing Ti O2 nanobowl(NB) arrays as a nanostructured electron transport layer to integrate with a thin overlayer of perovskite on the NB arrays. A new crystalline precursor film based on lead acetate was prepared through a Lewis acid-base adduct approach, which allowed for the formation of a uniform overlayer of high-quality CH3 NH3 Pb I3 crystals on the inner walls of the NBs. The PSCs fabricated using the Ti O2 NB arrays showed angle-dependent vivid colors under light illumination. The resultant colorful PSCs exhibited a remarkable photovoltaic performance with a champion efficiency up to16.94% and an average efficiency of 15.47%, which are recordbreaking among the reported colorful PSCs.展开更多
基金the National Natural Science Foundation of China(21875133)Xijiang R&D Team(Wang X),the Science and Technology Program of Guangzhou(2019050001)Science and Technology Commission of Shanghai Municipality(19ZR1479500)。
文摘Integration of fast electrochemical double-layer capacitance and large pseudocapacitance is a practical way to improve the overall capability of supercapacitor,yet remains challenging.Herein,an effective cyanogel synthetic strategy was demonstrated to prepare ultrathin Ni(OH)2 nanosheets coupling with conductive reduced graphene oxide(rGO)(rGO-Ni(OH)2)at ambient condition.Ultrathin Ni(OH)2 nanosheet with 3–4 layers of edge-sharing octahedral MO6 maximally exposes the active surface of Faradic reaction and promotes the ion diffusion,while the conductive rGO sheet boosts the electron transport during the reaction.Even at 30 A g−1,the optimal sample can deliver a specific capacitance of 1119.52 F g−1,and maintain 82.3%after 2000 cycles,demonstrating much higher electrochemical capability than bare Ni(OH)2 nanosheets.A maximum specific energy of 44.3 W h kg^−1(148.5 W kg^−1)is obtained,when assembled in a two-electrode system rGO-Ni(OH)2//rGO.This study provides an insight into efficient construction of two dimensional hybrid electrodes with high performance for the new-generation energy storage system.
基金supported by the National Basic Research Program of China(Grant No.2012CB934101)the National Natural Science Foundation of China(Grant Nos.51175282 and 51375254)
文摘The molecular coating on the surface of microvascular endothelium has been identified as a barrier to transvascular exchange of solutes. With a thickness of hundreds of nanometers, this endothelial surface layer （ESL） has been treated as a porous do- main within which fluid shear stresses are dissipated and transmitted to the solid matrix to initiate mechanotransduction events. The present study aims to examine the effects of the ESL thickness and permeability on the transmission of shear stress throughout the ESL. Our results indicate that fluid shear stresses rapidly decrease to insignificant levels within a thin transition layer near the outer boundary of the ESL with a thickness on the order of ten nanometers. The thickness of the transition zone between free fluid and the porous layer was found to be proportional to the square root of the Darcy permeability. As the per- meability is reduced ten-fold, the interfacial fluid and solid matrix shear stress gradients increase exponentially two-fold. While the interracial fluid shear stress is positively related to the ESL thickness, the transmitted matrix stress is reduced by about 50% as the ESL thickness is decreased from 500 to 100 nm, which may occur under pathological conditions. Thus, thickness and permeability of the ESL are two main factors that determine flow features and the apportionment of shear stress- es between the fluid and solid phases of the ESL. These results may shed light on the mechanisms of force transmission through the ESL and the pathological events caused by alterations in thickness and permeability of the ESL.
基金supported by the National Natural Science Foundation of China (21673007)
文摘The rapid development of perovskite solar cells(PSCs) has stimulated great interest in the fabrication of colorful PSCs to meet the needs of aesthetic purposes in varied applications including building integrated photovoltaics and wearable electronics. However, it remains challenging to prepare high-efficiency PSCs with attractive colors using perovskites with broad optical absorption and large absorption coefficients. Here we show that high-efficiency PSCs exhibiting distinct structural colors can be readily fabricated by employing Ti O2 nanobowl(NB) arrays as a nanostructured electron transport layer to integrate with a thin overlayer of perovskite on the NB arrays. A new crystalline precursor film based on lead acetate was prepared through a Lewis acid-base adduct approach, which allowed for the formation of a uniform overlayer of high-quality CH3 NH3 Pb I3 crystals on the inner walls of the NBs. The PSCs fabricated using the Ti O2 NB arrays showed angle-dependent vivid colors under light illumination. The resultant colorful PSCs exhibited a remarkable photovoltaic performance with a champion efficiency up to16.94% and an average efficiency of 15.47%, which are recordbreaking among the reported colorful PSCs.
