Depleting fossil energy sources and conventional polluting power generation pose a threat to sustainable development.Hydroelectricity generation from ubiquitous and spontaneous phase transitions between liquid and gas...Depleting fossil energy sources and conventional polluting power generation pose a threat to sustainable development.Hydroelectricity generation from ubiquitous and spontaneous phase transitions between liquid and gaseous water has been considered a promising strategy for mitigating the energy crisis.Fibrous materials with unique flexibility,processability,multifunctionality,and practicability have been widely applied for fibrous materials-based hydroelectricity generation(FHG).In this review,the power generation mechanisms,design principles,and electricity enhancement factors of FHG are first introduced.Then,the fabrication strategies and characteristics of varied constructions including 1D fiber,1D yarn,2D fabric,2D membrane,3D fibrous framework,and 3D fibrous gel are demonstrated.Afterward,the advanced functions of FHG during water harvesting,proton dissociation,ion separation,and charge accumulation processes are analyzed in detail.Moreover,the potential applications including power supply,energy storage,electrical sensor,and information expression are also discussed.Finally,some existing challenges are considered and prospects for future development are sincerely proposed.展开更多
Boundary engineering has proven effective in enhancing the thermoelectric performance of materials.SnSe,known for its low thermal conductivity,has garnered significant interest;however,its application is hindered by p...Boundary engineering has proven effective in enhancing the thermoelectric performance of materials.SnSe,known for its low thermal conductivity,has garnered significant interest;however,its application is hindered by poor electrical conductivity.Herein,the Ag_(8)GeSe_(6) is introduced into the p-type polycrystalline SnSe matrix to optimize the thermoelectric performance,and the in-situ Ag_(2)Se precipitates are formed in grain boundaries,which play dual roles,acting as an electron attraction center for improving hole concentration and a phonon scattering center for reducing lattice thermal conductivity.It effectively decouples the thermal and electrical transport properties to optimize the thermoelectric performance.Importantly,the amount of Ag_(2)Se can be controlled by adjusting the amount of Ag_(8)GeSe_(6) added to the SnSe matrix.The introduction of Ag_(8)GeSe_(6) enhances electrical conductivity due to the increased hole carrier caused by the introduced Ag+and the formed electron attraction center(in-situ Ag_(2)Se precipitates).Based on the DFT calculations,the band gap of the Ag_(8)GeSe_(6)-doped samples is considerably decreased,facilitating carrier transport.As a result,the electrical transport properties increase to 808μW m^(−1) K^(−2) at 823 K for SnSe+0.5 wt%Ag_(8)GeSe_(6).In addition,in-situ Ag_(2)Se precipitates in grain boundaries strongly enhance phonon scattering,causing a decrease in lattice thermal conductivity.Furthermore,the presence of defects contributes to a reduction in lattice thermal conductivity.Specifically,the thermal conductivity of SnSe+1.0 wt%Ag_(8)GeSe_(6) decreases to 0.29 W m^(−1) K^(−1) at 823 K.Consequently,SnSe+0.5 wt%Ag_(8)GeSe_(6) obtains a high ZT value of 1.7 at 823 K and maintains a high average ZT value of 0.57 over the temperature range of 323−773 K.Additionally,the mechanical properties of Ag_(8)GeSe_(6)-doped also show an improvement.These advancements can be applied to energy supply applications during deep space exploration.展开更多
During the excavation of large-scale rock slopes and deep hard rock engineering,the induced rapid unloading serves as the primary cause of rock mass deformation and failure.The essence of this phenomenon lies in the o...During the excavation of large-scale rock slopes and deep hard rock engineering,the induced rapid unloading serves as the primary cause of rock mass deformation and failure.The essence of this phenomenon lies in the opening-shear failure process triggered by the normal stress unloading of fractured rock mass.In this study,we focus on local-scale rock fracture and conduct direct shear tests under different normal stress unloading rates on five types of non-persistent fractured hard rocks.The aim is to analyze the influence of normal stress unloading rates on the failure modes and shear mechanical characteristics of non-persistent fractured rocks.The results indicate that the normal unloading displacement decreases gradually with increasing normal stress unloading rate,while the influence of normal stress unloading rate on shear displacement is not significant.As the normal stress unloading rate increases,the rocks brittle failure process accelerates,and the degree of rocks damage decreases.Analysis of the stress state on rock fracture surfaces reveals that increasing the normal stress unloading rate enhances the compressive stress on rocks,leading to a transition in the failure mode from shear failure to tensile failure.A negative exponential strength formula was proposed,which effectively fits the relationship between failure normal stress and normal stress unloading rate.The findings enrich the theoretical foundation of unloading rock mechanics and provide theoretical support for disasters prevention and control in rock engineering excavations.展开更多
Hydraulic fracturing is a key technology for the efficient development of deep oil and gas reservoirs.However,fracture propagation behavior is influenced by rock elastoplasticity and thermal stress,making it difficult...Hydraulic fracturing is a key technology for the efficient development of deep oil and gas reservoirs.However,fracture propagation behavior is influenced by rock elastoplasticity and thermal stress,making it difficult for traditional linear elastic models to accurately describe its dynamic response.To address this,this study employs the Continuum-Discontinuum Element Method(CDEM),incorporating an elastoplastic constitutive model,thermo-hydro-mechanical(THM)coupling effects,and cohesive zone characteristics at the fracture tip to establish a numerical model for hydraulic fracture propagation in deep elastoplastic reservoirs.A systematic investigation was conducted into the effects of fluid viscosity,reservoir temperature,injection rate,elastic modulus,and horizontal stress difference on fracture propagation.The findings show that a larger horizontal stress differential results in a more rectangular fracture geometry,a shorter fracture length,and a wider fracture.An increase in elastic modulus has a negligible impact on fracture length but reduces fracture width,resulting in a rounded rectangular morphology.Elevated reservoir temperature induces thermal tensile stress around the fracture,mitigating in-situ stress effects and reducing both breakdown and propagation pressures.Higher injection rates and fluid viscosity increase fracture initiation difficulty,promoting shorter but wider fractures with enhanced height growth beyond interlayer barriers.Additionally,horizontal stress significantly affects near-fracture plastic deformation:when the stress difference increases from 10 to 25 MPa,the maximum cumulative plastic strain in the surrounding rock rises by 66.67%.By integrating elastoplasticity and thermal stress effects,this study overcomes the limitations of conventional hydraulic fracturing simulations,offering novel insights for optimizing extraction strategies in deep unconventional reservoirs.展开更多
The group Ⅳ–Ⅵ semiconductor,SnSe,is abundant on the earth and is a promising thermoelectric(TE)material due to its low thermal conductivity.However,the p-type SnSe polycrystals have low electrical conductivities du...The group Ⅳ–Ⅵ semiconductor,SnSe,is abundant on the earth and is a promising thermoelectric(TE)material due to its low thermal conductivity.However,the p-type SnSe polycrystals have low electrical conductivities due to their low carrier concentration,significantly limiting their further applications.This study introduced the argyrodite-type Ag_(9)GaSe_(6) compound into the SnSe matrix to effectively increase the hole carrier concentration,increasing the electrical conductivity.A high electrical conductivity of 50.5 S cm^(−1) was obtained for the SnSe+0.5 wt%Ag_(9)GaSe_(6) sample at 323 K.Due to the increased electrical conductivity,the SnSe+0.5 wt%Ag_(9)GaSe_(6) sample had an average power factor(PFave)value of~410μW m^(-1) K^(-2) in the 323–823 K temperature range,a nearly four times enhancement compared to the undoped SnSe sample.Additionally,the thermal conductivity slightly increased due to the introduction of the Ag_(9)GaSe_(6) compound.However,the electrical transport properties were significantly enhanced,making up for the improvement in thermal conductivity.Consequently,the SnSe+0.5 wt%Ag_(9)GaSe_(6) sample obtained a peak thermoelectric figure of merit ZT value of~1.2 at 823 K and a ZT_(ave) value of 0.58 in the 323–823 K temperature range.The proposed strategy improved the ZT and ZT_(ave) values of SnSe-based TE materials at room temperature and provided a systematic strategy for modifying SnSe-based TE materials.Moreover,the thermoelectric properties of SnSe can be effectively improved by introducing the Ag_(9)GaSe_(6) compound for doping,and waste heat power generation can be effectively carried out in the middle temperature region.展开更多
基金funding support from the National Key Research and Development Program of China(No.2022YFB3805800)the National Natural Science Foundation of China(52173059)+1 种基金The Major Basic Research Project of the Natural Science Foundation of the Jiangsu Higher Education Institutions(21KJA540002)Jiangsu Funding Program for Excellent Postdoctoral Talent(2022ZB555).
文摘Depleting fossil energy sources and conventional polluting power generation pose a threat to sustainable development.Hydroelectricity generation from ubiquitous and spontaneous phase transitions between liquid and gaseous water has been considered a promising strategy for mitigating the energy crisis.Fibrous materials with unique flexibility,processability,multifunctionality,and practicability have been widely applied for fibrous materials-based hydroelectricity generation(FHG).In this review,the power generation mechanisms,design principles,and electricity enhancement factors of FHG are first introduced.Then,the fabrication strategies and characteristics of varied constructions including 1D fiber,1D yarn,2D fabric,2D membrane,3D fibrous framework,and 3D fibrous gel are demonstrated.Afterward,the advanced functions of FHG during water harvesting,proton dissociation,ion separation,and charge accumulation processes are analyzed in detail.Moreover,the potential applications including power supply,energy storage,electrical sensor,and information expression are also discussed.Finally,some existing challenges are considered and prospects for future development are sincerely proposed.
基金supported by the Outstanding Youth Fund of Yunnan Province(Grant No.202201AV070005)the National Natural Science Foundation of China(Grant No.52162029)the National Key R&D Program of China(Grant No.2022YFF0503804).
文摘Boundary engineering has proven effective in enhancing the thermoelectric performance of materials.SnSe,known for its low thermal conductivity,has garnered significant interest;however,its application is hindered by poor electrical conductivity.Herein,the Ag_(8)GeSe_(6) is introduced into the p-type polycrystalline SnSe matrix to optimize the thermoelectric performance,and the in-situ Ag_(2)Se precipitates are formed in grain boundaries,which play dual roles,acting as an electron attraction center for improving hole concentration and a phonon scattering center for reducing lattice thermal conductivity.It effectively decouples the thermal and electrical transport properties to optimize the thermoelectric performance.Importantly,the amount of Ag_(2)Se can be controlled by adjusting the amount of Ag_(8)GeSe_(6) added to the SnSe matrix.The introduction of Ag_(8)GeSe_(6) enhances electrical conductivity due to the increased hole carrier caused by the introduced Ag+and the formed electron attraction center(in-situ Ag_(2)Se precipitates).Based on the DFT calculations,the band gap of the Ag_(8)GeSe_(6)-doped samples is considerably decreased,facilitating carrier transport.As a result,the electrical transport properties increase to 808μW m^(−1) K^(−2) at 823 K for SnSe+0.5 wt%Ag_(8)GeSe_(6).In addition,in-situ Ag_(2)Se precipitates in grain boundaries strongly enhance phonon scattering,causing a decrease in lattice thermal conductivity.Furthermore,the presence of defects contributes to a reduction in lattice thermal conductivity.Specifically,the thermal conductivity of SnSe+1.0 wt%Ag_(8)GeSe_(6) decreases to 0.29 W m^(−1) K^(−1) at 823 K.Consequently,SnSe+0.5 wt%Ag_(8)GeSe_(6) obtains a high ZT value of 1.7 at 823 K and maintains a high average ZT value of 0.57 over the temperature range of 323−773 K.Additionally,the mechanical properties of Ag_(8)GeSe_(6)-doped also show an improvement.These advancements can be applied to energy supply applications during deep space exploration.
基金supported by the National Natural Science Foundation of China(Grant Nos.42372326 and 42090054)supported by the State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Independent Research Project(SKLGP2023Z015).
文摘During the excavation of large-scale rock slopes and deep hard rock engineering,the induced rapid unloading serves as the primary cause of rock mass deformation and failure.The essence of this phenomenon lies in the opening-shear failure process triggered by the normal stress unloading of fractured rock mass.In this study,we focus on local-scale rock fracture and conduct direct shear tests under different normal stress unloading rates on five types of non-persistent fractured hard rocks.The aim is to analyze the influence of normal stress unloading rates on the failure modes and shear mechanical characteristics of non-persistent fractured rocks.The results indicate that the normal unloading displacement decreases gradually with increasing normal stress unloading rate,while the influence of normal stress unloading rate on shear displacement is not significant.As the normal stress unloading rate increases,the rocks brittle failure process accelerates,and the degree of rocks damage decreases.Analysis of the stress state on rock fracture surfaces reveals that increasing the normal stress unloading rate enhances the compressive stress on rocks,leading to a transition in the failure mode from shear failure to tensile failure.A negative exponential strength formula was proposed,which effectively fits the relationship between failure normal stress and normal stress unloading rate.The findings enrich the theoretical foundation of unloading rock mechanics and provide theoretical support for disasters prevention and control in rock engineering excavations.
基金supported by the Shandong Provincial Natural Science Foundation for Distinguished Young Scholars(Grant No.ZR2024JQ012)This research was financially supported by the National Natural Science Foundation of China(General Program,Grant No.52474069)This research was financially supported by the Natural Gas Research Institute of Shaanxi Yanchang Petroleum(Group)Co.,Ltd.(Grant No.TYTY0824SFW0003).
文摘Hydraulic fracturing is a key technology for the efficient development of deep oil and gas reservoirs.However,fracture propagation behavior is influenced by rock elastoplasticity and thermal stress,making it difficult for traditional linear elastic models to accurately describe its dynamic response.To address this,this study employs the Continuum-Discontinuum Element Method(CDEM),incorporating an elastoplastic constitutive model,thermo-hydro-mechanical(THM)coupling effects,and cohesive zone characteristics at the fracture tip to establish a numerical model for hydraulic fracture propagation in deep elastoplastic reservoirs.A systematic investigation was conducted into the effects of fluid viscosity,reservoir temperature,injection rate,elastic modulus,and horizontal stress difference on fracture propagation.The findings show that a larger horizontal stress differential results in a more rectangular fracture geometry,a shorter fracture length,and a wider fracture.An increase in elastic modulus has a negligible impact on fracture length but reduces fracture width,resulting in a rounded rectangular morphology.Elevated reservoir temperature induces thermal tensile stress around the fracture,mitigating in-situ stress effects and reducing both breakdown and propagation pressures.Higher injection rates and fluid viscosity increase fracture initiation difficulty,promoting shorter but wider fractures with enhanced height growth beyond interlayer barriers.Additionally,horizontal stress significantly affects near-fracture plastic deformation:when the stress difference increases from 10 to 25 MPa,the maximum cumulative plastic strain in the surrounding rock rises by 66.67%.By integrating elastoplasticity and thermal stress effects,this study overcomes the limitations of conventional hydraulic fracturing simulations,offering novel insights for optimizing extraction strategies in deep unconventional reservoirs.
基金supported by the Outstanding Youth Fund of Yunnan Province(Grant No.202201AV070005)the National Natural Science Foundation of China(Grant No.52162029)+1 种基金the National Key R&D Program of China(Grant No.2022YFF0503804)the Yunnan Science and Technology Program(202401AT070403).
文摘The group Ⅳ–Ⅵ semiconductor,SnSe,is abundant on the earth and is a promising thermoelectric(TE)material due to its low thermal conductivity.However,the p-type SnSe polycrystals have low electrical conductivities due to their low carrier concentration,significantly limiting their further applications.This study introduced the argyrodite-type Ag_(9)GaSe_(6) compound into the SnSe matrix to effectively increase the hole carrier concentration,increasing the electrical conductivity.A high electrical conductivity of 50.5 S cm^(−1) was obtained for the SnSe+0.5 wt%Ag_(9)GaSe_(6) sample at 323 K.Due to the increased electrical conductivity,the SnSe+0.5 wt%Ag_(9)GaSe_(6) sample had an average power factor(PFave)value of~410μW m^(-1) K^(-2) in the 323–823 K temperature range,a nearly four times enhancement compared to the undoped SnSe sample.Additionally,the thermal conductivity slightly increased due to the introduction of the Ag_(9)GaSe_(6) compound.However,the electrical transport properties were significantly enhanced,making up for the improvement in thermal conductivity.Consequently,the SnSe+0.5 wt%Ag_(9)GaSe_(6) sample obtained a peak thermoelectric figure of merit ZT value of~1.2 at 823 K and a ZT_(ave) value of 0.58 in the 323–823 K temperature range.The proposed strategy improved the ZT and ZT_(ave) values of SnSe-based TE materials at room temperature and provided a systematic strategy for modifying SnSe-based TE materials.Moreover,the thermoelectric properties of SnSe can be effectively improved by introducing the Ag_(9)GaSe_(6) compound for doping,and waste heat power generation can be effectively carried out in the middle temperature region.
