Aqueous zinc-tellurium(Zn-Te) batteries have garnered much attention due to their inherent safety and high specific capacity.Unfortunately,the problem of low utilization and severe volume expansion represents a signif...Aqueous zinc-tellurium(Zn-Te) batteries have garnered much attention due to their inherent safety and high specific capacity.Unfortunately,the problem of low utilization and severe volume expansion represents a significant obstacle to the development of aqueous Zn-Te batteries.Herein,a synergistic defect engineering and gradient pore structure strategy is proposed to construct tellurium nanoclusters/carbon composite cathode materials(DP-C/Te) for high-performance aqueous Zn-Te batteries.The gradient pore structure supplies confinement spaces that restrict crystalline tellurium formation,facilitating high-activity tellurium nanoclusters and enhancing structural stability.A defect-rich structure can accelerate the migration and aggregation of tellurium,not only leading to the formation of tellurium nanoclusters but also boosting the redox reaction of aqueous Zn-Te batteries.Additionally,robust C-O bonds can further facilitate the interfacial electron transfer.Consequently,the DP-C/Te cathode for aqueous zinc-tellurium batteries demonstrates sufficient specific capacity(481.75 mAh g^(-1) at 0.1 A g^(-1)),superior rate performance(114 mAh g^(-1) even at 3 A g^(-1))and reliable cycling stability(81% capacity retention at 1 A g^(-1) after 1100 cycles).Furthermore,this work offers a promising perspective for high-performance aqueous ZnTe batteries.展开更多
Electrochemical CO_(2)reduction reaction(CO_(2)RR)on gas diffusion electrodes(GDEs)offers a promising route for carbon-neutral fuel production at commercially relevant current densities(J>200 mA cm^(-2))[1,2].Howev...Electrochemical CO_(2)reduction reaction(CO_(2)RR)on gas diffusion electrodes(GDEs)offers a promising route for carbon-neutral fuel production at commercially relevant current densities(J>200 mA cm^(-2))[1,2].However,under high-rate operation,GDE performance deteriorates due to mass transport limitations[3,4].First,local CO_(2)depletion near the catalyst surface intensifies the competing hydrogen evolution reaction(HER),diminishing the selectivity[5].展开更多
Subsurface water flow velocity influences the hydrodynamic characteristics of soil seepage and the interaction between subsurface water flow and surface runoff during soil erosion and sediment transport.A visualized m...Subsurface water flow velocity influences the hydrodynamic characteristics of soil seepage and the interaction between subsurface water flow and surface runoff during soil erosion and sediment transport.A visualized method and equipment was adopted in this study to observe the subsurface water flow.Quartz sand was used as the test material of subsurface water flow and fluorescent dye was used as the indicator for tracing subsurface water flow.Water was supplied at the same flow discharge to the three parts at the bottom of the test flume,and the subsurface water flow were determined with four slope gradients(4°,8°,10°,and 12°).The results showed that the seepage velocity gradually increased with increasing slope gradient.The pore water velocity at different depths of sand layer profile increased with increasing slope gradient,whereas the thickness of the flow front gradually decreased.For the same slope gradient,the pore water velocity in the lower layer was the largest,whereas the thickness of the flow front was the smallest.Comparative analysis of the relationship between seepage velocity and pore water velocity at different depths of sand layer profile showed that the maximum relative difference between the measured pore water velocity and the computational pore water velocity at different depths of sand profile in the experiment was 4.38%.Thus,the test method for measuring the subsurface water flow velocity of sand layer profile adopted in this study was effective and feasible.The development of this experiment and the exploration of research methods would lay a good test foundation for future studies on the variation law of subsurface water flow velocity and the determination of flow velocity in purple soils,thus contributing to the improvement of the hydrodynamic mechanism of purple soils.展开更多
Design and optimization of electrode material structures are critical steps in the development of supercapacitors.This work presented a design strategy based on SiC nanowires(NWs)as supercapacitor electrode with gradi...Design and optimization of electrode material structures are critical steps in the development of supercapacitors.This work presented a design strategy based on SiC nanowires(NWs)as supercapacitor electrode with gradient pore structure,superhydrophilicity,and enhanced conductivity.SiCNWs were in-situ fabricated on a carbon fabric substrate radially via chemical vapor deposition(CVD),constructing conical channels with gradient pore sizes that generate capillary forces and promote ion transport.An ultrathin pyrolytic carbon(PyC)shell(4.98 nm)was coated on the SiCNWs,to improve electrical conductivity without compromising pore structure or wettability.SiCNWs@PyC electrodes with a diameter of∼0.93μm exhibited excellent electrochemical performance from 0 to 60℃.At 25℃and a current density of 0.2 mA/cm^(2),the areal capacitance of SiCNWs@PyC electrode was 32.48 mF/cm^(2),representing 227.58%of the areal specific capacitance of pure SiCNWs.At 60℃,the capacitance remained high at 28.09 mF/cm^(2) under the same current density.The in-situ growth strategy and high mechanical stability of the material enabled the symmetric supercapacitor to maintain outstanding rate performance and cycling stability across a wide temperature range.The SiCNWs@PyC core-shell nanostructure is a promising supercapacitor electrode material,offering valuable insights for the development of next-generation energy storage devices.展开更多
This study investigated the cause of identified zones of overpressure in some selected wells in a field in the Niger Delta sedimentary basin. Two models were used each for predicting pore pressure and the correspondin...This study investigated the cause of identified zones of overpressure in some selected wells in a field in the Niger Delta sedimentary basin. Two models were used each for predicting pore pressure and the corresponding fracture pressure using well log and drilling data. Shale lithology in Niger Delta is massive and characterized by high pore pressure;hence shale compaction theory is utilized in this study. The petrophysical data were evaluated using Ikon’s Science Rokdoc software. The two major pore pressure prediction techniques employed are the Eaton’s and Bowers’ models while the Eaton’s fracture pressure model and the Hubbert and Willis fracture pressure prediction models were utilized for fracture prediction. The density and sonic logs were used respectively to generate the shale trend and the shale normal compaction trend used for the prediction. The wells studied showed disequilibrium compaction of sediment to be the major mechanism that gave rise to overpressure in the Niger Delta. Clay diagenesis and fluid expansion were also observed as the secondary overpressure generation mechanism in well X-1. This secondary overpressure mechanism was observed to start approximately at depths of 10,000 ft (TVD). The top of overpressure and the pressure range in the wells studied varied from 6000 to 11,017 ft (TVD) and 1796.70 to 5297.00 psi respectively. The Eaton’s model under-predicts pore pressure at the depth interval where unloading mechanism is witnessed. Since the study revealed presence of secondary overpressure generation mechanism, Bowers model was observed to be the most reliable pore pressure prediction model in the area.展开更多
基金financially supported by the Natural Science Foundation of Fujian Province(No.2024J011210)the Technology Innovation Project of Xiamen University of Technology(No.YKJCX2023073)
文摘Aqueous zinc-tellurium(Zn-Te) batteries have garnered much attention due to their inherent safety and high specific capacity.Unfortunately,the problem of low utilization and severe volume expansion represents a significant obstacle to the development of aqueous Zn-Te batteries.Herein,a synergistic defect engineering and gradient pore structure strategy is proposed to construct tellurium nanoclusters/carbon composite cathode materials(DP-C/Te) for high-performance aqueous Zn-Te batteries.The gradient pore structure supplies confinement spaces that restrict crystalline tellurium formation,facilitating high-activity tellurium nanoclusters and enhancing structural stability.A defect-rich structure can accelerate the migration and aggregation of tellurium,not only leading to the formation of tellurium nanoclusters but also boosting the redox reaction of aqueous Zn-Te batteries.Additionally,robust C-O bonds can further facilitate the interfacial electron transfer.Consequently,the DP-C/Te cathode for aqueous zinc-tellurium batteries demonstrates sufficient specific capacity(481.75 mAh g^(-1) at 0.1 A g^(-1)),superior rate performance(114 mAh g^(-1) even at 3 A g^(-1))and reliable cycling stability(81% capacity retention at 1 A g^(-1) after 1100 cycles).Furthermore,this work offers a promising perspective for high-performance aqueous ZnTe batteries.
基金supported by the Natural Science Foundation of China(22178394,22376222,and 52404332)the Science and Technology Innovation Program of Hunan Province(2022RC3048 and 2023RC1012)+1 种基金Central South University Research Program of Advanced Interdisciplinary Studies(2023QYJC012)the Postdoctoral Fellowship Program of CPSF(GZB20240860)for financial support。
文摘Electrochemical CO_(2)reduction reaction(CO_(2)RR)on gas diffusion electrodes(GDEs)offers a promising route for carbon-neutral fuel production at commercially relevant current densities(J>200 mA cm^(-2))[1,2].However,under high-rate operation,GDE performance deteriorates due to mass transport limitations[3,4].First,local CO_(2)depletion near the catalyst surface intensifies the competing hydrogen evolution reaction(HER),diminishing the selectivity[5].
基金This work was supported by the Fundamental Research Funds for the National Natural Science Foundation of China(No.41571265,41971244)the Key Research and Development Project of Social Livelihood in Chongqing(cstc2018jscxmszdX0061)the Foundation of Graduate Research and Innovation in Chongqing under project CYB18089.
文摘Subsurface water flow velocity influences the hydrodynamic characteristics of soil seepage and the interaction between subsurface water flow and surface runoff during soil erosion and sediment transport.A visualized method and equipment was adopted in this study to observe the subsurface water flow.Quartz sand was used as the test material of subsurface water flow and fluorescent dye was used as the indicator for tracing subsurface water flow.Water was supplied at the same flow discharge to the three parts at the bottom of the test flume,and the subsurface water flow were determined with four slope gradients(4°,8°,10°,and 12°).The results showed that the seepage velocity gradually increased with increasing slope gradient.The pore water velocity at different depths of sand layer profile increased with increasing slope gradient,whereas the thickness of the flow front gradually decreased.For the same slope gradient,the pore water velocity in the lower layer was the largest,whereas the thickness of the flow front was the smallest.Comparative analysis of the relationship between seepage velocity and pore water velocity at different depths of sand layer profile showed that the maximum relative difference between the measured pore water velocity and the computational pore water velocity at different depths of sand profile in the experiment was 4.38%.Thus,the test method for measuring the subsurface water flow velocity of sand layer profile adopted in this study was effective and feasible.The development of this experiment and the exploration of research methods would lay a good test foundation for future studies on the variation law of subsurface water flow velocity and the determination of flow velocity in purple soils,thus contributing to the improvement of the hydrodynamic mechanism of purple soils.
基金supported by National Natural Science Foundation of China(52202047,524B2015)China Postdoctoral Science Foundation(2023T160530)+3 种基金Young Talent Fund of Association for Science and Technology in Shaanxi,China(20220435)the Creative Research Foundation of Science and Technology on Thermo-structural Composite Materials Laboratory(2022-JCJQ-LB-073-03)Joint Fund for Science and Technology Research of Henan Province and Henan Academy of Sciences(225200810002)Practice and Innovation Funds for Graduate Students of Northwestern Polytechnical University(PF2024054).
文摘Design and optimization of electrode material structures are critical steps in the development of supercapacitors.This work presented a design strategy based on SiC nanowires(NWs)as supercapacitor electrode with gradient pore structure,superhydrophilicity,and enhanced conductivity.SiCNWs were in-situ fabricated on a carbon fabric substrate radially via chemical vapor deposition(CVD),constructing conical channels with gradient pore sizes that generate capillary forces and promote ion transport.An ultrathin pyrolytic carbon(PyC)shell(4.98 nm)was coated on the SiCNWs,to improve electrical conductivity without compromising pore structure or wettability.SiCNWs@PyC electrodes with a diameter of∼0.93μm exhibited excellent electrochemical performance from 0 to 60℃.At 25℃and a current density of 0.2 mA/cm^(2),the areal capacitance of SiCNWs@PyC electrode was 32.48 mF/cm^(2),representing 227.58%of the areal specific capacitance of pure SiCNWs.At 60℃,the capacitance remained high at 28.09 mF/cm^(2) under the same current density.The in-situ growth strategy and high mechanical stability of the material enabled the symmetric supercapacitor to maintain outstanding rate performance and cycling stability across a wide temperature range.The SiCNWs@PyC core-shell nanostructure is a promising supercapacitor electrode material,offering valuable insights for the development of next-generation energy storage devices.
文摘This study investigated the cause of identified zones of overpressure in some selected wells in a field in the Niger Delta sedimentary basin. Two models were used each for predicting pore pressure and the corresponding fracture pressure using well log and drilling data. Shale lithology in Niger Delta is massive and characterized by high pore pressure;hence shale compaction theory is utilized in this study. The petrophysical data were evaluated using Ikon’s Science Rokdoc software. The two major pore pressure prediction techniques employed are the Eaton’s and Bowers’ models while the Eaton’s fracture pressure model and the Hubbert and Willis fracture pressure prediction models were utilized for fracture prediction. The density and sonic logs were used respectively to generate the shale trend and the shale normal compaction trend used for the prediction. The wells studied showed disequilibrium compaction of sediment to be the major mechanism that gave rise to overpressure in the Niger Delta. Clay diagenesis and fluid expansion were also observed as the secondary overpressure generation mechanism in well X-1. This secondary overpressure mechanism was observed to start approximately at depths of 10,000 ft (TVD). The top of overpressure and the pressure range in the wells studied varied from 6000 to 11,017 ft (TVD) and 1796.70 to 5297.00 psi respectively. The Eaton’s model under-predicts pore pressure at the depth interval where unloading mechanism is witnessed. Since the study revealed presence of secondary overpressure generation mechanism, Bowers model was observed to be the most reliable pore pressure prediction model in the area.
