Photoelectrochemical(PEC)water splitting is considered as an ideal technology to produce hydrogen.Photogenerated carrier migration is one of the most important roles in the whole process of PEC water splitting.It incl...Photoelectrochemical(PEC)water splitting is considered as an ideal technology to produce hydrogen.Photogenerated carrier migration is one of the most important roles in the whole process of PEC water splitting.It includes bulk transfer inside of the photoelectrode and the exchange at the solid-liquid interface.The energy barriers during the migration process lead to the dramatic recombination of photogenerated hot carrier and the reducing of their redox capacity.Thus,an applied bias voltage should be provided to overcome these energy barriers,which brings the additional loss of energy.Plentiful researches indicate that some methods for the regulation of photogenerated hot carrier,such as p-n junction,unique transfer nanochannel,tandem nanostructure and Z-Scheme transfer structure et al.,show great potential to achieve high-efficient PEC water overall splitting without any applied bias voltage.Up to now,many reviews have summarized and analyzed the methods to enhance the PEC or photocatalysis water splitting from the perspectives of materials,nanostructures and surface modification etc.However,few of them focus on the topic of photogenerated carrier transfer regulation,which is an important and urgent developing technique.For this reason,this review focuses on the regulation of photogenerated carriers generated by the photoelectrodes and summarizes different advanced methods for photogenerated carrier regulation developed in recent years.Some comments and outlooks are also provided at the end of this review.展开更多
Numerical simulation of oil migration and accumulation is to describe the history of oil migration and accumulation in basin evolution. It is of great value in the exploration of oil resources and their rational evalu...Numerical simulation of oil migration and accumulation is to describe the history of oil migration and accumulation in basin evolution. It is of great value in the exploration of oil resources and their rational evaluation. In this paper, from such actual conditions as the effects of mechanics of fluids in porous media and 3-dimensional geology characteristics, a kind of modified method of second order splitting-up implicit interactive scheme is pur forward. For the famous hydraulic experiment of secondary migration-accumulation, the numerical simulation test has been done, and both the computational and experimental results are basically identical. For the actual problem of Dongying hollow of Shengli Petroleum Oil Field, the numerical simulation test and the actual conditions are basically coincident. Thus the well-known problem has been solved.展开更多
The alternately directional implicit （ADI） scheme is usually used in 3D depth migration. It splits the 3D square-root operator along crossline and inline directions alternately. In this paper, based on the ideal of ...The alternately directional implicit （ADI） scheme is usually used in 3D depth migration. It splits the 3D square-root operator along crossline and inline directions alternately. In this paper, based on the ideal of data line, the four-way splitting schemes and their splitting errors for the finite-difference （FD） method and the hybrid method are investigated. The wavefield extrapolation of four-way splitting scheme is accomplished on a data line and is stable unconditionally. Numerical analysis of splitting errors show that the two-way FD migration have visible numerical anisotropic errors, and that four-way FD migration has much less splitting errors than two-way FD migration has. For the hybrid method, the differences of numerical anisotropic errors between two-way scheme and four-way scheme are small in the case of lower lateral velocity variations. The schemes presented in this paper can be used in 3D post-stack or prestack depth migration. Two numerical calculations of 3D depth migration are completed. One is the four-way FD and hybrid 3D post-stack depth migration for an impulse response, which shows that the anisotropic errors can be eliminated effectively in the cases of constant and variable velocity variations. The other is the 3D shot-profile prestack depth migration for SEG/EAEG benchmark model with two-way hybrid splitting scheme, which presents good imaging results. The Message Passing Interface （MPI） programme based on shot number is adopted.展开更多
By employing metal oxides as oxygen carriers,chemical looping demonstrates its effectiveness in transferring oxygen between reduction and oxidation environments to partially oxidize fuels into syngas and convert CO_(2...By employing metal oxides as oxygen carriers,chemical looping demonstrates its effectiveness in transferring oxygen between reduction and oxidation environments to partially oxidize fuels into syngas and convert CO_(2) into CO.Generally,NiFe_(2_)O_(4) oxygen carriers have demonstrated remarkable efficiency in chemical looping CO_(2) conversion.Nevertheless,the intricate process of atomic migration and evolution within the internal structure of bimetallic oxygen carriers during continuous high‐temperature redox cycling remains unclear.Consequently,the lack of a fundamental understanding of the complex ionic migration and oxygen transfer associated with energy conversion processes hampers the design of high‐performance oxygen carriers.Thus,in this study,we employed in situ characterization techniques and theoretical calculations to investigate the ion migration behavior and structural evolution in the bulk of NiFe_(2_)O_(4) oxygen carriers during H_(2) reduction and CO_(2)/lab air oxidation cycles.We discovered that during the H_(2) reduction step,lattice oxygen rapidly migrates to vacancy layers to replenish consumed active oxygen species,while Ni leaches from the material and migrates to the surface.During the CO_(2) splitting step,Ni migrates toward the core of the bimetallic oxygen carrier,forming Fe–Ni alloys.During the air oxidation step,Fe–Ni migrates outward,creating a hollow structure owing to the Kirkendall effect triggered by the swift transfer of lattice oxygen.The metal atom migration paths depend on the oxygen transfer rates.These discoveries highlight the significance of regulating the release–recovery rate of lattice oxygen to uphold the structures and reactivity of oxygen carriers.This work offers a comprehensive understanding of the oxidation/reduction‐driven atomic interdiffusion behavior of bimetallic oxygen carriers.展开更多
基金financially supported by the National Natural Science Foundation of China,China(Grant Nos.41506093)。
文摘Photoelectrochemical(PEC)water splitting is considered as an ideal technology to produce hydrogen.Photogenerated carrier migration is one of the most important roles in the whole process of PEC water splitting.It includes bulk transfer inside of the photoelectrode and the exchange at the solid-liquid interface.The energy barriers during the migration process lead to the dramatic recombination of photogenerated hot carrier and the reducing of their redox capacity.Thus,an applied bias voltage should be provided to overcome these energy barriers,which brings the additional loss of energy.Plentiful researches indicate that some methods for the regulation of photogenerated hot carrier,such as p-n junction,unique transfer nanochannel,tandem nanostructure and Z-Scheme transfer structure et al.,show great potential to achieve high-efficient PEC water overall splitting without any applied bias voltage.Up to now,many reviews have summarized and analyzed the methods to enhance the PEC or photocatalysis water splitting from the perspectives of materials,nanostructures and surface modification etc.However,few of them focus on the topic of photogenerated carrier transfer regulation,which is an important and urgent developing technique.For this reason,this review focuses on the regulation of photogenerated carriers generated by the photoelectrodes and summarizes different advanced methods for photogenerated carrier regulation developed in recent years.Some comments and outlooks are also provided at the end of this review.
文摘Numerical simulation of oil migration and accumulation is to describe the history of oil migration and accumulation in basin evolution. It is of great value in the exploration of oil resources and their rational evaluation. In this paper, from such actual conditions as the effects of mechanics of fluids in porous media and 3-dimensional geology characteristics, a kind of modified method of second order splitting-up implicit interactive scheme is pur forward. For the famous hydraulic experiment of secondary migration-accumulation, the numerical simulation test has been done, and both the computational and experimental results are basically identical. For the actual problem of Dongying hollow of Shengli Petroleum Oil Field, the numerical simulation test and the actual conditions are basically coincident. Thus the well-known problem has been solved.
基金This research is supported by the Major State Basic Research Program of Peoples＇s Republic of China （No.C1999032803）, the National Key Nature Science Foundation （No.40004003） and ICMSEC Institute Director Foundation.
文摘The alternately directional implicit （ADI） scheme is usually used in 3D depth migration. It splits the 3D square-root operator along crossline and inline directions alternately. In this paper, based on the ideal of data line, the four-way splitting schemes and their splitting errors for the finite-difference （FD） method and the hybrid method are investigated. The wavefield extrapolation of four-way splitting scheme is accomplished on a data line and is stable unconditionally. Numerical analysis of splitting errors show that the two-way FD migration have visible numerical anisotropic errors, and that four-way FD migration has much less splitting errors than two-way FD migration has. For the hybrid method, the differences of numerical anisotropic errors between two-way scheme and four-way scheme are small in the case of lower lateral velocity variations. The schemes presented in this paper can be used in 3D post-stack or prestack depth migration. Two numerical calculations of 3D depth migration are completed. One is the four-way FD and hybrid 3D post-stack depth migration for an impulse response, which shows that the anisotropic errors can be eliminated effectively in the cases of constant and variable velocity variations. The other is the 3D shot-profile prestack depth migration for SEG/EAEG benchmark model with two-way hybrid splitting scheme, which presents good imaging results. The Message Passing Interface （MPI） programme based on shot number is adopted.
基金National Natural Science Foundation of China,Grant/Award Numbers:52076209,52006224,52106285,22179027Foundation and Applied Foundation Research of Guangdong Province,Grant/Award Number:2022B1515020045+1 种基金Natural Science Foundation of Guangxi Province,Grant/Award Number:2021GXNSFAA075036Young Talent Support Project of Guangzhou Association for Science and Technology,Grant/Award Number:QT‐2023‐042。
文摘By employing metal oxides as oxygen carriers,chemical looping demonstrates its effectiveness in transferring oxygen between reduction and oxidation environments to partially oxidize fuels into syngas and convert CO_(2) into CO.Generally,NiFe_(2_)O_(4) oxygen carriers have demonstrated remarkable efficiency in chemical looping CO_(2) conversion.Nevertheless,the intricate process of atomic migration and evolution within the internal structure of bimetallic oxygen carriers during continuous high‐temperature redox cycling remains unclear.Consequently,the lack of a fundamental understanding of the complex ionic migration and oxygen transfer associated with energy conversion processes hampers the design of high‐performance oxygen carriers.Thus,in this study,we employed in situ characterization techniques and theoretical calculations to investigate the ion migration behavior and structural evolution in the bulk of NiFe_(2_)O_(4) oxygen carriers during H_(2) reduction and CO_(2)/lab air oxidation cycles.We discovered that during the H_(2) reduction step,lattice oxygen rapidly migrates to vacancy layers to replenish consumed active oxygen species,while Ni leaches from the material and migrates to the surface.During the CO_(2) splitting step,Ni migrates toward the core of the bimetallic oxygen carrier,forming Fe–Ni alloys.During the air oxidation step,Fe–Ni migrates outward,creating a hollow structure owing to the Kirkendall effect triggered by the swift transfer of lattice oxygen.The metal atom migration paths depend on the oxygen transfer rates.These discoveries highlight the significance of regulating the release–recovery rate of lattice oxygen to uphold the structures and reactivity of oxygen carriers.This work offers a comprehensive understanding of the oxidation/reduction‐driven atomic interdiffusion behavior of bimetallic oxygen carriers.
