The two-dimensional electron gas(2DEG)formed at the interface between two oxide insulators provides new opportunities for electronics and spintronics.The broken inversion symmetry at the heterointerface results in a R...The two-dimensional electron gas(2DEG)formed at the interface between two oxide insulators provides new opportunities for electronics and spintronics.The broken inversion symmetry at the heterointerface results in a Rashba spin-orbit coupling(RSOC)effect that enables the conversion between spin and charge currents.However,conducting oxide interfaces that simultaneously exhibit strong RSOC and high carrier mobility-a combination query for achieving high spin-to-charge inter-conversion efficiencies-remain scarce.Herein,we report a correlated 2DEG with giant Rashba splitting and high electron mobility in(111)-oriented EuTiO_(3)/KTaO_(3)(ETO/KTO)heterostructures under light illumination.Upon light modulation,a unique carrier-dependent giant anomalous Hall effect,the signature of spin-polarized 2DEG,emerges with a sign crossover at a carrier density of approximately 5.0×10^(13)cm^(-2),highlighting dramatic changes in the band topology of KTO(111)interface.Furthermore,at 2 K,the carrier mobility is enhanced from 103 cm^(2)·V^(-1)·s^(-1)to 1800 cm^(2)·V^(-1)·s^(-1),a remarkable enhancement of approximately 20 times.Accompanying with a giant Rashba coefficient αR up to 360meV·˚A,this high mobility ferromagnetic 5d oxide 2DEG is predicted to achieve a giant spin-to-charge conversion efficiency ofλ~10 nm,showing great potential for designing low-power spin-orbitronic devices.展开更多
Our recent experimental work on metallic and insulating interfaces controlled by interfacial redox reactions in SrTiO3-based heterostructures is reviewed along with a more general background of two-dimensional electro...Our recent experimental work on metallic and insulating interfaces controlled by interfacial redox reactions in SrTiO3-based heterostructures is reviewed along with a more general background of two-dimensional electron gas （2DEG） at oxide interfaces. Due to the presence of oxygen vacancies at the SrTiO3 surface, metallic conduction can be created at room temperature in perovskite-type interfaces when the overlayer oxide ABO3 has Al, Ti, Zr, or Hf elements at the B sites. Furthermore, relying on interface-stabilized oxygen vacancies, we have created a new type of 2DEG at the heterointerface between SrTiO3 and a spinel γ-Al2O3 epitaxial film with compatible oxygen ion sublattices. This 2DEG exhibits an electron mobility exceeding 100000 cm2·V-1·s-1, more than one order of magnitude higher than those of hitherto investigated perovskite-type interfaces. Our findings pave the way for the design of high-mobility all-oxide electronic devices and open a route toward the studies of mesoscopic physics with complex oxides.展开更多
The effect of nitric oxide（NO） annealing on charge traps in the oxide insulator and transition layer in n-type4H–Si C metal–oxide–semiconductor（MOS） devices has been investigated using the time-dependent bias s...The effect of nitric oxide（NO） annealing on charge traps in the oxide insulator and transition layer in n-type4H–Si C metal–oxide–semiconductor（MOS） devices has been investigated using the time-dependent bias stress（TDBS）,capacitance–voltage（C–V）,and secondary ion mass spectroscopy（SIMS）.It is revealed that two main categories of charge traps,near interface oxide traps（Nniot） and oxide traps（Not）,have different responses to the TDBS and C–V characteristics in NO-annealed and Ar-annealed samples.The Nniotare mainly responsible for the hysteresis occurring in the bidirectional C–V characteristics,which are very close to the semiconductor interface and can readily exchange charges with the inner semiconductor.However,Not is mainly responsible for the TDBS induced C–V shifts.Electrons tunneling into the Not are hardly released quickly when suffering TDBS,resulting in the problem of the threshold voltage stability.Compared with the Ar-annealed sample,Nniotcan be significantly suppressed by the NO annealing,but there is little improvement of Not.SIMS results demonstrate that the Nniotare distributed within the transition layer,which correlated with the existence of the excess silicon.During the NO annealing process,the excess Si atoms incorporate into nitrogen in the transition layer,allowing better relaxation of the interface strain and effectively reducing the width of the transition layer and the density of Nniot.展开更多
The microstructures of the oxide layers formed on near （0001） plane of Zircaloy-4 were investigated by autoclave tests at 360 ℃ in lithiated aqueous solution. Oxygen-rich regions with hcp structure were observed at...The microstructures of the oxide layers formed on near （0001） plane of Zircaloy-4 were investigated by autoclave tests at 360 ℃ in lithiated aqueous solution. Oxygen-rich regions with hcp structure were observed at the undulating O/M interface, and the inner surface morphology of the oxide layers formed on （0001） was only concave- convex. Monoclinic, tetragonal and cubic phases and a kind of zirconium sub-oxide with bcc structure were detected in the oxide layer near the metal matrix. This zirconium sub-oxide layer had a coherent relationship with a-Zr matrix, and the growth direction of the zirconium sub-oxide layer was nearly parallel to the [0001] direction of a-Zr regardless of the orientation of metal matrix. The orientations scattering of columnar grains formed on near （0001） plane differ from that formed on near （1010） plane.展开更多
The Al22Si/ZL102 bimetal was designed and prepared by extrusion at near-eutectic temperature.The properties and fracture behaviors of different surface treatments between oxide film and zinc coating were compared betw...The Al22Si/ZL102 bimetal was designed and prepared by extrusion at near-eutectic temperature.The properties and fracture behaviors of different surface treatments between oxide film and zinc coating were compared between the Al22 Si and ZL102 bimetal.The average bonding strength of bimetal with intermittent oxide film interface was about 89.3MPa,which is higher than that of the bimetal fabricated by zinc coating method（about 76.3MPa）.During the process of extrusion,the oxidation film was extruded to crush and the metal was extruded through the micro-cracks of the oxidation film,then the two surfaces were joined together.Altogether,the results showed that extrusion at near-eutectic temperature is favorable for achieving a high-quality metallurgical bonded interface.展开更多
The adhesion and wetting of non-reactive liquid metals with solid ionocovalent oxides are studied on the basis of the experimental work of adhesion W data obtained with the sessile drop method.An analysis of the exper...The adhesion and wetting of non-reactive liquid metals with solid ionocovalent oxides are studied on the basis of the experimental work of adhesion W data obtained with the sessile drop method.An analysis of the experimental W values of different liquid metals on various solid oxides is first performed to evidence the de- pendence of the work of adhesion of a metal/oxide system on the electron density of the metal and on the thermodynamic stability of the oxide.An electronic model is then proposed to describe the microscopic mech- anism of metal-oxide interactions.Based on the model,the contact angle and the work of adhesion of different liquid metals on various solid oxides can be interpreted and estimated,and their correlations to the various physical quantities of the oxides can be easily deduced.The basic consideration of the model is that the adhe- sion between a metal and an oxide is assured by the electron transfer from the metal into the oxide valence band which is not completely filled of electrons at high temperatures,and is enhanced when this electron trans- fer at the metal/oxide interface is intensified.The influence of interface defects on the wetting and adhesion is suggested and discussed.展开更多
A systematic study of the two-dimensional electron gas at La AlO_3/SrTiO_3（110） interface reveals an anisotropy along two specific directions, [001] and 1ī0. The anisotropy becomes distinct for the interface prepar...A systematic study of the two-dimensional electron gas at La AlO_3/SrTiO_3（110） interface reveals an anisotropy along two specific directions, [001] and 1ī0. The anisotropy becomes distinct for the interface prepared under high oxygen pressure with low carrier density. Angular dependence of magnetoresistance shows that the electron confinement is stronger along the 1ī0 direction. Gate-tunable magnetoresistance reveals a clear in-plane anisotropy of the spin–orbit coupling,and the spin relaxation mechanism along both directions belongs to D＇yakonov–Perel＇（DP） scenario. Moreover, in-plane anisotropic superconductivity is observed for the sample with high carrier density, the superconducting transition temperature is lower but the upper critical field is higher along the 1ī0 direction. This in-plane anisotropy could be ascribed to the anisotropic band structure along the two crystallographic directions.展开更多
Bismuth vanadate(BiVO_(4))is an excellent photoanode material for photoelectrochemical(PEC)water splitting system,possessing high theoretical photoelectrocatalytic conversion efficiency.However,the actual PEC activity...Bismuth vanadate(BiVO_(4))is an excellent photoanode material for photoelectrochemical(PEC)water splitting system,possessing high theoretical photoelectrocatalytic conversion efficiency.However,the actual PEC activity and stability of BiVO_(4)are faced with great challenges due to factors such as severe charge recombination and slow water oxidation kinetics at the interface.Therefore,various interface regulation strategies have been adopted to optimize the BiVO_(4)photoanode.This review provides an in-depth analysis for the mechanism of interface regulation strategies from the perspective of factors affecting the PEC performance of BiVO_(4)photoanodes.These interface regulation strategies improve the PEC performance of BiVO_(4)photoanode by promoting charge separation and transfer,accelerating interfacial reaction kinetics,and enhancing stability.The research on the interface regulation strategies of BiVO_(4)photoanode is of great significance for promoting the development of PEC water splitting technology.At the same time,it also has inspiration for providing new ideas and methods for designing and preparing efficient and stable catalytic materials.展开更多
Recently, the quasi-two-dimensional electron gas （q2DEG） confined at the interface between LaAlO3 and SrTiO3 has attracted significant attention. In this paper, we briefly review experimental methods that have been ...Recently, the quasi-two-dimensional electron gas （q2DEG） confined at the interface between LaAlO3 and SrTiO3 has attracted significant attention. In this paper, we briefly review experimental methods that have been used to tune the carrier density and mobility of this q2DEG. These methods can be classified into two categories： growth-related tuning （i.e. substrate, growth temperature, oxygen pressure, post-annealing, LaAlO3 thickness, stoichiometry, and capping layers） and post-growth tuning （i.e. electrostatic field gating, conductive atomic force microscopy and surface adsorbates）. Taken together, these methods enable the broad tuning of the electronic properties of this interface.展开更多
This paper reports that a double N layer （a-Si：H/μc-Si：H） is used to substitute the single microcrystalline silicon n layer （n-μc-Si：H） in n/p tunnel recombination junction between subcells in a-Si：H/μc-Si...This paper reports that a double N layer （a-Si：H/μc-Si：H） is used to substitute the single microcrystalline silicon n layer （n-μc-Si：H） in n/p tunnel recombination junction between subcells in a-Si：H/μc-Si：H tandem solar cells. The electrical transport and optical properties of these tunnel recombination junctions are investigated by current voltage measurement and transmission measurement. The new n/p tunnel recombination junction shows a better ohmic contact. In addition, the n/p interface is exposed to the air to examine the effect of oxidation on the tunnel recombination junction performance. The open circuit voltage and FF of a-Si：H/μc-Si：H tandem solar cell are all improved and the current leakage of the subcells can be effectively prevented efficiently when the new n/p junction is implemented as tunnel recombination junction.展开更多
A nanostructured ternary coating of Ti/（Ru ＋ Ti ＋ Ce）O2 was prepared by the conventional electrodeposition on the titanium substrate as the cathode with different numbers of coating layers. The main objective of t...A nanostructured ternary coating of Ti/（Ru ＋ Ti ＋ Ce）O2 was prepared by the conventional electrodeposition on the titanium substrate as the cathode with different numbers of coating layers. The main objective of this work was to study nanostructured coatings of ceramic materials. For this purpose, the amount of precursor materials in the electrolyte was a variable parameter. Furthermore, the salt of TiCl4/RuCl3·xH2 O/Ce（NO3）3·6 H2 O with different amounts, hydrogen peroxide, methanol, and distilled water were used as an aqueousunaqueous bath. In addition, the coated samples were put to heat at 300, 450, 650, and 850℃ in an electric furnace for1 h. The crystalline phase of the coating was characterized by X-ray diffraction（XRD）. The chemical composition and microstructure of the coating were studied using energydispersive spectroscopy（EDS） and scanning electron microscopy analysis（SEM）. Moreover, the electrochemical measurement of Ti/（Ru ＋ Ti ＋ Ce）O2 coatings was carried out. Results show that with the increase in the number of coating layers, the quality of morphology is improved.Then, the best quality of coatings is obtained at six layers on the titanium substrate with electrolyte including TiO2/RuO2/CeO2 with the molar ratio of 70：5：25 after heat treatment at 450 ℃ for 1 h. Besides,with the increase in Ce02 content from 5 wt% to 25 wt% and the number of coating layers, higher thickness of about（20.0±0.1） μm and minimum over potential for chlorine evolution were obtained.展开更多
Due to the unique interface and electronic structure,metal/metal oxide composite electrocatalysts have been designed and exploited for electrocatalytic oxygen evolution reaction(OER)in alkaline solution.However,how to...Due to the unique interface and electronic structure,metal/metal oxide composite electrocatalysts have been designed and exploited for electrocatalytic oxygen evolution reaction(OER)in alkaline solution.However,how to fabricate metal/metal oxides with abundant interfaces and well-dispersed metal phases is a challenge,and the synergistic effect between metal and metal oxides on boosting the electrocatalytic activities is still ambiguous.Herein,by controlling the lithium-induced conversion reaction of metal oxides,metal/metal oxide composites with plentiful interfaces and excellent electrical interconnection are fabricated,which can enhance the active sites,and accelerate the mass transfer during the electrocatalytic reaction.As a result,the electrocatalytic oxygen evolution activities of the as-fabricated metal/metal oxide composite catalysts including NiCo/NiCo2O4,NiMn/NiMn2O4 and CoMn/CoMn2O4 are greatly improved.The catalytic mechanism is also explored using the in-situ X-ray and Raman spectroscopic tracking to uncover the real active centers and the synergistic effect between the metal and metal oxides during water oxidation.Density functional theory plus U(DFT+U)calculation confirms the metal in the composite can optimize the catalytic reaction path and reduce the reaction barrier,thus boosting the electrocatalytic kinetics.展开更多
The determination of catalytically active sites is crucial for the design of efficient and stable catalysts toward desired reactions.However,the complexity of supported noble metal catalysts has led to controversy ove...The determination of catalytically active sites is crucial for the design of efficient and stable catalysts toward desired reactions.However,the complexity of supported noble metal catalysts has led to controversy over the locations of catalytically active sites(e.g.,metal,support,and metal/support interface).Here we develop a structurally controllable catalyst system(Pd/SBA-15)to reveal the catalytic active sites for the selective hydrogenation of ketones to alcohol using acetophenone hydrogenation as model reaction.Systematic investigations demonstrated that unsupported Pd nanocrystals have no catalytic activity for acetophenone hydrogenation.However,oxidized Pd species were catalytically highly active for acetophenone hydrogenation.The catalytic activity decreased with the decreased oxidation state of Pd.This work provides insights into the hydrogenation mechanism of ketones but also other unsaturated compounds containing polar bonds,e.g.,nitrobenzene,N-benzylidene-benzylamine,and carbon dioxide.展开更多
基金supported by the Science Center of the National Science Foundation of China(Grant No.52088101)the National Key Research and Development Program of China(Grant Nos.2023YFA1406400,2021YFA1400300,and 2023YFA1607403)the National Natural Science Foundation of China(Grant Nos.T2394472 and T2394470).
文摘The two-dimensional electron gas(2DEG)formed at the interface between two oxide insulators provides new opportunities for electronics and spintronics.The broken inversion symmetry at the heterointerface results in a Rashba spin-orbit coupling(RSOC)effect that enables the conversion between spin and charge currents.However,conducting oxide interfaces that simultaneously exhibit strong RSOC and high carrier mobility-a combination query for achieving high spin-to-charge inter-conversion efficiencies-remain scarce.Herein,we report a correlated 2DEG with giant Rashba splitting and high electron mobility in(111)-oriented EuTiO_(3)/KTaO_(3)(ETO/KTO)heterostructures under light illumination.Upon light modulation,a unique carrier-dependent giant anomalous Hall effect,the signature of spin-polarized 2DEG,emerges with a sign crossover at a carrier density of approximately 5.0×10^(13)cm^(-2),highlighting dramatic changes in the band topology of KTO(111)interface.Furthermore,at 2 K,the carrier mobility is enhanced from 103 cm^(2)·V^(-1)·s^(-1)to 1800 cm^(2)·V^(-1)·s^(-1),a remarkable enhancement of approximately 20 times.Accompanying with a giant Rashba coefficient αR up to 360meV·˚A,this high mobility ferromagnetic 5d oxide 2DEG is predicted to achieve a giant spin-to-charge conversion efficiency ofλ~10 nm,showing great potential for designing low-power spin-orbitronic devices.
文摘Our recent experimental work on metallic and insulating interfaces controlled by interfacial redox reactions in SrTiO3-based heterostructures is reviewed along with a more general background of two-dimensional electron gas （2DEG） at oxide interfaces. Due to the presence of oxygen vacancies at the SrTiO3 surface, metallic conduction can be created at room temperature in perovskite-type interfaces when the overlayer oxide ABO3 has Al, Ti, Zr, or Hf elements at the B sites. Furthermore, relying on interface-stabilized oxygen vacancies, we have created a new type of 2DEG at the heterointerface between SrTiO3 and a spinel γ-Al2O3 epitaxial film with compatible oxygen ion sublattices. This 2DEG exhibits an electron mobility exceeding 100000 cm2·V-1·s-1, more than one order of magnitude higher than those of hitherto investigated perovskite-type interfaces. Our findings pave the way for the design of high-mobility all-oxide electronic devices and open a route toward the studies of mesoscopic physics with complex oxides.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61404098 and 61274079)the Doctoral Fund of Ministry of Education of China(Grant No.20130203120017)+2 种基金the National Key Basic Research Program of China(Grant No.2015CB759600)the National Grid Science&Technology Project,China(Grant No.SGRI-WD-71-14-018)the Key Specific Project in the National Science&Technology Program,China(Grant Nos.2013ZX02305002-002 and 2015CB759600)
文摘The effect of nitric oxide（NO） annealing on charge traps in the oxide insulator and transition layer in n-type4H–Si C metal–oxide–semiconductor（MOS） devices has been investigated using the time-dependent bias stress（TDBS）,capacitance–voltage（C–V）,and secondary ion mass spectroscopy（SIMS）.It is revealed that two main categories of charge traps,near interface oxide traps（Nniot） and oxide traps（Not）,have different responses to the TDBS and C–V characteristics in NO-annealed and Ar-annealed samples.The Nniotare mainly responsible for the hysteresis occurring in the bidirectional C–V characteristics,which are very close to the semiconductor interface and can readily exchange charges with the inner semiconductor.However,Not is mainly responsible for the TDBS induced C–V shifts.Electrons tunneling into the Not are hardly released quickly when suffering TDBS,resulting in the problem of the threshold voltage stability.Compared with the Ar-annealed sample,Nniotcan be significantly suppressed by the NO annealing,but there is little improvement of Not.SIMS results demonstrate that the Nniotare distributed within the transition layer,which correlated with the existence of the excess silicon.During the NO annealing process,the excess Si atoms incorporate into nitrogen in the transition layer,allowing better relaxation of the interface strain and effectively reducing the width of the transition layer and the density of Nniot.
基金financially supported by the National Natural Science Foundation of China (Nos. 51171102 and 51271104)
文摘The microstructures of the oxide layers formed on near （0001） plane of Zircaloy-4 were investigated by autoclave tests at 360 ℃ in lithiated aqueous solution. Oxygen-rich regions with hcp structure were observed at the undulating O/M interface, and the inner surface morphology of the oxide layers formed on （0001） was only concave- convex. Monoclinic, tetragonal and cubic phases and a kind of zirconium sub-oxide with bcc structure were detected in the oxide layer near the metal matrix. This zirconium sub-oxide layer had a coherent relationship with a-Zr matrix, and the growth direction of the zirconium sub-oxide layer was nearly parallel to the [0001] direction of a-Zr regardless of the orientation of metal matrix. The orientations scattering of columnar grains formed on near （0001） plane differ from that formed on near （1010） plane.
文摘The Al22Si/ZL102 bimetal was designed and prepared by extrusion at near-eutectic temperature.The properties and fracture behaviors of different surface treatments between oxide film and zinc coating were compared between the Al22 Si and ZL102 bimetal.The average bonding strength of bimetal with intermittent oxide film interface was about 89.3MPa,which is higher than that of the bimetal fabricated by zinc coating method（about 76.3MPa）.During the process of extrusion,the oxidation film was extruded to crush and the metal was extruded through the micro-cracks of the oxidation film,then the two surfaces were joined together.Altogether,the results showed that extrusion at near-eutectic temperature is favorable for achieving a high-quality metallurgical bonded interface.
文摘The adhesion and wetting of non-reactive liquid metals with solid ionocovalent oxides are studied on the basis of the experimental work of adhesion W data obtained with the sessile drop method.An analysis of the experimental W values of different liquid metals on various solid oxides is first performed to evidence the de- pendence of the work of adhesion of a metal/oxide system on the electron density of the metal and on the thermodynamic stability of the oxide.An electronic model is then proposed to describe the microscopic mech- anism of metal-oxide interactions.Based on the model,the contact angle and the work of adhesion of different liquid metals on various solid oxides can be interpreted and estimated,and their correlations to the various physical quantities of the oxides can be easily deduced.The basic consideration of the model is that the adhe- sion between a metal and an oxide is assured by the electron transfer from the metal into the oxide valence band which is not completely filled of electrons at high temperatures,and is enhanced when this electron trans- fer at the metal/oxide interface is intensified.The influence of interface defects on the wetting and adhesion is suggested and discussed.
基金Project supported by the Ministry of Science and Technology of China(Grant Nos.2013CB921701,2013CBA01603,and 2014CB920903)the National Natural Science Foundation of China(Grant Nos.10974019,51172029,91121012,11422430,11374035,11474022,and 11474024)+1 种基金the Program for New Century Excellent Talents in the University of the Ministry of Education of China(Grant No.NCET-13-0054)the Beijing Higher Education Young Elite Teacher Project,China(Grant No.YETP0238)
文摘A systematic study of the two-dimensional electron gas at La AlO_3/SrTiO_3（110） interface reveals an anisotropy along two specific directions, [001] and 1ī0. The anisotropy becomes distinct for the interface prepared under high oxygen pressure with low carrier density. Angular dependence of magnetoresistance shows that the electron confinement is stronger along the 1ī0 direction. Gate-tunable magnetoresistance reveals a clear in-plane anisotropy of the spin–orbit coupling,and the spin relaxation mechanism along both directions belongs to D＇yakonov–Perel＇（DP） scenario. Moreover, in-plane anisotropic superconductivity is observed for the sample with high carrier density, the superconducting transition temperature is lower but the upper critical field is higher along the 1ī0 direction. This in-plane anisotropy could be ascribed to the anisotropic band structure along the two crystallographic directions.
基金supported by the National Natural Science Foundation of China(52202261)Outstanding Youth Foundation of Shandong Province,China(ZR2019JQ 14)Taishan Scholar Young Talent Program(tsqn201909114).
文摘Bismuth vanadate(BiVO_(4))is an excellent photoanode material for photoelectrochemical(PEC)water splitting system,possessing high theoretical photoelectrocatalytic conversion efficiency.However,the actual PEC activity and stability of BiVO_(4)are faced with great challenges due to factors such as severe charge recombination and slow water oxidation kinetics at the interface.Therefore,various interface regulation strategies have been adopted to optimize the BiVO_(4)photoanode.This review provides an in-depth analysis for the mechanism of interface regulation strategies from the perspective of factors affecting the PEC performance of BiVO_(4)photoanodes.These interface regulation strategies improve the PEC performance of BiVO_(4)photoanode by promoting charge separation and transfer,accelerating interfacial reaction kinetics,and enhancing stability.The research on the interface regulation strategies of BiVO_(4)photoanode is of great significance for promoting the development of PEC water splitting technology.At the same time,it also has inspiration for providing new ideas and methods for designing and preparing efficient and stable catalytic materials.
基金Project supported by the Department of Energy,Office of Basic Energy Sciences(Grant No.DE-AC02-76SF00515)
文摘Recently, the quasi-two-dimensional electron gas （q2DEG） confined at the interface between LaAlO3 and SrTiO3 has attracted significant attention. In this paper, we briefly review experimental methods that have been used to tune the carrier density and mobility of this q2DEG. These methods can be classified into two categories： growth-related tuning （i.e. substrate, growth temperature, oxygen pressure, post-annealing, LaAlO3 thickness, stoichiometry, and capping layers） and post-growth tuning （i.e. electrostatic field gating, conductive atomic force microscopy and surface adsorbates）. Taken together, these methods enable the broad tuning of the electronic properties of this interface.
基金Project supported by the State Key Development Program for Basic Research of China (Grant Nos 2006CB202602 and2006CB202603)the National Natural Science Foundation of China (Grant No 60506003)
文摘This paper reports that a double N layer （a-Si：H/μc-Si：H） is used to substitute the single microcrystalline silicon n layer （n-μc-Si：H） in n/p tunnel recombination junction between subcells in a-Si：H/μc-Si：H tandem solar cells. The electrical transport and optical properties of these tunnel recombination junctions are investigated by current voltage measurement and transmission measurement. The new n/p tunnel recombination junction shows a better ohmic contact. In addition, the n/p interface is exposed to the air to examine the effect of oxidation on the tunnel recombination junction performance. The open circuit voltage and FF of a-Si：H/μc-Si：H tandem solar cell are all improved and the current leakage of the subcells can be effectively prevented efficiently when the new n/p junction is implemented as tunnel recombination junction.
基金financially supported by the Semnan University Foundation of Iran
文摘A nanostructured ternary coating of Ti/（Ru ＋ Ti ＋ Ce）O2 was prepared by the conventional electrodeposition on the titanium substrate as the cathode with different numbers of coating layers. The main objective of this work was to study nanostructured coatings of ceramic materials. For this purpose, the amount of precursor materials in the electrolyte was a variable parameter. Furthermore, the salt of TiCl4/RuCl3·xH2 O/Ce（NO3）3·6 H2 O with different amounts, hydrogen peroxide, methanol, and distilled water were used as an aqueousunaqueous bath. In addition, the coated samples were put to heat at 300, 450, 650, and 850℃ in an electric furnace for1 h. The crystalline phase of the coating was characterized by X-ray diffraction（XRD）. The chemical composition and microstructure of the coating were studied using energydispersive spectroscopy（EDS） and scanning electron microscopy analysis（SEM）. Moreover, the electrochemical measurement of Ti/（Ru ＋ Ti ＋ Ce）O2 coatings was carried out. Results show that with the increase in the number of coating layers, the quality of morphology is improved.Then, the best quality of coatings is obtained at six layers on the titanium substrate with electrolyte including TiO2/RuO2/CeO2 with the molar ratio of 70：5：25 after heat treatment at 450 ℃ for 1 h. Besides,with the increase in Ce02 content from 5 wt% to 25 wt% and the number of coating layers, higher thickness of about（20.0±0.1） μm and minimum over potential for chlorine evolution were obtained.
基金the National Natural Science Foundation of China(21603157)Young Elite Scientists Sponsorship Program by CAST(2018QNRC001)the support of Suzhou Key Laboratory for Advanced Carbon Materials and Wearable Energy Technologies and Soochow University Analysis and Testing Center。
文摘Due to the unique interface and electronic structure,metal/metal oxide composite electrocatalysts have been designed and exploited for electrocatalytic oxygen evolution reaction(OER)in alkaline solution.However,how to fabricate metal/metal oxides with abundant interfaces and well-dispersed metal phases is a challenge,and the synergistic effect between metal and metal oxides on boosting the electrocatalytic activities is still ambiguous.Herein,by controlling the lithium-induced conversion reaction of metal oxides,metal/metal oxide composites with plentiful interfaces and excellent electrical interconnection are fabricated,which can enhance the active sites,and accelerate the mass transfer during the electrocatalytic reaction.As a result,the electrocatalytic oxygen evolution activities of the as-fabricated metal/metal oxide composite catalysts including NiCo/NiCo2O4,NiMn/NiMn2O4 and CoMn/CoMn2O4 are greatly improved.The catalytic mechanism is also explored using the in-situ X-ray and Raman spectroscopic tracking to uncover the real active centers and the synergistic effect between the metal and metal oxides during water oxidation.Density functional theory plus U(DFT+U)calculation confirms the metal in the composite can optimize the catalytic reaction path and reduce the reaction barrier,thus boosting the electrocatalytic kinetics.
基金supported by the National Natural Science Foundation of China(Nos.92261207,21890752,and 22002126)。
文摘The determination of catalytically active sites is crucial for the design of efficient and stable catalysts toward desired reactions.However,the complexity of supported noble metal catalysts has led to controversy over the locations of catalytically active sites(e.g.,metal,support,and metal/support interface).Here we develop a structurally controllable catalyst system(Pd/SBA-15)to reveal the catalytic active sites for the selective hydrogenation of ketones to alcohol using acetophenone hydrogenation as model reaction.Systematic investigations demonstrated that unsupported Pd nanocrystals have no catalytic activity for acetophenone hydrogenation.However,oxidized Pd species were catalytically highly active for acetophenone hydrogenation.The catalytic activity decreased with the decreased oxidation state of Pd.This work provides insights into the hydrogenation mechanism of ketones but also other unsaturated compounds containing polar bonds,e.g.,nitrobenzene,N-benzylidene-benzylamine,and carbon dioxide.
