Electrocatalysts for oxygen reduction reactions(ORR)and oxygen evolution reactions(OER)are highly crucial and challenging toward the energy storage and conversion technologies such as fuel cells,metal-air batteries an...Electrocatalysts for oxygen reduction reactions(ORR)and oxygen evolution reactions(OER)are highly crucial and challenging toward the energy storage and conversion technologies such as fuel cells,metal-air batteries and water electrolysis.To replace noble-metal based catalysts and boost catalytic performance of carbon-based materials,we initially develop the nickel,phospho rus,sulfur and nitrogen co-modified mesoporous carbon(NiPS_(3)@NMC)as a bifunctional oxygen electrocatalyst.The perfo rmance for ORR(half-wave potential at 0.90 V)and OER(10 mA cm^(-2)at 1.48 V)surpasses those of Pt/C coupled with IrO_(2)catalysts and most of the non-precious metal based bifunctional electrocatalysts reported in related literature.Moreover,the electrochemical durability is also confirmed by accelerated durability tests(ADTs)and long-term chronoamperometry(CA)tests.We demonstrated that the interfacial effect between NiPS_(3)quantum sheets(QS s)and NMC substrates by thermal activation contributed to the enhanced oxygen electrode bifunctionality with more active sites,due to the electrons-donating from nickel,phosphorus and sulfur elements and relatively enriched pyridinic type N.Such excellent overall performance highlights the potential application of NiPS3 QSs and NMC composites as the materials on energy conversion and storage.展开更多
Fifteen periods of Si/Si_(0.7)Ge_(0.3)multilayers(MLs)with various Si Ge thicknesses are grown on a 200 mm Si substrate using reduced pressure chemical vapor deposition(RPCVD).Several methods were utilized to characte...Fifteen periods of Si/Si_(0.7)Ge_(0.3)multilayers(MLs)with various Si Ge thicknesses are grown on a 200 mm Si substrate using reduced pressure chemical vapor deposition(RPCVD).Several methods were utilized to characterize and analyze the ML structures.The high resolution transmission electron microscopy(HRTEM)results show that the ML structure with 20 nm Si_(0.7)Ge_(0.3)features the best crystal quality and no defects are observed.Stacked Si_(0.7)Ge_(0.3)ML structures etched by three different methods were carried out and compared,and the results show that they have different selectivities and morphologies.In this work,the fabrication process influences on Si/Si Ge MLs are studied and there are no significant effects on the Si layers,which are the channels in lateral gate all around field effect transistor(L-GAAFET)devices.For vertically-stacked dynamic random access memory(VS-DRAM),it is necessary to consider the dislocation caused by strain accumulation and stress release after the number of stacked layers exceeds the critical thickness.These results pave the way for the manufacture of high-performance multivertical-stacked Si nanowires,nanosheet L-GAAFETs,and DRAM devices.展开更多
Simultaneously achieving high activity,selectivity and stability for electrochemical CO_(2)reduction reaction(CO_(2)RR)remains great challenges.Herein,a phosphorus-modified Sn/Sn Oxcore/shell(P-Sn/SnO_x)catalyst,deriv...Simultaneously achieving high activity,selectivity and stability for electrochemical CO_(2)reduction reaction(CO_(2)RR)remains great challenges.Herein,a phosphorus-modified Sn/Sn Oxcore/shell(P-Sn/SnO_x)catalyst,derived from in situ electrochemical reduction of an amorphous Sn(HPO_(4))_(2) pre-catalyst,exhibits high CO_(2)RR performance.The total Faradaic efficiency(FE)of C_(1) products is close to 100%in a broad potential range from-0.49 to-1.02 V vs.reversible hydrogen electrode,and a total current density of 315.0 m A cm^(-2)is achieved.Moreover,the P-Sn/SnO_(x) catalyst maintains a formate FE of~90%for 120 h.Density functional theory calculations suggest that the phosphorus-modified Sn/SnO_(x) core/shell structure effectively facilitates formate production by enhancing CO_(2)adsorption and improving free energy profile of formate formation.展开更多
The lunar soils evolution over time is mainly caused by space weathering that includes the impacts of varying-sized meteoroids and charged particles implantation of solar/cosmic winds as well.It has long been establis...The lunar soils evolution over time is mainly caused by space weathering that includes the impacts of varying-sized meteoroids and charged particles implantation of solar/cosmic winds as well.It has long been established that space weathering leads to the formation of outmost amorphous layers(50–200 nm in thickness)embedded nanophase iron(npFe^(0))around the mineral fragments,albeit the origin of the npFe^(0) remains controversial.The Chang’e-5(CE-5)mission returned samples feature the youngest mare basalt and the highest latitude sampling site,providing an opportunity to seek the critical clues for understanding the evolution of soils under space weathering.Here,we report the surface microstructures of the major minerals including olivine,pyroxene,anorthite,and glassy beads in the lunar soil of CE-5.Unlike the previous observations,only olivine in all crystals is surrounded by a thinner outmost amorphous SiO_(2) layer(∼10 nm thick)and embedded wüstite nanoparticles FeO(np-FeO,3–12 nm in size)instead of npFe^(0).No foreign volatile elements deposition layer and solar flare tracks can be found on the surface or inside the olivine and other minerals.This unique rim structure has not been reported for any other lunar,terrestrial,Martian,or meteorite samples so far.The observation of wüstite FeO and the microstructures support the existence of an intermediate stage in space weathering for lunar minerals by thermal decomposition.展开更多
一氧化氮电还原反应将工业废气转化为有价值的氨,表现出极具潜力的应用前景.在本工作中,我们合成了具有高比表面积和丰富缺陷的氧化铜纳米片催化剂,在流动池中氨法拉第效率达到92.1%,在-0.2 V vs.RHE时,一氧化氮电还原电流密度和氨的生...一氧化氮电还原反应将工业废气转化为有价值的氨,表现出极具潜力的应用前景.在本工作中,我们合成了具有高比表面积和丰富缺陷的氧化铜纳米片催化剂,在流动池中氨法拉第效率达到92.1%,在-0.2 V vs.RHE时,一氧化氮电还原电流密度和氨的生产速率分别达到1.1 A cm^(-2)和7356μmol cm^(-2)h^(-1).在电流密度超过400 m A cm-2时,氨法拉第效率在50小时保持在80%以上.准原位X射线光电子能谱和原位X射线吸收光谱结果表明氧化铜纳米片在一氧化氮电还原过程中被电化学还原成单质铜.与铜纳米颗粒相比,氧化铜纳米片展现出较高的电化学表面积和一氧化氮电还原的内在活性.展开更多
基金supported financially by the National Natural Science Foundation of China(Nos.51902027,61674019,51976143,61874014,61874013 and 61974011)the National Basic Research of China(No.2015CB932500)+1 种基金the Fundamental Research Funds for the Central Universities(No.2019RC20)the Fund of State Key Laboratory of Information Photonics and Optical Communications(Beijing University of Posts and Telecommunications,P.R.China)。
文摘Electrocatalysts for oxygen reduction reactions(ORR)and oxygen evolution reactions(OER)are highly crucial and challenging toward the energy storage and conversion technologies such as fuel cells,metal-air batteries and water electrolysis.To replace noble-metal based catalysts and boost catalytic performance of carbon-based materials,we initially develop the nickel,phospho rus,sulfur and nitrogen co-modified mesoporous carbon(NiPS_(3)@NMC)as a bifunctional oxygen electrocatalyst.The perfo rmance for ORR(half-wave potential at 0.90 V)and OER(10 mA cm^(-2)at 1.48 V)surpasses those of Pt/C coupled with IrO_(2)catalysts and most of the non-precious metal based bifunctional electrocatalysts reported in related literature.Moreover,the electrochemical durability is also confirmed by accelerated durability tests(ADTs)and long-term chronoamperometry(CA)tests.We demonstrated that the interfacial effect between NiPS_(3)quantum sheets(QS s)and NMC substrates by thermal activation contributed to the enhanced oxygen electrode bifunctionality with more active sites,due to the electrons-donating from nickel,phosphorus and sulfur elements and relatively enriched pyridinic type N.Such excellent overall performance highlights the potential application of NiPS3 QSs and NMC composites as the materials on energy conversion and storage.
基金supported in part by the Strategic Priority Research Program of the Chinese Academy of Sciences (Project ID.XDA0330300)in part by Innovation Program for Quantum Science and Technology (Project ID.2021ZD0302301)in part by the Youth Innovation Promotion Association of CAS (Project ID.2020037)。
文摘Fifteen periods of Si/Si_(0.7)Ge_(0.3)multilayers(MLs)with various Si Ge thicknesses are grown on a 200 mm Si substrate using reduced pressure chemical vapor deposition(RPCVD).Several methods were utilized to characterize and analyze the ML structures.The high resolution transmission electron microscopy(HRTEM)results show that the ML structure with 20 nm Si_(0.7)Ge_(0.3)features the best crystal quality and no defects are observed.Stacked Si_(0.7)Ge_(0.3)ML structures etched by three different methods were carried out and compared,and the results show that they have different selectivities and morphologies.In this work,the fabrication process influences on Si/Si Ge MLs are studied and there are no significant effects on the Si layers,which are the channels in lateral gate all around field effect transistor(L-GAAFET)devices.For vertically-stacked dynamic random access memory(VS-DRAM),it is necessary to consider the dislocation caused by strain accumulation and stress release after the number of stacked layers exceeds the critical thickness.These results pave the way for the manufacture of high-performance multivertical-stacked Si nanowires,nanosheet L-GAAFETs,and DRAM devices.
基金supported by the National Key R&D Program of China (2021YFA1501503)the National Natural Science Foundation of China (22125205,22002155,22002158,92045302)+5 种基金the“Transformational Technologies for Clean Energy and Demonstration”Strategic Priority Research Program of the Chinese Academy of Sciences (XDA21070613)the Fundamental Research Funds for the Central Universities (20720220008)the China Postdoctoral Science Foundation (2019M661142)the Natural Science Foundation of Liaoning Province (2021-MS-022)the High-Level Talents Innovation Project of Dalian City (2020RQ038)the support from the Photon Science Center for Carbon Neutrality。
文摘Simultaneously achieving high activity,selectivity and stability for electrochemical CO_(2)reduction reaction(CO_(2)RR)remains great challenges.Herein,a phosphorus-modified Sn/Sn Oxcore/shell(P-Sn/SnO_x)catalyst,derived from in situ electrochemical reduction of an amorphous Sn(HPO_(4))_(2) pre-catalyst,exhibits high CO_(2)RR performance.The total Faradaic efficiency(FE)of C_(1) products is close to 100%in a broad potential range from-0.49 to-1.02 V vs.reversible hydrogen electrode,and a total current density of 315.0 m A cm^(-2)is achieved.Moreover,the P-Sn/SnO_(x) catalyst maintains a formate FE of~90%for 120 h.Density functional theory calculations suggest that the phosphorus-modified Sn/SnO_(x) core/shell structure effectively facilitates formate production by enhancing CO_(2)adsorption and improving free energy profile of formate formation.
基金supported by the Key Research Program of Chinese Academy of Sciences(ZDBS-SSW-JSC007-2)the Project from China National Space Administration(CE5C0400YJFM00507)。
文摘The lunar soils evolution over time is mainly caused by space weathering that includes the impacts of varying-sized meteoroids and charged particles implantation of solar/cosmic winds as well.It has long been established that space weathering leads to the formation of outmost amorphous layers(50–200 nm in thickness)embedded nanophase iron(npFe^(0))around the mineral fragments,albeit the origin of the npFe^(0) remains controversial.The Chang’e-5(CE-5)mission returned samples feature the youngest mare basalt and the highest latitude sampling site,providing an opportunity to seek the critical clues for understanding the evolution of soils under space weathering.Here,we report the surface microstructures of the major minerals including olivine,pyroxene,anorthite,and glassy beads in the lunar soil of CE-5.Unlike the previous observations,only olivine in all crystals is surrounded by a thinner outmost amorphous SiO_(2) layer(∼10 nm thick)and embedded wüstite nanoparticles FeO(np-FeO,3–12 nm in size)instead of npFe^(0).No foreign volatile elements deposition layer and solar flare tracks can be found on the surface or inside the olivine and other minerals.This unique rim structure has not been reported for any other lunar,terrestrial,Martian,or meteorite samples so far.The observation of wüstite FeO and the microstructures support the existence of an intermediate stage in space weathering for lunar minerals by thermal decomposition.
基金supported by the National Key R&D Program of China (2023YFA1508002)the National Natural Science Foundation of China (22125205 and 92015302)+2 种基金the Fundamental Research Funds for the Central Universities (20720220008)Dalian National Laboratory for Clean Energy (DNL201923)the Photon Science Center for Carbon Neutrality。
文摘一氧化氮电还原反应将工业废气转化为有价值的氨,表现出极具潜力的应用前景.在本工作中,我们合成了具有高比表面积和丰富缺陷的氧化铜纳米片催化剂,在流动池中氨法拉第效率达到92.1%,在-0.2 V vs.RHE时,一氧化氮电还原电流密度和氨的生产速率分别达到1.1 A cm^(-2)和7356μmol cm^(-2)h^(-1).在电流密度超过400 m A cm-2时,氨法拉第效率在50小时保持在80%以上.准原位X射线光电子能谱和原位X射线吸收光谱结果表明氧化铜纳米片在一氧化氮电还原过程中被电化学还原成单质铜.与铜纳米颗粒相比,氧化铜纳米片展现出较高的电化学表面积和一氧化氮电还原的内在活性.
