Given their unique structure-dependent properties,strategically designing semiconductor-based photocatalysts,which expose highly reactive crystalline facets,is widely used to tune their performance.Herein,AgBr/Ag/TiO_...Given their unique structure-dependent properties,strategically designing semiconductor-based photocatalysts,which expose highly reactive crystalline facets,is widely used to tune their performance.Herein,AgBr/Ag/TiO_(2){100}nanorods Z-scheme heterojunction composites were prepared via hydrothermal and in situ facet-induced reduction.Transmission electron microscopy,X-ray diffraction,X-ray photoelectron spectroscopy,electron paramagnetic resonance spectroscopy,and density functional theory calculations reveal that the selective exposure of TiO_(2){100}facets with abundant oxygen vacancies(OV)promotes the formation of metallic silver on the interfaces between AgBr and TiO_(2){100}.Metallic silver can mediate interfacial charge transfer by facilitating the photogenerated carrier recombination of the conduction band of TiO_(2){100}and the valence band of AgBr.As a result,a Z-scheme heterojunction is formed in AgBr/Ag/TiO_(2){100}.The AgBr/Ag/TiO_(2){100}exhibits faster degradation of tetracycline in aqueous solution compared to pristine AgBr,TiO_(2){101},TiO_(2){100}and AgBr/TiO_(2){101}p-n heterojunctions.This is attributed to the effect of the Z-scheme heterojunction on prolonging the lifetime of photogenerated carriers,which is confirmed by femtosecond transient absorption spectroscopy.The photocatalytic mechanism and degradation pathways are discussed along with a toxicity assessment of the intermediates.Overall,this work develops a new approach for designing Z-scheme heterojunction photocatalysts via selective facet control of anatase TiO_(2).展开更多
Capacitor-less 2T0C dynamic random-access memory(DRAM)employing oxide semiconductors(OSs)as a channel has great potential in the development of highly scaled three dimensional(3D)-structured devices.However,the use of...Capacitor-less 2T0C dynamic random-access memory(DRAM)employing oxide semiconductors(OSs)as a channel has great potential in the development of highly scaled three dimensional(3D)-structured devices.However,the use of OS and such device structures presents certain challenges,including the trade-off relationship between the field-effect mobility and stability of OSs.Conventional 4-line-based operation of the 2T0C enlarges the entire cell volume and complicates the peripheral circuit.Herein,we proposed an IGO(In-Ga-O)channel 2-line-based 2T0C cell design and operating sequences comparable to those of the conventional Si-channel 1 T1C DRAM.IGO was adopted to achieve high thermal stability above 800℃,and the process conditions were optimized to simultaneously obtain a high μFE of 90.7 cm^(2)·V^(-)1·s^(-1),positive Vth of 0.34 V,superior reliability,and uniformity.The proposed 2-line-based 2T0C DRAM cell successfully exhibited multi-bit operation,with the stored voltage varying from 0 V to 1 V at 0.1 V intervals.Furthermore,for stored voltage intervals of 0.1 V and 0.5 V,the refresh time was 10 s and 1000 s in multi-bit operation;these values were more than 150 and 15000 times longer than those of the conventional Si channel 1T1C DRAM,respectively.A monolithic stacked 2-line-based 2T0C DRAM was fabricated,and a multi-bit operation was confirmed.展开更多
The electrochemical carbon dioxide reduction reaction(CO_(2)RR)to high value-added fuels or chemicals driven by the renewable energy is promising to alleviate global warming.However,the selective CO_(2)reduction to C_...The electrochemical carbon dioxide reduction reaction(CO_(2)RR)to high value-added fuels or chemicals driven by the renewable energy is promising to alleviate global warming.However,the selective CO_(2)reduction to C_(2)products remains challenge.Cu-based catalyst with the specific Cu^(0)and Cu^(+)sites is important to generate C_(2)products.This work used nitrogen(N)to tune amounts of Cu^(0)and Cu^(+)sites in Cu_(2)O catalysts and improve C_(2)-product conversion.The controllable Cu^(0)/Cu^(+)ratio of Cu_(2)O catalyst from 0.16 to 15.19 was achieved by adjusting the N doping amount using NH3/Ar plasma treatment.The major theme of this work was clarifying a volcano curve of the ethylene Faraday efficiency as a function of the Cu^(0)/Cu^(+)ratio.The optimal Cu^(0)/Cu^(+)ratio was determined as 0.43 for selective electroreduction CO_(2)to ethylene.X-ray spectroscopy and density functional theory(DFT)calculations were employed to elucidate that the strong interaction between N and Cu increased the binding energy of N–Cu bond and stabilize Cu^(+),resulting in a 92.3%reduction in the potential energy change for^(∗)CO-^(∗)CO dimerization.This study is inspiring in designing high performance electrocatalysts for CO_(2)conversion.展开更多
The Cu^(+)/Cu^(0)sites of copper-based catalysts are crucial for enhancing the production of multicarbon(C_(2+))products from electrochemical CO_(2)reduction reaction(eCO_(2)RR).However,the unstable Cu^(+)and insuffic...The Cu^(+)/Cu^(0)sites of copper-based catalysts are crucial for enhancing the production of multicarbon(C_(2+))products from electrochemical CO_(2)reduction reaction(eCO_(2)RR).However,the unstable Cu^(+)and insufficient Cu^(+)/Cu^(0)active sites lead to their limited selectivity and stability for C_(2+)production.Herein,we embedded copper oxide(CuO_(x))particles into porous nitrogen-doped carbon nanofibers(CuO_(x)@PCNF)by pyrolysis of the electrospun fiber film containing ZIF-8 and Cu_(2)O particles.The porous nitrogendoped carbon nanofibers protected and dispersed Cu^(+)species,and its micro porous structure enhanced the interaction between CuO_(x)and reactants during eCO_(2)RR.The obtained CuO_(x)@PCNF created more effective and stable Cu^(+)/Cu^(0)active sites.It showed a high Faradaic efficiency of 62.5%for C_(2+)products in Hcell,which was 2 times higher than that of bare CuO_(x)(~31.1%).Furthermore,it achieved a maximum Faradaic efficiency of 80.7%for C_(2+)products in flow cell.In situ characterization and density functional theory(DFT)calculation confirmed that the N-doped carbon layer protected Cu^(+)from electrochemical reduction and lowered the energy barrier for the dimerization of^(*)CO.Stable and exposed Cu^(+)/Cu^(0)active sites enhanced the enrichment of^(*)CO and promoted the C-C coupling reaction on the catalyst surface,which facilitated the formation of C_(2+)products.展开更多
DRAM作为计算机存储系统的核心组件,在HPC、云计算、AI等领域至关重要。然而,传统1T1C DRAM受电容缩放瓶颈、刷新功耗及制造复杂度等问题限制,难以满足先进制程需求。2T0C DRAM采用双晶体管架构,利用浮体效应、栅极耦合等机制存储电荷,...DRAM作为计算机存储系统的核心组件,在HPC、云计算、AI等领域至关重要。然而,传统1T1C DRAM受电容缩放瓶颈、刷新功耗及制造复杂度等问题限制,难以满足先进制程需求。2T0C DRAM采用双晶体管架构,利用浮体效应、栅极耦合等机制存储电荷,实现高密度、低功耗及工艺兼容性提升。本研究分析2T0C DRAM的技术原理、结构设计及其相较于1T1C DRAM的优势,探讨数据保持、读写干扰、工艺变异等挑战,并综述器件优化、电路创新及先进制造工艺的应对策略。此外,结合CIM、3D集成等趋势,探讨其在HPC、嵌入式及新型存储中的应用价值。当前,三星、美光等厂商已展开2T0C DRAM研发,预计未来逐步进入量产。随着半导体工艺演进,2T0C DRAM有望成为下一代高密度、低功耗存储技术。然而,量子效应、工艺适配及产业链完善仍是关键挑战。未来研究将聚焦器件微缩、存算一体及异质集成,推动2T0C DRAM发展与产业化进程。As a core component of computer memory systems, DRAM plays a critical role in HPC, cloud computing, and AI. However, traditional 1T1C DRAM faces challenges such as capacitor scaling limitations, high refresh power consumption, and increasing fabrication complexity, restricting its scalability in advanced process nodes. To address these issues, 2T0C DRAM adopts a two-transistor architecture, utilizing floating-body effects and gate coupling mechanisms to store charge, thereby enhancing storage density, reducing power consumption, and improving process compatibility. This study analyzes the technical principles and structural design of 2T0C DRAM, highlighting its advantages over 1T1C DRAM while addressing challenges such as data retention, read/write disturbances, and process variations. Various optimization strategies, including device engineering, circuit design innovations, and advanced fabrication techniques, are also reviewed. Furthermore, considering emerging trends like CIM and 3D integration, we explore the potential applications of 2T0C DRAM in HPC, embedded systems, and next-generation memory technologies. Currently, leading memory manufacturers such as Samsung and Micron have initiated research on 2T0C DRAM, with commercialization expected in the near future. With the continuous advancement of semiconductor technology, 2T0C DRAM is poised to become a key candidate for next-generation high-density, low-power memory solutions. However, challenges such as quantum effects, process adaptation, and supply chain maturity remain critical. Future research will focus on device scaling, in-memory computing, and heterogeneous integration to accelerate the development and industrialization of 2T0C DRAM.展开更多
Electrocatalytic CO_(2)reduction reaction(CO_(2)RR)to produce multicarbon(C_(2+))products over Cubased catalysts represents an ideal approach for renewable energy storage and carbon emissions reduction.The Cu^(0)/Cu^(...Electrocatalytic CO_(2)reduction reaction(CO_(2)RR)to produce multicarbon(C_(2+))products over Cubased catalysts represents an ideal approach for renewable energy storage and carbon emissions reduction.The Cu^(0)/Cu^(δ+)interfaces are widely recognized as crucial sites that promote C-C coupling and enhance the generation of C2+products.However,a major challenge arises from the tendency of Cu^(δ+)active sites within Cu^(0)/Cu^(δ+)interfaces to undergo reduction to Cu^(0)during the CO_(2)RR process,leading to a decline in catalytic performance.Hence,it is crucial to establish durable Cu^(0)/Cu^(δ+)interfaces to enhance the conversion of CO_(2)to C_(2+)products.In this work,an iodine modification strategy is proposed to prepare a stable Cu@CuI composite catalyst with well-maintained Cu^(0)/Cu^(δ+)interfaces through a one-step redox reaction between iodine and copper.The optimized Cu@CuI-3composite catalyst demonstrates an excellent performance in CO_(2)RR,achieving a Faradaic efficiency of 75.7%for C^(2+)products and a partial current density of 288 mA·cm^(-2)at-1.57 V_(RHE)in a flow cell.Operando techniques reveal that a numerous persistent Cu^(δ+)species exist on the surface of the Cu@CuI-X composite catalyst even after CO_(2)RR due to the presence of adsorbed iodine ions,which prevent complete reduction of Cu^(δ+)species to Cu^(0)owing to their high electronegativity.Density functional theory calculations further verify that adsorbed iodine ions on the surface of Cu@CuI-X serve as charge regulators by adjusting local charge density,thereby facilitating the formation of*CHO intermediates from CO_(2)and lowering the energy barriers associated with coupling the*CHO and*CO intermediates during CO_(2)RR.Consequently,this phenomenon enhances the selectivity toward C_(2+)products during electrocatalytic CO_(2)reduction.展开更多
文摘Given their unique structure-dependent properties,strategically designing semiconductor-based photocatalysts,which expose highly reactive crystalline facets,is widely used to tune their performance.Herein,AgBr/Ag/TiO_(2){100}nanorods Z-scheme heterojunction composites were prepared via hydrothermal and in situ facet-induced reduction.Transmission electron microscopy,X-ray diffraction,X-ray photoelectron spectroscopy,electron paramagnetic resonance spectroscopy,and density functional theory calculations reveal that the selective exposure of TiO_(2){100}facets with abundant oxygen vacancies(OV)promotes the formation of metallic silver on the interfaces between AgBr and TiO_(2){100}.Metallic silver can mediate interfacial charge transfer by facilitating the photogenerated carrier recombination of the conduction band of TiO_(2){100}and the valence band of AgBr.As a result,a Z-scheme heterojunction is formed in AgBr/Ag/TiO_(2){100}.The AgBr/Ag/TiO_(2){100}exhibits faster degradation of tetracycline in aqueous solution compared to pristine AgBr,TiO_(2){101},TiO_(2){100}and AgBr/TiO_(2){101}p-n heterojunctions.This is attributed to the effect of the Z-scheme heterojunction on prolonging the lifetime of photogenerated carriers,which is confirmed by femtosecond transient absorption spectroscopy.The photocatalytic mechanism and degradation pathways are discussed along with a toxicity assessment of the intermediates.Overall,this work develops a new approach for designing Z-scheme heterojunction photocatalysts via selective facet control of anatase TiO_(2).
基金supported by the Technology Innovation Program(Grant Nos.20017382 and 20023023)funded by the Ministry of Trade,Industry&Energy(MOTIE,Republic of Korea)supported by a National Research Foundation of Korea(NRF)grant funded by the Korean Government(MSIT)(Grant No.RS-2023-00260527).
文摘Capacitor-less 2T0C dynamic random-access memory(DRAM)employing oxide semiconductors(OSs)as a channel has great potential in the development of highly scaled three dimensional(3D)-structured devices.However,the use of OS and such device structures presents certain challenges,including the trade-off relationship between the field-effect mobility and stability of OSs.Conventional 4-line-based operation of the 2T0C enlarges the entire cell volume and complicates the peripheral circuit.Herein,we proposed an IGO(In-Ga-O)channel 2-line-based 2T0C cell design and operating sequences comparable to those of the conventional Si-channel 1 T1C DRAM.IGO was adopted to achieve high thermal stability above 800℃,and the process conditions were optimized to simultaneously obtain a high μFE of 90.7 cm^(2)·V^(-)1·s^(-1),positive Vth of 0.34 V,superior reliability,and uniformity.The proposed 2-line-based 2T0C DRAM cell successfully exhibited multi-bit operation,with the stored voltage varying from 0 V to 1 V at 0.1 V intervals.Furthermore,for stored voltage intervals of 0.1 V and 0.5 V,the refresh time was 10 s and 1000 s in multi-bit operation;these values were more than 150 and 15000 times longer than those of the conventional Si channel 1T1C DRAM,respectively.A monolithic stacked 2-line-based 2T0C DRAM was fabricated,and a multi-bit operation was confirmed.
基金supported by“Pioneer”and“Leading Goose”R&D Program of Zhejiang(Nos.2022C03146 and 2023C03017)the National Natural Science Foundation of China(Nos.U23A20677 and 22022610)+1 种基金Zhejiang Provincial Natural Science Foundation of China(No.LDT23E06015B06)the National Funded Postdoctoral Researcher Program of China(No.GZC20232363).
文摘The electrochemical carbon dioxide reduction reaction(CO_(2)RR)to high value-added fuels or chemicals driven by the renewable energy is promising to alleviate global warming.However,the selective CO_(2)reduction to C_(2)products remains challenge.Cu-based catalyst with the specific Cu^(0)and Cu^(+)sites is important to generate C_(2)products.This work used nitrogen(N)to tune amounts of Cu^(0)and Cu^(+)sites in Cu_(2)O catalysts and improve C_(2)-product conversion.The controllable Cu^(0)/Cu^(+)ratio of Cu_(2)O catalyst from 0.16 to 15.19 was achieved by adjusting the N doping amount using NH3/Ar plasma treatment.The major theme of this work was clarifying a volcano curve of the ethylene Faraday efficiency as a function of the Cu^(0)/Cu^(+)ratio.The optimal Cu^(0)/Cu^(+)ratio was determined as 0.43 for selective electroreduction CO_(2)to ethylene.X-ray spectroscopy and density functional theory(DFT)calculations were employed to elucidate that the strong interaction between N and Cu increased the binding energy of N–Cu bond and stabilize Cu^(+),resulting in a 92.3%reduction in the potential energy change for^(∗)CO-^(∗)CO dimerization.This study is inspiring in designing high performance electrocatalysts for CO_(2)conversion.
基金supported by the National Natural Science Foundation of China(22222601 and 22076019)the Fundamental Research Funds for the Central Universities(DUT23LAB611).
文摘The Cu^(+)/Cu^(0)sites of copper-based catalysts are crucial for enhancing the production of multicarbon(C_(2+))products from electrochemical CO_(2)reduction reaction(eCO_(2)RR).However,the unstable Cu^(+)and insufficient Cu^(+)/Cu^(0)active sites lead to their limited selectivity and stability for C_(2+)production.Herein,we embedded copper oxide(CuO_(x))particles into porous nitrogen-doped carbon nanofibers(CuO_(x)@PCNF)by pyrolysis of the electrospun fiber film containing ZIF-8 and Cu_(2)O particles.The porous nitrogendoped carbon nanofibers protected and dispersed Cu^(+)species,and its micro porous structure enhanced the interaction between CuO_(x)and reactants during eCO_(2)RR.The obtained CuO_(x)@PCNF created more effective and stable Cu^(+)/Cu^(0)active sites.It showed a high Faradaic efficiency of 62.5%for C_(2+)products in Hcell,which was 2 times higher than that of bare CuO_(x)(~31.1%).Furthermore,it achieved a maximum Faradaic efficiency of 80.7%for C_(2+)products in flow cell.In situ characterization and density functional theory(DFT)calculation confirmed that the N-doped carbon layer protected Cu^(+)from electrochemical reduction and lowered the energy barrier for the dimerization of^(*)CO.Stable and exposed Cu^(+)/Cu^(0)active sites enhanced the enrichment of^(*)CO and promoted the C-C coupling reaction on the catalyst surface,which facilitated the formation of C_(2+)products.
文摘DRAM作为计算机存储系统的核心组件,在HPC、云计算、AI等领域至关重要。然而,传统1T1C DRAM受电容缩放瓶颈、刷新功耗及制造复杂度等问题限制,难以满足先进制程需求。2T0C DRAM采用双晶体管架构,利用浮体效应、栅极耦合等机制存储电荷,实现高密度、低功耗及工艺兼容性提升。本研究分析2T0C DRAM的技术原理、结构设计及其相较于1T1C DRAM的优势,探讨数据保持、读写干扰、工艺变异等挑战,并综述器件优化、电路创新及先进制造工艺的应对策略。此外,结合CIM、3D集成等趋势,探讨其在HPC、嵌入式及新型存储中的应用价值。当前,三星、美光等厂商已展开2T0C DRAM研发,预计未来逐步进入量产。随着半导体工艺演进,2T0C DRAM有望成为下一代高密度、低功耗存储技术。然而,量子效应、工艺适配及产业链完善仍是关键挑战。未来研究将聚焦器件微缩、存算一体及异质集成,推动2T0C DRAM发展与产业化进程。As a core component of computer memory systems, DRAM plays a critical role in HPC, cloud computing, and AI. However, traditional 1T1C DRAM faces challenges such as capacitor scaling limitations, high refresh power consumption, and increasing fabrication complexity, restricting its scalability in advanced process nodes. To address these issues, 2T0C DRAM adopts a two-transistor architecture, utilizing floating-body effects and gate coupling mechanisms to store charge, thereby enhancing storage density, reducing power consumption, and improving process compatibility. This study analyzes the technical principles and structural design of 2T0C DRAM, highlighting its advantages over 1T1C DRAM while addressing challenges such as data retention, read/write disturbances, and process variations. Various optimization strategies, including device engineering, circuit design innovations, and advanced fabrication techniques, are also reviewed. Furthermore, considering emerging trends like CIM and 3D integration, we explore the potential applications of 2T0C DRAM in HPC, embedded systems, and next-generation memory technologies. Currently, leading memory manufacturers such as Samsung and Micron have initiated research on 2T0C DRAM, with commercialization expected in the near future. With the continuous advancement of semiconductor technology, 2T0C DRAM is poised to become a key candidate for next-generation high-density, low-power memory solutions. However, challenges such as quantum effects, process adaptation, and supply chain maturity remain critical. Future research will focus on device scaling, in-memory computing, and heterogeneous integration to accelerate the development and industrialization of 2T0C DRAM.
基金financially supported by the National Natural Science Foundation of China(Nos.52073009,52272182,51872013 and 52011530190)the Program of the Ministry of Education of China for Introducing Talents of Discipline to Universities(No.B14009)。
文摘Electrocatalytic CO_(2)reduction reaction(CO_(2)RR)to produce multicarbon(C_(2+))products over Cubased catalysts represents an ideal approach for renewable energy storage and carbon emissions reduction.The Cu^(0)/Cu^(δ+)interfaces are widely recognized as crucial sites that promote C-C coupling and enhance the generation of C2+products.However,a major challenge arises from the tendency of Cu^(δ+)active sites within Cu^(0)/Cu^(δ+)interfaces to undergo reduction to Cu^(0)during the CO_(2)RR process,leading to a decline in catalytic performance.Hence,it is crucial to establish durable Cu^(0)/Cu^(δ+)interfaces to enhance the conversion of CO_(2)to C_(2+)products.In this work,an iodine modification strategy is proposed to prepare a stable Cu@CuI composite catalyst with well-maintained Cu^(0)/Cu^(δ+)interfaces through a one-step redox reaction between iodine and copper.The optimized Cu@CuI-3composite catalyst demonstrates an excellent performance in CO_(2)RR,achieving a Faradaic efficiency of 75.7%for C^(2+)products and a partial current density of 288 mA·cm^(-2)at-1.57 V_(RHE)in a flow cell.Operando techniques reveal that a numerous persistent Cu^(δ+)species exist on the surface of the Cu@CuI-X composite catalyst even after CO_(2)RR due to the presence of adsorbed iodine ions,which prevent complete reduction of Cu^(δ+)species to Cu^(0)owing to their high electronegativity.Density functional theory calculations further verify that adsorbed iodine ions on the surface of Cu@CuI-X serve as charge regulators by adjusting local charge density,thereby facilitating the formation of*CHO intermediates from CO_(2)and lowering the energy barriers associated with coupling the*CHO and*CO intermediates during CO_(2)RR.Consequently,this phenomenon enhances the selectivity toward C_(2+)products during electrocatalytic CO_(2)reduction.
