Graphene edges with a zigzag-type atomic structure can theoretically produce spontaneous spin polarization despite being a critical-metal-free material. We have demonstrated this in graphene nanomeshes (GNMs) with hon...Graphene edges with a zigzag-type atomic structure can theoretically produce spontaneous spin polarization despite being a critical-metal-free material. We have demonstrated this in graphene nanomeshes (GNMs) with honeycomb-like arrays of low-defect hexagonal nanopores by observing room-temperature ferromagnetism and spin-based phenomena arising from the zigzag-pore edges. Here, we apply extremely high electric fields to the ferromagnetic (FM) GNMs using an ionic-liquid gate. A large on/off-ratio for hole current is observed for even small applied ionic-liquid gate voltages (Vig). Observations of the magnetoresistance behavior reveal high carrier densities of ~1013 cm-2 at large Vig values. We find a maximum conductance peak in the high -Vig region and its separation into two peaks upon applying a side-gate (in-plane external) voltage (Vex). It is discussed that localized edge-π band with excess-density electrons induced by Vig and its spin splitting for majority and minority of spins by Vex (half-metallicity model) lead to these phenomena. The results must realize critical-element-free novel spintronic devices.展开更多
IrRu bimetallic oxides are recognized as the promising acidic oxygen evolution reaction(OER)catalysts,but breaking the trade-off between their activity and stability is an unresolved question.Meanwhile,addressing the ...IrRu bimetallic oxides are recognized as the promising acidic oxygen evolution reaction(OER)catalysts,but breaking the trade-off between their activity and stability is an unresolved question.Meanwhile,addressing the issues of mass transport obstruction of IrRu bimetallic oxides under high current remains a challenge for the development of proton exchange membrane water electrolysis(PEM-WE).Herein,we prepared an IrRuO_(x)nanomeshes(IrRuO_(x)NMs)with high coordination number(CN)of Ir-O-Ru bonds in a mixed molten salt with high solubility of the Ir/Ru precursor.X-ray absorption spectroscopy analysis revealed that the IrRuO_(x)NMs possess high coordination number of Ir-O-Ru bonds(CNIr-O-Ru=5.6)with a distance of 3.18Å.Moreover,the nanomesh structures of IrRuO_(x)NMs provided hierarchical channels to accelerate the transport of oxygen and water,thus further improving the electrochemical activity.Consequently,the IrRuO_(x)NMs as OER catalysts can simultaneously achieve high activity and stability with low overpotential of 196 mV to reach 10 mA·cm^(−2)and slightly increase by 70 mV over 650 h test.Differential electrochemical mass spectrometry tests suggest that the preferred OER mechanism for IrRuO_(x)NMs is the adsorbent evolution mechanism,which is beneficial for the robust structural stability.展开更多
Layered bismuth sulfide （Bi2S3） has emerged as an important type of Li-storage material due to its high theoretical capacity and intriguing reaction mechanism. The engineering and fabrication of Bi2S3 materials with...Layered bismuth sulfide （Bi2S3） has emerged as an important type of Li-storage material due to its high theoretical capacity and intriguing reaction mechanism. The engineering and fabrication of Bi2S3 materials with large capacity and stable cyclability via a facile approach is essential, but still remains a great challenge. Herein, we employ a one-pot hydrothermal route to fabricate carbon-coated Bi2S3 nanomeshes （Bi2S3/C） as an efficient Li-storage material. The nanomeshes serve as a highly conducting and porous scaffold facilitating electron and ion transport, while the carbon coating layer provides flexible space for efficient reduction of mechanical strain upon electrochemical cycling. Consequently, the fabricated Bi2S3/C exhibits a high and stable capacity delivery in the 0.01-2.5 V region, notably outperforming previously reported Bi2S3 materials. It is able to discharge 472 mA·h·g^-1 at 120 mA.g^-1 over 50 full cycles, and to retain 301 mA·h·g^-1 in the 40th cycle at 600 mA.g^-l, demonstrating the potential of Bi2S3 as electrode materials for rechargeable batteries.展开更多
Hierarchical WO3 nanomesh,assembled from single-crystalline WO3 nanowires,is prepared via a hydrothermal method using thiourea(Tu)as the morphology-controlling agent.Formation of the hierarchical architecture comprisi...Hierarchical WO3 nanomesh,assembled from single-crystalline WO3 nanowires,is prepared via a hydrothermal method using thiourea(Tu)as the morphology-controlling agent.Formation of the hierarchical architecture comprising of WO3 nanowires takes place via Ostwald ripening mechanism with the growth orientation.The sensor based on WO3 nanomesh has good electrical conductivity and is therefore suitable as NO2 sensing material.The WO3 nanomesh sensor exhibited high response,short response and recovery time,and excellent selectivity towards ppb-level NO2 at low temperature of 160℃.The superior gas performance of the sensor was attributed to the high-purity hexagonal WO3 with high specific surface area,which gives rise to enhanced surface adsorption sites for gas adsorption.The electron depletion theory was used for explaining the NO2-sensing mechanism by the gas adsorption/desorption and charge transfer happened on the surface of WO3 nanomesh.展开更多
A new type of single-walled carbon nanotube （SWNT） thin-film transistor （TFT） structure with a nanomesh network channel has been fabricated from a pre- separated semiconducting nanotube solution and simultaneously...A new type of single-walled carbon nanotube （SWNT） thin-film transistor （TFT） structure with a nanomesh network channel has been fabricated from a pre- separated semiconducting nanotube solution and simultaneously achieved both high uniformity and a high on/off ratio for application in large-scale integrated circuits. The nanomesh structure is prepared on a high-density SWNT network channel and enables a high on/off ratio while maintaining the excellent uniformity of the electrical properties of the SWNT TFTs. These effects are attributed to the effective elimination of metallic paths across the source/drain electrodes by forming the nanomesh structure in the high-density SWNT network channel. Therefore, our approach can serve as a critical foundation for future nanotube-based thin- film display electronics.展开更多
The formation and control of a room-temperature magnetic order in two- dimensional （2D） materials is a challenging quest for the advent of innovative magnetic- and spintronic-based technologies. To date, edge magnet...The formation and control of a room-temperature magnetic order in two- dimensional （2D） materials is a challenging quest for the advent of innovative magnetic- and spintronic-based technologies. To date, edge magnetism in 2D materials has been experimentally observed in hydrogen （H）-terminated graphene nanoribbons （GNRs） and graphene nanomeshes （GNMs）, but the measured magnetization remains far too small to allow envisioning practical applications. Herein, we report experimental evidences of large room-temperature edge ferromagnetism （FM） obtained from oxygen （O）-terminated zigzag pore edges of few-layer black phosphorus （P） nanomeshes （BPNMs）. The magnetization values per unit area are -100 times larger than those reported for H-terminated GNMs, while the magnetism is absent for H-terminated BPNMs. The magnetization measurements and the first-principles simulations suggest that the origin of such a magnetic order could stem from ferromagnetic spin coupling between edge P with O atoms, resulting in a strong spin localization at the edge valence band, and from uniform oxidation of full pore edges over a large area and interlayer spin interaction. Our findings pave the way for realizing high-efficiency 2D flexible magnetic and spintronic devices without the use of rare magnetic elements.展开更多
As a member of the 2 D family of materials, h-BN is an intrinsic insulator and could be employed as a dielectric or insulating inter-layer in ultra-thin devices. Monolayer h-BN can be synthesized on Rh(111) surfaces u...As a member of the 2 D family of materials, h-BN is an intrinsic insulator and could be employed as a dielectric or insulating inter-layer in ultra-thin devices. Monolayer h-BN can be synthesized on Rh(111) surfaces using borazine as a precursor. Using in-situ variable-temperature scanning tunneling microscopy(STM), we directly observed the formation of h-BN in real-time. By analyzing the deposition under variable substrate temperatures and the filling rate of the h-BN overlayer vacant hollows during growth, we studied the growth kinetics of how the borazine molecules construct the h-BN overlayer grown on the Rh surface.展开更多
The inherent shortcomings of a zinc anode in aqueous zinc‐ion batteries(ZIBs)such as zinc dendrites and side reactions severely limit their practical application.Herein,to address these issues,an ion‐oriented transp...The inherent shortcomings of a zinc anode in aqueous zinc‐ion batteries(ZIBs)such as zinc dendrites and side reactions severely limit their practical application.Herein,to address these issues,an ion‐oriented transport channel constructed by graphdiyne(GDY)nanowalls is designed and grown in situ on the surface of a zinc electrode.The vertically stacked GDY nanowalls with a unique hierarchical porous structure and mechanical properties form a nanomesh‐like interface on the zinc electrode,acting as an ion‐oriented channel,which can efficiently confine the segmented growth of zinc metal in microscopic regions of hundreds of nanometers.In those microscopic regions,the uniform domain current density is effortlessly maintained compared with a large surface area,thereby inhibiting zinc dendrites effectively.Besides,due to the presence of the ion‐oriented channel,the modified zinc anode demonstrates long‐term stable zinc plating/stripping performance for more than 600 h at 1 mAh cm^(−2)in an aqueous electrolyte.In addition,full‐cells coupled with MnO2 show high specific capacity and power density,as well as excellent cycling stability with a capacity retention of 82%after 5000 cycles at 1 A g^(−1).This work provides a feasible and accessible surface engineering approach to modify the electrode interface for confined and dendrite‐free zinc deposition in aqueous ZIBs.展开更多
文摘Graphene edges with a zigzag-type atomic structure can theoretically produce spontaneous spin polarization despite being a critical-metal-free material. We have demonstrated this in graphene nanomeshes (GNMs) with honeycomb-like arrays of low-defect hexagonal nanopores by observing room-temperature ferromagnetism and spin-based phenomena arising from the zigzag-pore edges. Here, we apply extremely high electric fields to the ferromagnetic (FM) GNMs using an ionic-liquid gate. A large on/off-ratio for hole current is observed for even small applied ionic-liquid gate voltages (Vig). Observations of the magnetoresistance behavior reveal high carrier densities of ~1013 cm-2 at large Vig values. We find a maximum conductance peak in the high -Vig region and its separation into two peaks upon applying a side-gate (in-plane external) voltage (Vex). It is discussed that localized edge-π band with excess-density electrons induced by Vig and its spin splitting for majority and minority of spins by Vex (half-metallicity model) lead to these phenomena. The results must realize critical-element-free novel spintronic devices.
基金The National Key Research and Development Program of China(Nos.2018YFA0702001 and 2021YFA1500400)the National Natural Science Foundation of China(Nos.22371268 and 22175163)+2 种基金Fundamental Research Funds for the Central Universities(No.WK2060000016)Anhui Development and Reform Commission(No.AHZDCYCX-2SDT2023-07)Youth Innovation Promotion Association of the Chinese Academy of Science(No.2018494)supported this work.
文摘IrRu bimetallic oxides are recognized as the promising acidic oxygen evolution reaction(OER)catalysts,but breaking the trade-off between their activity and stability is an unresolved question.Meanwhile,addressing the issues of mass transport obstruction of IrRu bimetallic oxides under high current remains a challenge for the development of proton exchange membrane water electrolysis(PEM-WE).Herein,we prepared an IrRuO_(x)nanomeshes(IrRuO_(x)NMs)with high coordination number(CN)of Ir-O-Ru bonds in a mixed molten salt with high solubility of the Ir/Ru precursor.X-ray absorption spectroscopy analysis revealed that the IrRuO_(x)NMs possess high coordination number of Ir-O-Ru bonds(CNIr-O-Ru=5.6)with a distance of 3.18Å.Moreover,the nanomesh structures of IrRuO_(x)NMs provided hierarchical channels to accelerate the transport of oxygen and water,thus further improving the electrochemical activity.Consequently,the IrRuO_(x)NMs as OER catalysts can simultaneously achieve high activity and stability with low overpotential of 196 mV to reach 10 mA·cm^(−2)and slightly increase by 70 mV over 650 h test.Differential electrochemical mass spectrometry tests suggest that the preferred OER mechanism for IrRuO_(x)NMs is the adsorbent evolution mechanism,which is beneficial for the robust structural stability.
文摘Layered bismuth sulfide （Bi2S3） has emerged as an important type of Li-storage material due to its high theoretical capacity and intriguing reaction mechanism. The engineering and fabrication of Bi2S3 materials with large capacity and stable cyclability via a facile approach is essential, but still remains a great challenge. Herein, we employ a one-pot hydrothermal route to fabricate carbon-coated Bi2S3 nanomeshes （Bi2S3/C） as an efficient Li-storage material. The nanomeshes serve as a highly conducting and porous scaffold facilitating electron and ion transport, while the carbon coating layer provides flexible space for efficient reduction of mechanical strain upon electrochemical cycling. Consequently, the fabricated Bi2S3/C exhibits a high and stable capacity delivery in the 0.01-2.5 V region, notably outperforming previously reported Bi2S3 materials. It is able to discharge 472 mA·h·g^-1 at 120 mA.g^-1 over 50 full cycles, and to retain 301 mA·h·g^-1 in the 40th cycle at 600 mA.g^-l, demonstrating the potential of Bi2S3 as electrode materials for rechargeable batteries.
基金The National Key Basic Research Program of China (973 Program) (No. 2013CB934301)
文摘Hierarchical WO3 nanomesh,assembled from single-crystalline WO3 nanowires,is prepared via a hydrothermal method using thiourea(Tu)as the morphology-controlling agent.Formation of the hierarchical architecture comprising of WO3 nanowires takes place via Ostwald ripening mechanism with the growth orientation.The sensor based on WO3 nanomesh has good electrical conductivity and is therefore suitable as NO2 sensing material.The WO3 nanomesh sensor exhibited high response,short response and recovery time,and excellent selectivity towards ppb-level NO2 at low temperature of 160℃.The superior gas performance of the sensor was attributed to the high-purity hexagonal WO3 with high specific surface area,which gives rise to enhanced surface adsorption sites for gas adsorption.The electron depletion theory was used for explaining the NO2-sensing mechanism by the gas adsorption/desorption and charge transfer happened on the surface of WO3 nanomesh.
文摘A new type of single-walled carbon nanotube （SWNT） thin-film transistor （TFT） structure with a nanomesh network channel has been fabricated from a pre- separated semiconducting nanotube solution and simultaneously achieved both high uniformity and a high on/off ratio for application in large-scale integrated circuits. The nanomesh structure is prepared on a high-density SWNT network channel and enables a high on/off ratio while maintaining the excellent uniformity of the electrical properties of the SWNT TFTs. These effects are attributed to the effective elimination of metallic paths across the source/drain electrodes by forming the nanomesh structure in the high-density SWNT network channel. Therefore, our approach can serve as a critical foundation for future nanotube-based thin- film display electronics.
文摘The formation and control of a room-temperature magnetic order in two- dimensional （2D） materials is a challenging quest for the advent of innovative magnetic- and spintronic-based technologies. To date, edge magnetism in 2D materials has been experimentally observed in hydrogen （H）-terminated graphene nanoribbons （GNRs） and graphene nanomeshes （GNMs）, but the measured magnetization remains far too small to allow envisioning practical applications. Herein, we report experimental evidences of large room-temperature edge ferromagnetism （FM） obtained from oxygen （O）-terminated zigzag pore edges of few-layer black phosphorus （P） nanomeshes （BPNMs）. The magnetization values per unit area are -100 times larger than those reported for H-terminated GNMs, while the magnetism is absent for H-terminated BPNMs. The magnetization measurements and the first-principles simulations suggest that the origin of such a magnetic order could stem from ferromagnetic spin coupling between edge P with O atoms, resulting in a strong spin localization at the edge valence band, and from uniform oxidation of full pore edges over a large area and interlayer spin interaction. Our findings pave the way for realizing high-efficiency 2D flexible magnetic and spintronic devices without the use of rare magnetic elements.
基金supported by the National Natural Science Foundation of China(Grant Nos.51402026,11774154,and 11790311)the Program for High-Level Entrepreneurial and Innovative Talents Introduction,Jiangsu Province,the Basic Research Program of Jiangsu Province(Grant No.BK20130236)the National Key Research and Development Plan(Grant No.2016YFE0125200)
文摘As a member of the 2 D family of materials, h-BN is an intrinsic insulator and could be employed as a dielectric or insulating inter-layer in ultra-thin devices. Monolayer h-BN can be synthesized on Rh(111) surfaces using borazine as a precursor. Using in-situ variable-temperature scanning tunneling microscopy(STM), we directly observed the formation of h-BN in real-time. By analyzing the deposition under variable substrate temperatures and the filling rate of the h-BN overlayer vacant hollows during growth, we studied the growth kinetics of how the borazine molecules construct the h-BN overlayer grown on the Rh surface.
基金National Natural Science Foundation of China,Grant/Award Numbers:21701182,21771187,21790050,21790051,22005323Frontier Science Research Project of the Chinese Academy of Sciences,Grant/Award Number:QYZDB‐SSWJSC052+1 种基金Taishan Scholars Program of Shandong Province,Grant/Award Number:tsqn201812111ICCAS Institute Research Project。
文摘The inherent shortcomings of a zinc anode in aqueous zinc‐ion batteries(ZIBs)such as zinc dendrites and side reactions severely limit their practical application.Herein,to address these issues,an ion‐oriented transport channel constructed by graphdiyne(GDY)nanowalls is designed and grown in situ on the surface of a zinc electrode.The vertically stacked GDY nanowalls with a unique hierarchical porous structure and mechanical properties form a nanomesh‐like interface on the zinc electrode,acting as an ion‐oriented channel,which can efficiently confine the segmented growth of zinc metal in microscopic regions of hundreds of nanometers.In those microscopic regions,the uniform domain current density is effortlessly maintained compared with a large surface area,thereby inhibiting zinc dendrites effectively.Besides,due to the presence of the ion‐oriented channel,the modified zinc anode demonstrates long‐term stable zinc plating/stripping performance for more than 600 h at 1 mAh cm^(−2)in an aqueous electrolyte.In addition,full‐cells coupled with MnO2 show high specific capacity and power density,as well as excellent cycling stability with a capacity retention of 82%after 5000 cycles at 1 A g^(−1).This work provides a feasible and accessible surface engineering approach to modify the electrode interface for confined and dendrite‐free zinc deposition in aqueous ZIBs.
基金Acknowledgements This work was supported by Key Project of Chinese National Programs for Fundamental Research and Development （Grant No. 2010CB631002）, National Natural Science Foundation of China （Grant No.50771078, 50901057） and Xi＇ an Applied Materials Innovation Fund （XA-AM-200904）. The authors thank Dr. Yunjin Sun for some good suggestions.
