We propose a neural network equalization delta-sigma modulation(DSM)technique.After performing DSM on the multiorder quadrature amplitude modulation(QAM)orthogonal frequency division multiplexing(OFDM)signal at the tr...We propose a neural network equalization delta-sigma modulation(DSM)technique.After performing DSM on the multiorder quadrature amplitude modulation(QAM)orthogonal frequency division multiplexing(OFDM)signal at the transmitting end,neural network equalizer technology is used in the digital signal processing at receiving end.Applying this technology to a 4.6 km W-band millimeter wave system,it is possible to achieve a 1 Gbaud 8192-QAM OFDM signal transmission.The data rate reached 23.4 Gbit/s with the bit error rate at 3.8×10^(-2),lower than soft-decision forward-error correction threshold(4×10^(-2)).展开更多
The molybdenum carbide(Mo_(2)C)has been regarded as one of the most cost-efficient and stable electrocatalyst for the hydrogen evolution reaction(HER)by the virtue of its Pt-like electronic structures.However,the inhe...The molybdenum carbide(Mo_(2)C)has been regarded as one of the most cost-efficient and stable electrocatalyst for the hydrogen evolution reaction(HER)by the virtue of its Pt-like electronic structures.However,the inherent limitation of high density of empty valence band significantly reduces its catalytic reactivity by reason of strong hydrogen desorption resistance.Herein,we propose a multiscale confinement synthesis method to design the nitrogen-rich Mo_(2)C for modulating the band structure via decomposing the pre-coordination bonded polymer in a pressure-tight tube sealing system.Pre-bonded c/N-Mo in the coordination precursor constructs a micro-confinement space,enabling the homogeneous nitrogenization in-situ happened during the formation of Mo_(2)C.Simultaneously,the evolved gases from the precursor decomposition in tube sealing system establish a macro-confinement environment,preventing the lattice N escape and further endowing a continuous nitridation.Combining the multiscale confinement effects,the nitrogen-rich Mo2C displays as high as 25%N-Mo concentration in carbide lattice,leading to a satisfactory band structure.Accordingly,the constructed nitrogen-rich Mo_(2)C reveals an adorable catalytic activity for HER in both alkaline and acid solution.It is anticipated that the multiscale confinement synthesis strategy presents guideline for the rational design of electrocatalysts and beyond.展开更多
The oxygen evolution reaction(OER)electrocatalysts,which can keep active for a long time in acidic media,are of great significance to proton exchange membrane water electrolyzers.Here,Ru-Co_(3)O_(4)electrocatalysts wi...The oxygen evolution reaction(OER)electrocatalysts,which can keep active for a long time in acidic media,are of great significance to proton exchange membrane water electrolyzers.Here,Ru-Co_(3)O_(4)electrocatalysts with transition metal oxide Co_(3)O_(4)as matrix and the noble metal Ru as doping element have been prepared through an ion exchange–pyrolysis process mediated by metal-organic framework,in which Ru atoms occupy the octahedral sites of Co_(3)O_(4).Experimental and theoretical studies show that introduced Ru atoms have a passivation effect on lattice oxygen.The strong coupling between Ru and O causes a negative shift in the energy position of the O p-band centers.Therefore,the bonding activity of oxygen in the adsorbed state to the lattice oxygen is greatly passivated during the OER process,thus improving the stability of matrix material.In addition,benefiting from the modulating effect of the introduced Ru atoms on the metal active sites,the thermodynamic and kinetic barriers have been significantly reduced,which greatly enhances both the catalytic stability and reaction efficiency of Co_(3)O_(4).展开更多
We experimentally built a W-band photonics-aided millimeter-wave radio-over-fiber transmission system and demonstrated the delivery of up to 8192-ary quadrature amplitude modulation[QAM] signal.Discrete multitone sign...We experimentally built a W-band photonics-aided millimeter-wave radio-over-fiber transmission system and demonstrated the delivery of up to 8192-ary quadrature amplitude modulation[QAM] signal.Discrete multitone signals are converted into 1-bit data streams through delta-sigma modulation and then modulated onto a 76.2 GHz carrier.An envelope detector is used at the receiver side for direct detection.The results prove that our proposed system can support 2048QAM and 8192QAM transmission while meeting the hard decision forward error correction threshold of 3.8×10^(-3)and the soft decision forward error correction threshold of 4.2×10^(-2),respectively.We believe this cost-effective scheme is a promising candidate for future high-order QAM millimeter-wave downlink transmission.展开更多
To solve the problem of the low on-state current in p-type tunnel field-effect transistors(p-TFETs),this paper analyzes the mechanism of adjusting the tunneling current of a TFET device determined by studying the infl...To solve the problem of the low on-state current in p-type tunnel field-effect transistors(p-TFETs),this paper analyzes the mechanism of adjusting the tunneling current of a TFET device determined by studying the influence of the peak position of ion implantation on the potential of the p-TFET device surface and the width of the tunneling barrier.Doping-regulated silicon-based high on-state p-TFET devices are designed and fabricated,and the test results show that the on-state current of the fabricated devices can be increased by about two orders of magnitude compared with the current of other devices with the same structure.This method provides a new idea for the realization of high on-state current TFET devices.展开更多
Lead(Pb)-free halide perovskites have recently attracted increasing attention as potential catalysts for CO_(2) photoreduction to CO due to their potential to capture solar energy and drive catalytic reaction.However,...Lead(Pb)-free halide perovskites have recently attracted increasing attention as potential catalysts for CO_(2) photoreduction to CO due to their potential to capture solar energy and drive catalytic reaction.However,issues of the poor charge transfer still remain one of the main obstacles limiting their performance due to the overwhelming radiative and nonradiative charge-carrier recombination losses.Herein,Pb-free Sb-alloyed all-inorganic quadruple perovskite Cs_(4)Mn(Bi_(1-x)Sb_(x))_(2)Cl_(12)(0≤x≤1)is synthesized as efficient photocatalyst.By Sb alloying,the undesired relaxation of photogenerated electrons from conduction band to emission centers of[MnCl6]^(4-)is greatly suppressed,resulting in a weakened PL emission and enhanced charge transfer for photocatalyst.The ensuing Cs_(4)Mn(Bi_(1-x)Sb_(x))_(2)Cl_(12) photocatalyst accomplishes efficient conversion of CO_(2)into CO,accompanied by a surprising production of H_(2)O_(2),a high valueadded product associated with water oxidation.By optimizing Sb^(3+) concentration,a high CO evolution rate of 35.1μmol g^(-1)h^(-1)is achieved,superior to most other Pb and Pb-free halide perovskites.Our findings provide new insights into the mixed-cation alloying strategies for improved photocatalytic performance of Pb-free perovskites and shed light on the rational design of robust band structure toward efficient energy transfer.展开更多
The introduction of vacancy defects in semiconductors has been proven to be a highly effective approach to improve their photocatalytic activity owing to their advantages of promoting light absorption,facilitating pho...The introduction of vacancy defects in semiconductors has been proven to be a highly effective approach to improve their photocatalytic activity owing to their advantages of promoting light absorption,facilitating photogenerated carrier separation,optimizing electronic structure,and enabling the production of reactive radicals.Herein,we outline the state-of-the-art vacancy-engineered photocatalysts in various applications and reveal how the vacancies influence photocatalytic performance.Specifically,the types of vacancy defects,the methods for tailoring vacancies,the advanced characteri-zation techniques,the categories of photocatalysts with vacancy defects,and the corresponding photocatalytic behaviors are presented.Meanwhile,the methods of vacancies creation and the related photocatalytic performance are correlated,which can be very useful to guide the readers to quickly obtain in-depth knowledge and to have a good idea about the selection of defect engineering methods.The precise characterization of vacancy defects is highly challenging.This review describes the accurate use of a series of characterization techniques with detailed comments and suggestions.This represents the uniqueness of this comprehensive review.The challenges and development prospects in engineering photocatalysts with vacancy defects for practical applications are discussed to provide a promising research direction in this field.展开更多
The Ultra-WideBand(UWB) technique, which offers good energy efficiency, flexible data rate, and high ranging accuracy, has recently been recognized as a revived wireless technology for short distance communication.Thi...The Ultra-WideBand(UWB) technique, which offers good energy efficiency, flexible data rate, and high ranging accuracy, has recently been recognized as a revived wireless technology for short distance communication.This paper presents a brief overview of two UWB techniques, covering Impulse-Radio UWB(IR-UWB) and FrequencyModulation UWB(FM-UWB) methods. The link margin enhancement technique, Very-WideBand(VWB), and power consumption reducing technique, chirp UWB, are also introduced. Then, several potential applications of IR-UWB with transceiver architectures are addressed, including high data rate proximity communication and secure wireless connectivity. With fine-ranging and energy-efficient communication features, the UWB wireless technology is highly promising for secure mobile Internet of Things(IoT) applications.展开更多
基金supported by the National Natural Science Foundation of China(Nos.62225503,61835005,and 62205151)。
文摘We propose a neural network equalization delta-sigma modulation(DSM)technique.After performing DSM on the multiorder quadrature amplitude modulation(QAM)orthogonal frequency division multiplexing(OFDM)signal at the transmitting end,neural network equalizer technology is used in the digital signal processing at receiving end.Applying this technology to a 4.6 km W-band millimeter wave system,it is possible to achieve a 1 Gbaud 8192-QAM OFDM signal transmission.The data rate reached 23.4 Gbit/s with the bit error rate at 3.8×10^(-2),lower than soft-decision forward-error correction threshold(4×10^(-2)).
基金supported by the National Natural Science Foundation of China(52372201,52125202,52202247)the Natural Science Foundation of Jiangsu Province(1192261031693)the Fundamental Research Funds for the Central Universities(30919011110,1191030558)。
文摘The molybdenum carbide(Mo_(2)C)has been regarded as one of the most cost-efficient and stable electrocatalyst for the hydrogen evolution reaction(HER)by the virtue of its Pt-like electronic structures.However,the inherent limitation of high density of empty valence band significantly reduces its catalytic reactivity by reason of strong hydrogen desorption resistance.Herein,we propose a multiscale confinement synthesis method to design the nitrogen-rich Mo_(2)C for modulating the band structure via decomposing the pre-coordination bonded polymer in a pressure-tight tube sealing system.Pre-bonded c/N-Mo in the coordination precursor constructs a micro-confinement space,enabling the homogeneous nitrogenization in-situ happened during the formation of Mo_(2)C.Simultaneously,the evolved gases from the precursor decomposition in tube sealing system establish a macro-confinement environment,preventing the lattice N escape and further endowing a continuous nitridation.Combining the multiscale confinement effects,the nitrogen-rich Mo2C displays as high as 25%N-Mo concentration in carbide lattice,leading to a satisfactory band structure.Accordingly,the constructed nitrogen-rich Mo_(2)C reveals an adorable catalytic activity for HER in both alkaline and acid solution.It is anticipated that the multiscale confinement synthesis strategy presents guideline for the rational design of electrocatalysts and beyond.
基金the National Natural Science Foundation of China(Nos.12025503,U23B2072,and 12105208)。
文摘The oxygen evolution reaction(OER)electrocatalysts,which can keep active for a long time in acidic media,are of great significance to proton exchange membrane water electrolyzers.Here,Ru-Co_(3)O_(4)electrocatalysts with transition metal oxide Co_(3)O_(4)as matrix and the noble metal Ru as doping element have been prepared through an ion exchange–pyrolysis process mediated by metal-organic framework,in which Ru atoms occupy the octahedral sites of Co_(3)O_(4).Experimental and theoretical studies show that introduced Ru atoms have a passivation effect on lattice oxygen.The strong coupling between Ru and O causes a negative shift in the energy position of the O p-band centers.Therefore,the bonding activity of oxygen in the adsorbed state to the lattice oxygen is greatly passivated during the OER process,thus improving the stability of matrix material.In addition,benefiting from the modulating effect of the introduced Ru atoms on the metal active sites,the thermodynamic and kinetic barriers have been significantly reduced,which greatly enhances both the catalytic stability and reaction efficiency of Co_(3)O_(4).
基金partially supported by the National Key R&D Program of China(No.2018YFB1801703)the National Natural Science Foundation of China(Nos.62127802 and 61720106015)。
文摘We experimentally built a W-band photonics-aided millimeter-wave radio-over-fiber transmission system and demonstrated the delivery of up to 8192-ary quadrature amplitude modulation[QAM] signal.Discrete multitone signals are converted into 1-bit data streams through delta-sigma modulation and then modulated onto a 76.2 GHz carrier.An envelope detector is used at the receiver side for direct detection.The results prove that our proposed system can support 2048QAM and 8192QAM transmission while meeting the hard decision forward error correction threshold of 3.8×10^(-3)and the soft decision forward error correction threshold of 4.2×10^(-2),respectively.We believe this cost-effective scheme is a promising candidate for future high-order QAM millimeter-wave downlink transmission.
基金Project supported by the Key Research and Development Program of Shaanxi(Grant No.2021GY-010)the National Defense Science and Technology Foundation Strengthening Program of China(Grant No.2019-XXXX-XX-236-00).
文摘To solve the problem of the low on-state current in p-type tunnel field-effect transistors(p-TFETs),this paper analyzes the mechanism of adjusting the tunneling current of a TFET device determined by studying the influence of the peak position of ion implantation on the potential of the p-TFET device surface and the width of the tunneling barrier.Doping-regulated silicon-based high on-state p-TFET devices are designed and fabricated,and the test results show that the on-state current of the fabricated devices can be increased by about two orders of magnitude compared with the current of other devices with the same structure.This method provides a new idea for the realization of high on-state current TFET devices.
基金financially supported by the National Natural Science Foundation of China(22179072,22002070)the Natural Science Foundation of Shandong Province(ZR2021QF006)+3 种基金the Outstanding Youth Science Foundation of Shandong Province(Overseas)(2022HWYQ-006)the Natural Science Foundation of Shandong Province(ZR2020QB059)the Fundamental Research Center of Artificial Photosynthesis(FReCAP)financially supported by the National Natural Science Foundation of China(22088102)the China Postdoctoral Science Foundation(No.2022M711898)。
文摘Lead(Pb)-free halide perovskites have recently attracted increasing attention as potential catalysts for CO_(2) photoreduction to CO due to their potential to capture solar energy and drive catalytic reaction.However,issues of the poor charge transfer still remain one of the main obstacles limiting their performance due to the overwhelming radiative and nonradiative charge-carrier recombination losses.Herein,Pb-free Sb-alloyed all-inorganic quadruple perovskite Cs_(4)Mn(Bi_(1-x)Sb_(x))_(2)Cl_(12)(0≤x≤1)is synthesized as efficient photocatalyst.By Sb alloying,the undesired relaxation of photogenerated electrons from conduction band to emission centers of[MnCl6]^(4-)is greatly suppressed,resulting in a weakened PL emission and enhanced charge transfer for photocatalyst.The ensuing Cs_(4)Mn(Bi_(1-x)Sb_(x))_(2)Cl_(12) photocatalyst accomplishes efficient conversion of CO_(2)into CO,accompanied by a surprising production of H_(2)O_(2),a high valueadded product associated with water oxidation.By optimizing Sb^(3+) concentration,a high CO evolution rate of 35.1μmol g^(-1)h^(-1)is achieved,superior to most other Pb and Pb-free halide perovskites.Our findings provide new insights into the mixed-cation alloying strategies for improved photocatalytic performance of Pb-free perovskites and shed light on the rational design of robust band structure toward efficient energy transfer.
基金This study was also supported by the European Commission Interreg V France-Wallonie-Vlaanderen project“DepollutAir.”Yang Ding is grateful for the financial support of the China Scholarship Council(201808310127)This study was financially supported by the National Natural Science Foundation of China(U20A20122)+1 种基金the Program for Changjiang Scholars and Innovative Research Team in University(IRT_15R52)of the Chinese Ministry of Education,the Program of Introducing Talents of Discipline to Universities-Plan 111(Grant No.B20002)the Ministry of Science and Technology and the Ministry of Education of China,and the National Key R&D Program of China(2016YFA0202602).
文摘The introduction of vacancy defects in semiconductors has been proven to be a highly effective approach to improve their photocatalytic activity owing to their advantages of promoting light absorption,facilitating photogenerated carrier separation,optimizing electronic structure,and enabling the production of reactive radicals.Herein,we outline the state-of-the-art vacancy-engineered photocatalysts in various applications and reveal how the vacancies influence photocatalytic performance.Specifically,the types of vacancy defects,the methods for tailoring vacancies,the advanced characteri-zation techniques,the categories of photocatalysts with vacancy defects,and the corresponding photocatalytic behaviors are presented.Meanwhile,the methods of vacancies creation and the related photocatalytic performance are correlated,which can be very useful to guide the readers to quickly obtain in-depth knowledge and to have a good idea about the selection of defect engineering methods.The precise characterization of vacancy defects is highly challenging.This review describes the accurate use of a series of characterization techniques with detailed comments and suggestions.This represents the uniqueness of this comprehensive review.The challenges and development prospects in engineering photocatalysts with vacancy defects for practical applications are discussed to provide a promising research direction in this field.
基金supported in part by the National Natural Science Foundation of China (No. 61774092)。
文摘The Ultra-WideBand(UWB) technique, which offers good energy efficiency, flexible data rate, and high ranging accuracy, has recently been recognized as a revived wireless technology for short distance communication.This paper presents a brief overview of two UWB techniques, covering Impulse-Radio UWB(IR-UWB) and FrequencyModulation UWB(FM-UWB) methods. The link margin enhancement technique, Very-WideBand(VWB), and power consumption reducing technique, chirp UWB, are also introduced. Then, several potential applications of IR-UWB with transceiver architectures are addressed, including high data rate proximity communication and secure wireless connectivity. With fine-ranging and energy-efficient communication features, the UWB wireless technology is highly promising for secure mobile Internet of Things(IoT) applications.
