IEEE1588定义了一种精准时钟同步协议(PTP),因其具有高同步精度,故逐渐取代传统的NTP(Network Time Protocol)被广泛应用于更高时钟同步精度的分布式测控系统中。PTP协议可以通过纯硬件或纯软件方式实现,纯硬件方式通过硬件编程实现,同...IEEE1588定义了一种精准时钟同步协议(PTP),因其具有高同步精度,故逐渐取代传统的NTP(Network Time Protocol)被广泛应用于更高时钟同步精度的分布式测控系统中。PTP协议可以通过纯硬件或纯软件方式实现,纯硬件方式通过硬件编程实现,同步精度可达纳秒量级,但是开发难度大;而纯软件实现的PTP利用协议实现完整的开源代码PTPd实现,开发难度较低,同步精度略低于纯硬件实现的PTP协议。文中在深入比较、分析了IEEE1588协议与NTP的同步机理后,并对纯软件实现的PTP(PTPd)进行同步精度测试。结果表明,PTPd的同步精度可达±10μs,远优于传统的NTP同步协议±200 ms的同步精度,而被成功应用于载人航天嵌入式软件第三方评测分布式测试系统中。展开更多
PtPd bimetallic alloy nanoparticle (NP)-modified graphitic carbon nitride (g-C3N4) nanosheet photocatalysts were synthesized via chemical deposition precipitation. Characterization of the photocatalytic H2 evolution o...PtPd bimetallic alloy nanoparticle (NP)-modified graphitic carbon nitride (g-C3N4) nanosheet photocatalysts were synthesized via chemical deposition precipitation. Characterization of the photocatalytic H2 evolution of the g-C3N4 nanosheets shows that it was significantly enhanced when PtPd alloy NPs were introduced as a co-catalyst. The 0.2 wt% PtPd/g-C3N4 composite photocatalyst gave a maximum H2 production rate of 1600.8 μmol g^–1 h^–1. Furthermore, when K2HPO4 was added to the reaction system, the H2 production rate increased to 2885.0 μmol g^–1 h^–1. The PtPd/g-C3N4 photocatalyst showed satisfactory photocatalytic stability and was able to maintain most of its photocatalytic activity after four experimental photocatalytic cycles. In addition, a possible mechanism for the enhanced photocatalytic activity was proposed and verified by various photoelectric techniques. These results demonstrate that the synergistic effect between PtPd and g-C3N4 helps to greatly improve the photocatalytic activity of the composite photocatalyst.展开更多
Different components of PtPd bimetallic cocatalysts modified Zn_(0.5)Cd_(0.5)S nanorods have already been designed and prepared in this study.The obtained hybrid photocatalysts were tested and characterized by XPS,ICP...Different components of PtPd bimetallic cocatalysts modified Zn_(0.5)Cd_(0.5)S nanorods have already been designed and prepared in this study.The obtained hybrid photocatalysts were tested and characterized by XPS,ICP-OES and UV-Vis spectra,TEM and EDX tools.Such characterizations can prove the formation of PtPd bimetallic alloy particles in hybrid catalysts.Under visible light illumination,an outstanding hydrogen producing rate of 9.689mmol·g^(-1)·h^(-1) and a high AQY efficiency up to 10.43%at 420 nm are achieved in this work.In addition,thermodynamics(DFT calculations)and kinetics(Photoluminescence emission,photocurrent responses,electrochemical impedance spectroscopy and surface photovoltage spectra)investigations illustrate that PtPd bimetallic alloy has similar catalytic thermodynamic properties to Pt,which can greatly boost the charge separation and speed up the charge transfer,and decrease the activation energy of H2 generation.Notably,the calculation data suggests that Pt is thermodynamically favorable,while PtPd alloy is kinetically beneficial to H_(2)production,which can be ascribed to the higher activity of PtPd/Zn_(0.5)Cd_(0.5)S than Pt/Zn_(0.5)Cd_(0.5)S.This work can propose a fresh perspective for preparing high efficiency hybrid photocatalysts.展开更多
Nanometer scale thin film material of PtPd alloy supported on glassy carbon (nm-PtPd/GC) was prepared by the electrochemical codeposition method under cyclic voltammetric conditions. STM patterns demonstrated that the...Nanometer scale thin film material of PtPd alloy supported on glassy carbon (nm-PtPd/GC) was prepared by the electrochemical codeposition method under cyclic voltammetric conditions. STM patterns demonstrated that the prepared thin films are composed of layered crystallites in elliptic form. Electrochemical in situ FTIRS studies explored the abnormal infrared effects (AIREs) of nm-PtPd/GC for CO adsorption, which are (i) the remarkable enhancement of IR absorption, (ii) the inversion of COad band direction, and (iii) notable increase in the full width at half maximum (FWHM) of COad bands. The results demonstrated also that the enhancement factor of IR absorption varies with the thickness of PtPd alloy film and has reached a maximum value of 38.3 under the experimental conditions.展开更多
文摘IEEE1588定义了一种精准时钟同步协议(PTP),因其具有高同步精度,故逐渐取代传统的NTP(Network Time Protocol)被广泛应用于更高时钟同步精度的分布式测控系统中。PTP协议可以通过纯硬件或纯软件方式实现,纯硬件方式通过硬件编程实现,同步精度可达纳秒量级,但是开发难度大;而纯软件实现的PTP利用协议实现完整的开源代码PTPd实现,开发难度较低,同步精度略低于纯硬件实现的PTP协议。文中在深入比较、分析了IEEE1588协议与NTP的同步机理后,并对纯软件实现的PTP(PTPd)进行同步精度测试。结果表明,PTPd的同步精度可达±10μs,远优于传统的NTP同步协议±200 ms的同步精度,而被成功应用于载人航天嵌入式软件第三方评测分布式测试系统中。
基金supported by the National Natural Science Foundation of China(51572295,21273285,21003157)the Beijing Nova Program(2008B76)the Science Foundation of China University of Petroleum Beijing(KYJJ2012-06-20 and 2462016YXBS05)~~
文摘PtPd bimetallic alloy nanoparticle (NP)-modified graphitic carbon nitride (g-C3N4) nanosheet photocatalysts were synthesized via chemical deposition precipitation. Characterization of the photocatalytic H2 evolution of the g-C3N4 nanosheets shows that it was significantly enhanced when PtPd alloy NPs were introduced as a co-catalyst. The 0.2 wt% PtPd/g-C3N4 composite photocatalyst gave a maximum H2 production rate of 1600.8 μmol g^–1 h^–1. Furthermore, when K2HPO4 was added to the reaction system, the H2 production rate increased to 2885.0 μmol g^–1 h^–1. The PtPd/g-C3N4 photocatalyst showed satisfactory photocatalytic stability and was able to maintain most of its photocatalytic activity after four experimental photocatalytic cycles. In addition, a possible mechanism for the enhanced photocatalytic activity was proposed and verified by various photoelectric techniques. These results demonstrate that the synergistic effect between PtPd and g-C3N4 helps to greatly improve the photocatalytic activity of the composite photocatalyst.
文摘Different components of PtPd bimetallic cocatalysts modified Zn_(0.5)Cd_(0.5)S nanorods have already been designed and prepared in this study.The obtained hybrid photocatalysts were tested and characterized by XPS,ICP-OES and UV-Vis spectra,TEM and EDX tools.Such characterizations can prove the formation of PtPd bimetallic alloy particles in hybrid catalysts.Under visible light illumination,an outstanding hydrogen producing rate of 9.689mmol·g^(-1)·h^(-1) and a high AQY efficiency up to 10.43%at 420 nm are achieved in this work.In addition,thermodynamics(DFT calculations)and kinetics(Photoluminescence emission,photocurrent responses,electrochemical impedance spectroscopy and surface photovoltage spectra)investigations illustrate that PtPd bimetallic alloy has similar catalytic thermodynamic properties to Pt,which can greatly boost the charge separation and speed up the charge transfer,and decrease the activation energy of H2 generation.Notably,the calculation data suggests that Pt is thermodynamically favorable,while PtPd alloy is kinetically beneficial to H_(2)production,which can be ascribed to the higher activity of PtPd/Zn_(0.5)Cd_(0.5)S than Pt/Zn_(0.5)Cd_(0.5)S.This work can propose a fresh perspective for preparing high efficiency hybrid photocatalysts.
基金the National Naturalscience Foundation of China (Grant Nos. 29833060 and 29525307) and the Ministry of Education of China (Grant Nos. 1999038403 and 99177).
文摘Nanometer scale thin film material of PtPd alloy supported on glassy carbon (nm-PtPd/GC) was prepared by the electrochemical codeposition method under cyclic voltammetric conditions. STM patterns demonstrated that the prepared thin films are composed of layered crystallites in elliptic form. Electrochemical in situ FTIRS studies explored the abnormal infrared effects (AIREs) of nm-PtPd/GC for CO adsorption, which are (i) the remarkable enhancement of IR absorption, (ii) the inversion of COad band direction, and (iii) notable increase in the full width at half maximum (FWHM) of COad bands. The results demonstrated also that the enhancement factor of IR absorption varies with the thickness of PtPd alloy film and has reached a maximum value of 38.3 under the experimental conditions.
