CaN nanorods are successfully fabricated by adjusting the flow rate ratio of hydrogen （H2）/nitrogen （N2） and growth temperature of the selective area growth （SAG） method with metal organic chemical vapor deposit...CaN nanorods are successfully fabricated by adjusting the flow rate ratio of hydrogen （H2）/nitrogen （N2） and growth temperature of the selective area growth （SAG） method with metal organic chemical vapor deposition （MOCVD）. The SAG template is obtained by nanospherical-lens photolithography. It is found that increasing the flow rate of 1-12 will change the CaN crystal shape from pyramid to vertical rod, while increasing the growth temperature will reduce the diameters of GaN rods to nanometer scale. Finally the CaN nanorods with smooth lateral surface and relatively good quality are obtained under the condition that the H2：N2 ratio is 1：1 and the growth temperature is 1030℃. The good crystal quality and orientation of GaN nanorods are confirmed by high resolution transmission electron microscopy. The cathodoluminescence spectrum suggests that the crystal and optical quality is also improved with increasing the temperature.展开更多
Hydrogenated microcrystalline silicon(μc-Si:H)films were prepared on glass and silicon substrates by radio frequency magnetron sputtering at 100°C using a mixture of argon(Ar)and hydrogen(H2)gasses as precursor ...Hydrogenated microcrystalline silicon(μc-Si:H)films were prepared on glass and silicon substrates by radio frequency magnetron sputtering at 100°C using a mixture of argon(Ar)and hydrogen(H2)gasses as precursor gas.The effects of the ratio of hydrogen flow(H2/(Ar+H2)%)on the microstructure were evaluated.Results show that the microstructure,bonding structure,and surface morphology of theμc-Si:H films can be tailored based on the ratio of hydrogen flow.An amorphous to crystalline phase transition occurred when the ratio of hydrogen flow increased up to 50%.The crystallinity increased and tended to stabilize with the increase in ratio of hydrogen flow from 40%to 70%.The surface roughness of thin films increased,and total hydrogen content decreased as the ratio of hydrogen flow increased.Allμc-Si:H films have a preferred(111)orientation,independent of the ratio of hydrogen flow.And theμc-Si:H films had a dense structure,which shows their excellent resistance to post-oxidation.展开更多
This paper addresses the damaging role of the parasitic hydrogen evolution reaction (HER) in the negative half-cell of a vanadium redox flow battery (VRFB) on state-of-the-art carbon felt electrodes at different tempe...This paper addresses the damaging role of the parasitic hydrogen evolution reaction (HER) in the negative half-cell of a vanadium redox flow battery (VRFB) on state-of-the-art carbon felt electrodes at different temperatures. It was found that increasing the temperature resulted in a better catalytic performance for both the positive and negative half-cell reactions. In addition, increasing the temperature significantly enhanced the undesired HER at the negative side. Operating the VRFB cell at higher temperature led to a decrease in the coulombic efficiency attributed to the higher hydrogen production. More pronounced hydrogen production caused an oxidation on the surface of the carb on fibers and a degradation of the electrode as indicated from scanning electron microscopy and X-ray photoelectron spectroscopy measurements. This observed degradation results in fading of the overall performance of the vanadium redox flow battery over time.展开更多
为实现“双碳”目标,综合能源系统(integrated energy systems, IES)成为了近几年的重要研究方向之一,然而传统的IES能流计算已经无法精确地反映电制气(power-to-gas, P2G)技术带来的氢气注入天然气网络后的混合燃气的参数变化对IES的...为实现“双碳”目标,综合能源系统(integrated energy systems, IES)成为了近几年的重要研究方向之一,然而传统的IES能流计算已经无法精确地反映电制气(power-to-gas, P2G)技术带来的氢气注入天然气网络后的混合燃气的参数变化对IES的影响。为此,在传统天然气系统稳态分析方法的基础上加入了SRK(Soawk-Redlich-Kwong)气体状态方程,将压缩因子作为状态变量,提出可以反映氢气注入天然气系统,对气体流量和混合燃气热值产生影响的稳态分析方法。以此为基础,提出了计及氢气注入与压缩因子的电-热-气IES能流分解求解计算方法。最后通过算例验证了所提方法可有效反映混合燃气的参数变化对IES的影响。展开更多
氢和氨作为清洁能源受到广泛关注,为深入探究氢-氨混燃的燃烧特性和影响因素,本文借助Chemkin仿真平台建立相关反应模型,以氢-氨混合气体为燃料,空气作为助燃剂,采用Otomo等人提出的一种氨氧化机理对其燃烧过程进行模拟计算,并模拟研究...氢和氨作为清洁能源受到广泛关注,为深入探究氢-氨混燃的燃烧特性和影响因素,本文借助Chemkin仿真平台建立相关反应模型,以氢-氨混合气体为燃料,空气作为助燃剂,采用Otomo等人提出的一种氨氧化机理对其燃烧过程进行模拟计算,并模拟研究了混合气体的点火延迟时间、层流燃烧速度、绝热燃烧温度、NO排放等燃烧特性随当量比、初始压力以及燃料中H_(2)比例的具体变化规律,对不同工况下的层流火焰结构、H和OH自由基的产率(rate of production,ROP)、NO生成的敏感度进行了化学动力学分析。结果表明:纯氨气体的点火延迟时间长、层流燃烧速度慢,掺氢后燃烧特性均有所改善,且提高了火焰的绝热燃烧温度,但掺氢比例越大,NO排放越多。NO摩尔分数随当量比变化的趋势先增后减,在当量比为0.8左右达到峰值。综合考虑氢-氨混燃的一系列燃烧特性以及掺氢、加压的成本和收益情况,推荐H_(2)占比15%、当量比φ=1.1、压力P=0.2 MPa为氢-氨混合燃烧的最优条件。展开更多
氢是推动海上水、风、光、电资源清洁高效利用的理想媒介,构建深海氢能产业体系对保障能源的供应安全、实现“双碳”目标、促进能源领域企业转型升级具有重要意义。为了开展氢能等海上新能源的实验教学活动,加深学生对机械设计基础(含...氢是推动海上水、风、光、电资源清洁高效利用的理想媒介,构建深海氢能产业体系对保障能源的供应安全、实现“双碳”目标、促进能源领域企业转型升级具有重要意义。为了开展氢能等海上新能源的实验教学活动,加深学生对机械设计基础(含课程设计)、流体力学(含实验)、氢能及新型能源动力系统、氢能存储与利用等专业课程内容的掌握,该文设计了应用于海上氢气液化系统(liquid hydrogen floating production storage and offloading unit,FLH2)的浮式多孔介质通道内外流动实验装置,包括浮式通道内多孔介质流动阻力测试实验装置与浮式通道外降膜流动测试实验装置两个部分。该装置具有较好的实验教学效果,可提升学生的工程实践能力和研究海洋能源高效利用领域的创新能力,拓展学生在深海氢能储运方面的知识储备。展开更多
基金Supported by the Key Program of the National Natural Science Foundation of China under Grant No 61334009the National High Technology Research and Development Program of China under Grant No 2014AA032604
文摘CaN nanorods are successfully fabricated by adjusting the flow rate ratio of hydrogen （H2）/nitrogen （N2） and growth temperature of the selective area growth （SAG） method with metal organic chemical vapor deposition （MOCVD）. The SAG template is obtained by nanospherical-lens photolithography. It is found that increasing the flow rate of 1-12 will change the CaN crystal shape from pyramid to vertical rod, while increasing the growth temperature will reduce the diameters of GaN rods to nanometer scale. Finally the CaN nanorods with smooth lateral surface and relatively good quality are obtained under the condition that the H2：N2 ratio is 1：1 and the growth temperature is 1030℃. The good crystal quality and orientation of GaN nanorods are confirmed by high resolution transmission electron microscopy. The cathodoluminescence spectrum suggests that the crystal and optical quality is also improved with increasing the temperature.
基金Projects(51505050,51805063) supported by the National Natural Science Foundation of China for Young ScholarsProjects(KJ1500942,KJQN201801134) supported by the Scientific and Technological Research Program of Chongqing Education Commission of ChinaProjects(cstc2017jcyjAX0075,cstc2015jcyj A50033) supported by the Chongqing Research Program of Basic Research and Frontier Technology,China
文摘Hydrogenated microcrystalline silicon(μc-Si:H)films were prepared on glass and silicon substrates by radio frequency magnetron sputtering at 100°C using a mixture of argon(Ar)and hydrogen(H2)gasses as precursor gas.The effects of the ratio of hydrogen flow(H2/(Ar+H2)%)on the microstructure were evaluated.Results show that the microstructure,bonding structure,and surface morphology of theμc-Si:H films can be tailored based on the ratio of hydrogen flow.An amorphous to crystalline phase transition occurred when the ratio of hydrogen flow increased up to 50%.The crystallinity increased and tended to stabilize with the increase in ratio of hydrogen flow from 40%to 70%.The surface roughness of thin films increased,and total hydrogen content decreased as the ratio of hydrogen flow increased.Allμc-Si:H films have a preferred(111)orientation,independent of the ratio of hydrogen flow.And theμc-Si:H films had a dense structure,which shows their excellent resistance to post-oxidation.
基金a fellowship from the Alexander von Humboldt Foundation (AvH)
文摘This paper addresses the damaging role of the parasitic hydrogen evolution reaction (HER) in the negative half-cell of a vanadium redox flow battery (VRFB) on state-of-the-art carbon felt electrodes at different temperatures. It was found that increasing the temperature resulted in a better catalytic performance for both the positive and negative half-cell reactions. In addition, increasing the temperature significantly enhanced the undesired HER at the negative side. Operating the VRFB cell at higher temperature led to a decrease in the coulombic efficiency attributed to the higher hydrogen production. More pronounced hydrogen production caused an oxidation on the surface of the carb on fibers and a degradation of the electrode as indicated from scanning electron microscopy and X-ray photoelectron spectroscopy measurements. This observed degradation results in fading of the overall performance of the vanadium redox flow battery over time.
文摘为实现“双碳”目标,综合能源系统(integrated energy systems, IES)成为了近几年的重要研究方向之一,然而传统的IES能流计算已经无法精确地反映电制气(power-to-gas, P2G)技术带来的氢气注入天然气网络后的混合燃气的参数变化对IES的影响。为此,在传统天然气系统稳态分析方法的基础上加入了SRK(Soawk-Redlich-Kwong)气体状态方程,将压缩因子作为状态变量,提出可以反映氢气注入天然气系统,对气体流量和混合燃气热值产生影响的稳态分析方法。以此为基础,提出了计及氢气注入与压缩因子的电-热-气IES能流分解求解计算方法。最后通过算例验证了所提方法可有效反映混合燃气的参数变化对IES的影响。
文摘氢和氨作为清洁能源受到广泛关注,为深入探究氢-氨混燃的燃烧特性和影响因素,本文借助Chemkin仿真平台建立相关反应模型,以氢-氨混合气体为燃料,空气作为助燃剂,采用Otomo等人提出的一种氨氧化机理对其燃烧过程进行模拟计算,并模拟研究了混合气体的点火延迟时间、层流燃烧速度、绝热燃烧温度、NO排放等燃烧特性随当量比、初始压力以及燃料中H_(2)比例的具体变化规律,对不同工况下的层流火焰结构、H和OH自由基的产率(rate of production,ROP)、NO生成的敏感度进行了化学动力学分析。结果表明:纯氨气体的点火延迟时间长、层流燃烧速度慢,掺氢后燃烧特性均有所改善,且提高了火焰的绝热燃烧温度,但掺氢比例越大,NO排放越多。NO摩尔分数随当量比变化的趋势先增后减,在当量比为0.8左右达到峰值。综合考虑氢-氨混燃的一系列燃烧特性以及掺氢、加压的成本和收益情况,推荐H_(2)占比15%、当量比φ=1.1、压力P=0.2 MPa为氢-氨混合燃烧的最优条件。
文摘氢是推动海上水、风、光、电资源清洁高效利用的理想媒介,构建深海氢能产业体系对保障能源的供应安全、实现“双碳”目标、促进能源领域企业转型升级具有重要意义。为了开展氢能等海上新能源的实验教学活动,加深学生对机械设计基础(含课程设计)、流体力学(含实验)、氢能及新型能源动力系统、氢能存储与利用等专业课程内容的掌握,该文设计了应用于海上氢气液化系统(liquid hydrogen floating production storage and offloading unit,FLH2)的浮式多孔介质通道内外流动实验装置,包括浮式通道内多孔介质流动阻力测试实验装置与浮式通道外降膜流动测试实验装置两个部分。该装置具有较好的实验教学效果,可提升学生的工程实践能力和研究海洋能源高效利用领域的创新能力,拓展学生在深海氢能储运方面的知识储备。
