Cobalt-Encapsulated in Nitrogen-Doped Carbon Nanotubes Prepared by Hydrothermal Method as Catalyst for Hydrogen Evolution

Abstract

Cobalt-encapsulated in nitrogen-doped carbon nanotubes (Co-NCNT) were prepared by hydrothermal method. CoCl₂·6H₂O and graphitic carbon nitride (g-C₃N₄) were used as raw material. Samples containing such defective structures were synthesized by hydrothermal methods, while there is an excellent synergistic effect between cobalt nanoparticles and carbon nanotubes on hydrogen evolution reaction (HER). In order to improving the HER performance, different samples were fabricated by changing the molar ratio of raw materials and pyrolysis temperature. The results show that Co-NCNT has the best HER performances at the ratio of CoCl₂·6H₂O and g-C₃N₄ (1:7) when the pyrolysis temperature reached 700?°C. The overpotential has reached 285?mV when the current density is 10?mA·cm^?2, the Tafel slope of the sample is 103?mV·dec^?1.     

关于建设海绵城市的思考

习近平总书记在中央城镇化工作会议上指出"城市规划建设的每个细节都要考虑对自然的影响,更不要打破自然系统。"为什么这么多城市缺水?一个重要原因就是水泥地太多,把能够涵养水源的林地、草地、湖泊、湿地给占用了,切断了自然的水循环,雨水来了,只能当作污水排走,地下水越抽越少。解决城市缺水问题,必须顺应自然。比如,在提升城市排水系统时要优先考虑把有限的雨水留下来,优先考虑更多利用自然力量排水,建设自然储存、自然渗透、自然     

Evaluation of solar temperature field under different wind speeds for Shanghai 65 m radio telescope

The Shanghai 65 m radio telescope is currently the largest full range rotatable radio telescope in Asia. Gravity, wind and temperature are the three main factors which may have a bad effect on the reflector’s surface precision. To study the effect of the thermal deformation caused by daily non-uniform temperature fields on the surface precision of the main reflector, both the temperature field and its effect were studied in detail for two typical days (January 15th and July 15th). The method to simulate temperature fields was studied initially, considering heat conduction, solar radiation, shadowing, air convection, sky radiation and ground radiation. Then, an integral parametric thermal finite element model (FEM) of the telescope was established using the ANSYS thermal analysis module. Finally, the effect of non-uniform temperature fields on the surface precision of the main reflector was estimated in terms of the Root Mean Square (RMS) deformation based on temperature transient analysis. The proposed methods and conclusions drawn can provide valuable information for thermal design, thermal monitoring and thermal control of the Shanghai 65 m radio telescope and other similar giant antenna structures.     

钼及La_2O_3对激光原位合成TiC-VC颗粒增强镍基复合涂层组织和性能的影响

研究添加钼粉及稀土氧化物La_2O_3对Km TBCr15Mo高铬铸铁表面激光原位合成TiC-VC颗粒增强镍基复合涂层组织及耐磨性的影响,分析钼及La_2O_3的作用机理。结果表明,熔覆层无裂纹且组织致密,熔覆层的组织主要由(Fe,Ni)固溶体,细小颗粒状或树枝状TiC-VC复合碳化物组成。随着钼粉的加入,熔覆层的组织更为均匀,钼元素起到细化晶粒的作用,使弥散分布的TiC、VC颗粒难以聚集长大。随着La_2O_3的加入,熔覆层的形核核心增多,更多的雪花状TiC-VC弥散分布于熔覆层组织中。由于钼具有较强的碳化物形成能力以及对显微组织起到晶粒细化作用,La_2O_3对显微组织的细化及涂层的净化具有较大作用,因此适当的钼粉(5%)或稀土La2O3能提高熔覆层的硬度及耐磨性。     

技改工程桩基设计探讨

以上海某在产炼钢厂增建300 t LF炉工程桩基设计及其施工实践为例,探讨了在受到拟建场地环境狭小、工程地质条件差、桩基施工对在产厂房结构产生不利影响等特定条件下桩基设计及施工应重视的问题,可供类似工程项目借鉴。     

公路沥青路面大修方案实例

沥青路面大修方案的制定是一项系统工程,是在对原路面状况进行检测、调查和评估的基础上制定的。以某沥青公路路面大修工程为例,从沥青路面养护标准、路面使用性能评价及大修养护对策等方面着手,分析了公路沥青路面大修养护中的关键点。     

城市污水处理厂生物气应用安全性分析

厌氧污泥生物气的应用能够节约能源、降低环境污染,但在其应用过程中可能由于各种因素的共同作用而引发一定的安全隐患。结合石家庄市桥东污水处理厂生物气应用实例,分析了运行中出现的事故隐患成因及危害,有针对性地提出了解决的措施。     

艺术，让城市更美好--遵循艺术方式建设城市人居软环境探索

衡量一座城市是否宜居,不仅要看它的硬环境,同时还要看它的软环境。软环境作为人居环境大系统的组成部分,对于改善城市形象,提升城市品质,创造宜居生活均有十分重要的意义。从世界人居环境发展的趋势来看,软环境建设已成为各国关注的焦点。文章通过对我国人居软环境建设问题的分析,进而提出艺术介入人居软环境建设的必要性以及发展建议,以期能为我国当前的城市人居环境建设提供有益的参考或借鉴。     

浅谈施工过程中建设单位对变更费用的控制

作为一个现场管理人员,施工过程变更费用的控制至关重要。本文对施工过程中工程变更的主要类型及成因、变更费用的确定,管理过程应注意的问题、变更控制程序等方面进行了经验论述,以供读者参考。     

浅谈生态理念下的园林景观设计

如何正确认识园林景观设计在社会生活中所起到的重要作用,使其应具有的社会价值得到最大程度发挥,是当前园林景观设计单位所面临的重要课题。