第一性原理研究锂修饰的类石墨烯碳氮纳米结构的储氢性能

利用基于密度泛函理论的第一性原理方法,研究了锂修饰的类石墨烯碳氮纳米结构的储氢性能.结果表明该体系是一种理想的储氢材料,锂原子通过向衬底转移电荷而带正电,通过静电场的极化作用,每个锂原子可以吸附3个氢分子,其储氢的质量比可达11.5 wt%.氢分子的平均吸附能比较理想,可以实现在室温下可逆的储氢和放氢.     

微晶碳在镁基复合储氢材料中的作用

为了提高金属镁的放氢动力学性能,将无烟煤经脱灰并碳化后制得的微晶碳添加到镁粉中,用氢气反应球磨法一步制得高性能镁碳复合储氢材料。用X射线衍射和红外光谱对微晶碳的结构进行了表征,用透射电镜、引射线能谱、粉末X射线衍射对储氢材料的结构进行了测试,用差示扫描量热分析和P—C-T分析对材料的储氢性能进行了研究。结果表明,微晶碳具有类石墨晶体结构,对镁有良好的助磨作用,并与镁有协同吸氢和放氢作用。镁粉中添加40％微晶碳,球磨2h的粒度即可达到30-50nm,储氢材料的初始放氢温度可低至227.4℃,储氢密度可达6.7％。     

液相有机氢载体的催化研究与应用

氢能清洁高效、能量密度高，是理想的能源载体，也是公认的未来能源发展方向之一。氢气的存储是氢能利用的关键环节，目前仍没有完美适配所有场景的储氢材料，储氢技术的选择势必要以使用场景为导向。液相有机氢载体（liquid organic hydrogen carriers，LOHCs）作为一种液相储氢材料，在运输方面具有独特的应用优势。本文介绍了常见的液相有机储氢材料，重点探讨了适用于运输工具（车、船、航空器等）的LOHCs，综述其加氢/脱氢的催化研究进展、应用技术难点，并展望了其应用前景。     

碳基储氢材料研究进展

氢能以其可再生性和环境友好性成为未来最具发展潜力的能源载体，储氢技术是氢能应用中的关键问题。本文综述了近年来超级活性炭、石墨纳米纤维、碳纳米纤维和碳纳米管等碳基储氢材料的研究进展，并对该领域未来的研究工作进行了展望。     

氮化碳材料的研究进展

氮化碳材料是通过理论计算设计的化合物材料,其研究在科学和技术上具有重大意义,是凝聚态物理学和材料科学研究的热点之一.本文总结了氮化碳材料的结构预测、表征、合成的研究进展,并且讨论了这类材料的性能,尤其是电导率的研究现状.     

Functionalization of graphene materials by heteroatom-doping for energy conversion and storage

Recent development in nanoscience and nanotechnology has opened up new frontiers in materials science and engineering to create new materials for energy generation and storage. Owing to their earth abundance, low-cost, structural tunability, large-surface area, and unique physicochemical properties, graphitic carbon materials have attracted a great deal of attention for energy-related applications. However, the pristine graphene materials without functionalization is intractable (insoluble and infusible), which has hindered their practical applications. Therefore, considerable research effort has been devoted to the development of functionalized graphene materials with desirable properties for specific applications, including energy conversion and storage. It was demonstrated that functionalized graphene materials with tunable work functions were useful as charge-extraction materials to effectively improve solar cell performance while those with high electrocatalytic activities could be used as metal-free catalysts in fuel cells, metal-air batteries, water splitting and integrated energy systems. This article provides a timely focused review on the development of heteroatom-doped graphene materials for low-cost, but efficient, energy generation and storage.     

BCN薄膜的硬度和剩余应力的研究

类金刚石结构的立方“BCN”材料由于兼有金刚石和立方氮化硼超硬、低摩擦的优点, 如有低摩抗磨、高的热稳定性和化学稳定性,并克服了它们的缺点,因而BCN薄膜材料被作为耐磨保护层,在电学、光学方面的性能也得到广泛应用。应用反应磁控溅射法将高质量的BCN 薄膜沉淀在硅基底上,通过用微压痕测量和弯曲技术研究了他们硬度和剩余应力,发现施于薄膜沉淀物上的偏压对其硬度和剩余应力均有重要影响。     

Electrochemical hydrogen storage of aligned multiwalled carbon nanotubes

Hydrogen storage of aligned multi-walled carbon nanotubes (a-MWNTs),non-aligned MWNTs(n-MWNTs) and graphite electrodes are studied by the electro-chemical measurements .The electrodes are prepared by mixing carbon nanotubes (CNTs) copper powder and ptfe binder in a weight ratio of 1:5:3 and compressing the mixture into porous nickel collector,The results show that the electrochemical hydrogen storage capacity of the a-MWNT electrode is up to 1625 mAh/g corresponding to a high hydrogen storage of 5.7 wt% ,which is 10 times that of graphite electrode and is 13 times that of n-MWNT electrode, suggesting that a-MWNTs are promising materials for electrochemical hydrogen storage.     

碳纳米管的电化学储氢

用电化学方法使碳纳米管储氢,是把碳纳米管当作储氢负极,形成Ni MH电池·用碳纳米管与镍纳米粉做成负极试样,电解液采用KOH溶液·实验中,对Ni MH电池充放电的50个循环进行测试,通过测量电池的充放电容量和能量,来测量碳纳米管的储氢性能·测试过程由Arbin公司的BF 2043系列电池测试系统控制·实验表明,相对每克碳纳米管,当充电电流为120mA时,电池容量可达126 368mA·h·g-1,而且电池放电非常平稳,放电平台利用率高达97%·可见,碳纳米管是一种很有前途的储氢材料·本研究对利用碳纳米管制做储氢电池提供了实验依据·     

MXenes电催化析氢的研究进展

面向“碳达峰”“碳中和”国家重大战略,氢能作为一种能量密度高、无污染的绿色能源,将成为我国乃至世界未来能源战略领域发展的重中之重.电解水制氢由于其制备方法简单、制氢纯度高、制备过程无污染等优势而备受关注,但是该方法存在一个严重的缺陷,就是缺乏低成本、高效率析氢反应(HER)催化剂.MXenes是一种新兴的二维(2D)过渡金属碳化物、氮化物和碳氮化物,由于其具有极好的导电性、良好的亲水性、极大的比表面积、可调节的分子结构及多样的化学组成等优势,在析氢催化剂领域存在着潜在的巨大应用.该文总结了 MXenes制备、MXenes基电催化析氢性能调控策略及利用机器学习设计MXenes基析氢电催化剂面临的挑战和新的机遇.该文为今后开发新型高效的MXenes基析氢电催化剂,推动氢能的绿色制备提供了参考.     

Tuning clathrate hydrates for hydrogen storage

The storage of large quantities of hydrogen at safe pressures is a key factor in establishing a hydrogen-based economy. Previous strategies--where hydrogen has been bound chemically, adsorbed in materials with permanent void space or stored in hybrid materials that combine these elements--have problems arising from either technical considerations or materials cost. A recently reported clathrate hydrate of hydrogen exhibiting two different-sized cages does seem to meet the necessary storage requirements; however, the extreme pressures (approximately 2 kbar) required to produce the material make it impractical. The synthesis pressure can be decreased by filling the larger cavity with tetrahydrofuran (THF) to stabilize the material, but the potential storage capacity of the material is compromised with this approach. Here we report that hydrogen storage capacities in THF-containing binary-clathrate hydrates can be increased to approximately 4 wt% at modest pressures by tuning their composition to allow the hydrogen guests to enter both the larger and the smaller cages, while retaining low-pressure stability. The tuning mechanism is quite general and convenient, using water-soluble hydrate promoters and various small gaseous guests.     

Impact of supercritical adsorption mechanism on research of hydrogen carrier

Hydrogen storage receives the worldwide attention due to its importance in sustainable energy and the solution of greenhouse effect.Adsorption provides an efficient way to compress gases and,therefore, has been applied to the development of hydrogen storage technology.However,hydrogen is a super- critical gas at the temperature of engineering interest and follows a different adsorption mechanism compared to the sub-critical gases.The present work shows why only monolayer coverage mechanism functions at above-critical temperatures and what consequences will result in the application study. Although there are pros and cons to this point of view,understanding the adsorption mechanism is,in- deed,essential for the research of hydrogen storage method since it claims that any storage material based on adsorption will not satisfy the practical need of on board storage no matter how novel the material is.     

单壁氮化硼纳米管储氢的理论研究

采用蒙特卡罗方法模拟常温、中等压强下单壁氮化硼纳米管的储氢,重点研究了单壁氮化硼纳米管的管径、管长和手性以及压强对其物理吸附储氢的影响.与单壁碳纳米管的物理吸附储氢相比较,氮化硼纳米管的储氢性能明显优于碳纳米管.计算结果显示,在常温、中等压强下单壁氮化硼纳米管的物理吸附储氢量(质量百分数)可以达到美国能源部提出的商业标准.     

Hydrogen absorption-desorption cycle decay mechanism of palladium nanoparticle decorated nitrogen doped graphene

As a hydrogen storage material, palladium nanoparticle decorated nitrogen doped graphene (Pd/N-rGO) has drawn much attention owing to its high absorption capacity at moderate conditions. However, its hydrogen absorption-desorption cycle performance, which is essential for their practical application, has been rarely studied. In this paper, a simple and convenient high temperature thermal reduction method was used to synthesize nitrogen-doped graphene decorated with Pd nanoparticles (Pd/N-rGO). Taken it as a representative, the hydrogen absorption-desorption cycle performance of Pd/N-rGO was investigated. The results showed that after three cycles the hydrogen storage capacity dropped from 2.9 ​wt% to 0.8 ​wt% at 25 ​°C and 4 ​MPa pressure. It was found that the palladium nanoparticles shed from Pd/N-RGO sheet after cycle performance test, and then agglomerated. These phenomena will weaken the hydrogen spillover effect, leading to the decrease of hydrogen storage capacity. Meanwhile, decreased defects reduce the hydrogen absorption sites, which will thus deteriorate the hydrogen storage capacity.     

Recent advances in hydrogen storage technologies based on nanoporous carbon materials

Hydrogen is a promising energy carrier that can potentially facilitate a transition from fossil fuels to sustainable energy sources without producing harmful by-products. Prior to realizing a hydrogen economy, however, viable hydrogen storage materials must be developed. Physical adsorption in porous solids provides an opportunity for hydrogen storage under low-stringency conditions. Physically adsorbed hydrogen molecules are weakly bound to a surface and, hence, are easily released. Among the various surface candidates, porous carbons appear to provide efficient hydrogen storage, with the advantages that porous carbon is relatively low-cost to produce and is easily prepared. In this review, we summarize the preparation methods, pore characteristics, and hydrogen storage capacities of representative nanoporous carbons, including activated carbons, zeolite-templated carbon, and carbide-derived carbon. We focus particularly on a series of nanoporous carbons developed recently: metal–organic framework-derived carbons, which exhibit promising properties for use in hydrogen storage applications.     

镁基合金与碳纳米纤维复合储氢材料的制备与性能研究(Ⅰ)--以化学镀Ni碳纳米纤维为前驱物热扩散法合成Mg2Ni-CNFs复合储氢材料

利用金属Mg易热扩散制合金的特性，以化学镀Ni的碳纳米纤维(Ni-CNFs)为前驱物，制备出了Mg-Ni合金与CNFs的复合储氢材料．并测试了其电化学性能，提出了镁基储氢合金与CNFs复合储氢材料的储氢机理．     

Nanostructure designing and hybridizing of high-capacity silicon-based anode for lithium-ion batteries

Lithium-ion batteries have long been used in electronic products and electric vehicles, but their energy density is slowly failing to keep up with demand. Because of its extraordinarily high theoretical specific capacity, silicon is regarded as the most potential next-generation anode material for practical lithium-ion batteries. However, its unavoidable volume expansion issue can cause electrode deformation and loss of electrical contact during cycling,resulting in significant performance reduc...     

Ultrafastly activated needle coke as electrode material for supercapacitors

The uniform porous structure makes activated porous carbons (APCs) superior electrode material. Traditionally, APCs are produced by a combination of time-consuming high-temperature heat treatment and activation, with a production time of up to several hours. The produced APCs have relatively low specific surface area (SSA) and porosity. Therefore, the electrochemical performance is poor, which limits its application in high-power energy storage devices. Here, APCs materials are directly synthesized by a high temperature shock (HTS) strategy using needle coke as a precursor. The structure of as-prepared APC is characterized by XRD, SEM and Raman, and electrochemical tests confirmed its good electrochemical performance. In the two-electrode system, the supercapacitor with HTS-APC as the electrode material provides a high energy density of 35 ?Wh kg^?1 and a high power density of 875 ?W ?kg^?1 in EMIMBF₄ ionic liquid. This work is instructive for the rapid synthesis of electrode materials, and also provides guidance for the large-scale application of porous carbon materials.     

Porous graphene: Properties, preparation, and potential applications

Graphene has recently emerged as an important and exciting material.Inspired by its outstanding properties,many researchers have extensively studied graphene-related materials both experimentally and theoretically.Porous graphene is a collection of graphene-related materials with nanopores in the plane.Porous graphene exhibits properties distinct from those of graphene,and it has widespread potential applications in various fields such as gas separation,hydrogen storage,DNA sequencing,and supercapacitors.In this review,we summarize recent progress in studies of the properties,preparation,and potential applications of porous graphene,and show that porous graphene is a promising material with great potential for future development.     

CN_x薄膜的制备及电子结构

采用反应溅射方法制备了氮化碳薄膜,研究了反应气体压力、溅射功率对薄膜形成的影响,并用Ｘ射线电子能谱（ＸＰＳ） 和富里叶变换红外光谱（ＦＴＩＲ）对样品的电子结构进行了分析．结果表明：反应气体Ｎ２ 的压力太高或太低、溅射功率太大或太小,均不利于氮化碳膜的形成;在Ｎ２ 压力为８ Ｐａ、溅射功率为２００ Ｗ 时,薄膜的氮原子数分数得到最大值４１％ ;ＸＰＳ和ＦＴＩＲ分析结果揭示了膜中没有自由的Ｎ原子,所有的Ｎ原子均与Ｃ原子作用形成化学键,而且Ｃ Ｎ 单键、Ｃ Ｎ 双键、Ｃ Ｎ 三键共存．膜中Ｃ Ｈ 和Ｎ Ｈ 振动模式的存在,说明沉积在Ｓｉ 衬底上的氮化碳薄膜有较强的从空气中吸收氢的能力．