Nitrogen Doped Graphene as Potential Material for Hydrogen Storage

The nitrogen doped graphene was synthesized by hydrothermal route utilizing 2-Chloroethylamine hydrochloride as nitrogen precursor in the presence of graphene oxide (GO). Nitrogen-doped graphene material is developed for its application in hydrogen storage at room temperature. Nitrogen doped graphene layered material shows ~1.5 wt% hydrogen storage capacity achieved at room temperature and 90 bar pressure.

Tailoring local structures of atomically dispersed copper sites for highly selective CO_(2) electroreduction

Atomically‐dispersed copper sites coordinated with nitrogen‐doped carbon(Cu–N–C)can provide novel possibilities to enable highly selective and active electrochemical CO_(2) reduction reactions.However,the construction of optimal local electronic structures for nitrogen‐coordinated Cu sites(Cu–N_(4))on carbon remains challenging.Here,we synthesized the Cu–N–C catalysts with atomically‐dispersed edge‐hosted Cu–N_(4) sites(Cu–N_(4)C_(8))located in a micropore between two graphitic sheets via a facile method to control the concentration of metal precursor.Edge‐hosted Cu–N_(4)C_(8) catalysts outperformed the previously reported M–N–C catalysts for CO_(2)‐to‐CO conversion,achieving a maximum CO Faradaic efficiency(FECO)of 96%,a CO current density of–8.97 mA cm^(–2) at–0.8 V versus reversible hydrogen electrode(RHE),and over FECO of 90%from–0.6 to–1.0 V versus RHE.Computational studies revealed that the micropore of the graphitic layer in edge‐hosted Cu–N_(4)C_(8) sites causes the d‐orbital energy level of the Cu atom to shift upward,which in return decreases the occupancy of antibonding states in the*COOH binding.This research suggests new insights into tailoring the locally coordinated structure of the electrocatalyst at the atomic scale to achieve highly selective electrocatalytic reactions.

Enhanced Electrochemical Capacitance of Nitrogen-Doped Carbon Nanotubes Synthesized from Amine Flames

This paper presents a new process for synthesizing a kind of nitrogen- doped carbon nanotubes (N-CNTs) with primarily a ‘graphite-like’ structure at N substitutions from flames using n-propylamine and n-butylamine as fuels. When the N-CNTs are used as the supercapacitor electrode materials, they exhibit a much larger capacitance than the regular carbon nanotubes (CNTs). It is proposed that the high proportional ‘graphite-like’ N dopant in the as-grown N-CNTs improves their surface chemical activity and conductivity and then results in a desirable performance for electro-chemical capacitors.

Pyridinic nitrogen enriched porous carbon derived from bimetal organic frameworks for high capacity zinc ion hybrid capacitors with remarkable rate capability

Aqueous zinc ion hybrid capacitors(ZIHCs)hold great potential for large-scale energy storage applications owing to their high safety and low cost,but suffer from low capacity and energy density.Herein,pyridinic nitrogen enriched porous carbon(nPC)was successfully synthesized via the growth,subsequent annealing and acid etching of bimetal organic frameworks for high capacity and safe ZIHCs with exceptional rate capability.Benefiting from the mesopores for easy ion diffusion,high electrical conductivity enabled by in-situ grown carbon nanotubes matrix and residual metal Co nanoparticles for fast electron transfer,sufficient micropores and high N content(8.9 at%)with dominated pyridinic N(54%)for enhanced zinc ion storage,the resulting nPC cathodes for ZIHCs achieved high capacities of 302 and137 m Ah g^(-1) at 1 and 18 A g^(-1),outperforming most reported carbon based cathodes.Theoretical results further disclosed that pyridinic N possessed larger binding energy of-4.99 eV to chemically coordinate with Zn2+than other N species.Moreover,quasi-solid-state ZIHCs with gelatin based gel electrolytes exhibited high energy density of 157.6 Wh kg^(-1) at 0.69 kW kg^(-1),high safety and mechanical flexibility to withstand mechanical deformation and drilling.This strategy of developing pyridinic nitrogen enriched porous carbon will pave a new avenue to construct safe ZIHCs with high energy densities.

Sulfur-encapsulated in heteroatom-doped hierarchical porous carbon derived from goat hair for high performance lithium–sulfur batteries

Biomass-derived carbon materials have aroused widespread concern as host material of sulfur to enhance electrochemical performances for lithium–sulfur batteries. Herein, goat hair, as a low-cost and eco-friendly precursor, is employed to fabricate cauliflower-like in-situ nitrogen, oxygen and phosphorus tri-doped porous biomass carbon(NOPC) by a facile activation with H_3PO_4 and carbonization process.The morphology and microstructure of NOPC can be readily tuned by altering pyrolysis temperature. The as-prepared NOPC matrix material carbonized at 600 °C possesses 3D hierarchical porous structure, high specific surface area(535.352 m^2 g^(-1)), and appropriate pore size and pore size distribution. Encapsulating sulfur into the NOPC depends on a stem-melting technology as cathode materials of Li–S batteries. Due to the synergistic effect of special physical structure and inherent tri-doping of N, O and P, electrons and ions transfer and utilization of active sulfur in the materials are improved, and the shuttle behaviors of soluble lithium polysulfides are also mitigated. Consequently, the S/NOPC-600 composite exhibits excellent electrochemical performance, giving a high initial discharge capacity of 1185 mA h g^(-1) at 0.05 C and maintaining a relatively considerable capacity of 489 m A h g^(-1) at 0.2 C after 300 cycles. Our work shows that a promising candidate for cathode material of Li–S batteries can be synthesized using low-cost and renewable biomass materials by a facile process.

Low Temperature H_(2) Production from Formic Acid Aqueous Solution Catalyzed on Metal Doped Mo_(2)C

Hydrogen is recognized as a promising energy scours in the close future.Online hydrogen preparation from formic acid under mild reaction conditions causes extensive interests.Mo_(2)C and metal(Fe,Ni,Co,K)doped Mo_(2)C on granular activated carbon(GAC)were prepared and used as heterogeneous catalysts for H2 generation from formic acid on a fixed bed reactor at 100–250°C.The formic acid conversions on doped Mo_(2)C-Me/GAC are clearly improved,especially at lower reaction temperatures.Co doping presents outstanding effect on H2 selectivity and conversion rate compared to Ni and Fe.A 56.3%formic acid conversion was reached on Mo_(2)C-Co/GAC at 100°C,which triples that on Mo_(2)C/GAC at the same temperature.At 150°C,a high formic acid conversion over 90%was reached on Mo_(2)C-Co/GAC.These long lifetime catalysts with no precious metal provide a low cost route to hydrogen production from formic acid.

Preparation of nitrogen doped clews-like carbon materials and their application as the electrode in supercapacitor

In this work, nitrogen doped clews-like carbon materials were successfully fabricated through hydrothermal polymerization method, followed by post treatment that integrated the carbonization,activation and post-nitrogen doping into one process. This preparation method can form particular hierarchical porous structure without using any sacrificial templates. The experimental results show that the nitrogen doped clews-like hierarchical porous carbon materials possess a relatively high specific surface area of 815 m^2/g with the nitrogen content of 10.58 at%. The electrochemical properties show that the resulting sample delivers 258 F/g at a 0.5 A/g and excellent capacity retention of 79% at 20 A/g. After conducting 10,000 charge-discharge cycles at 10 A/g, the capacitance retention of 98.3% is achieved.These intriguing results demonstrate that the obtained nitrogen doped clews-like carbon materials will be promising electrode materials for supercapacitor and other energy storage devices.

Nitrogen-doped hierarchical porous carbon materials derived from diethylenetriaminepentaacetic acid (DTPA) for supercapacitors

Nitrogen-doped porous carbon materials（NPCs） have been successfully fabricated by a simple one-step pyrolysis of diethylenetriaminepentaacetic acid（DTPA） in the presence of KOH. The as-synthesized NPCs displayed a high specific surface area(3214 m;g;) and a well-defined porous structure when the annealing temperature reached 800 ℃, which showed superior electrochemical performance as supercapacitor electrode materials. Electrochemical tests showed that the NPCs achieved an impressive specific capacitance of 323 F g;at a current density of 0.5 A g;in 6 M KOH aqueous solution and an outstanding cycle stability, negligible specific capacitance decay after 5000 cycles at 10 A g;. This strategy offered a new insight into the preparation of novel carbon materials for the advanced energy storage devices, such as supercapacitors, fuel cells and lithium ion batteries.

Confined synthesis of MoS_(2) with rich co-doped edges for enhanced hydrogen evolution performance

Activating MoS_(2) with atomic metal doping is promising to harvest desirable Pt-matched hydrogen evolution reaction(HER)catalytic performance.Herein,we developed an efficient method to access edgerich lattice-distorted MoS_(2) for highly efficient HER via in-situ sulphuration of atomic Co/Mo species that were well-dispersed in a formamide-derived N-doped carbonaceous(f-NC)substrate.Apart from others,pre-embedding Co/Mo species in f-NC controls the release of metal sources upon annealing in S vapor,grafting the as-made MoS_(2) with merits of short-range crystallinity,distorted lattices,rich defects,and more edges exposed.The content of atomic Co species embedded in MoS_(2) reaches up to 2.85 at.%,and its atomic dispersion has been systematically confirmed by using XRD,HRTEM,XPS,and XAS characterizations.The Co-doped MoS_(2) sample exhibits excellent HER activity,achieving overpotentials of 67 and155 m V at j=10 m A cm^(-2) in 1.0 M KOH and 0.5 M H_(2)SO_(4),respectively.Density functional theory simulations suggest that,compared with free-doping MoS_(2),the edged Co doping is responsible for the significantly improved HER activity.Our method,in addition to providing reliable Pt-matched HER catalysts,may also inspire the general synthesis of edge-rich metal-doped metal chalcogenide for a wide range of energy conversion applications.

High lithiophilic nitrogen-doped carbon nanotube arrays prepared by in-situ catalyze for lithium metal anode

Lithium metal has a very outstanding theoretical capacity(3860 mAh/g)and is one of the most superior anode materials for high energy density batteries.However,the uncontrollable dendrite growth and the fo rmation of"dead lithium"are the important hidden dangers of short cycle life and low safety.However,the uncontrollable dendrite growth and the fo rmation of dead lithium leads to short cycle life and hidden dange r,which hinder its practical application.Controlling the nucleation and growth process of lithium is an effective strategy to inhibit lithium dendrite.Herein,a simple in situ self-catalytic method is used to construct nitrogen doped carbon nanotube arrays on stainless steel mesh(N-CNT@SS)as a lithium composite anode.The N-doped CNTs provide a great number of N-functional groups,which enhance the lithiophilic of anode and provide a large number of uniform nucleation sites,hence it has excellent structural stability for cycles.The arrays provide neat lithium-ion transport channels to uniform lithiumion flux and inhibits dendrite generation,revealed by the COMSOL multi-physics concentration field simulation.The N-CNT@SS composite anode sustain stable at 98.9%over 300 cycles at 1 mA/cm2.NCNT@SS as the anode is coupled LiFePO_(4)(LFP)as the cathode construct a full battery,demonstrating excellent cycling stability with a capacity of 152.33 mAh/g and capacity retaining ratio of 95.4%after 100 cycles at 0.5 C.

Cascading V_(2)O_(3)/N-doped carbon hybrid nanosheets as high-performance cathode materials for aqueous zinc-ion batteries

In recent years, especially when there is increasing concern about the safety issue of lithium-ion batteries (LIBs), aqueous Zn-ion batteries (ZIBs) have been getting a lot of attention because of their cost-effectiveness, materials abundance, high safety, and ecological friendliness. Their working voltage and specific capacity are mainly determined by their cathode materials. Vanadium oxides are promising cathode materials for aqueous ZIBs owing to their low cost, abundant resources, and multivalence. However, vanadium oxide cathodes still suffer from unsatisfactory capacity, poor stability, and low electrical conductivity. In this work, cascading V_(2)O_(3)/nitrogen doped carbon (V_(2)O_(3)/NC) hybrid nanosheets are prepared for high-performance aqueous ZIBs by pyrolyzing pentyl viologen dibromide (PV) intercalated V_(2)O5 nanosheets. The unique structure features of V_(2)O_(3)/NC nanosheets, including thin sheet-like morphology, small crystalline V_(2)O_(3) nanoparticles, and conductive NC layers, endow V_(2)O_(3)/NC with superior performance compared to most of the reported vanadium oxide cathode materials for aqueous ZIBs. The V_(2)O_(3)/NC cathode exhibits the discharge capacity of 405 mAh/g at 0.5 A/g, excellent rate capability (159 mAh/g at 20 A/g), and outstanding cycling stability with 90% capacity retention over 4000 cycles at 20 A/g.

氮掺杂淀粉基硬碳负极材料制备及其储钠性能研究

钠离子电池(sodium-ion batteries,SIBs)作为未来极具竞争力的大型储能装置之一,由于没有合适的负极材料,其商业化应用受到严重阻碍,因此,开发新型高性能SIBs负极材料是目前亟待解决的问题之一。硬碳材料由于来源丰富和成本低廉受到广泛关注,使用马铃薯淀粉为前驱体,采用不同的氮源对马铃薯淀粉进行掺杂改性,从而制备出氮掺杂硬碳材料。测试结果表明氮掺杂硬碳材料相比于未掺杂改性材料,其电化学性能显著提高。以二氰二胺为氮源掺杂的硬碳材料在0.1 A/g的电流密度下循环100圈后,仍能保持220.47 mA·h/g的可逆比容量,以尿素为氮源的硬碳材料能保持233.36 mA·h/g可逆比容量。结果表明,氮元素的掺杂可以有效地提升硬碳材料的离子电导率、增加硬碳材料的可逆比容量,从而整体提升硬碳材料的电化学性能。

Wear-resistant Ag-MAX phase 3D interpenetrating-phase composites:Processing,structure,and properties

Electrical contact materials are generally Ag-or Cu-based composites and play a critical role in ensuring the reliability and efficiency of electrical equipments and electronic instruments.The MAX(M is an early transition metal,A is an element from III or IV main groups,and X is carbon or/and nitrogen)phase ceramics display a unique combination of properties and may serve as an ideal reinforcement phase for electrical contact materials.The biological materials evolved in nature generally exhibit three-dimensional(3D)interpenetrating-phase architectures,which may offer useful inspiration for the architectural design of electrical contact materials.Here,a series of bi-continuous Ag-Ti_(3)SiC_(2) MAX phase composites with high ceramic contents exceeding 50 vol.%and having micron-and ultrafine-scaled 3D interpenetrating-phase architectures,wherein both constituents were continuous and mutually interspersed,were exploited by pressureless infiltration of Ag melt into partially sintered Ti_(3)SiC_(2) scaffolds.The mechanical and electrical properties as well as the friction and wear performance of the composites were investigated and revealed to be closely dependent on the ceramic contents and characteristic structural dimensions.The composites exhibited a good combination of properties with high hardness over 2.3 GPa,high flexural strength exceeding 530 MPa,decent fracture toughness over 10 MPa·m^(1/2),and good wear resistance with low wear rate at an order of 10^(-5)mm^(3)/(N·m),which were much superior compared to the counterparts made by powder metallurgy methods.In particular,the hardness,electrical conductivity,strength,and fracture toughness of the composites demonstrated a simultaneous improvement as the structure was refined from micron-to ultrafine-scales at equivalent ceramic contents.The good combination of properties along with the facile processing route makes the Ag-Ti_(3)SiC_(2)3D interpenetrating-phase composites appealing for electrical contact applications.

氮掺杂碳材料MG-T多相催化硝基苯加氢制苯胺

苯胺作为重要的化学中间体,主要通过催化硝基苯加氢反应制备.本文利用三聚氰胺和三聚氰酸制备牺牲模板MCA,以葡萄糖为碳源,合成了前驱体MG,再经高温碳化得到氮掺杂碳材料MG-T(T/℃,表示碳化温度),用于多相催化硝基苯加氢制苯胺反应.结合材料表征和催化评价结果初步探讨了反应机理.实验结果表明,碳化温度影响MG-T中氮物种构型的变化,石墨氮对催化剂的加氢活性起到关键作用.催化剂MG-800在水合肼作还原剂的乙醇溶剂中于80℃反应4h,硝基苯转化率为96%,产物选择性为100%,催化剂可循环使用至少9次,具有良好的稳定性和循环性,是一类可循环使用的硝基苯加氢制苯胺多相催化剂.

氮掺杂粉煤灰磁珠@碳纳米管的制备及活化过硫酸盐去除罗丹明B试验研究

近年来,氮掺杂碳材料因无金属浸出和良好的过硫酸盐活化能力而受到越来越多的关注,但其存在易团聚、回收难等问题。本文利用燃煤废料粉煤灰磁珠的磁性和易于回收的特点,通过化学气相沉积法和水热法合成高缺陷氮掺杂碳纳米(MSs@N-CNTs)。采用扫描电子显微镜(SEM)、X射线衍射(XRD)、X射线光电子光谱学(XPS)、拉曼光谱(Raman spectra)、比表面分析仪(BET)等手段对MSs@N-CNTs的成分和微观结构进行了分析。并以罗丹明B(Rh B)为目标污染物,探究了不同掺氮量以及催化剂、过单硫酸盐(PMS)用量、温度、pH等因素对降解的影响。结果表明:在中性室温条件下,60 mL初始浓度为50 mg/L的Rh B溶液中,当催化剂用量为0.4 g/L、PMS用量为5 mg/L时,40 min内MSs@N-CNTs/PMS体系降解Rh B的效率可达99.2%;MSs@N-CNTs在去除污染物3个循环后降解率仍高达72%;MSs@N-CNTs的饱和磁化值为18.47 emu/g,在外加磁场的作用下可迅速从溶液中分离。本研究成果为粉煤灰磁珠在催化领域的高值利用提供了一条新途径。

多孔氮氟共掺杂碳气凝胶的制备及其在锂硫电池中的应用

锂硫电池以其超高的理论能量密度,已成为最具发展潜力的新一代电化学储能技术,但硫正极存在电导率低、体积膨胀、多硫化物穿梭效应等技术瓶颈问题,制约了其实际应用。通过甲醛和3-氨丙基三乙氧基硅烷的醛胺缩合和溶胶-凝胶化反应合成了席夫碱二氧化硅凝胶,经与聚四氟乙烯乳液冷冻干燥、热处理同步刻蚀二氧化硅以及碳化制备了多孔氮氟共掺杂碳气凝胶(NF-CA)。以NF-CA为载体制备的NF-CA/S正极材料表现出优异的循环性能和倍率性能,0.2 C循环初始放电比容量高达1322 mA∙h/g,1 C循环200圈可逆比容量可保持564 mA∙h/g,2C倍率下可逆比容量高达598mA∙h/g。

高温高压非金属元素掺杂金刚石的研究进展

金刚石因其优越的极限特性,使得其应用领域非常广泛。金刚石的功能特性往往由其内部所含杂质元素决定,包括非金属元素如硼(B)、氮(N)、硫(S)和磷(P)等。掺杂这些单元素以合成金刚石一直是国内外研究课题的热点。本文首先介绍了金刚石单晶在高温高压条件下的合成方法及其研究发展现状,随后分析了硼(B)、氮(N)、硫(S)、磷(P)等单元素掺杂对金刚石晶体生长和电学等性能的影响。同时对金刚石在半导体中的应用以及金刚石中的含氮色心进行了分析。最后展望了掺杂后金刚石的光学和电学性能研究前景,并指出进一步探索多元素共掺杂的理论和实验方法对提升掺杂金刚石的性能具有重要意义。

模板和发泡双策略制备氮掺杂介孔碳材料及电化学性能

以尿素作为氮源,聚乙烯吡咯烷酮为碳源,同时利用硬模板法和发泡双策略在不同预活化温度(90℃、140℃、180℃和250℃)下探究前驱体缩合反应程度。通过SEM对其形貌分析,通过BET分析不同的发泡温度对孔径的影响,进而探究其作为电极材料的电化学性能。结果表明,在预活化温度为180℃的条件下煅烧的NPCNs样品呈三维网状形貌,拥有较高的比表面积且伴随着丰富的分级多孔结构。同时,NPCNs的导电性高,电化学性能良好,在1 mV/s的扫速下比电容高达382 F/g,即使在2 A/g的电流密度下经过1000次循环后仍保持近100%的容量保持率,放电比容量能达到302 F/g。

基于氮掺杂碳材料光催化传感器对食品中重金属离子的检测

为克服当前食品重金属检测方法的不足,以食品中重金属Cu^(2+)检测为例,研究基于氮掺杂碳材料光催化传感器在食品中重金属离子检测中的应用。本文论述氮掺杂碳点的制备方法,探究氮掺杂碳点浓度、检测时间对Cu^(2+)检测效果及其荧光强度的影响;以Mg^(2+)、Hg^(2+)、Ca^(2+)、Fe^(3+)、Zn^(2+)、Ni^(2+)、Ba^(2+)、Pb^(2+)、Cd^(2+)和Mn^(2+)10种金属离子为干扰物,分析氮掺杂碳点检测法对Cu^(2+)的选择特异性。结果表明,氮掺杂碳材料光催化传感器可实现室温下对Cu^(2+)的即时检测,且具有检测灵敏度高(检出限Cu^(2+)为5.26 μmol·L^(-1))、抗干扰性强、检测要求低等特点,在食品铜污染检测、铜污染治理方面具有较强的应用价值。

金属复合氧化物基燃烧催化剂在固体推进剂中的研究进展

为了阐明不同结构类型的金属复合氧化物及其复合材料作为燃烧催化剂时对固体推进剂含能组分的热分解催化性能,分别对尖晶石型、钙钛矿型、类钙钛矿型、碳材料基金属复合氧化物及金属元素掺杂的金属复合氧化物的催化活性进行总结。根据其结构及负载材料的不同,分析其对固体推进剂燃烧速率、压力指数及含能组分热分解峰温、放热量及表观活化能的影响,发现金属复合氧化物及其复合材料表现出比单一金属氧化物更为优异的催化活性。最后,指出了今后金属复合氧化物基燃烧催化剂在固体推进剂中的研究方向。