氮掺杂石墨烯的制备及其氧还原电催化性能

以三聚氰胺和氧化石墨烯(GO)为原料,经物理研磨和高温热解得到氮掺杂石墨烯(三聚氰胺-NG).扫描电子显微镜(SEM)测量显示,所制备的三聚氰胺-NG厚度和表面褶皱较掺杂前略有增加.X射线光电子能谱(XPS)表明,在三聚氰胺-NG中氮元素以吡咯N、吡啶N和石墨N 3种形式掺杂在石墨烯中,它们的比例分别是14.5%、24.5%和61.0%.同时运用循环伏安法(CV)和旋转圆盘电极技术(RDE)测试了三聚氰胺-NG在碱性介质中的氧还原电催化活性.结果表明,与商业石墨烯和由聚吡咯为氮源制备的氮掺杂石墨烯(ppy-NG)相比,三聚氰胺-NG具有较高的电催化活性和较正的氧还原起始电位(-0.09V),并且电催化还原氧气时主要为4电子反应.由于其较高的氧还原性能和较低的成本,三聚氰胺-NG在碱性燃料电池阴极电催化剂中有良好的应用前景.     

Co@Co-N-G催化剂的制备及其催化氧还原反应的研究

以氧化石墨烯(GO)为载体,席夫碱为氮源,CoCl2·6H2O为金属前体,通过简单的热处理法制备了一种氧还原反应(ORR)电催化剂Co@Co-N-G.用扫描电镜(SEM)、透射电镜(TEM)、X射线衍射(XRD)和X射线光电子能谱(XPS)等手段对催化剂的微观形貌、组分、物相和化合价进行了测试表征,用电化学方法对电催化...     

高电化学性能三维网状氮掺杂石墨烯的制备

以氧化石墨烯(GO)为原料,三聚氰胺为还原剂和氮掺杂剂,经过水热法制备出了氮掺杂石墨烯(NRG)三维网络.通过扫描电子显微镜(SEM)、X射线光电子能谱(XPS)、拉曼光谱(Raman)、氮气吸脱附分析和电化学表征等测试手段对样品的形貌、结构和电化学性能进行表征.结果表明:三聚氰胺在水热的条件下有效地将GO还原并实现氮掺杂,三聚氰胺将氧化石墨烯还原之后,使得石墨烯之间的相互作用力增强,从而使石墨烯搭建出三维网络结构,其氮含量可达4.37%.电化学测试表明,当GO与三聚氰胺质量比为1∶2(NRG-2)时,在1A/g时其最大比电容值达到了296F/g,这个比电容值高于其他不同GO与三聚氰胺质量比所制备出的氮掺杂石墨烯的比电容值.NRG-2还显示出优良的循环寿命,经过1 000次恒电流充放电循环后比电容保留量为88.5%.     

钴掺杂含氮碳气凝胶的制备及性能研究

以三聚氰胺、甲醛为原料,钴盐为金属前驱体,采用溶胶-凝胶法制备氮掺杂的有机气凝胶及含过渡金属的氮掺杂气凝胶,并通过高温炭化得到钴掺杂含氮碳氧还原电催化材料.在酸性介质中,通过旋转环盘电极研究金属复合的氮掺杂炭气凝胶的电化学氧还原活性.     

氮掺杂聚苯胺-碳氧还原催化剂的制备与表征

采用软模版法合成聚苯胺前躯体，通过改变过渡金属制备出PANI-FeCo-C、PANI-Fe-C、PANI-Co-C和PANI-C质子交换膜燃料电池(PEMFC)阴极非贵金属催化剂。电化学测试结果表明：4种催化剂中，PANI-Fe-C的催化活性最好，其氧还原反应起始电位达到0.87V。通过X射线衍射光谱（XRD）、拉曼（Raman）光谱、透射电子显微镜（TEM）、能量色散X射线光谱（EDS）和X射线光电子能谱（XPS）测试可知，PANI-Fe-C催化剂中含有较多晶格畸变的碳和石墨型的氮，这些特性是其具有优越氧还原催化性能的重要原因。     

Co-N-C氧还原反应电催化剂的制备及性能研究

锌空气电池可作为一种无污染、长效、稳定可靠的电源,但其阴极氧还原反应(Oxygen Reduction Reaction, ORR)缓慢的动力学过程严重阻碍了大规模应用。本文通过表面活化策略在炭黑上构筑不饱和位点用于锚定Co,再以不同质量比的尿素作为氮源,制备了不同氮掺杂量的催化剂,并测试了一系列催化剂的ORR活性,及其在不同电解液中活性的差异。将催化剂用于组装锌空气电池,开路电压达1.441 V,并表现出良好的放电性能,峰值功率密度可达123.5 mW·cm^-2。     

一步炭化制备氮氧共掺杂柚子皮纤维基活性炭及其电容性能研究

本研究以粉碎后的柚子皮为原料,采用一步炭化制备柚子皮纤维基活性炭,利用多种分析仪器对其分别进行元素分析、结构表征和电化学性能测试.结果表明:实验所得柚子皮纤维基活性炭含有较为丰富的氮(N)和氧(O)元素,其质量分数分别为9.04%和3.28%;其比表面积为6.67 m~2/g,含有少量孔径为2.5～10.0 nm的介孔;当电流密度为0.5 A/g时,比电容可达122.0 F/g;在5.0 A/g的电流密度下,持续进行5 000圈的恒电流充放电循环后,电容值保持在最高值的93.2%,且该过程中电极的库伦效率几乎始终维持在100%.     

模板法制备氮掺杂多孔碳材料氧还原性能研究

以水溶性盐NaCl和Na_2SiO_3为双重模板,以葡萄糖为碳源,尿素为氮源,通过冷冻干燥以及随后的热解过程,合成了具有分级多孔结构的氮掺杂碳纳米片作为高效的氧还原催化剂,并探究了不同模板剂对碳纳米片性能的影响.结果表明,以NaCl和Na_2SiO_3为模板可使碳源、氮源分散,形成具有较大比表面积和分级多孔结构的碳纳米片.这种结构不但有利于提高催化剂和电解质的有效接触面积,促进氧分子的扩散,缩短电催化过程中电子和离子的传输路径,还有助于产生更多的活性位点,提高氧还原催化性能.     

氮掺杂暴露（001）面二氧化钛的制备及其可见光催化性能研究

以尿素为氮源、HF为调控剂,采用水热法制备了以（001）活性面为主的氮掺杂型TiO2催化剂.SEM、TEM、XRD、Raman及UV-Vis测试结果表明,TiO2及N-TiO2产品均为暴露（001）面的纳米片状锐钛矿结构,TiO2在高温900℃煅烧仍能保持锐钛矿结构.F-不仅对（001）面的暴露起到很好的调控作用,而且抑制了TiO2在高温下向金红石相的转化.氮的掺杂窄化了TiO2的禁带宽度,使其边带红移,在可见光区域有很强的吸收峰.并且,随着氮掺杂量的增多,N-TiO2在可见光的吸收峰增强.以可见光降解染料罗丹明B溶液作为探针反应,研究了不同N/Ti配比的N-TiO2的可见光催化活性,氮掺杂TiO2的可见光催化活性比照纯TiO2有明显的改善.     

高电化学性能三维氮掺杂多孔炭/石墨烯的研究

通过在氧化石墨烯(GO)表面原位聚合吡咯(Py)制备了聚吡咯(PPy)/GO复合物(PGO);以PGO为前驱体,经水热过程后,用KOH作为活化剂得到了三维氮掺杂多孔炭/石墨烯(NPCG)网络结构,采用XPS、SEM和N2吸/脱附等手段对其形貌和结构进行了表征;系统地研究了GO与Py的质量比和活化温度对合成的NPCG电化学性能的影响。结果表明:当GO与Py和PGO与KOH的质量比分别为1/15和1/3时,650℃活化温度下合成的NPCG具有优异的电化学性能,当电流密度为1 A/g时,其比容量高达398 F/g;在电流密度为10 A/g条件下,经1000次充放电循环后,其比容量保持率为94%。     

Carbon-nitrogen/graphene composite as metal-free electrocatalyst for the oxygen reduction reaction

Sheet-like carbon-nitrogen (CNx)/graphene composites with a high content of nitrogen (x≤0.15) was prepared by the carbonization of polypyrrole (PPy)/reduced-graphene-oxide (rGO) composite at 600-800°C. We used rGO instead of graphene oxide (GO) sheets as a template and a substrate to immobilize PPy since the PPy/GO composite agglomerates easily because of the dehydration of excess oxygen-containing groups on the GO sheets during the drying process. The dried PPy/rGO intermediate and its derived CNx/graphene products retain their high dispersion and loose-powder features. The as-prepared CNx/graphene composites have a total nitrogen content of about 10 at% and their nitrogen state is mainly of pyridinic and graphitic type. CNx/graphene composites exhibit excellent performance for the oxygen reduction reaction (ORR) in terms of electrocatalytic activity, stability and immunity towards methanol crossover and CO poisoning, suggesting their potential as metal-free electrocatalysts for the ORR.     

Carbon-nitrogen/graphene composite as metal-free electrocatalyst for the oxygen reduction reaction

Sheet-like carbon-nitrogen (CNx)/graphene composites with a high content of nitrogen (x≤0.15) was prepared by the carbonization of polypyrrole (PPy)/reduced-graphene-oxide (rGO) composite at 600-800°C. We used rGO instead of graphene oxide (GO) sheets as a template and a substrate to immobilize PPy since the PPy/GO composite agglomerates easily because of the dehydration of excess oxygen-containing groups on the GO sheets during the drying process. The dried PPy/rGO intermediate and its derived CNx/graphene...     

Nitrogen-doped graphene nanosheets as high efficient catalysts for oxygen reduction reaction

It is of great significance in exploring alternative catalysts to platinum (Pt)-based materials for oxygen reduction reaction (ORR),because this reaction is invariably involved in various fuel cells and metal-air batteries.We herein reported the nitrogen doped graphene nanosheets (NGNSs) with pore volume of as high as 3.42 m 3 /g and investigated their potential application as ORR catalysts,it was demonstrated the NGNSs featured high activity,improved kinetics and excellent long-term stability for ORR.The NGNSs were successfully used as cathode catalysts of microbial fuel cells (MFCs) and performed even better than the commercial Pt/C (Pt 10%) catalysts at the maximum power output.     

The synthesis and characterization of a Co-N/C composite catalyst for the oxygen reduction reaction in acidic solution

A non-precious metal Co-N/C catalyst for the oxygen reduction reaction (ORR) was synthesized by heating a mechanical mixture of cobalt chloride, urea and acetylene black under a nitrogen atmosphere. The catalyst was characterized by XRD and XPS. The electrocatalytic activity in the ORR was evaluated by linear sweep voltammetry in 0.5 mol L⁻¹ H₂SO₄ solution. The results show that the Co-N/C catalyst aids the reduction of oxygen. The presence of elemental cobalt in the precursor allows nitrogen atoms to embed themselves in the graphite matrix to form pyridinic and graphitic type C-N structures as the ORR active sites. The effect of heat-treating temperature on the catalytic activity was also investigated. The results also show that the Co-N/C catalyst is most active when pyrolyzed at 600°C. The obtained Co-N/C catalyst loses some activity after initial exposure to the H₂SO₄ solution because of leaching, but is then stable for up to 20 h immersion. The catalyst is also stable when charged, which is supported by the cyclic voltammetry results.     

提升Pd基电催化剂氧还原活性的策略

氧还原反应(ORR)是许多电化学相关技术的核心反应,许多研究致力于制备同时具备高活性、高稳定性和低成本的催化剂.Pd基纳米材料由于其相对较优的催化性能和相对丰富的储量,有望成为Pt的替代品,受到了广泛关注,但要达到商品化程度,其性能需进一步提高.本文以Pd基催化剂应用于ORR电催化为背景,综述了近年来Pd基催化剂ORR...     

氮掺杂还原氧化石墨包覆金属钴复合材料的制备及其氧还原性能的研究

采用搅拌反应法制备了ZnCo（ZIF）与氧化石墨（graphite oxide,GO）的复合材料,热处理得到Co@N-doped rGO催化剂。通过X射线衍射（X-ray diffraction,XRD）和扫描电子显微镜（scanning electron microscopy,SEM）对催化剂进行结构表征,通过X射线光电子能谱（X-ray photoelectron spectroscopy,XPS）对催化剂进行表面元素分析,分别考察了金属（Zn和Co）加入量和热处理温度对催化剂氧气还原反应（oxygen reduction reaction,ORR）催化性能的影响,结果表明：所制备的催化剂整体呈层状分布,表面附着金属小颗粒团簇;随着金属加入量的增加,催化剂的ORR催化性能先增强后减弱;随着热处理温度的升高,催化剂的ORR催化性能先增强后减弱。所制备的S-2-850催化剂具有最好的ORR催化性能,在0.1 mol/L KOH电解液中,其起始电位和半波电位分别为0.871 V和0.804 V,在相同测试条件下活性稳定性优于20% Pt/C。     

Scalable synthesis and electrochemical performance of mesoporous graphene from calcium carbonate by magnesiothermic reaction

A novel scalable synthetic method of mesoporous graphene has been developed using the compressed mixture of Mg and excess CaCO₃ in a closed container. The generated solid oxide and unreacted CaCO₃ could act as mesopore-forming agents, and the closed container could prevent the carbon dioxide from CaCO₃ flow away. As a result, the graphenes with a large number of 2–30 ?nm mesopores and high utilization ratio of Mg achieved. The graphenes had high specific surface area and excellent electrochemical performance. In particular, the Mg utilization ratio was up to 53.3% in the preparation of graphene using 2:1 CaCO₃/Mg at 700 ?°C, which is superior to previous researches. The obtained mesoporous graphene exhibited high specific surface area of 743.7 ?m² ?g^-1, large specific capacitance of 140 ?F ?g^-1, and high capacitance retention rate of 64.3%.     

酞菁铁的模板合成及其对氧还原的电催化性能

针对直接甲醇燃料电池阴极常用的铂基催化剂易中毒、选择性差等问题,以Fe2＋为模板剂控制合成了酞菁铁配合物催化剂.红外光谱测试表明,Fe2＋与酞菁中的N形成了配键.研究结果表明,随着温度的升高,酞菁铁对氧还原反应的电催化活性逐渐增强,且对甲醇氧化反应无催化活性,证明酞菁铁具有较好的催化选择性.     

Effect of solvent on Se-modified ruthenium/carbon catalyst for oxygen reduction

Se-modified ruthenium supporting on carbon(Sex–Ru/C) electrocatalyst was prepared by solvothermal one-step synthesis method. The reaction mechanism was revealed after discussing impact of different solvents(i-propanol and EG) in solvotermal reaction. The result showed that the grain size of Se-modified ruthenium electrocatalyst was as small as 1 to 3 nm and highly dispersed on carbon surface. X-ray photoelectron spectroscopy(XPS) presented that selenium mainly existed in the catalyst in the form of elemental selenium and selenium oxides when the solvent was EG and i-propanol, respectively. The oxygen reduction reaction(ORR) performance was improved by appearance of selenium oxides.     

Nickel-introduced structurally ordered PtCuNi/C as high performance electrocatalyst for oxygen reduction reaction

Designing highly active and durable oxygen reduction reaction (ORR) electrocatalysts is essential for developing efficient proton-exchange membrane fuel cells (PEMFCs). In this work, ordered PtCuNi/C nanoparticles (NPs) were synthesized using an impregnation reduction method. This study shows that the incorporation of Ni in ordered PtCu/C can effectively adjust the electronic structure of Pt, thereby optimizing oxygen binding energy for the ORR. The obtained intermetallic ordered PtCuNi/C NPs significantly improved ORR activity and durability compared to ordered PtCu/C. Specifically, PtCu_0·5Ni_0·5/C-700 shows a mass activity of 1.29 ​A ​mg _Pt⁻¹ ​at 0.9 ​V vs. reversible hydrogen electrode (RHE), which is about 9.2 times higher than that of commercial Pt/C. PtCu_0.5Ni_0.5/C-700 is also shown to be competent cathode catalyst for a single-cell system exhibiting high power density (461 ​mW ​cm⁻²). This work demonstrates that ordered PtCu_0·5Ni_0·5/C-700 can be used as a highly active and durable ORR catalyst in PEMFCs.