石墨烯基氧还原催化剂在金属空气电池中的应用

随着金属空气电池技术的不断发展,氧还原催化剂成为限制其动力化的最主要瓶颈之一。近几年来,石墨烯基氧还原催化剂(GORRC)由于优异的氧还原催化活性而备受关注。本文结合石墨烯基氧还原催化剂的研究现状,将其分为三类:石墨烯作氧还原催化剂载体,氮掺杂石墨烯作为氧还原催化剂,以及氮掺杂石墨烯与其他催化剂形成的复合催化体系,并对这三种石墨烯基氧还原催化剂进行了详细的综述。石墨烯作为一种优良的催化剂载体,能够显著降低活性物质负载量,提高氧还原催化剂的催化活性和长期稳定性。氮掺杂石墨烯显示了优良的氧还原催化性能。氮掺杂石墨烯与其他催化剂复合后,由于两者之间的相互作用,可得到性能更为优异的氧还原催化剂。最后,本文还对石墨烯基氧还原催化剂及其在金属空气电池中的研究前景和发展方向进行了展望,指出了将来的研究重点。     

基于内嵌钴/氮掺杂多孔碳三维石墨烯笼的抗团聚高效氧还原电催化剂

氧还原反应是决定燃料电池、金属-空气电池等多种新型清洁能源存储与转化技术之性能与应用的关键反应. 铂及其合金是目前催化活性最好的氧还原反应催化剂,但其高昂的成本限制了规模化应用. 在小尺寸效应作用下,微纳米结构催化剂颗粒在电极制备与电化学反应过程中的团聚限制了催化剂本征催化活性的充分发挥. 本文基于喷雾热解技术,发展了一种基于内嵌钴/氮掺杂多孔碳三维石墨烯笼的高活性、抗团聚非贵金属氧还原反应催化剂. 此结构中,金属有机骨架化合物ZIF-67衍生的钴/氮掺杂多孔碳纳米结构是催化氧还原反应的活性中心,包覆其外的三维石墨烯笼不仅可在钴/氮掺杂碳纳米结构之间构建连续的三维载流子传导网络,且可高效抑制其在催化剂制备与电化学反应过程中的团聚与活性损失. 在碱性电解液中,此类非贵金属催化剂表现出可与铂基催化剂媲美的氧还原反应活性和优异的稳定性.     

单源MOF衍生具有三维有序大孔结构的氮掺杂碳包覆铁-氮合金复合材料用于高效氧还原

氧还原反应在一些能源转换系统如金属-空气电池中起着至关重要的作用.目前贵金属基材料(Pt/C)被认为是最有效的氧还原电催化剂,然而价格昂贵和储量有限等因素限制了它的商业化应用,因此探索高效的非贵金属氧还原电催化剂具有重要的意义.近年来,负载过渡金属铁的多孔碳催化剂由于独特的结构和优异的氧还原催化活性成为替代铂基催化剂最有潜力的候选者.该类材料的合成通常采用直接煅烧含有氮源、碳源和铁盐的混合前驱体的制备方法,但是热解时材料的多孔结构以及活性位点的均匀分布很难得到有效的控制.近年来,金属有机框架(MOFs)由于其多孔结构和组成可控等优点而经常被用作自牺牲模板来制备负载铁基纳米材料的多孔碳催化剂,并表现出优异的电催化活性.目前以MOF为前驱体制备高活性的载铁氮掺杂碳复合材料通常需要引入额外的氮源或铁源,因此选择氮含量丰富的铁基MOF材料作为单源前驱体制备载铁氮掺杂多孔碳复合材料具有重要的意义.除此之外,具有多级孔隙率的催化剂可以改善反应时的传质过程,同时有序交联的网络结构能够提供连续的电子传输.本文报道了一种简单可控的制备具有三维有序大孔结构的载铁氮掺杂多孔碳复合催化剂的合成方法,该材料表现出优异的电催化氧气还原性能和优异的催化稳定性.首先,以氮含量丰富的双氰胺和吡嗪配体所构筑的Fe-MOF作为前驱体,利用具有均一尺寸的聚苯乙烯微球作为造孔剂,合成得到了具有三维有序大孔结构的Fe-MOF前驱体,然后通过高温煅烧该单源前驱体制备得到具有三维有序大孔结构的氮掺杂多孔碳包覆铁-氮合金的复合型催化剂(3DOM Fe/Fe-NA@NC).扫描电镜和透射电镜结果表明,材料内形成了有序交联的大孔结构;氮气吸附测试表明,刻蚀之后材料的比表面积明显增加,结合分级多孔特性可以共同促进催化反应的传质过程.粉末X射线衍射结果证实了多孔碳材料中铁和铁-氮合金物种的成功合成.电化学测试结果表明,在0.1 M KOH电解液中,3DOM Fe/Fe-NA@NC-800催化剂表现出优于Pt/C的氧还原活性,其半波电位(E_1/2)为0.88 V,大于商业Pt/C的半波电位(E_1/2=0.85 V).同时,3DOM Fe/Fe-NA@NC-800表现出更加优异的稳定性,经过20000 s测试后,其电流保持率为94%,而Pt/C只保持了78%.关于活性位点探究的对比实验证明在所制备的复合材料中,铁物种作为高效的活性位点参与了电催化氧还原反应,与氮掺杂多孔碳之间的协同作用共同主导了3DOM Fe/Fe-NA@NC优异的氧还原活性.得益于其优异的氧还原活性,将其作为阴极活性材料组装为锌-空气电池进一步探究了其在实际应用中的可行性.本结果拓宽了高效的铁基催化剂的类型,同时也为制备封装非贵金属的多孔碳基催化剂提供了实验指导和理论依据.     

氮掺杂碳材料负载Pd纳米催化剂在有机反应中的最新研究进展

氮掺杂碳材料负载Pd纳米催化剂因其具有反应活性高、反应完成后便于分离和重复使用等优点,在催化领域引起了极为广泛的关注.简要综述了基于氮掺杂多孔/介孔碳NC、氮掺杂石墨烯NG、氮掺杂碳纳米管NCNT和氮掺杂碳纳米片NCNS等不同类型碳材料载体制备的负载型Pd纳米催化剂的合成与应用的最新研究进展,同时对氮掺杂碳材料负载Pd纳米催化剂的发展方向进行了展望.     

Ya‐Ru Lv,Xue‐Jing Zhai,Shan Wang,Hong Xu,Rui Wang #, Shuang‐Quan Zang

氧还原反应在一些能源转换系统如金属-空气电池中起着至关重要的作用.目前贵金属基材料(Pt/C)被认为是最有效的氧还原电催化剂,然而价格昂贵和储量有限等因素限制了它的商业化应用,因此探索高效的非贵金属氧还原电催化剂具有重要的意义.近年来,负载过渡金属铁的多孔碳催化剂由于独特的结构和优异的氧还原催化活性成为替代铂基催化剂最有潜力的候选者.该类材料的合成通常采用直接煅烧含有氮源、碳源和铁盐的混合前驱体的制备方法,但是热解时材料的多孔结构以及活性位点的均匀分布很难得到有效的控制.近年来,金属有机框架(MOFs)由于其多孔结构和组成可控等优点而经常被用作自牺牲模板来制备负载铁基纳米材料的多孔碳催化剂,并表现出优异的电催化活性.目前以MOF为前驱体制备高活性的载铁氮掺杂碳复合材料通常需要引入额外的氮源或铁源,因此选择氮含量丰富的铁基MOF材料作为单源前驱体制备载铁氮掺杂多孔碳复合材料具有重要的意义.除此之外,具有多级孔隙率的催化剂可以改善反应时的传质过程,同时有序交联的网络结构能够提供连续的电子传输.本文报道了一种简单可控的制备具有三维有序大孔结构的载铁氮掺杂多孔碳复合催化剂的合成方法,该材料表现出优异的电催化氧气还原性能和优异的催化稳定性.首先,以氮含量丰富的双氰胺和吡嗪配体所构筑的Fe-MOF作为前驱体,利用具有均一尺寸的聚苯乙烯微球作为造孔剂,合成得到了具有三维有序大孔结构的Fe-MOF前驱体,然后通过高温煅烧该单源前驱体制备得到具有三维有序大孔结构的氮掺杂多孔碳包覆铁-氮合金的复合型催化剂(3DOM Fe/Fe-NA@NC).扫描电镜和透射电镜结果表明,材料内形成了有序交联的大孔结构;氮气吸附测试表明,刻蚀之后材料的比表面积明显增加,结合分级多孔特性可以共同促进催化反应的传质过程.粉末X射线衍射结果证实了多孔碳材料中铁和铁-氮合金物种的成功合成.电化学测试结果表明,在0.1 MKOH电解液中, 3DOMFe/Fe-NA@NC-800催化剂表现出优于Pt/C的氧还原活性,其半波电位(E1/2)为0.88 V,大于商业Pt/C的半波电位(E1/2=0.85 V).同时, 3DOM Fe/Fe-NA@NC-800表现出更加优异的稳定性,经过20000 s测试后,其电流保持率为94%,而Pt/C只保持了78%.关于活性位点探究的对比实验证明在所制备的复合材料中,铁物种作为高效的活性位点参与了电催化氧还原反应,与氮掺杂多孔碳之间的协同作用共同主导了3DOM Fe/Fe-NA@NC优异的氧还原活性.得益于其优异的氧还原活性,将其作为阴极活性材料组装为锌-空气电池进一步探究了其在实际应用中的可行性.本结果拓宽了高效的铁基催化剂的类型,同时也为制备封装非贵金属的多孔碳基催化剂提供了实验指导和理论依据.     

氮掺杂还原氧化石墨烯/四氧化三钴双功能催化剂的制备及表征

采用尿素作为氮源,通过热退火法制备氮掺杂还原氧化石墨烯,然后以乙酰丙酮钴作为钴源通过水热法制备氮掺杂还原氧化石墨烯/四氧化三钴杂化纳米片作为催化氧还原和氧析出反应的双功能催化剂。利用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线电子能谱仪(XPS)等对其进行形貌结构表征,通过旋转圆盘电极等电化学测试对其电催化性能进行分析,可以看出该催化剂具有良好的氧还原和氧析出催化性能。     

钴/氮掺杂碳纳米管/石墨烯复合材料的构筑及氧还原催化性能

以石墨烯/N-甲基吡咯烷酮(NMP)分散体和Co(NO_3)_2混合物为前驱体,经过高温和化学掺杂处理,制备了钴/氮掺杂的碳纳米管/石墨烯复合材料(Co/N-CNT/Gr-X,X代表煅烧温度),并对其进行物相表征和电化学性能测试.结果表明,在钴盐催化下,石墨烯分散体中的有机溶剂NMP成为碳源,在石墨烯表面形成高密度的碳纳米管,形成了三维多级结构;同时,钴离子部分氧化成为氧化物,部分与N形成Co—N活性位点,其协同作用极大改善了催化剂的氧还原性能.其中Co/N-CNT/Gr-800的还原峰电位为-0.137 V(vs.SCE),极限电流密度为4.24 m A/cm~2,电子转移数为3.34,表现出优异的耐甲醇中毒能力.     

铁氮掺杂对石墨烯担载铂催化剂氧还原反应活性的影响

高氧还原活性担载铂催化剂的研发是加快质子交换膜燃料电池商业化进程的主要手段之一。以石墨烯为碳源,1,10-菲啰啉为氮源,FeCl3为铁源,用浸渍法制备铁氮掺杂石墨烯(Fe/N-G)载体,并通过乙二醇还原法获得PtFe/N-G催化剂,探究铁氮原子的引入对石墨烯担载铂催化剂氧还原反应催化活性的影响。采用X射线衍射、比表面积和孔径分布测试、X射线光电子能谱等表征手段对载体及催化剂结构进行表征,使用电化学方法对载体和催化剂的氧还原反应活性进行测试。结果表明,PtFe/N-G催化剂的氧还原反应起始电位及半波电位分别为0.96 V、0.83 V,优于相同Pt担载量的商业20%Pt/C催化剂。铁氮掺杂后,石墨烯载体具有较大的孔径更有利于氧还原反应过程中生成物与反应物的传递,PtFe/N-G催化剂中存在吡啶氮和Fe-N型氮与铂纳米颗粒的协同催化,以及铂纳米颗粒与铁氮掺杂石墨烯载体间的相互作用,是PtFe/N-G催化剂具有优异的氧还原催化活性的可能原因。     

负载酞菁铁的氮掺杂中空碳球的电催化氧还原性能（英文）

开发低成本、高性能的氧还原反应（ORR）催化剂是当前的研究热点.虽然酞菁铁（FePc）在几十年前就被证明能高效地电催化氧还原反应,但由于其电子传导性和稳定性较差,无法取代商用的Pt/C催化剂.氮掺杂碳材料不仅化学性质稳定、电子传导性好,还有一定的氧还原催化活性.本文首先制备了聚苯乙烯@聚多巴胺球前驱体,经过高温碳化后制得了氮掺杂中空碳球,进而负载酞菁铁后制备了负载酞菁铁的氮掺杂中空碳球复合材料（FePc-NHCS）.通过调整煅烧温度和酞菁铁的负载量,可进一步调控FePc-NHCS的多孔结构、石墨化程度、氮掺杂的种类与含量及酞菁铁的负载状态.优化后的FePc-NHCS在碱性电解质中显示出优异的ORR催化活性,其半波电位和稳定性均高于商用Pt/C催化剂.研究结果表明,掺杂与复合是增强单项催化组分活性的有效途径.此外,通过调控催化剂的结构和组分也能有效地优化催化剂的氧化还原性能.     

氮掺杂的类石墨烯纳米片的制备及其在锌-空气电池中的应用（英文）

采用一种简单方法制备具有优异氧还原反应(ORR)活性的、无金属的氮掺杂碳材料。以双氰胺(DCD)为氮源,蔗糖、β-环糊精和壳聚糖为不同的碳源,通过简单的热解法制备出氮掺杂的类石墨烯纳米片催化剂CN-nanosh(suc)、CN-nanosh(cyc)和CN-nanosh(ch)。这些催化剂在碱性溶液中表现出优异的ORR活性,以CN-nanosh(suc)为阴极催化剂的锌-空气电池具有201.33m W·cm~(-2)的最大功率密度,在100 mA·cm~(-2)的大电流密度下能持续放电50多小时,电池性能接近目前报道的无金属阴极催化剂锌-空气电池的最好性能。     

Substituent position effect of Co porphyrin on oxygen electrocatalysis

Substituent effect of metal porphyrin molecular catalysts plays a crucial role in determining the catalytic activity of oxygen electrocatalysis. Herein, substituent position effect of Co porphyrins on oxygen electrocatalysis, including the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER), was investigated. Two Co porphyrins, namely 2,4,6-OMe-CoP and 3,4,5-OMe-CoP, were selected as the research objects. The ORR and OER performance was evaluated by drop-coating molecular catalysts on carbon nanotubes (CNTs). The resulted 3,4,5-OMe-CoP/CNT exhibited high bifunctional electrocatalytic activities and better long-term stability for both ORR and OER than 2,4,6-OMe-CoP/CNT. Furthermore, when applied in the Zn-air battery, 3,4,5-OMe-CoP/CNT exhibited comparable performance to that with precious metal-based materials. The enhanced catalytic activity may be attributed to the improved charge transfer rate, mass transfer and hydrophilicity. This work provides an effective strategy to further enhance catalytic activity by introducing substituent position effect, which is of great importance for developing more efficient energy-related electrocatalysts.     

Enhanced oxygen reduction at Pd catalytic nanoparticles dispersed onto heteropolytungstate-assembled poly(diallyldimethylammonium)-functionalized carbon nanotubes

Both Keggin-type phosphotungstic acid (HPW) and Pd are not prominent catalysts towards the oxygen reduction (ORR), but their composite Pd-HPW catalyst produces a significantly higher electrochemical activity for the ORR in acidic media. The novel composite catalyst was synthesized by self-assembly of HPW on multi-walled carbon nanotubes (MWCNTs) via the electrostatic attraction between negatively charged HPW and positively charged poly(diallyldimethylammonium (PDDA)-wrapped MWCNTs, followed by dispersion of Pd nanoparticles onto the HPW-PDDA-MWCNT assembly. The as-prepared catalyst was characterized by transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, thermal gravimetric analysis (TGA), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). TEM images show that Pd nanoparticles were uniformly dispersed on the surface of MWCNTs even when the Pd loading was increased to 60 wt%. Electrochemical activity of the catalysts for the ORR was evaluated by steady state polarization measurements using a rotating disk electrode. Compared with the acid treated MWCNTs, Pd nanoparticles supported on the HPW-assembled MWCNTs show a much higher ORR activity that is comparable to conventional Pt/C catalysts. The high electrocatalytic activities could be related to high dispersion of Pd nanoparticles as well as synergistic effects originating from the high proton conductivity of HPW. The Pd/HPW-PDDA-MWCNTs system as the cathode catalyst in proton exchange membrane fuel cells is demonstrated.     

改性炭黑-LaMnO3复合材料的制备及其共价复合效应对氧还原性能的影响

以VulcanXC-72炭黑为载体,通过对炭载体石墨化处理和表面化学修饰,将其与化学沉淀法制备的纳米级LaMnO₃颗粒共混,再经特定温度下煅烧,制备出改性炭黑-LaMnO₃复合材料.X射线光电子能谱和热重分析表明,当煅烧温度在300℃时,炭载体与LaMnO₃纳米颗粒之间形成了大量C-O-M（M=La,Mn）化学键.扫描电子显微镜和高分辨透射电子显微镜分析发现,纯相LaMnO₃纳米颗粒主要呈现短棒、三支棒或竹节棒的形貌特征,炭载体则为具有完整石墨层的空心球结构,LaMnO₃均匀分散在炭载体上.在25℃,1mol/LNaOH溶液中的电化学测试结果表明,成分比（LaMnO₃：C）为2：3的复合材料具有很高的氧还原电催化活性,氧还原反应电子数为3.81,中间产物H₂O₂产率为9.5%,其活性接近商业Pt/C催化剂（E-TEK）.高的氧还原电催化活性主要归因于LaMnO₃纳米颗粒与炭载体之间形成了大量共价键.     

Carbon nanotubes as a secondary support of a catalyst layer in a gas diffusion electrode for metal air batteries

In this paper, we report the use of binary carbon supports (carbon nanotubes (CNTs) and active carbon) as a catalyst layer for fabricating gas diffusion electrodes. The electrocatalytic properties for the oxygen reduction reaction (ORR) were evaluated by polarization curves and electrochemical impedance spectroscopy (EIS) in an alkaline electrolyte. The binary-support electrode exhibits better performance than the single-support electrode, and the best performance is obtained when the mass ratio of carbon nanotubes and active carbon is 50:50. The results from the electrode kinetic parameters indicate that the introduction of carbon nanotubes as a secondary support provides high accessible surface area, good electronic conductivity, and fast ORR kinetics. Furthermore, the effect of CNT support on the electrocatalytic properties of Pt nanoparticles for binary-support electrodes was also investigated by different loading-reduction methods. The electrocatalytic activity of the binary-support electrodes is improved dramatically by Pt loading on CNT carbon support, even at very low Pt loading. Additionally, the EIS analysis results indicate that the process of ORR may be controlled by diffusion of oxygen in the electrode thin film for binary-support electrodes with or without Pt catalyst.     

不同结构及氮掺杂NiO/rGO氧还原催化剂的制备与性能研究

本文以还原氧化石墨烯（rGO）为载体制备了片状NiO/rGO和球形NiO/N-rGO结构的氧还原催化剂. 通过X-射线衍射（XRD）、Raman（拉曼）测试、X-射线光电子能谱（XPS）、扫描电子显微镜（SEM）和透射电子显微镜（TEM）等方法表征了两种催化剂的结构和形貌. 采用循环伏安法（CV）、Tafel曲线、线性扫描伏安法（LSV）、旋转圆盘电极（RDE）和旋转环盘电极（RRDE）等技术测试研究了两种催化剂的电化学催化氧还原性能. 研究结果表明,球形NiO/N-rGO催化剂催化氧还原的峰电流密度和起始电位（0.89 V vs. RHE）与商业化的Pt/C（20%）催化剂相近. 旋转圆盘电极（RDE）和旋转环盘电极（RRDE）测试证明,在碱性电解液中NiO/rGO和NiO/N-rGO催化的氧还原反应均主要通过4?鄄电子途径反应途径发生,球形NiO/N-rGO催化剂展现出替代Pt/C基催化剂的潜力.     

DNA‐Directed Growth of Pd Nanocrystals on Carbon Nanotubes towards Efficient Oxygen Reduction Reactions

Unique DNA‐promoted Pd nanocrystals on carbon nanotubes (Pd/DNA–CNTs) are synthesized for the first time, in which through its regularly arranged PO₄^3? groups on the sugar–phosphate backbone, DNA directs the growth of ultrasmall Pd nanocrytals with an average size of 3.4 nm uniformly distributed on CNTs. The Pd/DNA–CNT catalyst shows much more efficient electrocatalytic activity towards oxygen reduction reaction (ORR) with a much more positive onset potential, higher catalytic current density and better stability than other Pd‐based catalysts including Pd nanocrystals on carbon nanotubes (Pd/CNTs) without the use of DNA and commercial Pd/C catalyst. In addition, the Pd/DNA–CNTs catalyst provides high methanol tolerance. The high electrocatalytic performance is mainly contributed by the ultrasmall Pd nanocrystal particles grown directed by DNA to enhance the mass transport rate and to improve the utilization of the Pd catalyst. This work may demonstrate a universal approach to fabricate other superior metal nanocrystal catalysts with DNA promotion for broad applications in energy systems and sensing devices.     

Self-assembled dopamine nanolayers wrapped carbon nanotubes as carbon-carbon bi-functional nanocatalyst for highly efficient oxygen reduction reaction and antiviral drug monitoring

Oxygen reduction reaction (ORR) catalysts are the heart of eco-friendly energy resources particularly low temperature fuel cells. Although valuable efforts have been devoted to synthesize high performance catalysts for ORR, considerable challenges are extremely desirable in the development of energy technologies. Herein, we report a simple self-polymerization method to build a thin film of dopamine along the tubular nanostructures of multi-walled carbon nanotubes (CNT) in a weak alkaline solution. The dopamine@CNT hybrid (denoted as DA@CNT) reveals an enhanced electrocatalytic activity towards ORR with highly positive onset potential and cathodic current as a result of their outstanding features of longitudinal mesoporous structure, high surface area, and ornamentation of DA layers with nitrogen moieties, which enable fast electron transport and fully exposed electroactive sites. Impressively, the as-obtained hybrid afford remarkable electrochemical durability for prolonged test time of 60,000 s compared to benchmark Pt/C (20 wt%) catalyst. Furthermore, the developed DA@CNT electrode was successfully applied to access the quality of antiviral drug named Valacyclovir (VCR). The DA@CNT electrode shows enhanced sensing performance in terms of large linear range (3–75 nM), low limit of detection (2.55 nM) than CNT based electrode, indicating the effectiveness of the DA coating. Interestingly, the synergetic effect of nanostructured DA and CNT can significantly boost the electronic configuration and exposure level of active species for ORR and biomolecule recognition. Therefore, the existing carbon-based porous electrocatalyst may find numerous translational applications as attractive alternative to noble metals in polymer electrolyte membrane fuel cells and quality control assessment of pharmaceutical and therapeutic drugs.     

Copolymer-Induced Intermolecular Charge Transfer: Enhancing the Activity of Metal-Free Catalysts for Oxygen Reduction

Breaking the electroneutrality of sp² carbon lattice is a viable way for nanocarbon material to modulate the charge delocalization and to further alter the electrocatalytic activity. Positive charge spreadsheeting is preferable for catalyzing the oxygen reduction reaction (ORR) and other electrochemical reactions. Analogously to the case of intramolecular charge transfer by heteroatom doping, electrons in the conjugated carbon lattice can be redistributed by the intermolecular charge transfer from the nanocarbon material to the polyelectrolyte. A copolymeric electrolyte, epichlorohydrin-dimethylamine copolymer (EDC) was synthesized. The EDC-modified carbon nanotube (CNT) hybrid was subsequently fabricated by sonication treatment and served as a metal-free carbonaceous electrocatalyst with remarkable catalytic activity and stability. The resultant hybrid presents positive charge spreadsheeting on CNT as a result of the interfacial electron transfer from CNT to EDC. DFT calculations were further carried out to reveal that the enhancement of the wrapped EDC polyelectrolyte originates from the synergetic effect of the quaternary ammonium-hydroxyl covalently bonded structure. The CNT-EDC hybrid not only provides an atomically precise regulation to modulate nanocarbon materials from inactive carbonaceous materials into efficient metal-free catalysts, but it also opens new avenues to develop metal-free catalysts with well-defined and highly active sites.     

溶剂热法制备磷掺杂碳纳米管作为氧气还原和氧气析出反应双功能电催化剂的研究

对氧气还原(ORR)和氧气析出(OER)反应都具有催化活性的双功能催化剂在金属-空气电池中起着关键作用.本文通过溶剂热反应,一步原位合成了磷掺杂碳纳米管(P-CNT).旋转环盘电极测试表明磷掺杂能够明显提高碳纳米管的催化活性,P-CNT在碱性电解质中对ORR和OER都具有优异的催化活性.P-CNT对ORR的催化还原为近4电子反应,可与商业催化剂Pt/C(20 wt%)相比;而其对OER的催化活性则高于Pt/C(20 wt%).此外,P-CNT的长期稳定性优于Pt/C(20 wt%).P-CNT对ORR和OER的高催化活性和稳定性主要归因于磷对碳的掺杂以及磷与碳间强的化学键合.     

纳米碳纤维的表面性质和微结构对氧还原催化活性的影响

采用超声处理的方法分别对管式纳米碳纤维(t-CNF)和鱼骨式纳米碳纤维(f-CNF)进行了表面化学处理. XPS结果表明, 在混酸(浓硫酸+浓硝酸)和氨水中进行超声化学处理可以在CNF表面分别引入含氧官能团和含氮官能团. 电化学测试结果表明, 2种不同微结构CNF的氧还原催化活性都遵循相同的趋势, 即CNF-P相似文献