钴掺杂氧化铈纳米粒子电催化性能研究

氧化铈的电子导电性较低、氧空位数量少, 难以单独用作为电催化剂。但是掺杂过渡金属或非金属元素可以提高氧化铈的CO催化能力, 同时在氧化物中掺杂钴可有效提高材料的电催化能力, 因此本工作开展了对钴掺杂的氧化铈电催化性能的研究。采用均相沉淀法制备了钴掺杂的氧化铈纳米粒子, 电化学测试发现当钴掺杂比例为20mol%时, 氧化铈纳米粒子对氧气还原反应(ORR)和氧气析出反应(OER)的综合催化能力最强。经过10 h的长时间催化作用, ORR、OER过程中的电流密度分别下降了20%、5%左右, 远优于贵金属和未掺杂氧化铈纳米粒子催化剂, 显示出良好的催化稳定性。拉曼光谱、阻抗图及XPS谱图等的测试分析表明钴掺杂后材料的电荷转移阻抗降低(电子导电性的提高)、氧活性物种和氧空位增加是氧化铈催化性能提高的主要原因。本工作通过钴掺杂大幅度提高了氧化铈的电催化性能, 同时为其它离子导体作为双功能电催化剂的使用提供了借鉴。     

金属掺杂聚吡咯碳化物PPY-M的制备及其氧还原反应电催化活性

在Fe³⁺或Co²⁺存在下进行吡咯的聚合反应, 得到金属离子掺杂的聚吡咯, 并在N₂气氛下700℃碳化, 再将该碳化产物在900℃焙烧得到含有不同金属的复合催化剂PPY-M(M为不同的金属)。采用SEM、XRD等对催化剂的结构进行了表征。通过循环伏安和线性电位扫描等电化学手段, 研究了催化剂对氧还原(ORR)的电催化活性及其稳定性。结果表明, 掺杂金属钴的催化剂的活性最好, 在酸性溶液中ORR的起始电位达到0.54 V(vs SCE),电流密度为7.5 mA/mg@-0.3 V(vs SCE); 在碱性溶液中ORR的起始电位为-0.11 V(vs SCE),电流密度为5.7 mA/mg@-0.8 V。Fe或Co掺杂的聚吡咯碳化物对ORR具有较强的电催化活性, 而且制备过程简单、成本低, 有较重要的研究意义。     

Fe,N掺杂二维多孔碳双功能催化剂及锌-空气电池中的应用

在石墨烯表面负载金属有机框架材料ZIF-8,同时在金属有机框架材料表面分散Fe-2,2-Bipy螯合物,通过高温煅烧分解制备了Fe, N掺杂多孔碳催化剂材料。采用SEM, XRD, XPS对制备的催化剂材料进行了形貌、结构以及成分分析。采用旋转圆盘电极,CV曲线,LSV曲线对Fe,N掺杂多孔碳催化剂材料的氧还原(ORR)以及析氧(OER)电催化性能进行了分析。并且将Fe, N掺杂多孔碳催化剂应用于锌-空气电池。结果表明,所制备的Fe, N掺杂多孔碳催化剂材料显示出均匀的二维结构形貌, Fe元素含量为1.32%。催化剂在0.1 mol/L KOH溶液中半波电位为0.83 V,在1 mol/L KOH溶液中, 10 mA/cm~2电流密度下过电势为420 mV。将催化剂应用于锌-空气电池,锌-空气电池功率密度达到245 mV/cm~2,并且表现出优异的循环稳定性。     

铂–镍双原子分散在具有新型(NiPt)-N4C2构型的氮掺杂碳纳米结构上用于协同电催化析氢反应(英文)

单原子催化剂具有原子利用率高、活性中心明确、催化中心原子配位数低等优点,有望提高电催化性能.具有相邻杂原子的双原子催化剂(DAC)有望发挥两个原子的协同作用,从而进一步提高活性.在本文中,我们报道了一种PtNi-NC催化剂,该催化剂由固定在氮掺杂碳基底上的PtNi双原子构成,该基底采用原子层沉积技术合成. X射线吸收光谱证实了Pt–Ni双原子的存在.所制备的PtNi-NC催化剂具有优异的催化活性,在10 m A cm^-2的电流密度下,酸性介质中析氢反应(HER)的过电位为30 m V,与市售20 wt%Pt/C相当.特别值得注意的是, PtNi-NC具有比20 wt%Pt/C更高的质量活性,约为其21倍.密度泛函理论计算表明, Pt–Ni双原子通过调节局部电子结构和优化电荷分布产生协同效应,有助于优化吸附性能和增强电催化性能.这项工作为DAC的制备提供了新途径,揭示了它们在电催化HER等领域的应用潜力.     

ZIF衍生钴镍笼状双金属硫化物高效双功能电催化剂

锌-空气电池的阴极氧还原反应(ORR)动力迟缓,急需开发活性高、成本低的阴极催化剂。本文采用两次热解法合成了沸石咪唑酯骨架结构(ZIF)衍生的多孔碳负载Co、Ni双金属硫化物笼状纳米颗粒材料,通过SEM、XRD、Raman、N₂吸附比表面分析、电化学分析等对负载Co、Ni笼状双金属硫化物的多孔碳进行形貌、结构表征以及性能测试。结果表明,金属硫化物导电性能优异,且热解后的多孔碳结构会暴露更多活性位点,具有优异的电催化活性,ORR性能测试中,其半波电位可达0.89 V,优于商用Pt/C催化剂的0.85 V。OER性能在电流密度为10 mA/cm²时电位为1.79 V,与商用IrO₂(电位可达1.68 V)相当。本文制备的笼状双金属硫化物具有优异的性能,可作为锌-空气电池的优异双功能电催化剂。     

简便的碳浴法制备N,S共掺杂类石墨烯炭提高氧还原反应性能（英文）

合理设计和优化氧还原反应(ORR)非金属电催化剂对于燃料电池和金属空气电池非常重要。然而,这现在仍然是一个巨大的挑战。本工作通过简单的碳浴法成功制备了N,S共掺杂的类石墨烯炭材料(GLC),并将其用于电催化氧还原反应。经高温热解和模板分解后,得到的GLC-11具有较高的比表面积(583.68 cm2/g)和孔体积(0.63 cm3/g)。其中,微孔表面积占总表面积的29.39%,微孔体积占总孔体积的12.70%。同时,通过XPS结果计算得到,GLC-11的吡啶氮和石墨氮含量总和高达92.2%。因此,GLC-11在碱性电解液中显示出了高电催化ORR性能,其中波电位(E1/2)为0.82 VRHE,优于Pt/C(E1/2=0.80 VRHE)。此外,GLC-11催化剂与商业Pt/C(20 wt%)催化剂相比表现出更好的稳定性和优异的甲醇耐受性。     

用于电催化氧还原制备双氧水的催化剂的研究进展

H2 O2及其水溶液双氧水具有强氧化性,被广泛应用于造纸、污水处理和消毒等方面.全球对H2 O2的需求量与日俱增,但传统的蒽醌法工艺复杂、成本高、效率低,氢氧直接合成法又存在很大的安全隐患.因此,电催化氧还原这种新型、绿色且安全的原位合成H2 O2方法近年来受到广泛关注.氧还原反应(ORR)是多电子反应,中间体复杂且难以测量,机理研究困难.ORR存在两种竞争的反应路径,两电子路径得到H2 O2,而四电子路径生成H2O.两电子氧还原反应(2e-ORR)的反应效率取决于催化剂的活性、选择性和稳定性.目前贵金属基催化剂(如Au、Pd)对2e-ORR显示出较好的催化性能,但昂贵、稀缺的特性限制了它们的广泛应用.当前关于电催化氧还原制备H2 O2所用催化剂的研究主要集中于三方面:(1)减少贵金属的负载.将惰性金属与活性金属相结合,得到了许多性能优异的合金材料,如Pt-Hg等.(2)发展非贵金属催化剂.碳基催化剂的缺陷、表面氧官能团(C=O、C-O等)、杂原子掺杂(N-、S-等)和过渡金属掺杂(Co、Fe等)都能够提高H2O2的选择性与催化活性.(3)发展非贵金属复合催化剂.非贵金属复合物催化剂(如MnO2/C、CoS2/C)可促进电子转移,提高H2 O2的选择性.本文系统介绍了2e-ORR的机理及测试方法,简要总结了近年来用于2e-ORR制H2 O2的贵金属基催化剂、碳基催化剂和非贵金属复合催化剂的研究进展,并在此基础上对电催化氧还原制双氧水未来的研究方向进行了展望.     

基于金属-有机框架的M-N/C类催化剂在氧还原反应中的应用

燃料电池阴极发生氧还原反应(ORR)的动力学过程缓慢，通常需要Pt/C作为催化剂降低反应过电位。然而Pt作为一种贵金属，其使用将极大增加燃料电池的生产成本，因此开发非贵金属催化剂来替代Pt/C催化剂具有重要意义。金属有机框架材料(MOFs)因其具有高比表面积、有序多孔结构、拓扑结构可调等特点作为前驱体被广泛应用于M-N/C类催化剂的合成。M-N/C类催化剂继承了MOFs的结构特征，且具有丰富的活性位点，提高催化活性和分级结构以促进传质过程，因此表现出良好的ORR催化性能。从单金属/氮/碳和多金属/氮/碳组成角度出发，对近几年来关于M-N/C类催化剂的结构设计思路和合成策略进行了总结，阐述了其在ORR中的催化性能，展望了其未来发展前景。     

杂原子掺杂碳材料在直接甲醇燃料电池催化剂中的研究进展

直接甲醇燃料电池(DMFCs)是解决能源短缺和环境污染问题的清洁能源之一。甲醇氧化反应(MOR)和氧还原反应(ORR)是DMFCs重要的电极反应，然而其迟缓的动力学过程严重制约其商业化进程。碳材料因具有低成本、高比表面积、发达的孔结构而备受关注。杂原子(氮、硫、磷、硼等)掺杂不仅有助于改善碳的表面惰性来提高导电性能和增加缺陷位点，还能通过强化金属-载体间相互作用提高电化学活性。因此，研发杂原子掺杂碳材料作为ORR催化剂和MOR催化剂载体对推动DMFCs的商业化具有重要意义。综述了杂原子掺杂碳材料常见的制备方法及其在ORR和MOR领域的研究进展，并展望多组分共掺杂、材料稳定性的提升及催化机制的深入剖析是未来研究的方向。     

铁氮共掺杂介孔碳材料的简易制备及其氧还原反应催化性能

氧还原反应(ORR)是燃料电池阴极重要的电化学反应过程,其自发反应进程缓慢,对氧还原反应起高效催化作用的催化剂面临价格昂贵、合成流程复杂、污染环境等问题,因此探索合成简单、环境友好的氧还原催化剂制备方法具有重要意义。铁氮共掺杂介孔碳材料(Fe-N/MC)是一种有巨大应用价值的非贵金属氧还原反应催化剂。本工作通过在马弗炉中的半封闭体系内高温碳化小分子前驱体得到介孔碳材料(MC_M),再把获得的MC_M与铁盐混合在管式炉中高温处理制备得到铁氮共掺杂介孔碳材料(Fe-N/MC_MT)。该方法热解条件简单,无需模板剂和NH₃、HF等有毒物质。由于MC_M含有较高的氮和氧元素,有利于提升介孔碳材料表面的亲水性和配位能力,通过MC_M和铁盐制备出的Fe-N/MC_MT含有丰富的、催化ORR的Fe-N_x活性位点,其起始电位和半波电位分别为0.941和0.831 V(vs RHE),比商业化Pt/C催化剂的起始电位和半波电位分别正34和16...     

MOF‐Based Metal‐Doping‐Induced Synthesis of Hierarchical Porous CuN/C Oxygen Reduction Electrocatalysts for Zn–Air Batteries

A transition‐metal–nitrogen/carbon (TM–N/C, TM = Fe, Co, Ni, etc.) system is a popular, nonprecious‐metal oxygen reduction reaction (ORR) electrocatalyst for fuel cell and metal–air battery applications. However, there remains a lack of comprehensive understanding about the ORR electrocatalytic mechanism on these catalysts, especially the roles of different forms of metal species on electrocatalytic performance. Here, a novel Cu?N/C ORR electrocatalyst with a hybrid Cu coordination site is successfully fabricated with a simple but efficient metal–organic‐framework‐based, metal‐doping‐induced synthesis strategy. By directly pyrolyzing Cu‐doped zeolitic‐imidazolate‐framework‐8 polyhedrons, the obtained Cu?N/C catalyst can achieve a high specific surface area of 1182 m² g^?1 with a refined hierarchical porous structure and a high surface N content of 11.05 at%. Moreover, regulating the Cu loading can efficiently tune the states of Cu(II) and Cu⁰, resulting in the successful construction of a highly active hybrid coordination site of N?Cu(II)?Cu⁰ in derived Cu?N/C catalysts. As a result, the optimized 25% Cu?N/C catalyst possesses a high ORR activity and stability in 0.1 m KOH solution, as well as excellent performance and stability in a Zn–air battery.     

Porous Carbon‐Hosted Atomically Dispersed Iron–Nitrogen Moiety as Enhanced Electrocatalysts for Oxygen Reduction Reaction in a Wide Range of pH

As one of the alternatives to replace precious metal catalysts, transition‐metal–nitrogen–carbon (M–N–C) electrocatalysts have attracted great research interest due to their low cost and good catalytic activities. Despite nanostructured M–N–C catalysts can achieve good electrochemical performances, they are vulnerable to aggregation and insufficient catalytic sites upon continuous catalytic reaction. In this work, metal–organic frameworks derived porous single‐atom electrocatalysts (SAEs) were successfully prepared by simple pyrolysis procedure without any further posttreatment. Combining the X‐ray absorption near‐edge spectroscopy and electrochemical measurements, the SAEs have been identified with superior oxygen reduction reaction (ORR) activity and stability compared with Pt/C catalysts in alkaline condition. More impressively, the SAEs also show excellent ORR electrocatalytic performance in both acid and neutral media. This study of nonprecious catalysts provides new insights on nanoengineering catalytically active sites and porous structures for nonprecious metal ORR catalysis in a wide range of pH.     

MOF‐Based Metal‐Doping‐Induced Synthesis of Hierarchical Porous Cu?N/C Oxygen Reduction Electrocatalysts for Zn–Air Batteries

A transition‐metal–nitrogen/carbon (TM–N/C, TM = Fe, Co, Ni, etc.) system is a popular, nonprecious‐metal oxygen reduction reaction (ORR) electrocatalyst for fuel cell and metal–air battery applications. However, there remains a lack of comprehensive understanding about the ORR electrocatalytic mechanism on these catalysts, especially the roles of different forms of metal species on electrocatalytic performance. Here, a novel Cu? N/C ORR electrocatalyst with a hybrid Cu coordination site is successfully fabricated with a simple but efficient metal–organic‐framework‐based, metal‐doping‐induced synthesis strategy. By directly pyrolyzing Cu‐doped zeolitic‐imidazolate‐framework‐8 polyhedrons, the obtained Cu? N/C catalyst can achieve a high specific surface area of 1182 m² g^?1 with a refined hierarchical porous structure and a high surface N content of 11.05 at%. Moreover, regulating the Cu loading can efficiently tune the states of Cu(II) and Cu⁰, resulting in the successful construction of a highly active hybrid coordination site of N? Cu(II)? Cu⁰ in derived Cu? N/C catalysts. As a result, the optimized 25% Cu? N/C catalyst possesses a high ORR activity and stability in 0.1 m KOH solution, as well as excellent performance and stability in a Zn–air battery.     

Facile construction of manganese oxide doped carbon nanotube catalysts with high activity for oxygen reduction reaction and investigations into the origin of their activity enhancement

MnOx-doped carbon nanotube (MnOx-CNTs) catalysts for the oxygen reduction reaction (ORR) were fabricated using a simple electrochemical deposition method. MnOx-CNTs (0.85 wt % MnOx) could exhibit an improved electrocatalytic activity, long-term stability and excellent resistance to crossover-effect compared to Pt/C catalysts. High-resolution transmission electron microscopy (HRTEM) and X-ray diffraction analysis confirm that the MnOx in the MnOx-CNTs exists in an amorphous state. Moreover, compared to the catalytic performances of MnOx on other substrates, the MnOx-CNTs exhibit a high ORR activity. X-ray photoelectron spectroscopy results suggest that the electron transfer, from the CNTs to the Mn ions occurs and the high positive charge is generated on the MnOx-CNT surface. This is believed to be origin of the catalytic activity observed in the ORR using MnOx-CNTs.     

Heteroatom Coordination Regulates Iron Single-Atom-Catalyst with Superior Oxygen Reduction Reaction Performance for Aqueous Zn-Air Battery

Platinum group metal (PGM)-free M-N-C catalysts have exhibited dramatic electrocatalytic performance and are considered the most promising candidate of the Pt catalysts in oxygen reduction reaction (ORR). However, the electrocatalytic performance of the M-N-C catalysts is still limited by their inferior intrinsic activity and finite active site density. Regulating the coordination environment and increasing the pore structure of the catalyst is an effective strategy to enhance the electrocatalytic performance of the M-N-C catalysts. In this work, the coordination environment and pore structure exquisitely regulated Fe-N-C catalyst exhibit excellent ORR activity and durability. With the enhanced intrinsic activity and increased active site density, the optimized Fe-N/S-C catalyst shows impressive ORR activity (E_1/2 = 0.904 V vs reversible hydrogen electrode (RHE)) and superior long-term durability in an alkaline medium. As the advanced physical characterization and theoretical chemistry methods illustrate, the S-modified Fe-N_x (Fe-N₃/S-C) moiety is confirmed as the improved active center for ORR, and the increased active site density further improved ORR efficiency. Based on the Fe-N/S-C cathode, a Zn-air battery is fabricated and shows superior power density (315.4 mW cm⁻²) and long-term discharge stability at 20 mA cm⁻². This work would open a new perspective to design atomically dispersed iron-metal site catalysts for advanced electro-catalysis.     

Bio‐Derived Co2P Nanoparticles Supported on Nitrogen‐Doped Carbon as Promising Oxygen Reduction Reaction Electrocatalyst for Anion Exchange Membrane Fuel Cells

Recently, nonnoble‐metal catalysts such as a metal coordinated to nitrogen doped in a carbon matrix have been reported to exhibit superior oxygen reduction reaction (ORR) activity in alkaline media. In this work, Co₂P nanoparticles supported on heteroatom‐doped carbon catalysts (NBSCP) are developed with an eco‐friendly synthesis method using bean sprouts. NBSCP can be easily synthesized through metal precursor absorption and carbonization at a high temperature. It shows a very large specific surface area with various dopants such as nitrogen, phosphorus, and sulfur derived from small organic molecules. The catalyst can exhibit activity in various electrochemical reactions. In particular, excellent performance is noted for the ORR. Compared to the commercial Pt/C, NBSCP exhibits a lower onset potential, higher current density, and superior durability. This excellent ORR activity and durability is attributable to the synergistic effect between Co₂P nanoparticles and nitrogen‐doped carbon. In addition, superior performance is noted on applying NBSCP to a practical anion exchange membrane fuel cell system. Through this work, the possibility of applying an easily obtained bio‐derived material to energy conversion and storage systems is demonstrated.     

ZIF‐8/ZIF‐67‐Derived Co‐Nx‐Embedded 1D Porous Carbon Nanofibers with Graphitic Carbon‐Encased Co Nanoparticles as an Efficient Bifunctional Electrocatalyst

Herein, an approach is reported for fabrication of Co‐N_x‐embedded 1D porous carbon nanofibers (CNFs) with graphitic carbon‐encased Co nanoparticles originated from metal–organic frameworks (MOFs), which is further explored as a bifunctional electrocatalyst for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Electrochemical results reveal that the electrocatalyst prepared by pyrolysis at 1000 °C (CoNC‐CNF‐1000) exhibits excellent catalytic activity toward ORR that favors the four‐electron ORR process and outstanding long‐term stability with 86% current retention after 40 000 s. Meanwhile, it also shows superior electrocatalytic activity toward OER, reaching a lower potential of 1.68 V at 10 mA cm^?2 and a potential gap of 0.88 V between the OER potential (at 10 mA cm^?2) and the ORR half‐wave potential. The ORR and OER performance of CoNC‐CNF‐1000 have outperformed commercial Pt/C and most nonprecious‐metal catalysts reported to date. The remarkable ORR and OER catalytic performance can be mainly attributable to the unique 1D structure, such as higher graphitization degree beneficial for electronic mobility, hierarchical porosity facilitating the mass transport, and highly dispersed CoN_xC active sites functionalized carbon framework. This strategy will shed light on the development of other MOF‐based carbon nanofibers for energy storage and electrochemical devices.     

Boosting Bifunctional Oxygen Electrolysis for N‐Doped Carbon via Bimetal Addition

The addition of transition metals, even in a trace amount, into heteroatom‐doped carbon (M‐N/C) is intensively investigated to further enhance oxygen reduction reaction (ORR) activity. However, the influence of metal decoration on the electrolysis of the reverse reaction of ORR, that is, oxygen evolution reaction (OER), is seldom reported. Moreover, further improving the bifunctional activity and corrosion tolerance for carbon‐based materials remains a big challenge, especially in OER potential regions. Here, bimetal‐decorated, pyridinic N‐dominated large‐size carbon tubes (MM′‐N/C) are proposed for the first time as highly efficient and durable ORR and OER catalysts. FeFe‐N/C, CoCo‐N/C, NiNi‐N/C, MnMn‐N/C, FeCo‐N/C, NiFe‐N/C, FeMn‐N/C, CoNi‐N/C, MnCo‐N/C, and NiMn‐N/C are systematically investigated in terms of their structure, composition, morphology, surface area, and active site densities. In contrast to conventional monometal and N‐decorated carbon, small amounts of bimetal (≈2 at%) added during the one‐step template‐free synthesis contribute to increased pyridinic N content, much longer and more robust carbon tubes, reduced metal particle size, and stronger coupling between the encapsulated metals and carbon support. The synergy of those factors accounts for the dramatically improved ORR and OER activity and stability. By comparison, NiFe‐N/C and MnCo‐N/C stand out and achieve superior bifunctional oxygen catalytic performance, exceeding most of state‐of‐the‐art catalysts.     

Fe-PPy-TsOH/C用作质子交换膜燃料电池氧电极催化剂的研究

氧电极催化剂是制约质子交换膜燃料电池(PEMFCs)发展和应用的一个重要因素, 开发低价高效的非贵金属催化剂对PEMFCs来说已成为当务之急。本研究选择氮掺杂的碳载过渡金属(M-N/C)类催化剂为研究对象, 以铁盐作为金属前驱体, BP2000为碳源, 聚吡咯(PPy)为氮源, 对甲基苯磺酸(TsOH)为掺杂剂, 合成了非贵金属催化剂Fe-PPy-TsOH/C, 探究了不同的热处理温度及钴原子的掺杂对其氧还原催化性能的影响。研究结果表明: 800℃制备的Fe-PPy-TsOH/C催化剂因结晶度高、颗粒大小适中且分布均匀而具有最佳的氧还原催化性能; 一定量的钴原子取代可以改善Fe-PPy-TsOH/C的氧还原催化性能, 当钴的掺杂量为33.33%时(铁钴原子比为2︰1), 催化剂的性能达到最优。     

Sustainable Hydrothermal Carbonization Synthesis of Iron/Nitrogen‐Doped Carbon Nanofiber Aerogels as Electrocatalysts for Oxygen Reduction

It is urgent to develop new kinds of low‐cost and high‐performance nonprecious metal (NPM) catalysts as alternatives to Pt‐based catalysts for oxygen reduction reaction (ORR) in fuel cells and metal–air batteries, which have been proved to be efficient to meet the challenge of increase of global energy demand and CO₂ emissions. Here, an economical and sustainable method is developed for the synthesis of Fe, N codoped carbon nanofibers (Fe–N/CNFs) aerogels as efficient NPM catalysts for ORR via a mild template‐directed hydrothermal carbonization (HTC) process, where cost‐effective biomass‐derived d (+)‐glucosamine hydrochloride and ferrous gluconate are used as precursors and recyclable ultrathin tellurium nanowires are used as templates. The prepared Fe/N‐CNFs catalysts display outstanding ORR activity, i.e., onset potential of 0.88 V and half‐wave potential of 0.78 V versus reversible hydrogen electrode in an alkaline medium, which is highly comparable to that of commercial Pt/C (20 wt% Pt) catalyst. Furthermore, the Fe/N‐CNFs catalysts exhibit superior long‐term stability and better tolerance to the methanol crossover effect than the Pt/C catalyst in both alkaline and acidic electrolytes. This work suggests the great promise of developing new families of NPM ORR catalysts by the economical and sustainable HTC process.