氮掺杂石墨烯原位生长碳纳米管复合过渡金属催化剂的制备及电催化性能EI北大核心CSCD

采用直接热解法,以石墨烯为载体,2-甲基咪唑锌盐MAF-4(ZIF8)为模板,尿素提供碳和氮源,Fe为过渡金属源,合成氮掺杂石墨烯(N/GO)和Fe-ZIF8(N-GO@Fe/ZIF8)的复合催化剂,并组装成锌空气电池。采用扫描电子显微镜(SEM)、透射电子显微镜(TEM)及电化学工作站等分析手段对催化剂的形貌、结构及电化学性能进行表征。结果表明:合成的N-GO@Fe/ZIF8-900催化剂具有优异的氧还原/氧析出(ORR/OER)性能。氧还原半波电位达到0.885 V,优于Pt/C(0.856 V),氧析出时,在10 mA/cm^(2)的电流密度下对应电位为1.811 V,优于贵金属Pt/C(1.968 V),与IrO_(2)(1.75 V)性能相当。组装成锌空气电池后,比能量和功率密度分别达到886.2 mW·h·g^(-1)和73.44 mW/cm^(2),高于贵金属Pt/C的比能量(791.04 mW·h·g^(-1))和功率密度(57.12 mW/cm^(2))。     

硫调控FeNi纳米合金作为双功能氧电极的研究（英文）

当前,FeNi合金由于其含量丰富、化学稳定性好的优点,在锌-空气二次电池(ZABs)中的氧还原反应(ORR)和析氧反应(OER)方面受到了广泛的关注.然而,传统FeNi合金还具有导电性差、比表面积小、活性低等缺点,严重阻碍了它们的催化性能.我们通过对金属有机前驱体进行热处理,合成了以分级多孔碳为载体的S-调控FeNi纳米合金材料(S-FeNi/PC),以实现高效的双功能氧催化.S调控赋予了FeNi纳米合金优越的OER性能,同时还使材料保持了与Pt/C相当的ORR性能.因此,SFeNi/PC具有很好的双功能氧催化活性,优于商业的Pt/C和RuO₂贵金属基复合催化剂.值得注意的是,以S-FeNi/PC为电极组装的ZABs具有较高的比容量(792 mA h g^-1)、高峰值功率密度(123.5mW cm^-2),以及在10 mA cm^-2电流密度下可700次放电/充电循环的优异耐久性,这些性能远高于商用Pt/C-RuO₂催化剂,甚至超过了许多先前报道的工作.我们相信这项研究不仅为高效的...     

负载在Co/碳纳米纤维上的分层非晶双金属硫化物纳米片用于协同促进水电解（英文）

设计分层异质结构作为一种经济且高效的催化剂,以实现水分解的电子和界面工程,是能源存储与转化中的一个有意义的决策.在这项工作中,通过静电纺丝-碳化-电沉积的策略,制备了负载在嵌入Co纳米颗粒的碳纤维上的非晶态NiFeS纳米片(Co-C/NiFeS纳米纤维)催化剂.该催化剂具有优异的析氧反应(OER)活性,在1 mol L^-1 KOH溶液中,在10 mA cm^-2下的过电位为233 mV,Tafel斜率为53.1 mV dec^-1,同时还具有良好的析氢反应活性.此外,由Co-C/NiFeS纳米纤维作为阳极,商用Pt/C作为阴极构建的碱性Pt/C‖Co-C/NiFeS电解槽在10 mA cm^-2下实现1.48 V的低电池电压,优于基准Pt/C‖RuO₂电解槽和许多其他报道的电解槽.作为双功能电催化剂,Co-C/NiFeS‖Co-C/NiFeS自身组装的电解槽表现出70小时的长期稳定性,显著优于Pt/C‖RuO₂电解槽.该催化剂显著的OER性能得益于Co-C纳米纤...     

超细铂纳米颗粒复合多孔碳纳米纤维催化剂用于高效氧还原反应（英文）

合理设计铂纳米颗粒尺寸是制备高效氧还原电催化剂的关键.本工作中,我们借助静电纺丝和ZIF-8的双重限域作用合成了超细铂纳米颗粒锚定在多孔碳纳米纤维上的催化材料.低Pt负载(4.2 wt%)的Pt@PCNFs在碱性和酸性电解质中均表现出优异的氧还原反应活性,其质量活性分别为41和51 A g_Pt^-1,分别是商业Pt/C催化剂相应值的8倍和10倍.在不同温度的碱性和酸性环境的计时安培试验和加速稳定性实验中, Pt@PCNFs的稳定性均优于Pt/C基准.该催化剂的优异性能可归因于小尺寸的Pt纳米颗粒、丰富多孔的纤维结构、Pt纳米颗粒与N掺杂碳纳米纤维之间的强金属载体相互作用以及碳壳层的保护作用.     

石墨化介孔碳包裹WC纳米粒子的构建及其氧还原性能研究

采用模板复型辅助的化学气相沉积法(CVD)成功制备出一种非贵金属的氧还原反应(ORR)催化剂材料—包裹碳化钨纳米粒子的石墨化介孔碳(WC/MG)复合物。制备的介孔结构WC/MG复合材料不仅具有高氧还原反应电化学催化活性, 还表现出良好的电化学稳定性。在O₂饱和的0.1 mol/L KOH电解质溶液中, 900℃制备的样品WC/ MG-900其半波电势(E_1/2)和极限电流密度仅比商用贵金属催化剂Pt/C分别低50 mV 和 0.2 mA/cm²。Koutecky- Levich曲线和旋转环盘电极实验均表明, 该介孔结构的WC/MG复合材料表现出近似4电子的ORR反应途径, 具有可与Pt/C催化剂相比拟的ORR催化活性, 以及比Pt/C更优越的电化学稳定性和耐甲醇性能, 使得该介孔结构WC/MG复合物在氧还原电极材料中表现出良好的应用前景。     

氢氧化钾活化制备可再生多孔碳及其电催化氧还原性能研究

氧还原反应缓慢的动力学过程严重限制了燃料电池的能量转换效率, 而商用Pt/C催化剂成本太高、资源稀缺、稳定性差, 需要寻找合适的材料来取代商用的Pt/C催化剂。近年来, 氮掺杂多孔碳材料因其独特的物理和化学特性吸引了大量的关注。本文使用富含氮元素的可再生土豆作为生物质前驱体, 通过简单的一步热解过程和KOH活化方法相结合制备出了一系列氮掺杂多孔碳电催化剂; 并系统研究了KOH用量和活化温度对碳基体孔结构和电催化性能的影响。结果表明, 当活化温度为750 ℃、KOH与碳的质量比为3/1时, 所制备的催化剂(NPC-750)的氧还原活性最高, 起始电位和半波电位分别达到0.89和0.79 V (vs. RHE), 极限电流密度达到5.53 mA?cm ^-2。NPC-750优异的氧还原催化活性主要归因于其发达的孔结构、高的比表面积(1134.2 m ²?g ^-1)和合适的氮含量(1.57at%)。同时, 优异的循环稳定性和抗甲醇中毒性能进一步说明这些生物多孔碳材料是潜在的低成本氧还原电催化剂。此外, 这些高比表面积多孔碳在超级电容、吸附/分离、催化以及电池等领域也具有潜在的应用前景。     

铱钴纳米纤维作为一种高效稳定的双功能电催化剂用于高性能水裂解（英文）

本文通过静电纺丝-煅烧-原位氢还原-置换工艺制备了嵌入铱的钴纳米纤维(Co-Ir-600).得益于独特的一维纳米纤维异质结构给予的快速电子传输和传质过程以及Ir和Co两组分之间的协同作用,Co-Ir催化剂在碱性电解质中达到10 mA cm^-2电流密度仅需169 mV的极低过电位,表现出优异的析氧电催化活性.此外,该催化剂还具有良好的析氢反应性能.我们构建了一种将Co-Ir-600纳米纤维催化剂同时作为阳极和阴极的碱性电解槽,其只需要1.51 V的低电池电压即可达到10 mA cm^-2的电流密度且耐用性好,性质明显优于参照的Pt/C||IrO₂以及许多已报道的水电解槽.本研究为制备经济高效的金属基水裂解电催化剂提供了一种通用有效的方法.     

镍基MOF衍生Ni@PC用于氧还原催化性能研究

开发高效、低成本的非贵金属氧还原催化剂是提高燃料电池效率的关键。以六水合硝酸镍和二甲基咪唑作为金属源和氮源，制备Ni-MOF前驱体，并采用低温热解法合成了纳米棒状镍掺杂多孔碳(Ni@PC)复合材料。通过扫描电子显微镜、X射线衍射仪、拉曼光谱和物理吸附仪等多种表征手段，对催化剂进行形貌和结构表征。利用旋转圆盘电极技术测试了其氧还原催化性能。结果表明：Ni@PC呈现三维交错的纳米棒状，其比表面积为178.7m²/g,具有介孔结构。在0.1mol/L KOH电解液中，Ni@PC的氧还原起始电位为0.89V(vs RHE),其极限电流密度可达4.91mA/cm²,在动力学电位区，Ni@PC的Tafel斜率为64mV/dec,氧气分子在Ni@PC催化剂上以四电子机理反应还原成水，该催化剂具有优异的耐久性和抗甲醇稳定性。因此，Ni@PC有望替代商业Pt/C催化剂，在能源领域具有广阔的应用前景。     

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。     

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。     

Single copper sites dispersed on hierarchically porous carbon for improving oxygen reduction reaction towards zinc-air battery

The demand for high-performance non-precious-metal electrocatalysts to replace the noble metal-based catalysts for oxygen reduction reaction(ORR)is intensively increasing.Herein,single-atomic copper sites supported on N-doped three-dimensional hierarchically porous carbon catalyst(Cu₁/NC)was prepared by coordination pyrolysis strategy.Remarkably,the Cu₁/NC-900 catalyst not only exhibits excellent ORR performance with a half-wave potential of 0.894 V(vs.RHE)in alkaline media,outperforming those of commercial Pt/C(0.851 V)and Cu nanoparticles anchored on N-doped porous carbon(CuNPs/NC-900),but also demonstrates high stability and methanol tolerance.Moreover,the Cu₁/NC-900 based Zn-air battery exhibits higher power density,rechargeability and cyclic stability than the one based on Pt/C.Both experimental and theoretical investigations demonstrated that the excellent performance of the as-obtained Cu₁/NC-900 could be attributed to the synergistic effect between copper coordinated by three N atoms active sites and the neighbouring carbon defect,resulting in elevated Cu d-band centers of Cu atoms and facilitating intermediate desorption for ORR process.This study may lead towards the development of highly efficient non-noble metal catalysts for applications in electrochemical energy conversion.     

Single Fe Atom on Hierarchically Porous S,N‐Codoped Nanocarbon Derived from Porphyra Enable Boosted Oxygen Catalysis for Rechargeable Zn‐Air Batteries

Iron–nitrogen–carbon materials (Fe–N–C) are known for their excellent oxygen reduction reaction (ORR) performance. Unfortunately, they generally show a laggard oxygen evolution reaction (OER) activity, which results in a lethargic charging performance in rechargeable Zn–air batteries. Here porous S‐doped Fe–N–C nanosheets are innovatively synthesized utilizing a scalable FeCl₃‐encapsulated‐porphyra precursor pyrolysis strategy. The obtained electrocatalyst exhibits ultrahigh ORR activity (E_1/2 = 0.84 V vs reversible hydrogen electrode) and impressive OER performance (E_{j = 10} = 1.64 V). The potential gap (ΔE = E_{j = 10} ? E_1/2) is 0.80 V, outperforming that of most highly active bifunctional electrocatalysts reported to date. Furthermore, the key role of S involved in the atomically dispersed Fe–Nx species on the enhanced ORR and OER activities is expounded for the first time by ultrasound‐assisted extraction of the exclusive S source (taurine) from porphyra. Moreover, the assembled rechargeable Zn–air battery comprising this bifunctional electrocatalyst exhibits higher power density (225.1 mW cm^?2) and lower charging–discharging overpotential (1.00 V, 100 mA cm^?2 compared to Pt/C + RuO₂ catalyst). The design strategy can expand the utilization of earth‐abundant biomaterial‐derived catalysts, and the mechanism investigations of S doping on the structure–activity relationship can inspire the progress of other functional electrocatalysts.     

Atomically Dispersed Fe/N4 and Ni/N4 Sites on Separate-Sides of Porous Carbon Nanosheets with Janus Structure for Selective Oxygen Electrocatalysis

Dual single atoms catalysts have promising application in bifunctional electrocatalysis due to their synergistic effect. However, how to balance the competition between rate-limiting steps (RDSs) of reversible oxygen reduction and oxygen evolution reaction (OER) and fully expose the active centers by reasonable structure design remain enormous challenges. Herein, Fe/N₄ and Ni/N₄ sites separated on different sides of the carbon nanosheets with Janus structure (FeNi_jns/NC) is synthesized by layer-by-layer assembly method. Experiments and calculations reveal that the side of Fe/N₄ is beneficial to oxygen reduction reaction (ORR) and the Ni/N₄ side is preferred to OER. Such Janus structure can take full advantage of two separate-sides of carbon nanosheets and balance the competition of RDSs during ORR and OER. FeNi_jns/NC possesses superior ORR and OER activity with ORR half-wave potential of 0.92 V and OER overpotential of 440 mV at J = 10 mA cm⁻². Benefiting from the excellent bifunctional activities, FeNi_jns/NC assembled aqueous Zn–air battery (ZAB) demonstrates better maximum power density, and long-term stability (140 h) than Pt/C+RuO₂ catalyst. It also reveals superior flexibility and stability in solid-state ZAB. This work brings a novel perspective for rational design and understanding of the catalytic mechanisms of dual single atom catalysts.     

Nitrogen-doped graphite encapsulated Fe/Fe_3C nanoparticles and carbon black for enhanced performance towards oxygen reduction

Non-noble metal(NNM) catalysts have recently attracted intensive interest for their high catalytic performance towards oxygen reduction reaction(ORR) at low cost.Herein,a novel NNM catalyst was synthesized by the simple pyrolysis of carbon black,urea and a Fe-containing precursor,which exhibits excellent ORR catalytic activity,superior durability and methanol tolerance versus the Pt/C catalyst in both alkaline and acidic solutions.Scanning electron microscopy(SEM),transmission electron microscopy(TEM) and X-ray diffraction(XRD) characterizations demonstrate that the product is a nitrogen-doped hybrid of graphite encapsulated Fe/Fe_3C nanoparticles and carbon black.X-ray photoelectron spectrum(XPS) and electrochemical analyses indicate that the catalytic performance and chemical stability correlate closely with a nitrogen-rich layer on the Fe/Fe_3C nanoparticle after pyrolysis with presence of urea,leading to the same four-electron pathway towards ORR as the Pt/C catalyst.The hybrid is prospective to be an efficient ORR electrocatalyst for direct methanol fuel cells with high catalytic performance at low cost.     

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。     

2D Nanoporous Fe−N/C Nanosheets as Highly Efficient Non‐Platinum Electrocatalysts for Oxygen Reduction Reaction in Zn‐Air Battery

It is an ongoing challenge to fabricate nonprecious oxygen reduction reaction (ORR) catalysts that can be comparable to or exceed the efficiency of platinum. A highly active non‐platinum self‐supporting Fe?N/C catalyst has been developed through the pyrolysis of a new type of precursor of iron coordination complex, in which 1,4‐bis(1H‐1,3,7,8–tetraazacyclopenta(1)phenanthren‐2‐yl)benzene (btcpb) functions as a ligand complexing Fe(II) ions. The optimal catalyst pyrolyzed at 700 °C (Fe?N/C?700) shows the best ORR activity with a half‐wave potential (E_1/2) of 840 mV versus reversible hydrogen electrode (RHE) in 0.1 m KOH, which is more positive than that of commercial Pt/C (E_1/2: 835 mV vs RHE). Additionally, the Fe?N/C?700 catalyst also exhibits high ORR activity in 0.1 m HClO₄ with the onset potential and E_1/2 comparable to those of the Pt/C catalyst. Notably, the Fe?N/C?700 catalyst displays superior durability (9.8 mV loss in 0.1 m KOH and 23.6 mV loss in 0.1 m HClO₄ for E_1/2 after 8000 cycles) and better tolerance to methanol than Pt/C. Furthermore, the Fe?N/C?700 catalyst can be used for fabricating the air electrode in Zn–air battery with a specific capacity of 727 mA hg^?1 at 5 mA cm^?2 and a negligible voltage loss after continuous operation for 110 h.     

Fe Isolated Single Atoms on S,N Codoped Carbon by Copolymer Pyrolysis Strategy for Highly Efficient Oxygen Reduction Reaction

Heteroatom‐doped Fe‐NC catalyst has emerged as one of the most promising candidates to replace noble metal‐based catalysts for highly efficient oxygen reduction reaction (ORR). However, delicate controls over their structure parameters to optimize the catalytic efficiency and molecular‐level understandings of the catalytic mechanism are still challenging. Herein, a novel pyrrole–thiophene copolymer pyrolysis strategy to synthesize Fe‐isolated single atoms on sulfur and nitrogen‐codoped carbon (Fe‐ISA/SNC) with controllable S, N doping is rationally designed. The catalytic efficiency of Fe‐ISA/SNC shows a volcano‐type curve with the increase of sulfur doping. The optimized Fe‐ISA/SNC exhibits a half‐wave potential of 0.896 V (vs reversible hydrogen electrode (RHE)), which is more positive than those of Fe‐isolated single atoms on nitrogen codoped carbon (Fe‐ISA/NC, 0.839 V), commercial Pt/C (0.841 V), and most reported nonprecious metal catalysts. Fe‐ISA/SNC is methanol tolerable and shows negligible activity decay in alkaline condition during 15 000 voltage cycles. X‐ray absorption fine structure analysis and density functional theory calculations reveal that the incorporated sulfur engineers the charges on N atoms surrounding the Fe reactive center. The enriched charge facilitates the rate‐limiting reductive release of OH* and therefore improved the overall ORR efficiency.     

Shape and composition-controlled platinum alloy nanocrystals using carbon monoxide as reducing agent

The shape of metal alloy nanocrystals plays an important role in catalytic performances. Many methods developed so far in controlling the morphologies of nanocrystals are however limited by the synthesis that is often material and shape specific. Here we show using a gas reducing agent in liquid solution (GRAILS) method, different Pt alloy (Pt-M, M = Co, Fe, Ni, Pd) nanocrystals with cubic and octahedral morphologies can be prepared under the same kind of reducing reaction condition. A broad range of compositions can also be obtained for these Pt alloy nanocrystals. Thus, this GRAILS method is a general approach to the preparation of uniform shape and composition-controlled Pt alloy nanocrystals. The area-specific oxygen reduction reaction (ORR) activities of Pt(3)Ni catalysts at 0.9 V are 0.85 mA/cm(2)(Pt) for the nanocubes, and 1.26 mA/cm(2)(Pt) for the nanooctahedra. The ORR mass activity of the octahedral Pt(3)Ni catalyst reaches 0.44 A/mg(Pt).     

Inflating strategy to fabricate highly dispersed Fe,N co-doped hierarchically porous carbon for ORR and supercapacitor

Doped-carbon nanomaterials as effective electrocatalysts have been received widespread attention in oxygen reduction reaction (ORR) and supercapacitors system. Herein, the high-active Fe atoms dispersed on hierarchically porous N-doped carbon (FeNC-X) is synthesized via inflating the Fe-ion-denatured egg-white, followed by activation and pyrolysis. Among them, the as-prepared FeNC-900 for ORR that has an inner-connecting hierarchically porous structure shows a superior performance with a limiting current density of 5.28 mA cm^?2 and half-wave potential (E_1/2) of 0.839 V (vs RHE), and exhibits a 4 e^? ORR pathway in the alkaline medium. FeNC-900 also shows better durability and good methanol tolerance than those of commercial Pt/C. Besides, FeNC-900 exhibits an outstanding specific capacity of 258 F g^?1 at 1 A g^?1 for supercapacitor. The method presented here may provide a cost-efficient approach to fabricate carbon-based materials for ORR and supercapacitors.