凹凸棒石黏土负载Ni催化裂解生物质焦油

利用浸渍法制备了凹凸棒石黏土(palygorskite,PG)Ni基催化剂(Ni/PG),探究了不同Ni负载量以及反应温度对凹凸棒石镍基催化剂催化裂解生物质焦油的影响,利用透射电镜、X射线粉末衍射、总碳等分析手段对催化剂的形貌、物相和积炭量进行表征.结果表明:活性组分高负载量有利于提高焦油去除率和氢产率;高温条件也有利...     

生物质热解焦油的热裂解与催化裂解

生物质气化过程中产生的焦油对气化系统和用气设备都有极大的危害。为了开发适合于商业应用的焦油缩减方法,探索达到最优焦油脱除效果的操作条件,在固定床反应器上,利用石灰石、白云石、高铝砖作为催化剂研究了生物质(稻秆、稻壳、木屑等)热解焦油的催化裂解反应,利用炭化硅作为热载体研究了焦油的热裂解反应,对热解煤气中焦油含量的变化以及热解煤气组成和热值的变化进行了比较,并对裂解温度、气相停留时间等因素对裂解效果的影响进行了探讨。实验发现,600-900℃范围内ηtar随裂解温度升高而升高,900℃时热裂解条件下可达60％,而催化裂解条件下可达90％以上。0．5～1s范围内,ηtar随停留时间增加而升高,幅度约7％～10％。相比于原始煤气,裂解后煤气组成出现了较大变化,热裂解后煤气热值增加,而催化裂解后煤气热值下降,且热裂解与催化裂解处理后煤气组成也有较大差异。     

过渡金属改性氮掺杂多孔碳负载Pt催化甘油氧化制备甘油酸

将不同过渡金属掺杂到金属有机骨架化合物中后,通过高温煅烧得到过渡金属改性氮掺杂多孔碳材料(M@NHC),然后通过胶体沉积法生成Pt/M@NHC催化剂,在碱性条件下用作催化剂将甘油氧化成甘油酸。研究表明：过渡金属的种类对甘油的转化率和甘油酸的选择性有较大影响,其中Ni掺杂的Pt/Ni@NHC催化剂的催化活性最佳。结合N₂物理吸附、X射线衍射、X射线光电子能谱、CO₂程序升温脱附等表征发现：Ni的加入既影响Pt表面电子结构,还能凭借Ni-Pt金属之间的协同作用增强Pt的抗氧化能力;表面N原子的掺杂会增加Pt和吸附氧表面的电子使分子氧快速活化并且产生更多的活性位点。此外,Pt/Ni@NHC催化剂中Pt纳米颗粒在所有催化剂中颗粒最小,有利于催化性能的提高。对Pt/Ni@NHC在不同制备条件下所得催化剂的催化性能进行考察发现：当Ni负载量为3%,在载体煅烧温度800℃,反应压力1 MPa,反应时间6 h的条件下制备的Pt/Ni@NHC具有最佳的催化活性,此时甘油的转化率为63%,甘油酸选择性为75%。     

珊瑚状氮掺杂多孔碳的制备及其超电容性能

在三聚氰胺为氮源、碳酸钾为活化剂的条件下,由菜籽饼制得了珊瑚状氮掺杂分级多孔碳(CNPCs)。采用场发射扫描电子显微镜、透射电子显微镜、X射线光电子能谱、氮吸脱附等表征手段,研究了三聚氰胺的用量对CNPCs微观形貌、组成及孔隙结构的影响。结果表明,当三聚氰胺的用量为2 g时,所得CNPC2的比表面积达2050 m2·g-1。以6 mol·L-1KOH为电解液,在0.05 A·g-1的电流密度下,CNPCs的比容可达274 F·g-1;当电流密度为50 A·g-1时,CNPCs的比容为169 F·g-1,显示了优异的倍率性能。经过10000次充放电测试后,比容保持率达96%,展现了良好的循环稳定性。此工作为从生物质大规模生产高性能储能用多孔碳材料提供了一种简单、绿色的方法。     

氮掺杂石墨烯/多孔碳复合材料的制备及其氧还原催化性能

采用简单、无模板的方法制备了氮掺杂多孔石墨烯/碳复合材料(NPGC)。采用SEM、XRD、Raman、XPS等分析手段对NPGC的形貌、组成以及结构进行了表征，利用旋转圆盘电极技术测试了其电催化氧还原反应(ORR)活性。结果表明，葡萄糖在水热后生成的碳与石墨烯成功复合，并在950℃炭化、活化后形成了相互渗透、结构良好的三维片状多孔网络结构；其氮含量高达9.47%。NPGC作为一种高效的非金属ORR电催化剂，在碱性溶液中具有较高的起始电位[0.87 V(vs RHE)]和较大的极限电流密度(4.7 mA?cm^?2)，以及其ORR平均转移电子数为3.8。与商业Pt/C催化剂相比，NPGC具有较强的耐甲醇性和长期耐久性，且制备成本较低，具有广阔的应用前景。     

生物质氮掺杂多孔碳高效催化还原4-硝基苯酚

采用生物质作为碳源,用尿素作为氮源进行掺氮,合成了一种生物质氮掺杂多孔碳催化剂。用4-硝基苯酚通过硼氢化钠还原为4-氨基苯酚作为基准反应,来衡量催化剂的催化效果。结果表明,生物质氮掺杂多孔碳催化剂具有高效的催化作用,并探究了退火温度对催化剂性能的影响。其中,800-NPC具有最高催化性能,能在4 min内将4-硝基苯酚完全还原。通过形貌表征,说明了催化效果高可能与催化剂有序多孔的结构有关。     

生物质多孔碳材料的水热合成及应用研究进展

生物质作为典型的可再生能源,具有负碳属性,符合绿色发展的要求。水热炭化是在相对温和的条件下将生物质转化为各种功能性碳材料的过程。本文综述了近年来以单糖(葡萄糖、果糖和木糖)、木质纤维(纤维素、半纤维素和木质素)和壳聚糖等生物质为原料,通过水热法转化为生物质多孔碳材料的研究进展,重点讨论了生物质多孔碳材料在气体吸附、染料吸附和重金属离子吸附领域的应用,并提出了生物质水热合成高性能和对环境友好的多孔碳材料的未来研究方向。     

铜泡沫负载Cu修饰氮掺杂碳用作催化析氧电极

以铜泡沫和三聚氰胺为原材料,通过煅烧途径制备了Cu/氮掺杂碳/铜泡沫催化电极.所得催化活性电极能促进氧析出动力学,在1M KOH溶液中,催化驱动50 mA cm-2的电流密度仅需320 mV的过电位.该催化电极还显示了较好的稳定性.     

氮掺杂多孔碳负载纳米钯银合金催化剂的制备及催化脱氢性能研究

为了减少Pd的用量,在不加任何保护剂的条件下,以乙醇为还原剂,在碱性环境下制备了氮掺杂多孔碳(NC)负载纳米钯银合金催化剂(Pd-Ag/NC),并应用于催化全氢化N-乙基咔唑(12H-NEC)脱氢反应.采用XRD,XPS和TEM对Pd-Ag/NC的结构、组成和形貌进行了表征.表征与催化实验结果表明:纳米Pd与Ag以合金...     

添加碳纳米颗粒对磷氮双掺杂石墨烯电化学特性的影响

燃料电池作为新型清洁能源技术具有高效的能源转化效率和环境友好等优点,在诸如交通运输以及航空航天等领域有着重要而广泛的应用。在影响燃料电池性能的众多因素中,电极的高效催化与稳定性对于整个燃料电池系统的性能至关重要。近年来,石墨烯材料由于优异的电学与力学性质为低铂高效催化研究提供了理论上的可行性。本研究以六氯环三磷腈（HCCP）为原料设计了一步热还原合成法实验制备了磷氮双掺杂石墨烯,并通过添加碳纳米颗粒增加了石墨烯层间间距,改善了石墨烯层间的团聚效应,提高了氧化还原（ORR）性能。研究结果表明,当AC添加含量与GO的质量比为10%时,其比表面积与电化学性能提升最为明显,极限电流密度达到-6.89 mA·cm^-2并且氧化活性能保持80%以上。因此,使用添加碳纳米颗粒对磷氮双掺杂石墨烯作为燃料电池非金属催化剂材料的进一步探索具有巨大的潜力。     

Spinel CoFe2O4 /carbon nanotube composites as efficient bifunctional electrocatalysts for oxygen reduction and oxygen evolution reaction

In the development of fuel cells, it is the key to large-scale commercialization of fuel cells to rationally design and synthesize efficient and non-noble metals-based bifunctional electrocatalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). In this paper, spinel CoFe₂O₄/carbon nanotube composites (CoFe₂O₄/CNTs/FA) were synthesized by solvothermal and calcination method. XRD, TEM, XPS and BET characterizations indicate that the addition of complexing agent fumaric acid can improve the crystal growth kinetics and morphology of CoFe₂O₄/CNTs nanohybirds. The as-synthesized CoFe₂O₄/CNTs/FA pyrolyzed at 500 °C have an outstanding bifunctional catalytic activity for ORR and OER with the potential of 1.62V (vs. RHE) at a current density of 10 mA/cm² and half-wave potential E_1/2 = 0.808V (vs. RHE) in alkaline electrolyte, respectively. It is obviously better than unloaded CoFe₂O₄ nanoparticles and commercial CNTs. CoFe₂O₄/CNTs/FA also exhibit better methanol tolerance ability and durability than commercial Pt/C and RuO₂ catalyst. This investigation broadens an idea of simple compounding of spinel with carbon-based materials to improve electrochemical properties.     

Electrospinning Ru doped Co3O4 porous nanofibers as promising bifunctional catalysts for oxygen evolution and oxygen reduction reactions

Enhancing the catalytic activity for oxygen evolution and oxygen reduction reactions is critical for rechargeable metal-air batteries. Herein, coral-like Ru-doped cobalt oxide nanofibers are prepared by electrospinning and subsequent heat treatment, which reduce the charge transfer resistance of cobalt oxide and optimize its active sites. Moreover, the large specific surface area and rich porosity of the one-dimensional nanomaterials prepared by the electrospinning method markedly improved the catalytic activity. Under the same catalyst load, Ru-doped cobalt oxide nanofibers have an overpotential of 300 mV, which is smaller than that of ruthenium oxide. In the oxygen reduction reaction, the positive half-wave potential of Ru-doped cobalt oxide nanofibers and Pt/C is the same (0.81 V). This work combines the strategies of doping and the advantages of electrospinning nanofibers to make a breakthrough in the catalytic activity of doped cobalt oxide nanofibers, and provides a new basis for the design of one-dimensional nanofiber bifunctional catalysts.     

FeNi doped porous carbon as an efficient catalyst for oxygen evolution reaction

Polymer-derived porous carbon was used as a support of iron and nickel species with an objective to obtain an efficient oxygen reduction reaction(OER)catalyst.The surface features were extensively characterized using X-ray diffraction,X-ray photoelectron spectroscopy and high-resolution transmission electron microscopy.On FeNi-modified carbon the overpotential for OER was very low(280 mV)and comparable to that on noble metal catalyst IrO₂.The electrochemical properties have been investigated to reveal the difference between the binary alloy-and single metal-doped carbons.This work demonstrates a significant step for the development of low-cost,environmentally-friendly and highly-efficient OER catalysts.     

铁/钴质量比对MWCNT-聚苯胺复合物氧还原电活性的影响

中心金属离子在非贵金属C-N复合物对氧还原反应（ORR）的电催化活性方面有重要作用。通过将含有多壁碳纳米管（MWCNTs）、聚苯胺与过渡金属Fe和Co的前驱体在N₂气氛下于900℃下加热,得到了不同金属比例的C-N催化剂。采用SEM、XRD等对催化剂的结构进行了表征。利用电化学伏安技术,研究了催化剂对ORR的电催化活性及其稳定性。结果表明,当Fe与Co质量比为6：1时催化剂的催化活性最好,在酸性溶液中ORR起始电位达到0.52 V（vs SCE）,电流密度为12.5 mA·mg^-1@-0.3 V （vs SCE）;在碱性溶液中ORR 起始电位为-0.09 V（vs SCE）,电流密度为7.8 mA·mg^-1@-0.8 V （vs SCE）。结果表明,催化剂中Fe与Co的质量比对催化剂的活性有很大影响。     

一步水热法制备电解水析氧反应Ni3S2@Mo2S3高效催化剂

采用一步水热法,由泡沫钼镍合金同时提供钼源和镍源在泡沫钼镍合金表面原位制备了Ni₃S₂@Mo₂S₃,并将其直接作为自支撑电极用于催化碱性介质中的电解水析氧反应（OER）。利用多种表征测试技术研究了样品的形貌、组成、OER电催化性能,结果显示：Ni₃S₂@Mo₂S₃呈纳米板形貌,由六方Ni₃S₂和单斜Mo₂S₃按5∶1的比例复合而成;在1 mol·L^-1 KOH 溶液中,Ni₃S₂@Mo₂S₃催化剂仅需要170 mV过电位就可达到10 mA·cm^-2电流密度（欧姆补偿后）,且在50 h的稳定性测试期间性能基本无衰减,优于贵金属催化剂IrO₂以及文献报道的Ni-Mo基复合催化剂。Ni₃S₂@Mo₂S₃具有优异电催化性能的原因可归于不同过渡金属化合物的协同作用、原位生长自支撑、电化学活性面积大以及液下疏气性等因素。     

Porous nitrogen doped carbon foam with excellent resilience for self-supported oxygen reduction catalyst

Fabrication of graphitized carbon materials (e.g. carbon nanotubes and graphene) normally entails the assistance of transition metal catalyst. In this paper, a nitrogen doped carbon foam (NCF) with both graphitized and porous carbon structure was fabricated by direct pyrolysis of melamine foam (MF) without using any transition metal catalyst. The graphitized carbon structure was possibly attributed to the triazine moieties in the MF precursor. The introduction of oxygen groups in the oxidation step resulted in the formation of large amount of micro- and mesopores and therefore high specific surface area. The NCF exhibited a three-dimensional cellular network consisting of carbon microfiber with abundant micro- and mesopores and giving rise to a specific surface area over 980 m² g⁻¹. Due to such graphitized porous structure, the NCF was demonstrated to have superior resilience, excellent electrocatalytic activity and good durability for oxygen reduction.     

富氧空位Co3O4纳米线的制备及其电解水性能研究

在室温下利用NaBH₄溶液还原Co₃O₄纳米线获得富含氧空位（V_O）的三维自支撑纳米线阵列用作全水解电催化剂,其中NaBH₄处理10 min的Co₃O₄/NF在碱性介质中对析氧反应（OER）和析氢反应（HER）表现出很高的活性,在10 mA·cm^-2电流密度下分别仅需240和132 mV的过电位。V_O-Co₃O₄/NF同时作为阴极和阳极电催化剂时,在10 mA·cm^-2下电解水槽电压仅为1.63 V,其耐久性可达60 h以上。该工作为富含氧空位结构的过渡金属氧化物双功能电催化剂的制备提供了新的方法和思路。     

Engineering oxygen vacancy-rich Co3O4 nanowire as high-efficiency and durable bifunctional electrocatalyst for overall alkaline water splitting

A novel kind of vacancy-rich nanowire arrays were prepared by reducing rough Co₃O₄ nanowires with NaBH₄ solution on 3D nickel foam at room temperature for overall water splitting. Co₃O₄/NF treated by NaBH₄ for 10 min was highly active for oxygen evolution reaction (OER) and simultaneously efficient for hydrogen evolution reaction (HER) with the need of the overpotentials of 240 and 132 mV to drive 10 mA·cm^-2 in alkaline media, respectively. Furthermore, the electrocatalysts as both cathode and anode in a two-electrode system presented excellent durability for over 60 h at 10 mA·cm^-2, maintaining the cell voltage of merely 1.63 V. This work provides new methods and ideas for the preparation of transition metal oxide bifunctional electrocatalysts rich in oxygen vacancies.     

Electrocatalytic activity of nitrogen doped carbon nanotubes with different morphologies for oxygen reduction reaction

Nitrogen doped carbon nanotubes (NCNTs) were synthesized by a single step chemical vapor deposition technique using either ferrocene or iron(II) phthalocyanine as catalyst and pyridine as the carbon and nitrogen precursor. Variations in surface morphology and electrocatalytic activity for oxygen reduction reaction (ORR) were observed between the NCNTs synthesized using different catalysts. The structural and chemical characterizations were carried out using transmission electron microscopy (TEM), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). The electrochemical activity of NCNTs was evaluated with rotating ring disc electrode (RRDE) voltammetry. Structural characterization suggested more defects formed on the NCNTs synthesized from ferrocene (Fc-NCNTs) which led to a rugged surface morphology compared to the NCNTs synthesized from iron(II) phthalocyanine (FePc-NCNTs). Based on the RRDE voltammetry study, Fc-NCNTs demonstrated much higher activity for ORR than FePc-NCNT. Evidences from the structural and chemical characterizations illustrate the potential impact of catalyst structure in shaping the surface structure of NCNTs and the positive effect of surface defects on ORR activity. These results showed that potential improvements on ORR activity of NCNTs could be achieved by tailoring the surface structure of NCNTs by using catalysts with different structures.     

Phosphorous,nitrogen co‐doped carbon from spent coffee grounds for fuel cell applications

Spent coffee grounds, which represents the vast solid residual matter generated from consumed coffee beans, requires proper reutilization. This work represents the production of an alternate material from spent coffee grounds to replace expensive metal based catalysts currently used as electrodes in fuel cells. A novel microwave assisted technique which is easy, rapid, and economical is utilized for the synthesis of Phosphorous, Nitrogen co‐doped carbon (PNDC) from spent coffee grounds and ammonium polyphosphate. SEM analysis revealed that PNDC is composed of distinct, spherical shaped particles. PNDC has a BET surface area of ～507 m² g^?1 and is predominantly mesoporous. XPS reveals that PNDC contains about 1.90% N and 3.02% P besides C and O. PNDC exhibits good O₂ reduction response in 0.1M KOH, which was found to be comparable to that of 20% Pt/C. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41948.