大比表面积氮化钴钼催化剂的制备和加氢性能

以 N2 - H2 为氮化气与钴钼氧化物进行程序升温反应制备了大比表面积的钴钼氮化物。研究结果表明 ,随着钴含量的增加 ,产物的比表面积有所减少 ,但比以 NH3 为氮化气制备的产物的比表面积大很多。本方法所用制备条件也较缓和。

负载型氮化钴钼催化剂的制备及催化性能

严格的环境法规规定了燃料中硫的质量分数,要求对燃料中的含硫成分进行深度脱硫,开发新型高效催化剂是降低硫的质量分数的一个有效方法。过渡金属氮化物是一种新型催化材料,其表面性质和催化性能类似于贵金属。通过一步浸渍法和分步浸渍法合成出氧化态催化剂,并以氢气和氮气通过程序升温还原反应制备出负载型氮化钴钼双金属催化剂,用模型化合物噻吩对催化剂的加氢脱硫性能进行了考察。结果表明,用分步浸渍法合成出的BⅡ类氮化钴钼催化剂的噻吩加氢脱硫活性最高;在其它条件相同情况下,高温、预活化有利于噻吩加氢脱硫反应,合成的AⅡ、BⅡ类催化剂HDS催化性能与氮化后的工业催化剂接近。应用氮化态催化剂可以避免因工业催化剂预硫化而带来的硫污染,因此具有广泛的应用前景。

碳纳米管负载氮化钴催化剂的制备及其对氨分解反应的活性

采用等体积浸渍法结合程序升温还原技术合成了一系列CoNx/CNTs催化剂,通过XRD、BET、TG-DSC、TPR等手段,结合氨分解反应,研究了它们的表面性质和反应性能,结果表明,CoNx/CNTs催化剂对氨分解反应具有良好的催化活性,在500℃时氨转化率可达到66.46%。

氮化钴电催化还原二氧化碳为一氧化碳（英文）

电催化还原二氧化碳是一种潜在的解决全球变暖的途径,但是仍有许多挑战.本文报道了使用氮化钴在水溶液中电催化还原二氧化碳为一氧化碳.通过对比不同煅烧温度及气氛合成的催化剂表明氮掺杂对催化活性的提高至关重要.其中700-Co5.47N/C展现了最高的催化活性,在较低的电势-0.7 V(vs. RHE)下,一氧化碳的电流密度达到9.78 mA·cm-2.另外,通过改变电解电压,CO/H2的比例能在1:3到3:2之间调节. 91 mV·dec-1的Tafel斜率表明形成表面吸附的CO2·-中间体是CO2表面还原的决速步骤,而氮化策略可以增加表面碱性位点的数量,从而稳定还原的中间体,提高反应效率和产物选择性.

电沉积制备氮化钴纳米片超级电容器

采用一种简单的电化学沉积和退火方法,实现了在碳布基底上碳氮结构修饰氮化钴(CC@Co_(2)N@CN)材料的制备,并将其用于高性能超级电容器.氮化钴表面修饰的碳氮结构不仅可以提高整个电极的电容,而且可以缓解氮化钴的氧化,从而提高整体的导电性能.同时,CC@Co_(2)N@CN表现出极长的寿命,在10000次循环后容量仍能保持其初始值的77%.在电流密度为1 mA·cm^(-2)时,该电极的面积电容最高可达429.4 mF·cm^(-2).因为具有较大的面积电容和良好的循环稳定性能,此类基于碳布基底的氮化钴碳氮结构超级电容器在储能领域具有广阔的应用前景.

在可见光下钴掺杂C_(3)N_(5)活化过氧硫酸盐降解四环素的研究

以氯化钴和3-氨基1,2,4-三唑为原料,采用固相热解法制备了一种掺钴的氮化碳基复合材料,并与过硫酸氢钾活化剂用于可见光催化降解水体中的四环素。对制备的掺钴氮化碳基催化材料进行了XRD,SEM,FT-IR等表征分析,从晶体结构、微观形貌,化学成分等方面分析了催化材料比单一催化剂降解四环素效果更好的原因。此外,考察了催化剂投加量、过硫酸氢钾投加量、四环素的初始浓度、不同质量配比的催化剂等因素对四环素降解效果的影响。实验结果表明:掺钴氮化碳基的复合材料活化PMS降解TC在钴掺杂为1.2%的C_(3)N_(5),投加量为0.2 g/L,PMS浓度为2 mmol/L时,反应时间150 min,采用可见光降解TC的降解率可到达99.8%(K=0.06774 min^(-1))。由此可见其在处理抗生素废水方面具有良好的应用前景。

铁钴镍双组分氮化钼催化剂的制备和丙烷氨氧化性能的研究

以氢气和氮气的混合气体为氮化气体与铁钼、钴钼及镍钼双金属氧化物进行程序升温氮化反应合成了铁钼、钴钼及镍钼双金属氮化物催化剂。将铁钼、钴钼和镍钼氮化物分别用于催化丙烷氨氧化反应,研究结果表明,钴钼和镍钼双金属氮化物催化剂具有更高的催化活性和更高的丙烯腈选择性。

双金属氮化物Co3W3N/CNTs纳米复合材料的制备及其室温常压氮还原性能

采用水热法并经氨气保护热处理制备了双过渡金属氮化物Co3W3N/CNTs复合材料,得到了价格低廉且拥有良好氮电化学还原性能(NRR)的催化剂。通过调节已经预氧化的CNTs与过渡金属氮化物前驱体CoWO4的比例以及氨气热处理温度,实现了Co3W3N在CNTs表面的均匀负载。扫描电子显微镜(SEM)及透射电子显微镜(TEM)测试结果显示该电化学活性纳米微粒均匀地分散于CNTs表面,表明经预氧化的CNTs由于表面富集了较多的活性基团,有利于双过渡金属氮化物的分散生长。热处理后CNTs表面的Co3W3N微粒尺寸约为20 nm,相较于无载体的Co3W3N尺寸(100 nm)有明显减小。室温条件下,在N2饱和的0.01 mol·L^-1 H2SO4溶液中测试了该纳米复合材料在不同过电位下的NRR,该材料在-0.3 V(vs RHE)时的产氨率及法拉第效率分别可达12.73μg·h^-1·cm-2和13.59%,对比同样条件下,纯相Co3W3N的产氨率及法拉第效率仅为1.08μg·h^-1·cm^-2和1.76%。结果表明,通过水热反应和氨气保护热处理的Co3W3N/CNTs纳米复合材料具有良好的NRR性能。

碱性燃料电池Co-N/C复合催化剂的电化学性能

碳黑经过酸处理后再加入醋酸钴经氨气900℃热处理后,以其制备的气体扩散电极在6mol·L―1KOH溶液中对氧还原反应(ORR)的电催化性能得到大大提高.XRD物相分析表明:碳粉中加入醋酸钴经氨气热处理生成了氮化钴(Co5.47N).通过极化曲线和交流阻抗方法对制备的气体扩散电极在空气中的性能进行了研究.室温时在-0.2V(vs.Hg/HgO)电位下,未经处理的碳电极对氧还原基本没有电流产生;用酸处理后的碳电极在空气中的电流密度提高到57mA·cm―2;而Co-N/C复合电极在同样条件下电流密度可达170mA·cm―2,交流阻抗显示氮化物的生成减小了氧还原反应的阻抗,增强了对氧还原反应的电催化作用.

二苯并噻吩在CoMoN_x催化剂上的加氢脱硫

以MoO3及沉淀法制得的CoMo氧化物为前驱体 ,在N2 H2 混合气中用程序升温反应制得一系列氮化 (钴 )钼催化剂 ;用二苯并噻吩加氢脱硫为模型反应 ,考察了催化剂的催化性能 .结果表明 :( 1 )二苯并噻吩在氮化钼催化剂上的加氢脱硫有两条反应途径 ,即噻吩环直接氢解加氢脱硫 ;苯环先加氢 ,然后噻吩环氢解脱硫 .( 2 )氮化钼有高的活性和选择C—S键断裂生成联苯的选择性 ,Co的加入明显提高了氮化钼的催化活性 .( 3)不同预处理条件对催化剂的催化性能有不同的影响 ,预还原降低催化活性 ,预硫化与未处理时的活性相当 ,预硫化使催化剂上生成联苯的选择性有所降低 .

铝合金Ni-Co-P/Si_3N_4镀层的化学复合镀制备及其硬度

针对铝合金硬度较低等缺点,采用化学复合镀方法在铝合金表面制备了Ni-Co-P/Si3N4镀层。通过正交试验,研究了铝硅合金基体化学镀Ni-Co-P/Si3N4镀层的工艺参数对镀层硬度的影响。得出镀液pH值、硫酸钴/(硫酸镍+硫酸钴)物质的量比、氮化硅粉末含量、施镀温度对硬度的影响规律。发现:增大pH值以及镀液中氮化硅含量,保持硫酸钴/(硫酸镍+硫酸钴)物质的量比适中、升高施镀温度可以提高镀层硬度。此外,研究了热处理温度对镀层硬度的影响,发现:硬度随着热处理温度升高而增大,当热处理温度超过400℃时,硬度开始下降。

High-efficiency oxidative esterification of furfural to methylfuroate with a non-precious metal Co-N-C/MgO catalyst

From both fundamental and practical perspectives, the production of chemicals from biomass re-sources using high-efficiency non-precious metal catalysts is important. However, many processes require addition of stoichiometric or excess quantities of base, which leads to high energy consump-tion, leaching problems, and side reactions. In this study, we investigated the high-efficiency oxida-tive esterification of furfural to methylfuroate by molecular oxygen with a Co-N-C/MgO catalyst. The catalyst was prepared by direct pyrolysis of a cobalt（Ⅱ） phenanthroline complex on MgO at 800℃ under N2 atmosphere. From furfural, 93.0% conversion and 98.5% selectivity toward methylfuroate were achieved under 0.5 MPa O2 with reaction at 100 ℃ for 12 h without a basic additive. The con-version and selectivity were much higher than those obtained with cobalt catalysts produced by pyrolysis of a cobalt（Ⅱ） phenanthroline complex on activated carbon or typical basic supports, in-cluding NaX, NaY, and CaO. X-ray photoelectron spectroscopy, X-ray diffraction, transmission elec-tron microscopy, and experimental results revealed that the high efficiency of Co-N-C/MgO for pro-duction of methylfuroate was closely related to the cobalt-nitrogen-doped carbon species and its catalytic ability in hydrogen abstraction. In contrast, Co-N-C（HCl） that synthesized by removing MgO with HCl from Co-N-C/MgO, as the catalyst produced mainly an acetal as a condensation prod-uct, and chloride ions had a negative effect on the oxidative esterification. Although the catalytic performance of the cobalt-nitrogen-doped carbon species was greatly affected by HCl treatment, it could be recovered to a great extent by addition of MgO. Moreover, changes in the oxygen pressure hardly affected the oxidative esterification of furfural with Co-N-C/MgO. This study not only pro-vides an effective approach to prepare methylfuroate, but also for designing high-performance non-precious metal catalysts for the oxidative esterification of biomass-derived compounds.

Effect of carrier and axial ligand on the photocatalytic activity of cobalt thioporphyrazine

The photocatalytic activity of cobalt octakis（butylthio） porphyrazine（CoPz（BuS）8） was assessed through photodegradation of the dye rhodamine B（RhB） in water under irradiation with a Xe lamp and aerated conditions.The photocatalytic activity of CoPz（BuS）8 loaded on Al2O3 or SiO2@Fe3O4nanoparticles or coordinated with an axial azide ligand was also investigated.The results demonstrated that the photocatalytic activity of CoPz（BuS）8 loaded on Al2O3 was higher than that loaded on SiO2@Fe3O4.The kinetic curves of RhB degradation in aqueous solutions at different pH indicated the pseudo first-order kinetics of the reaction.The highest degradation rate for CoPz（BuS）8 loaded Al2O3 at pH = 4 after 160 min was 84.6%.However,the advantages of easier separation and recycling as well as the ability to terminate the reaction at any time for the CoPz（BuS）8 loaded SiO2@Fe3O4 cannot be ignored.When electron-rich NaN3 was coordinated with CoPz（BuS）8 as an axial ligand and loaded on Al2O3,the resulting catalyst produced more active oxygen species such as O2^- and HO· to promote the quicker degradation of RhB than that by the other catalysts.For the N3-coordinated CoPz（BuS）8 loaded on Al2O3,the reactions at pH = 4 and 7 distinctly deviated from first-order kinetics,and the degradation rate reached 77.6%after 80 min at pH = 4.

Influence of the metal sites of M-N-C(M=Co, Fe, Mn) catalysts derived from metalloporphyrins in ethylbenzene oxidation

Transition metal catalysts M-N-C（M = Co,Fe,Mn） were synthesized by a template-free method by heating meso-tetraphenyl porphyrins（i.e.CoTPP,FeTPPCl,MnTPPCl） precursors.The catalysts were characterized by N2 adsorption-desorption,thermogravimetry,high-resolution transmission electron microscopy,and Raman and X-ray photoelectron spectroscopy.The selective oxidation of ethylbenzene with molecular oxygen under a solvent-free condition was carried out to explore the catalytic performance of the M-N-Cs,which exhibited different catalytic performance.That was ascribed to the difference in M（Co,Fe,Mn） and different graphitization degree forming during the heating process,in which M（Co,Fe,Mn） might have different catalytic activity on the formation of the M-N-C catalyst.All the M-N-C composites had remarkable recyclability in the selective oxidation of ethylbenzene.

Hierarchical CoSeS nanostructures assisted by Nb doping for enhanced hydrogen evolution reaction

Metal doping for active sites exhibits remarkable potential for improving the hydrogen evolution reaction(HER).Multi-doping and the use of a conductive substrate can further modulate catalytic performance.Herein,Nb-CoSe well dispersed in N-doped carbon nanospheres(NCs,Nb-CoSe@NC)was synthesized to serve as a conductive substrate and facilitated good dispersion of active sites for the HER.Nb doping can also change the electronic structure of CoSe,which facilitates the activity for the HER.In order to further improve the conductivity and intrinsic activity of Nb-CoSe@NC,dual,nonmetal doping was realized through gas sulfurization to prepare hierarchical Nb-CoSeS@NC.The prepared Nb-CoSeS@NC,with a core-shell structure,exhibited a low overpotential of 115 mV at 10 mA cm–2,which is smaller than that of the most doped catalysts.In addition,NCs not only improved the dispersion and conductivity of the catalyst but also prevented metal corrosion in an electrolyte,thus facilitating the long-term stability of Nb-CoSeS@NC.Moreover,the synergistic effect of the multi-doping of Nb,S,and Se was explained.This work provides a promising,multi-doping strategy for the large-scale application of transition-metal-based electrocatalysts for the HER.

Supported Cobalt Molybdenum Bimetallic Nitrides for Ammonia Decomposition

Co and Mo bimetallic nitrides supported on Mg（Al）O, MgO and γ-Al2O3 were prepared in temperatureprogrammed reactions with NH3. The surface morphology, chemical composition and catalytic activity for NH3 decomposition on the supported Co and Mo bimetallic nitrides were studied by X-ray diffractometer （XRD）, NH3 temperature-programmed desorption and mass spectrometer （NH3-TPD-MS）, temperature-programmed desorption and mass spectrometer （TPD-MS）, H2 temperature-programmed surface reaction （H2-TPSR） and activity test. The phases of Co3Mo3N and MoN could be formed on Mg（Al）O, MgO and Al2O3 during the nitridation, and they might be more uniformly dispersed on Mg（Al）O and MgO than on γ-Al2O3. Transition metallic nitrides are generally considered as potential catalysts for hydrogen-involving reactions due to the entrance of hydrogen atoms into subsurface and the lattice of metallic nitrides. The diffusion of nitrogen in the bulk and the structure transformation of Co and Mo nitride compounds occur during NH3-TPD, but the supported Co and Mo bimetallic nitrides are not easily reduced at H2 atmosphere. Co3Mo3N/Mg（Al）O catalyst exhibits the highest activity, while Co3Mo3N/Al2O3 exhibits the lowest activity for NH3 decomposition. Furthermore, the catalytic activity of Co and Mo bimetallic nitrides is not only much higher than that of supported single metallic nitride, but also highly dependent upon the surface acidity and BET surface area of support.

N‐doped porous carbon nanofibers inlaid with hollow Co_(3)O_(4) nanoparticles as an efficient bifunctional catalyst for rechargeable Li‐O_(2) batteries

Stable and high‐efficiency bifunctional catalysts for the oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)are desired for the practical application of Li‐O_(2)batteries with excellent rate performance and cycle stability.Herein,a novel hybrid bifunctional catalyst with carbon nanofibers inlaid with hollow Co_(3)O_(4)nanoparticles and separate active sites for ORR and OER were prepared and applied in Li‐O_(2)batteries.Benefiting from the synergistic effect of unique porous structural features and high electrocatalytic activity of hollow Co3O4 intimately bound to N‐doped carbon nanofibers,the assembled Li‐O_(2)batteries with novel catalyst exhibited high specific capacity,excellent rate capability,and cycle stability up to 150 cycles under a capacity limitation of 500 mAh g^(–1)at a current density of 100 mA g^(–1).The facile synthesis and preliminary results in this work show the as‐prepared catalyst as a promising bifunctional electrocatalyst for applications in metal‐air batteries,fuel cells,and electrocatalysis.

Atomic modulation of Fe‐Co pentlandite coupled with nitrogen‐doped carbon sphere for boosting oxygen catalysis

Reversible oxygen reaction plays a crucial role in rechargeable battery systems,but it is limited by the slow reaction kinetics.Herein,the ionic modulation of cobalt pentlandite coupled with nitrogen‐doped bowl‐like hollow carbon sphere is well designed on octahedral and tetrahedral sites.The robust FexCo9−xS8‐NHCS‐V with iron replacing at the octahedron possesses prolonged metal sulfur bond and exhibits excellent bifunctional electrocatalytic performance towards oxygen reduction reaction(ORR,E_(1/2)=0.80 V vs.RHE)and excellent oxygen evolution reaction(OER,E_(j=10)=1.53 V vs.RHE)in 0.1 mol/L KOH.Accordingly,a rechargeable Zn‐air battery of Fe_(x)Co_(9−x)S_(8)‐NHCS‐V cathode endows high energy efficiency(102 mW cm^(−2)),and a microbial fuel cell achieves a high‐power density(791±42 mW m^(−2)),outperforming the benchmark Pt/C catalyst.

Synthesis of 1-(5-nitro-3-benzopseudothiazolyl)-3-(4-phenylazophenyl)-triazene and Its Color Reaction with Cobalt

A new chromogenic reagent, 1 -（5 - nitro- 3 - benzopsendothiazde）- 3 -（4 - phenylazophenyl） - triazene （NBPTPAPT） has been synthesized and used as a sensitive reagent for the spectrophotometric determination of cobalt. In the presence of Tween - 80, the reagent with Co （ Ⅱ ） forms a yellow complex （1 ： 2） in the buffer solution of Na2B4O7 - NaOH at pH 10.54. The apparent molar absorptivity is 1.220× 10^5 L· mol^- 1· cm^- 1 with the linear range of 0 - 240μg/ L for Co （Ⅱ） by dual-wavelength spectrophotometry. Trace cobalt in vitamin B12 and tea samples has been determined with satisfactory results.

Al2O3-TiCN/Co-Ni 复合材料制备及力学性能

用真空热压烧结法制备了Al2O3-Ti C0.5N0.5/Co-Ni复合材料,用扫描电子显微镜、能谱仪、电子万能试验机和Vickers硬度仪等测试分析了不同烧结参数对样品显微组织及力学性能的影响。结果表明:当烧结温度1 650℃,压力25 MPa,保温时间30 min时,样品的相对密度、抗弯强度(σmax)、断裂韧性(KICmax)和Vickers硬度(HV)的最大值分别达到99.6%,σmax=1 100 MPa,KICmax=10.5 MPa·m1/2和HV=23.7 GPa,样品断口形貌存在混晶断裂特征。