Co9S8-CuS纳米片阵列的电沉积制备及其电催化产氧性能研究

过渡金属硫化物因其制备简单、导电性好以及具有丰富的氧化还原性质被广泛用作电催化剂。在导电基底上原位生长复合材料被认为可有效提高催化剂的电催化性能。基于此,利用简单、可控的电沉积法,以泡沫铜作为导电基底,以硝酸铜和硝酸钴作为铜源和钴源原位制备了Co_9S_8-Cu S纳米片阵列。在三电极体系中,将Co_9S_8-Cu S纳米片阵列作为阳极在1 mol/L KOH溶液中得到了优异的电催化析氧性能,Co_9S_8-Cu S纳米片阵列获取50 m A/cm~2电流密度所需的过电位仅为370 m V,其Tafel斜率低至108 m V/dec,其优异的电催化析氧性能归因于较大的催化活性面积以及复合材料中Co_9S_8与Cu S之间的协同作用。     

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。     

全pH范围下MoS2/Ni3S2/NF的高效电催化析氢行为

在全pH（0~14）范围下设计开发低廉、高活性的析氢电催化剂对新能源开发和利用具有重要实际意义。通过简单的溶剂热法在镍网（NF）上原位构筑了纳米线结构MoS2/Ni3S2/NF电催化剂，该催化剂在全PH范围下表现出优异的析氢（HER）活性。电化学测试结果表明，使用41 mg四硫代钼酸铵制得的MoS2/Ni3S2/NF-41电极,在电流密度10 mA/cm2时，其在碱性（1 moL/L KOH，pH=14）、中性（0.5 moL/L PBS，pH=7）和酸性（0.5 moL/L H2SO4，pH=0）介质中HER过电位分别为87、113和195 mV，并相应表现出较低的Tafel斜率。另外，SEM、TEM、EDX、XPS等表征手段表明该催化剂具有良好的结构稳定性。本研究为过渡金属硫化物在全pH环境下高效析氢提供了新途径。     

电沉积Ni-S-Co/ZrO_2复合电极及其催化析氢性能

在镀液中悬浮粒径为200～400 nm的ZrO2固体颗粒,以电沉积方法制备了Ni-S-Co/ZrO2复合电极。XRD和SEM测试结果表明,沉积层由非晶态的Ni、Co、S和单斜晶型的ZrO2粒子组成。镀层表面呈团粒状结构,无裂隙,与基体结合牢固。电化学测试结果表明,25℃时,Ni-S-Co/ZrO2复合电极在质量分数28%NaOH水溶液中,在电流密度100 mA/cm2下的超电势为145 mV,与未复合纳米ZrO2粒子的Ni-S-Co电极相比降低了50 mV。表明超细ZrO2的掺入有效提高了电极对析氢反应的催化效果。实验表明,沉积的最佳电流密度为70 mA/cm2,最适宜的ZrO2用量为15 g/L,采用Ni-S-Co作为过渡层可以显著改善复合镀层与基体的结合。     

一步水热合成In2S3/CdIn2S4异质结微球及其光催化性能

利用一步水热法成功制备了In₂S₃/CdIn₂S₄异质结微球催化剂,通过降解甲基橙(MO)、酸性橙Ⅱ(AOⅡ) 和罗丹明B(RhB)来评价所制备催化剂的活性。实验结果表明,In₂S₃/CdIn₂S₄异质结微球对MO、AOⅡ和RhB的光催化降解率分别达到了87%、75%和96%,明显高于催化剂In₂S₃和CdIn₂S₄。瞬态光电流和阻抗测试结果表明,In₂S₃/CdIn₂S₄异质结微球受光激发产生的电子空穴对能快速得到分离。捕获主要活性物种实验表明,该反应体系中主要是超氧自由基和空穴起关键性作用。In₂S₃/CdIn₂S₄异质结微球催化剂重复使用四次,其催化能力依然保持较高水平。In₂S₃/CdIn₂S₄异质结微球活性的增强归因于异质结的形成有助于电子的转移,从而降低了电子空穴对的复合概率。并且合适的能带结构有助于产生大量的光生电子,电子与活性氧的结合最终引起氧化能力的增强。     

NF@Ni3S4@CoFe-LDHs电极用于尿素辅助碱性析氧

具有较高过电势的阳极析氧反应(OER)是电解水的关键半反应。利用理论过电势为0.37 V的尿素氧化反应(UOR)来降低阳极反应过电势。采用水热法在泡沫镍(NF)基底上原位构建NF@Ni₃S₄后,利用电化学沉积的方法在NF@Ni₃S₄表面生长Co Fe-LDHs,得到异质核壳结构NF@Ni₃S₄@Co Fe-LDHs电极。在尿素辅助碱性析氧反应过程中,该电极的分级结构可加快对中间产物的吸附和质子的解吸速率。在浓度为1 mol/L KOH电解液中,该电极在283 mV的过电势下可驱动100 mA/cm²的电流密度,塔菲尔斜率为55.9 mV/dec。在浓度为0.10、0.33和0.50 mol/L尿素与1 mol/L KOH混合电解液中,该电极均仅需1.33 V vs.RHE电压即可获得10m A/cm²的电流密度。在0.33 mol/L尿素和1 mol/L KOH混合电解液中,该电极可稳定运行20 h。     

一步水热合成MoS2/C催化剂及其催化浆态床菲加氢反应性能

随着原油储量的急剧下降,急需将重质原料转化为轻质油品以缓解原油的供应压力。浆态床加氢是一种可以将重质原料高效转化的先进技术,其核心难题在于开发高活性的加氢催化剂。采用葡萄糖和麦芽糖为碳源一步水热法合成MoS₂/C纳米催化剂,并采用XRD、Raman、元素分析、SEM和HRTEM等方法表征催化剂的组成和结构。表征结果表明,MoS₂/C催化剂由MoS₂-C-MoS₂碳插层结构的纳米片组成,纳米片具有层间距大、侧边尺寸小且堆积层数少的结构特点。以菲为重油模型化合物评价MoS₂/C催化剂的加氢性能。结果表明,以葡萄糖为碳源且原料C/Mo原子比为5时制备的MoS₂/C-G-5催化剂具有优异的催化加氢活性。该催化剂的菲加氢转化率高达85.6%,加氢率37.4%,深度加氢产物八氢菲选择性56.4%,分别是不加碳源制备的MoS₂催化剂的1.6、2.4和2.3倍。MoS₂/C催化剂的MoS₂-C-MoS     

固体酸S2 O2-8/Fe2 O3-XrO2催化制备马来酸二己酯

用S2O2-8 浸渍铁锆复合氧化物制得固体酸催化剂S2O2-8/Fe2O3-ZrO2(PSFZ),得到了较佳的制备条件,用马来酸酐与正己醇的酯化反应考察了催化剂的活性.通过XRD和TEM分析,对催化剂的结构进行了表征.结果表明,PSFZ的催化活性比SO2-4 /Fe2O3-ZrO2更强;S2O2-8对Fe2O3-ZrO2的促进作用明显高于SO2-4;铁的引入减少了ZrO2的团聚,增加了分散效果;有较好的使用重复性;它代替硫酸、对甲苯磺酸用于催化马来酸酐和正己醇的酯化反应可得无色透明的酯化产物.     

金属有机骨架衍生的自支撑Co9S8/Ni3S2纳米片阵列用于高效电催化分解水性能研究

采用简单、可控的阳离子交换法和水热法在导电基底上成功构筑了具有自支撑纳米片阵列结构的Co_9S_8/Ni_3S_2电催化剂,在碱性电解液(1 mol/L KOH)中,采用三电极体系分别研究了Co_9S_8/Ni_3S_2的电催化析氧和析氢性能。在析氧性能测试中,Co_9S_8/Ni_3S_2/NF电催化剂获取50、100 mA/cm~2的催化电流密度所需要的过电位仅为230、280 mV。而在析氢性能测试中,Co_9S_8/Ni_3S_2/NF电催化剂获取-100 mA/cm~2的催化析氢电流密度所需的过电位仅为129 mV,同时该催化剂表现出了优异的电催化稳定性,其优异的电催化性能归因于其自支撑纳米片阵列结构,可提供更多的活性位点。     

纳米复合固体超强酸S2O2-8/ZrO2-Al2O3的制备及其催化合成乙酸苄酯

采用改性技术和浸渍一沉淀法制备出纳米固体超强酸催化剂S2O2-8/ZrO2-Al2O3.通过正交试验获得了催化荆制备的最佳条件.用XRD、TEM、BET、TG-DTG和化学分析等手段分析了S2O2-8/ZrO2-Al2O3的晶化过程、比表面积、含硫量和热稳定性,分析结果表明这四个方面对催化荆的酸性有较大影响.500～650℃焙烧温度下制备的催化荆属纳米材料(<41 nm),有较大比表面积和较好的热稳定性.以优化的催化剂S2O2-8/ZrO2-Al2O3通过正交试验得到合成乙酸苄酯的最佳条件为:n(苄醇):n(乙酸)=1.3:1.0,催化荆用量为0.8 g(以0.2 mol乙酸为准),带水荆苯用量为14 mL,反应时间为2.5 h,催化剂重复使用7次酯化率在90%以上,该催化荆具有催化活性高、不污染环境、可重复使用等特点.     

Co9S8/CdS heterostructures as efficient photocatalysts for degradation of organic pollutant

Because of its superior coupling and composition matching, narrow band gap semiconductor heterojunction can increase redox activity, reduce carrier recombination, and enhance light absorption. When heterojunction photocatalysts are constructed properly, it is thought to be an efficient technique to boost photocatalytic activity. The Co₉S₈/CdS heterostructures in this study were created using a two-step solvothermal technique. The as-prepared Co₉S₈/CdS heterostructures exhibit outstanding photocatalytic degradation performance of methyl orange (MO) owing to their unique structure and compositional properties. Co₉S₈/CdS heterostructures can offer a remarkable MO degradation rate that can reach 97% in 25 min when illuminated by visible light. In addition to demonstrating better long-term stability after numerous cycling photocatalytic tests, experiments with radical trapping have shown that ·O₂⁻ is crucial for the photocatalytic degradation of MO. The pertinent photogenerated charge transfer and catalytic mechanisms of Co₉S₈/CdS heterostructures are suggested and examined.     

LaCoO3-modified RuO2–TiO2/Ti electrode as an efficient electrocatalyst for oxygen evolution reaction

A RuO₂–TiO₂/Ti electrode modified with LaCoO₃ was successfully fabricated by thermal decomposition and its electrochemical properties were evaluated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and stability tests. In contrast with an unmodified RuO₂–TiO₂/Ti electrode, the LaCoO₃–RuO₂–TiO₂/Ti electrode displays a more uniform layer with smaller microparticles. This electrode also displays higher OER performance with lower overpotential (289 mV vs. 348 mV) at a current density of 10 mA cm⁻² and lower Tafel slope (87 mV dec⁻¹ vs. 104 mV dec⁻¹) than the unmodified RuO₂–TiO₂/Ti electrode. The modified LaCoO₃–RuO₂–TiO₂/Ti electrode possesses larger current density, higher specific voltammetric charge, and lower charge transfer resistance (R_ct) than the unmodified RuO₂–TiO₂/Ti electrode does in a KOH solution, according to CV and EIS studies. The LaCoO₃–RuO₂–TiO₂/Ti electrode is very stable. The results show that the modified LaCoO₃–RuO₂–TiO₂/Ti electrode presents higher electrocatalytic activity and good stability for OER.

Graphic abstract

     

Facile synthesis of three dimensional flower-like Co3O4@MnO2 core-shell microspheres as high-performance electrode materials for supercapacitors

In this work, we reported the synthesis of three dimensional flower-like Co₃O₄@MnO₂ core-shell microspheres by a controllable two-step reaction. Flower-like Co₃O₄ microspheres cores were firstly built from the self-assembly of Co₃O₄ nanosheets, on which MnO₂ nanosheets shells were subsequently grown through the hydrothermal decomposition of KMnO₄. The MnO₂ nanosheets shells were found to increase the electrochemical active sites and allow faster redox reaction kinetics. Based on these advantages, when used as an electrode for supercapacitors, the prepared flower-like Co₃O₄@MnO₂ core-shell composite electrode demonstrated a significantly enhanced specific capacitance (671 F g⁻¹ at 1 A g⁻¹) as well as improved rate capability (84% retention at 10 A g⁻¹) compared with the pristine flower-like Co₃O₄ electrode. Moreover, the optimized asymmetric supercapacitor device based on the flower-like Co₃O₄@MnO₂//active carbon exhibited a high energy density of 34.1 W h kg⁻¹ at a power density of 750 W kg⁻¹, meaning its great potential application for energy storage devices.     

One-step hydrothermal synthesis of Sb2S3/reduced graphene oxide nanocomposites for high-performance sodium ion batteries anode materials

Sb₂S₃/reduced graphene oxide (SSR) nanocomposites were successfully synthesized through a facile one-step hydrothermal process, as used as anode materials for sodium ion batteries (SIBs). The characterization and electrochemical performance of the as-prepared samples were characterized by X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, nitrogen adsorption-desorption isotherms, cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge/discharge tests, respectively. The results show that the introduction of reduced graphene oxide (RGO) can improve the electrochemical performances of SSR nanocomposites. SSR nanocomposites with 10 wt% RGO exhibits the highest reversible capacity of 581.2 mAh g⁻¹ at the current density of 50 mA g⁻¹ after 50 cycles, and excellent rate performance for SIBs. The improved electrochemical performance is attributed to the smaller Sb₂S₃ nanoparticles dispersed on RGO crumpled structure and synergetic effects between Sb₂S₃ and RGO matrix, which can increase specific surface area and improve electrical conductivity, reduce sodium ion diffusion distance, and effectively buffer volume changes during cycling process.     

One-step hydrothermal synthesis of 3D porous microspherical LiFePO4/graphene aerogel composite for lithium-ion batteries

Three-dimensional (3D) porous LiFePO₄/graphene aerogel (LFP/GA) composite was successfully prepared by an in-situ hydrothermal process. In this composite, the LiFePO₄ microspheres assembled by nanoparticles were embedded in a three-dimensional framework intertwined with the graphene sheets, which acts as a bridge for transfer of electron and diffusion of lithium ion. The large specific surface of the composite structure enables the increased infiltration area and utilization of the active material. The content of the graphene sheet is analyzed and is found important for the Li-storage characteristics of LiFePO₄. An aerogel composite with 10% of graphene displays the best electrochemical performance, with the specific discharge capacities of 168 mAh g⁻¹ and 155 mAh g⁻¹ at respectively 0.1C and 1C, and the capacity retains 96.3% for up to 800 cycles. This novel 3D porous aerogel composite is identified as a promising cathode material for the rechargeable Li battery, and the simple strategy may be applied to construct other high performing composite structure and materials.     

3D/2D ZnIn2S4/BiFeO3 as S-scheme heterojunction photocatalyst for boosted visible-light hydrogen evolution

Photocatalytic H₂ evolution technique has been proved to be one of the promising approaches to overcome the present energy and environmental issues caused by the combustion of fossil fuel. Constructing heterojunction can realize the efficient separation and migration of charges and thus achieve enhanced H₂ evolution performance. Herein, we designed and prepared a ZnIn₂S₄/BiFeO₃ heterojunction photocatalyst with a 3D/2D structure via an ultrasonic self-assembly process. The typical 3D/2D structure with intimate interface was obtained, which not only provided more active sites but also boosted the migration of photogenerated charges. The optimal mass ratio of BiFeO₃ in ZnIn₂S₄/BiFeO₃ was determined to be 10%, and a 10.5-fold increase in H₂ evolution rate in comparison with of pure ZnIn₂S₄ was achieved. Furthermore, the ZnIn₂S₄/BiFeO₃ composite exhibited excellent recyclability and structural stability based on cycling experiment. A S-scheme heterojunction mechanism was revealed according to the experimental results of photocatalytic H₂ evolution and electrochemical tests.     

Co/Al_(2)O_(3)固定床费托合成催化剂水热稳定性研究

考察不同水热条件对Al_(2)O_(3)载体、Co/Al_(2)O_(3)催化剂稳定性的影响。表征结果表明,在苛刻水热条件下,即使高温焙烧的Al_(2)O_(3)载体也存在水热不稳定性现象。在接近工业固定床费托合成条件下运行,蛋壳型Co/Al_(2)O_(3)催化剂水热稳定性好。少量Co、Si改性能明显提高载体水热稳定性。