多孔普鲁士蓝类似物的合成及电催化析氧性能

采用一种简单易行的共沉淀法合成了前驱体镍铁普鲁士蓝类似物NiFe-PBA(NF),然后通过溶剂热处理获得了镍铁普鲁士蓝纳米多孔材料(NFP).通过XRD、SEM、TEM、XPS、BET及电化学方法对所得材料进行了结构表征和析氧性能测试.结果表明,NFP相对于前驱体NF,电化学比表面积增大、催化活性位点增多,电催化析氧反...     

非晶态硼化物Ni-Fe-Co-B的合成及电催化析氧性能

电解水制氢是绿色氢能源研究中的热点课题。其中，析氧半反应较高的过电位是导致电解水动力学缓慢的主要原因。为了提高电解水制氢的效率，本文主要通过简单的液相合成方法，以硼氢化钠和过渡金属Ni，Fe，Co盐为原料，制备了非晶态的过渡金属硼化物Ni-Fe-Co-B，将其作为析氧半反应催化剂。对Ni-Fe-Co-B进行了SEM、TEM、XRD、XPS和电化学表征。结果表明，非晶态催化材料Ni-Fe-Co-B被成功合成，当n(Ni)∶n(Fe)∶n(Co)=1∶1∶1，电流密度为20 mA/cm2时，Ni-Fe-Co-B的过电位仅为299 mV，Tafel斜率为101 mV/dec。在0.47 V的恒电压测试下，Ni-Fe-Co-B具有12h以上的稳定性。     

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.     

Electrophoretic deposition of ZnCo2O4 spinel and its electrocatalytic properties for oxygen evolution reaction

In this paper, ZnCo₂O₄ was deposited on nickel substrate by electrophoretic deposition (EPD) method as electrocatalyst for the oxygen evolution reaction. The effect of electrophoresis variables including the deposition time, the applied voltages was discussed. XRD, SEM, and electrochemical measurement techniques were used to characterize the deposit and ZnCo₂O₄/Ni electrode. Compared with the ZnCo₂O₄ electrode prepared by nitrate decomposition method, the electrophoretic ZnCo₂O₄ electrodes exhibit better electrocatalytic properties and higher mechanical stability. And the electrode prepared at 10 V for 5 min has the best electrocatalytic properties with the overpotential of only 0.203 V at current density of 100 mA cm⁻².     

Interface engineering for enhancing electrocatalytic oxygen evolution reaction of CoS/CeO2 heterostructures

To realize renewable energy conversion,it is important to develop low-cost and high-efficiency electrocatalyst for oxygen evolution reaction.In this communication,a novel bijunction CoS/CeO₂ electrocatalyst grown on carbon cloth is prepared by the interface engineering.The interface engineering of CoS and CeO₂ facilitates a rapid charge transfer from CeO₂ to CoS.Such an electrocatalyst exhibits outstanding electrocatalytic activity with a low overpotential of 311 mV at 10 mA·cm?2 and low Tafel slope of 76.2 mV·dec?1,and is superior to that of CoS(372 mV)and CeO₂(530 mV)counterparts.And it has long-term durability under alkaline media.     

Cobalt oxide nanocomposites and their electrocatalytic behavior for oxygen evolution reaction

In this work, we have described the simple preparation method of cobalt oxide nanocomposites where cobalt oxide nanoparticles were grown on the surface of carbon nanotube, graphene oxide and graphene (Co₃O₄@CNT, Co₃O₄@GO, Co₃O₄@G). The as-grown Co₃O₄@CNT, Co₃O₄@GO, Co₃O₄@G were investigated for H₂O oxidation. The nanoparticles displayed high activity toward oxygen evolution. Further, the stability of the catalysts were tested in alkaline solution, which exhibited good stability. Among all nanoparticles, Co₃O₄@G exhibited higher current density at lower overpotential and also exhibited lower Tafel slope (157.1 mV dec⁻¹) as compared to Co₃O₄@CNT and Co₃O₄@GO. The Co₃O₄@G delivered a current density of 10 mAcm⁻² at 0.8 V (overpotential 535 V versus Ag/AgCl) in 0.1 M KOH solution, which is superior than many electrocatalysts reported for oxygen evolution so far. The good electrocatalytic performance might be due to the structural features of Co₃O₄@G, which cause enhancement of oxygen evolution activity.     

The electrocatalytic activities of the Pd-doped MnO2 for the chlorine evolution reaction

The anodic evolution of chlorine on the massive β-MnO₂ doped with various amounts of Pd was investigated in acidic chloride solution. A second-order relation was found between the rate of the chlorine evolution reaction and the number of active Pd sites at the electrode surface. And it was confirmed that, in the relatively low doped electrodes, the active sites are more effectively dispersed on the surface with microscopic homogeneity. From the activation energies, it was also suggested that the reaction mechanism on the MnO₂ doped with relatively small amounts of Pd is somewhat different from that on the pure PdO electrode.     

Fe/N/C catalysts systhesized using graphene aerogel for electrocatalytic oxygen reduction reaction in an acidic condition

Graphene aerogel was modified with polyaniline and Fe precursors to produce Fe/N/C catalysts for electrocatalytic oxygen reduction reaction in the acidic condition. The graphene aerogel was produced by a simple hydrothermal treatment of graphene oxide dispersion with a high surface area. Aniline was polymerized with the graphene aerogel powder, and the pyrolysis of the resulting material with FeCl₃ produced Fe/N/C catalyst. The loading amount on the electrode and the catalyst ink concentration was carefully selected to avoid the mass transfer limitation inside the catalyst layer. The pyrolysis temperature affected the states of nitrogen sites on the catalyst; the sample prepared at 900 °C presented the highest mass activity. The sulfur was also doped with various amounts of FeSO₄ with enhanced mass activity of up to 2.1 mA/mg at 0.8 V in 0.5 M H₂SO₄ solution. Its durability was also tested by repeating cyclic voltammetry in a range of 0.6–1.1 V 5000 cycles. This graphene-aerogel-based carbon catalysts showed improved activity and durability for the oxygen reduction reaction in the acidic condition.     

Stabilization of RuO2 by IrO2 for anodic oxygen evolution in acid media

Anodic evolution of oxygen on mixed oxides Ru_xIr_1−xO₂ has been investigated for x=0,0.3,0.5,0.8 and 1 using electrochemical as well as surface physical techniques. In terms of Tafel slope and corrosion rate the electrochemical behaviour of the mixed oxide is mainly determined by the iridium component for x <0.5. XPS results show that there is no change in surface composition during O₂ evolution. Valence band spectra and cyclic voltammetry results suggest that band mixing occurs, giving rise to a shift of oxidation potentials. While the activity of the RuO₂ component in the mixed oxide is lost the stability of the slightly activated IrO₂ component is maintained. A model for the stabilization effect is proposed.     

SnO2-C载体对Pd催化剂电催化性能的影响研究

以SnO₂和Cabot Vulcan XC-72为原料合成了SnO₂-C材料,并将其用作担载Pd纳米颗粒的载体,从而制备出Pd/SnO₂-C催化剂,并研究其在甲酸环境下的电催化氧化性能,在电化学测试中,催化剂的抗CO中毒能力以及活性有明显的提高,通过进一步优化SnO₂在载体材料中所占比例,当SnO₂占载体质量20%时,催化剂在甲酸中抗CO中毒能力以及活性达到最高。     

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

     

Effect of composition on the surface and electrocatalytic properties of Ti/IrO x +RhO x electrodes: H2 evolution from acidic solution

IrO _x +RhO _x mixed oxide layers on a Ti support were prepared by thermal decomposition at 450 °C over the whole composition range. The temperature range 450–600 °C was explored for the composition 30 mol% RhO _x . Samples were characterized by means of SEM, XPS, cyclic voltammetry and polarization curves. Their electrocatalytic properties were tested for the H₂ evolution reaction. The following experimental parameters were scrutinized: voltammetric charge, Tafel slope, reaction order (H⁺), electrical resistance of electrocatalysts. The electrocatalytic properties were evaluated at constant potential as a function of temperature as well as of composition. The electrode stability was assessed by comparing CV curves before and after groups of experiments. A reaction mechanism has been proposed. RhO _x is more active than IrO _x , its effect showing up for compositions >30 mol%. In honour of Professor G. Kreysa on the occasion of his 60th birthday. On leave from Institute for Nuclear Research, Pitesti, Romania.     

不锈钢基ZnO/PbO2阵列电极的制备及其析氧电催化性能

以不锈钢(SS)为基体,聚苯乙烯(PS)微球为模板,采用直流电沉积法制备了SS/ZnO/PbO2阵列电极.通过扫描电镜(SEM)分析和线性扫描伏安法(LSV)测试,研究了电流密度、施镀时间和Pb(NO3)2质量浓度对电极活性层微观形貌和析氧电催化性能的影响.结果表明,在电流密度5.0 mA/cm2和Pb(NO3)2质量浓度190 g/L的条件下施镀25 min所得SS/ZnO/PbO2阵列电极表面呈规则的花瓣状阵列结构,晶粒均匀、致密,电催化活性优异.     

ZIF-67衍生Co/NC多孔碳材料的改性及其电催化水氧化性能

通过将前体ZIF-67高温热解并采用Na BH₄还原的方法制得表面富含氧空位的多孔碳复合材料(R-Co/NC-800)。利用X射线衍射(XRD)、场发射扫描电镜(FESEM)、高分辨透射电镜(HRTEM)、X射线光电子能谱仪(XPS)等手段对材料的物相、形貌、元素分布以及表面化学键结构等进行了表征;采用线性扫描伏安法(LSV)等方法研究了材料的电催化水氧化活性。结果表明制得的多孔碳复合材料(R-Co/NC-800)与未经NaBH₄还原处理的Co/NC-800样品对比,其表面氧空位浓度明显增加,形成新的催化活性位点,有效提升了电催化水氧化活性。在1.0 mol/L KOH溶液中,达到10 mA/cm²的电流密度,所需过电势仅为287 mV,同时表现出优异的电化学稳定性。     

Characterization and electrocatalytic properties of PtRu/C catalysts prepared by impregnation-reduction method using Nd2O3 as dispersing reagent

A simple impregnation-reduction method introducing Nd₂O₃ as dispersing reagent has been used to synthesize PtRu/C catalysts with uniform Pt-Ru spherical nanoparticles. X-ray diffraction (XRD) analysis, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) analysis have been used to characterize the composition, particle size and crystallinity of the catalysts. Well-dispersed catalysts with average particle size about 2 nm are achieved. The electrochemically active surface area of the different PtRu/C catalysts is determined by the CO_ad-stripping voltammetry experiment. The electrocatalytic activities of these catalysts towards methanol electrooxidation are investigated by cyclic voltammetry measurements and ac impedance spectroscopy. The in-house prepared PtRu/C catalyst (PtRu/C-03) in 0.5 M H₂SO₄ + 1.0 M CH₃OH at 30 °C display a higher catalytic activity and lower charge-transfer resistance (R_t) than that of the standard PtRu/C catalyst (PtRu/C-C). It is mainly due to enhanced electrochemically active specific surface, higher alloying extent of Ru and the abundant Pt⁰ and Ru oxides on the surface of the PtRu/C catalyst.     

The physical–chemical properties and electrocatalytic performance of iridium oxide in oxygen evolution

An IrO₂ anode catalyst was prepared by using the Adams method for the application of a solid polymer electrolyte (SPE) water electrolyzer. The effect of calcination temperature on the physical–chemical properties and the electrochemical performance of IrO₂ were examined to obtain a low loading and a high catalytic activity of oxygen evolution at the electrode. The physical–chemical properties were studied via thermogravimetry–differential scanning calorimetry (TG–DSC), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The electrochemical activity was investigated by using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and chronopotentiometry in 0.1 mol L⁻¹ H₂SO₄ at room temperature. The optimum condition was found to be at the calcination temperature of 500 °C, where the total polarization reached a minimum at high current densities (>200 mA cm⁻²). The optimized catalyst was also applied to a membrane electrode assembly (MEA) and stationary current–potential relationships were investigated. With an optimized catalytic IrO₂ loading of 1.5 mg cm⁻² and a 40% Pt/C loading of 0.5 mg cm⁻², the terminal applied potential difference was 1.72 V at 2 A cm⁻² and 80 °C in a SPE water electrolysis cell.     

Boosting the electrocatalytic activity of lanthanum cobaltite ceramic through Zn doping for the oxygen evolution reaction

The development of economical and highly efficient electrocatalysts is crucial for the oxygen evolution reaction in water electrolysis, which is associated with producing clean and sustainable hydrogen fuel. For this purpose, we successfully elaborated a new series of LaCo_1-xZn_xO₃ oxides (x = 0, 0.1, 0.2, 0.3 and 0.4) via a facile sol-gel route and investigated their structural, morphological and electrochemical properties for a possible use as electrocatalysts toward oxygen evolution reaction in a basic solution. Among the developed materials, the LaCo_0.9Zn_0.1O₃ electrocatalyst displays a remarkable performance; an overpotential of merely 327 mV is needed to generate a specified current density of 10 mA.cm⁻²_geo; a current density of around 73.41 mA cm⁻² at 450 mV, almost twice as high compared to the pristine electrocatalyst; a faster reaction kinetic with a lower Tafel slope of ∼92 mV.dec⁻¹ and an activity loss of less than 4% after 24 h of utilization.     

Characterization of electroless Ni-Mo-P/SnO2/Ti electrodes for oxygen evolution in alkaline solution

Ni-Mo-P alloy electrodes, prepared by electroless plating, were characterized for application to oxygen evolution. The rate constants were estimated for oxygen evolution on electrodes prepared at various Mo-complex concentrations. The surface area and the crystallinity increase with increasing Mo content. The electrochemical characteristics of the electrodes were identified in relation to morphology and the structure of the surface. The results show that the electroless Ni-Mo-P electrode prepared at a Mo-complex concentration of 0.011 m provided the best electrocatalytic activity for oxygen evolution.List of symbols b Tafel slope (mV dec^–1) - b F/RT (mV^–1) - F Faraday constant (96 500 C mol^–1) - j current density (mA cm^–2) - k₁ reaction rate of Reaction 1, (mol^–1 cm³ s^–) - k ₁ = k₁C _OH ^–(mol cm^–2 s^–1) - k ₁₀ rate constant of Reaction 1 at = 0 (mol cm^–2 s^–1) - k_c1 rate constant of Reaction 2 (mol^–1 cm³ s^–1) - k _c1 = k_c1C _{H 2O} (mol cm^–2 s^–1) - k_c2 rate constant of chemical Reaction 3 (mol^–1 cm² s^–1) - k _c2 = k_c2² (mol cm^–2 s^–1) - k_c3 rate constant of Reaction 4 (mol^–1 cm² s^–1) - Q _a anodic capacity (mC) - Q _c cathodic capacity (mC) - R gas constant (8.314 J mol^–1 K^–1) - R _ct charge transfer resistance ( cm²) - R _ads charge transfer resistance due to adsorption effect ( cm²) - C _d1 double layer capacity (mF cm^–2) - _{C ads} double layer capacity due to adsorption effect (mF cm^–2) - T temperature (K) Greek symbols anodic transfer coefficient - _{O 2} oxygen overpotential (mV) - saturation concentration of surface oxide on nickel (mol cm^–2)     

Carbon nanocapsules as an electrocatalyst support for the oxygen reduction reaction in alkaline electrolyte

Carbon Nanocapsules (CNCs) were investigated for their electrocatalytic performances for the oxygen reduction reaction in alkaline electrolyte. With an average diameter of 10–30 nm, the CNCs are composed of graphene layers encapsulating a hollow core. A gas diffusion electrode (GDE) made of CNCs revealed a much enhanced i–V polarization response than that of Vulcan XC72. However, its performance was moderately lower than that of Black Pearls 2000. In addition, the CNCs were impregnated with nanoparticles of Ag, MnO _x and CoO _x . The i–V and galvanostatic results of the catalyzed CNCs indicated significant improvements over that of noncatalyzed CNCs. For example, a Ag–CNC derived GDE was capable of delivering 1.03 and 0.88 V at current densities of 100 and 200 mA cm⁻², respectively. Our study offers direct evidence that the CNCs not only exhibit unique electrocatalytic abilities but also function superbly as an electrocatalyst support.