Preparation and Electrochemical Properties of the Pd-modified Cu Electrode for Nitrate Reduction in Water

The Pd-modified Cu （Pd/Cu） electrodes for nitrate reduction were prepared using electro-deposition method at different potentials, Compared with other different electrodes so far studied in our work （Cu, Sn/Cu and Pd/Ti electrode） using cyclic voltammetry method, Pd/Cu electrode showed the highest electrocatalytic capacity of nitrate reduction. It was found that at more negative electrode potential the smaller Pd particles formed on the Cu electrode, which was beneficial to the nitrate reduction. With increasing deposition amount of Pd, the capacity of nitrate reduction increased. Too rich Pd, however, has a negative influence on the capacity of nitrate reduction. In our study, the maximum nitrate reduction current was 2.07 mA/cm^2, when electrodeposition potential of Pd was -0.3 V and deposition amount was 0.9 C.

Direct electrochemical reduction of copper sulfide in molten borax

In this study,for the first time,direct copper production from copper sulfide was carried out via direct electrochemical reduction method using inexpensive and stable molten borax electrolyte.The effects of current density(100–800 mA/cm^2)and electrolysis time(15–90 min)on both the cathodic current efficiency and copper yield were systematically investigated in consideration of possible electrochemical/chemical reactions at 1200℃.The copper production yield reached 98.09%after 90 min of electrolysis at a current density of 600 mA/cm^2.Direct metal production was shown to be possible with 6 kWh/kg energy consumption at a 600 mA/cm2 current density,at which the highest current efficiency(41%)was obtained.The suggested method can also be applied to metal/alloy production from single-and mixed-metal sulfides coming from primary production and precipitated sulfides,which are produced in the mining and metallurgical industries during treatment of process solutions or wastewaters.

Bio-inspired carbon electro-catalysts for the oxygen reduction reaction

We report the synthesis, characterisation and catalytic performance of two nature-inspired biomassderived electro-catalysts for the oxygen reduction reaction in fuel cells. The catalysts were prepared via pyrolysis of a real food waste（lobster shells） or by mimicking the composition of lobster shells using chitin and CaCO3 particles followed by acid washing. The simplified model of artificial lobster was prepared for better reproducibility. The calcium carbonate in both samples acts as a pore agent, creating increased surface area and pore volume, though considerably higher in artificial lobster samples due to the better homogeneity of the components. Various characterisation techniques revealed the presence of a considerable amount of hydroxyapatite left in the real lobster samples after acid washing and a low content of carbon（23%）, nitrogen and sulphur（〈1%）, limiting the surface area to 23 m^2/g, and consequently resulting in rather poor catalytic activity. However, artificial lobster samples, with a surface area of ≈200 m^2/g and a nitrogen doping of 2%, showed a promising onset potential, very similar to a commercially available platinum catalyst, with better methanol tolerance, though with lower stability in long time testing over 10,000 s.

Electrochemical Reduction of Nitrobenzene in Ionic Liquid BMImAc

Ionic liquid,1-butyl-3-methylimidazolium acetate（BMImAc）,was used in the electrochemical reduction of nitrobenzene.The electro-reduction of nitrobenzene on platinum electrode was studied by cyclic voltammetry（CV）,in situ Fourier transform infrared（FTIR） spectroscopy and constant-potential electrolysis.The experimental results show that electrochemical reduction process of nitrobenzene was controlled by diffusion,the main reduction product was azobenzen at-1.45 V,and the influences of scan rate and temperature on the electrochemical behaviors were obviously.A reduction mechanism of nitrobenzene in an ionic liquid was a probable ‘nitrobenzene→nitrosobenzene→azobenzene→aniline＇ main reductive reaction route.

Electro-reduction of Tetraphenylporphyrin (H_2TPP) and Its Eu(Ⅲ)-TPP Complex in Acetone——The Influence of Dissolved Oxygen

1 Introduction It is rather difficult for the rare earth ions to form complex with water-soluble porphyrins （e.g.TPPS4） in aqueous solution. In this note the formation of Eu（Ⅲ）TPP is conducted by introducing equal-molar concentrations of Eu（ClO4）3 and H2TPP into an acetone solution with 0.1 mol/L TEAP to obtain the 1: 1 complex. This complex is reduced with a peak potential at -0.28 V （vs. Ag/AgCl） in voltammetry, and it is found out that Eu3+-TPP is reduced to Eu2+-TPP. The height of the peak is directly propor-

Efficient and selective electro-reduction of nitrobenzene by the nano-structured Cu catalyst prepared by an electrodeposited method via tuning applied voltage

Pollution caused by toxic nitrobenzene has been a widespread environmental concern. Selective reduction of nitrobenzene to aniline is beneficial to further efficient and cost-effective biologic treatment. Electro- chemical reduction is a promising method and Cu-based catalysts have been found to be an efficient cathode material for this purpose. In this work, Cu catalysts with different morphologies were fabricated on Ti plate using a facile electrodepositon method via tuning the applied voltage. The dendritic nano-structured Cu catalysts obtained at high applied voltages exhibited an excellent efficiency and selectivity toward the reduction of nitro- benzene to aniline. Effects of the working potential and initial nitrobenzene concentration on the selective reduction of nitrobenzene to aniline using the Cu/Ti electrode were investigated. A high rate constant of 0.0251 mini and 97.1% aniline selectivity were achieved. The fabri- cated nano-structured Cu catalysts also exhibited good stability. This work provides a facile way to prepare highly efficient, cost-effective, and stable nano-sWuctured electro- catalysts for pollutant reduction.

Direct Reduction of Solid Fe_2O_3 in Molten CaCl_2 by Potentially Green Process

Sintered （300℃） porous pellets of Fe2O3 were electrolyzed to Fe in molten CaCl2 （800-900℃） under argon at 1.8-3.2 V for 2-20 h. The laboratory scale experiments show that it was a potentially direct green method to produce Fe powder. At lower electrolysis voltage （〈2.2 V）, higher current efficiency （〉90%） and smaller energy consumption （-3.0 kWh/kg） can be obtained. When the electrolysis voltage was above 2.4 V, the deposition of metal Ca from the salt lowered the current efficiency and increased the energy consumption. The electrolysis voltage also had effects on the micrographs of the reduced powder. The cubic particles can be seen in the products at the voltage lower than 2.2 V; when the voltage was higher than 2.2 V, it was nodular. The reduction proceeds at the cathode in two steps, i.e., from Fe2O3 to FeO and then to Fe. The oxygen emits at the anode. The process is potentially free of carbon emission and produces two useful products at both cathode and anode, promising a zero-emission technology for the extractive metallurgical industry.

An improved noise reduction transformation for algorithm based on wavelet MEMS gyroscope

To solve the large noise problem for the low- precision gyroscopes in micro-electro mechanical systems （MEMS） of inertial navigation system, an improved noise reduction method, based on the analyses of the fast Fourier transformation （FFT） noise reduction principle and the simple wavelet noise reduction principle, was proposed. Furthermore, the FFT noise reduction method, the simple wavelet noise reduction method and the improved noise reduction method were comparatively analyzed and experimentally verified in the case of the constant rate and dynamic rate. The experimental analysis results showed that the improved noise reduction method had a very good result in the noise reduction of the gyroscope data at different fi：equencies, and its performance was superior to those of the FFT noise reduction method and the simple wavelet noise reduction method.

Modeling of Three-Phase Flow and Interface Deformation of Metal/Bath in Aluminum Reduction Cell With Cathode Protrusion

Stabilizing the interface wave of the molten aluminum(metal)-electrolyte(bath)is beneficial to shorten the anode-cathode distance(ACD)which is critical to the energy saving.A coupled mathematical model was developed to study the impact of the novel cathode protrusion on the molten fluid motion as well as the metal-bath interface deformation.The molten fluid motion in the aluminum reduction ceils is under the combined effect of the electro-magnetic forces(EMFs)and the gas bubbles generated at the anode.A transient inhomogeneous three-phase model(metal-bath-gas bubble)was established in order to calculate more accurate.The results indicate that the metal-bath interface deformation can be reduced significantly by the novel cathode protrusion which is beneficial to the electric energy saving.Besides,The EMFs decreases as a result of the optimizing of the magnetic field due to the novel cathode convex which is an important driving force for the deformation of the interface.In addition,large vortex in the metal flow field is break up into the small vortex by the cathode protrusion and then dissipated due to the viscous force and the hindering effect of the cathode protrusion.The quantity of the vortex as well as the strength of the vortex reduces significantly in the reduction cell with novel cathode protrusion.

氧化石墨烯薄膜还原程度对测温与电热性能的影响

由于质量轻、韧性好、价格低廉且成型工艺简单等诸多优点,还原氧化石墨烯(reduced graphene oxide,rGO)薄膜在温度传感和电加热等领域颇受关注。分析了经不同温度热还原的rGO薄膜在微观结构、键合种类、力学及电学性能上的差异,以探究还原程度对rGO薄膜测温与加热能力的影响。结果表明,氧化石墨烯(graphene oxide,GO)薄膜内的C-O、C=O等含氧官能团在200℃还原后明显减少,碳原子的主要键合类型由C-C键变为C=C键。当还原温度升至600℃时,rGO薄膜内仍保留了部分含氧羟基官能团,C/O为7.18,而经800℃还原的rGO薄膜成分已趋近石墨烯。随着还原程度的增大,rGO薄膜的电阻率呈明显下降趋势,但氧原子的析出破坏了rGO薄膜的层间致密结构,使拉伸强度逐渐降低。当还原温度达到600℃时,电阻-温度曲线表现出优异的线性关系,室温电阻温度系数(temperature coefficient of resistance,TCR)为-1.60×10^(-3)/℃。在24 V直流驱动电压下,经600和800℃热还原的rGO薄膜可分别加热至242和367℃,但由于层间结构的松散和开裂,经800℃热还原的rGO薄膜的自发热升温曲线波动明显。因此,对于要求加热和测温双功能的应用场景,经600℃还原的rGO薄膜表现出更好的综合性能。

基于矢量控制的电励磁双凸极电机失磁容错运行转矩脉动抑制策略

电励磁双凸极电机(doubly salient electro-magnetic machine,DSEM)在航空和电动汽车等领域具有广阔的应用前景,这些领域对可靠性有更高的要求。DSEM通过励磁绕组实现他励,其励磁故障是影响DSEM电动运行可靠性的重要方面。针对DSEM驱动系统的励磁故障,该文提出一种基于矢量控制的DSEM失磁容错运行转矩脉动抑制策略。首先,根据瞬时功率不变原则建立DSEM失磁后极坐标系下的转矩数学模型,该模型建立磁阻转矩与电流矢量的幅值和相角之间的关系。随后,基于该模型,以铜耗最小化为目标确立电流矢量的相角,通过控制电流矢量的幅值抑制转矩脉动,将所得的电流矢量变换后得到三相参考电流,进行闭环控制。最后,针对1台18/12极DSEM,通过实验验证所提方法的可行性和有效性。

面向喷浆机械臂电液比例控制系统的降噪处理研究

考虑到系统辨识数据的预处理能够提高喷浆机械臂电液比例控制系统的建模精度,采用小波变换滤波算法对采集的传感器数据进行滤波降噪处理。应用表明,在以sym5为小波基函数时,信噪比数值最大且均方根误差最小,降噪效果最好。滤波降噪结果能够为电液比例控制系统数学模型的精确辨识奠定基础。

Gas-phase electrocatalytic conversion of CO_2 to chemicals on sputtered Cu and Cu–C catalysts electrodes

A novel gas-phase electrocatalytic cell containing a low-temperature proton exchange membrane(PEM)was developed to electrochemically convert CO_2into organic compounds.Two different Cu-based cathode catalysts(Cu and Cu–C)were prepared by physical vapor deposition method(sputtering)and subsequently employed for the gas-phase electroreduction of CO_2at different temperatures(70–90°C).The prepared electrodes Cu and Cu–C were characterized by X-ray diffraction(XRD),X-ray photoemission spectroscopy(XPS)and scanning electron microscopy(SEM).As revealed,Cu is partially oxidized on the surface of the samples and the Cu and Cu–C cathodic catalysts were comprised of a porous,continuous,and homogeneous film with nanocrystalline Cu with a grain size of 16 and 8 nm,respectively.The influence of the applied current and temperature on the electro-catalytic activity and selectivity of these materials was investigated.Among the two investigated electrodes,the pure Cu catalyst film showed the highest CO_2specific electrocatalytic reduction rates and higher selectivity to methanol formation compared to the Cu–C electrode,which was attributed to the higher particle size of the former and lower Cu O/Cu ratio.The obtained results show potential interest for the possible use of electrical renewable energy for the transformation of CO_2into valuable products using low metal loading Cu based electrodes(0.5 mg Cu cm^(-2))prepared by sputtering.

电渗透法降低黏土-金属界面黏附力的机理与试验研究

在岩土工程中机械法施工普遍,但黏土堵塞是困扰施工的一大难题。盾构、钻孔桩机等设备在黏性地层施工时易发生结泥饼、堵塞、排渣不畅等现象,导致器械扭矩增大,加剧刀具损耗,降低施工效率。黏土堵塞一般发生在黏土与金属界面之间,如何降低黏土对金属表面的黏附力是解决上述问题的关键。介绍了一种利用电渗透技术使黏土与金属界面之间形成一层水膜以达到降低黏土黏附性的方法。在不同电压和含水率条件下,对4种黏土进行倾斜板试验和电渗透试验。试验结果表明:黏土的电动力学行为不仅受含水率和黏土矿物的影响,还需要满足一定的阈值电压。试验的4种土样的滑动临界电压阈值集中在4 V左右,受含水率影响临界电压阈值有轻微差异。超过电压阈值后土样脱离时间急剧减少,电压由9 V增加到11 V,脱离时间无明显差异。当电压超过7 V后,增加电压对土样的降黏作用不明显,但电渗透过程中的能耗却呈倍数增长。电渗透法未来应用于实际工程,应综合考虑能耗、地层条件等因素,选择基于最优电压的电渗法降黏方案,提高施工效率。

空气中CO_(2)电辅助式光催化高选择性转化的研究

近年来,空气中CO_(2)浓度逐年升高,迫切需要一种技术将空气中低浓度CO_(2)转化为高附加值产品。研究设计了一种具有双池双界面的电辅助光催化系统,并通过聚多巴胺修饰法将Cu负载在二氧化钛纳米阵列(TNTAs)上,在催化过程中部分Cu被氧化成CuO,形成p-n结,在没有牺牲剂和碱性吸收液的条件下,通过电辅助式光催化实现了空气中CO_(2)稳定、高效、高选择性地转化为CO。在+0.8 V电位辅助下,紫外光照射8 h时CO产率达到113.7µmol/(m^(2)·h),是TNTAs[45µmol/(m^(2)·h)]的2.53倍;以8 h为一个循环,5个循环后,CO产率约为第一循环的72.4%。光催化性能的提高归因于Cu的引入增加了光谱的吸收范围,提高了对可见光的利用率,抑制了光生载流子的复合。此外,施加正电位时,电流方向与p-n结的内电场的电流方向相同,进一步促进电子的迁移,电子-空穴对得到更加有效的分离,使复合材料光催化还原CO_(2)的性能进一步提高。本研究推动了光催化技术向实际应用的发展,为碳循环提供了新的见解和支持。

Unique Nafion-Os(bpy)3^(2+) Modified Electrodes

It was newly found that the electrodes modified by applying ethanol solutions of Nationcontaining os(bpy)32+ onto the substrate electrode (the one-step method) show two pairs of stableredox peaks of Os(bpy)32+/3+ on cyclic voltammogram near 0.54V and 0.25V, respectively. Thesemoditied electrodes can effectively mediate and catalyze the first and second steps of nitritereduction in acidic media in the potential region 0-0.9V when the loading in the coating (X=F(Os2+) / F(SO3-)) and pH in solution are below 0. 17 and 4, respectively. When X is between 0.33and 0. 17. only the current peak near 0.54V appears regardless of solution pH and only the first stepof NO2 reduction is catalyzed. Thus the modified electrode provides a very useful flexibility thatone can control the reaction pathway and catalytic activity of nitrite reduction by simply changingthe concentration of the mediator in the coating.

Electrolysis of Converter Matte in Molten CaCl₂-NaCl

The electrolytic production of nickel-copper alloy by electrochemical reduction of converter matte in molten salt has been investigated. The sintered solid porous pellets of Ni3S2, Cu2S and converter matte were electrolyzed at a voltage of 3.0 V in molten CaCl2-NaCl under the protection of argon gas at 700℃, respectively. The electro-reduction processes were investigated and the products were characterized. The results show that the molten salt electro-reduction process can be used to produce nickel, copper and nickel-copper alloy directly from Ni3S2, Cu2S and converter matte precursors in molten CaCl2-NaCl, respectively. CaS would be formed as the intermediate compound during the electro-reduction process, and then the formed CaS can be gradually decomposed and removed with the increase of the electrolysis time. The experimental results show that the molten salt electro-reduction process has the potential to be used for the reduction of sulfide minerals in molten CaCl2-NaCl.

Coordinating optimization-based sliding mode variable structure control for electro-hydraulic servo system

A sliding mode variable structure control （SMVSC） based on a coordinating optimization algorithm has been developed. Steady state error and control switching frequency are used to constitute the system performance indexes in the coordinating optimization, while the tuning rate of boundary layer width （BLW） is employed as the optimization parameter. Based on the mathematical relationship between the BLW and steady-state error, an optimized BLW tuning rate is added to the nonlinear control term of SMVSC. Simulation experiment results applied to the positioning control of an electro-hydraulic servo system show the comprehensive superiority in dynamical and static state performance by using the proposed controller is better than that by using SMVSC without optimized BLW tuning rate. This succeeds in coordinately considering both chattering reduction and high-precision control realization in SMVSC.

模糊PID控制的细长工件加工主动减振控制研究

细长工件加工过程中的自激振动会增大工件表面粗糙度,降低工件的加工精度。因此这里提出了一种新型的主动减振机构对细长工件车削过程中产生的振动进行隔离。通过分析细长工件加工主动减振系统的简化结构,建立减振系统以及电液执行器的动力学模型,构建细长工件加工主动减振系统,并根据主动减振系统利用模糊规则进行模糊推理,开发了模糊PID控制器,实现细长工件加工主动减振系统的有效控制。采用数学软件MATLAB对细长工件加工的被动减振系统、传统PID控制器和模糊PID控制器控制的主动减振系统进行仿真,结果显示,主动减振系统相比于被动减振系统能够较大降低工件振动幅度;采用模糊PID控制器控制的主动减振系统,具有振幅小、控制电压低及能耗低的特点,同时振动抑制率相比传统PID控制器提高约9%。因此,采用模糊PID控制器控制的细长工件车削加工主动减振系统能够有效地限制振动幅值,提高车削加工稳定性。

光电跟踪系统的区间2型模糊滑模控制方法

为了提升高精度光电跟踪系统(ETS)的跟踪精度和其处理不确定性的能力,设计了一种1型模糊滑模控制方法,模糊控制用于在线自适应调整滑模控制(SMC)切换项参数;并采用区间2型模糊滑模控制(IT2FSMC)方法来提高系统处理不确定性的能力,进而提升跟踪精度,同时降低SMC抖振;此外,用粒子群优化算法来保证选取的SMC参数相对最优,并对提出的各种控制方法进行了理论分析和实验对比。结果表明,IT2FSMC能在降低SMC抖振的同时将SMC的稳态误差降低54.43%。仿真和实验分析验证了所提出控制方法在ETS中的有效性。