氧化—电解法从硫化氢获取廉价氢气方法的研究

利用硫化氢制取氢气是一种获得廉价氢的方法。采用氧化－电解的双反应器法对含硫化氢气体进行脱硫制氢研究。试验表明：双反应器法可以在较宽的范围内实现对硫化氢的有效吸收；在常压、７０－９０℃时，采用含盐酸（５－７Ｍ）的氯化铁溶液（０．４－０．８Ｍ）处理１５－４０％的含硫化氢气体，硫化氢的一次吸收率可达６０－９０％，并可同时制取氢气和硫磺；电解反应器采用石墨为阳极、镀阳石墨为阴极时，阳、阴极电流效率均接近１     

冰岛走向“氢动力”

多数燃料电池以氢为燃料 ,它由两个电极构成 ,中间夹一层极薄的聚合体电解液。一个电极是包裹了白金的阳极 ,起催化剂作用。氢通过阳极时就被电解 ,产生带负电的电子(即电流 )和带正电的氢离子。氢动力燃料电池不仅无污染且耐用。冰岛在发展这一技术已独领风骚几十年了。 1978年雷克雅未克大学教授柏拉基·阿纳松就指出 ,到 2 0 30～ 2 0 4 0年左右 ,冰岛可能会成为“氢动力”社会 ,完全不使用化石燃料 ,转而依靠清洁的氢能源 ,而它的副产品只有热和水。如今阿纳松的预言已成为诱人的投资机会 ,戴姆勒———克来斯勒公司、挪威水疗院、壳牌…     

生物质碳负载镍基纳米颗粒及其电解水析氢性能

电解水析氢反应(HER)相比于传统制氢方式,研究前景更为广阔,但考虑到其缓慢的动力学过程,开发价格低廉且高效的催化剂是克服HER应用瓶颈的关键。大多数现有的纳米微观结构的电催化剂需要复杂的合成过程,这无疑增加了开发的难度。本工作以生物质棉布为载体,采用施魏策尔试剂变体作为镍源,制备生物质碳负载镍纳米颗粒的HER催化电极,并在此基础上进行了磷化改性,研究了镍负载量、磷化对电催化析氢性能的影响。通过SEM、EDS、XRD、电化学测试对催化剂的形貌、物相及电催化析氢性能进行表征分析。结果表明,碳布上负载金属镍纳米颗粒存在临界值,磷化改性可以在降低析氢过电位的同时提高催化剂的耐久性能,通过浓度优化及磷化改性后的材料(1 mol/L NiP@C)具有优良的电催化析氢性能,在1 mol/L KOH溶液中,电流密度10 mA/cm2下拥有极低的过电位和塔菲尔斜率,同时在100 mA/cm2的大电流密度下,经过IR补偿后的过电势仅为23.5 mV。经过10 h的变电流测试后,电压保持率约为92%,表现出较好的耐久性能。     

Developments of electrodes for vanadium redox flow battery

本文介绍了钒液流电池电极材料的研究现状。详细介绍了电极种类、电极材料的改性途径、改性效果,并对电极的老化机制进行了分析。全钒液流电池（VFB）电极材料改性的方法主要包括增加电极催化活性和增大电极电化学反应面积两种方式。通过对电极进行热处理、酸处理,可以改变电极表面结构,提高电极催化活性,从而提高电极反应可逆性。通过在电极表面生长碳纳米管或者负载石墨烯、氧化铱等而制备的复合电极材料,以及采用天然废弃物制备的多孔碳电极,可以达到同时提高电极表面催化活性和增大电极电化学反应面积的效果。还可以通过制备电极和双极板复合一体化电极,降低电池的接触电阻,减小电池极化。而电极的化学降解及电化学降解对于电极的寿命会产生影响,而且对电池负极的影响比正极更加明显。最后,总结了VFB电极材料的现状并展望了未来研究发展的方向。     

CuInS_2、CuInSe_2及其固溶体作光阳极的光电化学太阳电池的研究

自1972年A.Fujishima和K.Honda报道了以n-TiO_2为光阳极,使水光电解为氢和氧之后,半导体光电化学电池(半导体液体结太阳电池)引起了人们的关注。半导体液体结太阳电池的特点是:成结容易,制作简单,晶格匹配和热膨胀问题小,可用多晶材料而效率降低不大。 制作液体结太阳电池应选择与阳光光谱相匹配的小禁带材料,并且这些材料的电子亲和势也要小。而且电解液应不腐蚀电极,并与电极能带相匹配,以提高效率及稳定性。影响     

使用不对称矩形脉冲电流沉积n-CdTe薄膜光阳极

用不对称矩形脉冲电流沉积制备的n-CdTe薄膜光阳极,质地致密,光电性能较好,在1MS~=/S_n~=电解液中,在60mW/cm~2光强下测得最大光电转换效率为1.06％。本文报道了沉积条件对电极质量的影响,对电极在电池中的极化曲线及I—V曲线进行了测试。沉积膜由CdTe、Cd、Te的微晶及无定型粉末构成,碲化镉微晶尺寸约500-1100(?)。     

醚基电解液中CoS_(2)/NC作为钠离子电池高性能阳极的原因分析北大核心CSCD

高性能钠离子电池负极材料的开发迫在眉睫,过渡金属硫化物具有较高的储钠比容量和良好的氧化还原反应可逆性等优点,但是存在充放电过程中的容量快速衰减问题。和电极材料的改性相比,通过优化电解液来提高电极的电化学性能是一种更加方便、环保且有效的策略。本文研究了CoS_(2)/NC在乙二醇二甲醚(DME)和碳酸乙烯酯/碳酸二乙酯(EC/DEC)两种电解液中作为钠离子电池负极材料的电化学和反应动力学差异,发现在与中间产物Na_(2)S_(6)副反应更少的DME电解液中,表现出优异的倍率性能、循环性能。通过紫外光谱证明了Na_(2)S_(6)在DME电解液中更高的稳定性,利用电化学阻抗测试和不同扫速下的循环伏安测试对电极材料的电子传输和离子扩散速率进行分析,证明了CoS_(2)/NC与电解液的副反应来自于中间产物多硫化钠与电解液的反应,中间产物在电解液中的稳定性是影响CoS_(2)/NC电化学性能的主要原因之一。我们的工作研究了多硫化钠在两种典型的电解液中的稳定性不同导致的电化学性能差异,并为过渡金属硫化物阳极和电解液之间的相互作用补充了新的见解。     

废弃酒糟制备钴氮共掺杂生物炭及其析氧和析氢反应催化性能研究

开发用于析氧反应(OER)和氢析出反应(HER)的低成本高效催化剂在水分解领域至关重要。以废弃酒糟为碳氮源,通过碳酸钠活化实现氮掺杂和钴纳米粒子负载,同时获得复合催化剂(Co(15)-DS-4)。对比实验分析表明,凭借多孔材料的介微孔结构,表面原子的高暴露特性和活性位点Co-N的协同效应,Co(15)-DS-4表现出优异的HER和OER双功能催化活性。在Co(15)-DS-4催化作用下,碱性电解液中的电极达到10 m A/cm2电流密度需要0.42 V过电压,这远低于商业上贵重的Ru O2催化剂(≈0.5 V)。此外,Co(15)-DS-4具有优异的水分解稳定性,经3 000次循环伏安,Co(15)-DS-4的OER极限扩散电流密度仍能保持97.5%(HER极限扩散电流密度仍能保持98.3%)。这一废弃酒糟衍生碳所构筑的N掺杂多孔碳负载Co纳米粒子复合材料在水电解领域具有巨大的应用潜力。     

镀铬溶液中影响硫酸根测定的因素

0 前言 活塞环镀铬生产中主要使用的是铬酸溶液。但是,纯(?)酸是镀不上铬的,电解时只会放出氢气,镀液中还必须含有起触媒作用的阴离子催化剂。在铬酸溶液中用作催化剂最普通的是硫酸根。 1 硫酸根的含量与电镀质量的关系 当硫酸根含量过低时,易造成溶液中的Cr~(3+)过少,镀液的沉镀能力下降,镀层易生成褐色斑点和条纹,表面粗糙,阴极附近析出大量氢气泡。其中在低电流密度部分易形成彩虹色,于后镀面呈残留水垢状。当硫酸根含量过高时,易使镀液中Cr~(3+)急骤增加,电镀液的粘度增加,镀液颜色变暗,阴极附近析出细小氢气泡。工件在高电流密度部分易锻烧,电镀液分散能力显著     

原位电解合成Ni-B析氧催化剂及其性能研究

以ITO玻片作为基体,在常温常压下采用原位电沉积法制备了Ni-B析氧催化剂。考察了K2B4O7溶液的浓度、温度以及pH值对催化剂的影响和电极反应的Faradaic效率,并通过循环伏安曲线和Tafel曲线考察了Ni-B催化剂的电化学性能,采用XRD、SEM和EDS等分析技术对催化剂的结构、形貌以及组成进行了表征。实验结果表明:原位电解沉积合成的Ni-B析氧催化剂在电解水过程中表现出较高的析氧活性和稳定性,在1mA/cm2电流密度时的析氧过电位约为0.31V。     

氢能发电技术的研究（Ⅱ）——电极添加剂对离子膜燃料电池放电性能 …

离子交换膜电池作为一种理想的氢能发电装置,是目前氢能研究开发的热点。研究了电极添加剂对离子交换膜燃料电池电化学性能的影响。     

Gas-phase electrolysis of hydrobromic acid using PTFE-bonded carbon electrode

The gas phase electrolysis of hydrobromic acid (48 wt%) was investigated for the development of the bromine-based thermochemical hydrogen production process, by using PTFE-bonded carbon electrode. Investigation of the anodic behaviour by using a half cell showed that the electrode performance was largely affected by the type of carbon used, the fabrication pressure, the content of PTFE, and the hydrophobicity of the electrode. The anodic potential was stable for 10 h at the current density of 144 mA cm⁻². The loading of Pt catalyst was very effective on the cathodic behavior. When adopted to a fuel-cell type electrolyser, the PTFE-bonded electrode showed better performance than the graphite-felt electrode; the current density of 120 mA cm⁻² and HBr conversion of 45% were achieved at cell voltage of 0.80 V at 423 K.     

Effect of micro-layer PTFE on the performance of PEM fuel cell electrodes

The function of gas diffusion layer in the fuel cell electrode is very critical as it acts as a current collector, facilitates the supply of reactants to the catalytic sites, and helps in removal of product water from the catalyst layer. In this paper attempts have been made to improve the dispersion of micro-layer by introducing an organic solvent. The electrodes were made by a screen printing method to improve the homogeneity of the gas diffusion layer. The main focus is on the effect of PTFE content in micro-layer using Ballard Avcarb 1071 carbon cloth as a substrate material. The percentage of PTFE on the substrate is kept constant in all the experiments, at about 18%. However, the percentage of PTFE in the micro-layer carbon is varied from 15 to 40 wt%. The micro-layer carbon loadingis about 3 mg/cm² for all the electrodes. The Gurley number decreases with increase in concentration of PTFE in the micro-layer. The PEMFC cells were tested at 60 °C and at ambient pressure with relative humidity of hydrogen and air kept at 90% and 70%, respectively. The results were analyzed from the polarization curves. The DC resistances of the electrodes were correlated with concentration of PTFE in the micro-layer. The over potential values were also correlated with the Gurley number. The gas permeability, contact angle of the samples was measured and the results were correlated with performance of the PEMFC. The long-term stability of the electrode was recorded at fixed current density for various concentration of PTFE content in the micro-layer. The detailed results are discussed in this paper.     

Direct electrolysis of bunsen reaction product for hydrogen production: The continuous-flow operation

Hydrogen sulfide (H₂S) emitted from oil industry's hydrotreating processes can be converted into hydrogen and used back to the same processes through a H₂S splitting cycle, where the Bunsen reaction and HI decomposition are two participating reactions. To overcome the difficulties and complications posted in the scaling up of the cycle, direct electrolysis of the Bunsen reaction product solution was proposed and has been studied in a batch electrolysis cell in our earlier work. This paper studies the direct electrolysis using a customer-made, continuous-flow electrolysis cell. The effects of the operating parameters including the current density, the entering HI concentration and flow rate of the anolyte, the toluene to aqueous phase ratio and stirring speed in anolyte cell, the H₂SO₄ concentration and circulation rate of the catholyte on the performing parameters such as the conversion of iodide ions, the yield of iodine transferred to toluene, and the anodic and cathodic current efficiencies for iodide conversion and hydrogen production were carefully investigated. The results show that the cathodic current efficiency for hydrogen production is nearly 100% for all the runs and that the anodic current efficiency for iodide ion conversion to iodine is relatively low (20%–70%) and varies with the changes in operating parameters. Running at high levels of the current density, the volumetric ratio of toluene to aqueous phase in anolyte, or the stirring speed in anolyte, and low levels of the entering concentration of I^? in anolyte or the flow rate of anolyte in electrolysis operation are in favor of having a high iodide conversion and high I₂-toluene yield. Iodide anions at a few mmol L^?1 level (a few thousandths of the entering concentration) are found in the cathodic chamber caused by its diffuse against the electric field and the proton exchange membrane. The continuous, direct electrolysis of the Bunsen product solution can be considered being adapted in the sulfur-iodine (S–I) water splitting cycle for hydrogen production.     

Electrochemical investigation of the Bunsen reaction in the sulfur–iodine cycle

The Bunsen reaction, as a part of the sulfur–iodine thermochemical cycle, was studied using an electrochemical cell. The effects of current density, operating temperature, H₂SO₄ concentration in the anolyte, HI concentration and I₂/HI molar ratio in the catholyte were explored. Both the H₂SO₄ in anolyte and the HI in catholyte were concentrated during electrolysis. Increasing current density amplified this H₂SO₄ and HI concentration, while the other operating parameters also varied the anolyte and catholyte concentration. The transport properties of the cation exchange membrane were examined. The electrode current efficiency remained close to 100% for most runs except those at high current density. Both the average cell voltage and the heat equivalent of electric energy were determined at different conditions.     

Effect of anolyte pH and cathode Pt loading on electricity and hydrogen co-production performance of the bio-electrochemical system

In a novel bio-electrochemical system (BES) for hydrogen and electricity co-production with acetate substrate, the anolyte pH and cathode Pt loading effects are investigated to improve the cell performance for hydrogen and electricity co-production and reduce the cost. The optimized anolyte pH is 9. The maximum hydrogen production rate of 0.55 m³ m⁻³ d⁻¹ and COD removal of 76% are obtained under optimal anolyte pH in the present BES. Over high or over low anolyte pH decreases the hydrogen production rate and COD removal. In addition, the experiments show that there is no considerable difference for the power density output and steady state current when the Pt catalyst loading is above 0.1 mg cm⁻². But when the Pt catalyst loading is lower than 0.1 mg cm⁻², the power density output and current decreases significantly. About 1.7 W m⁻³ power density output can be obtained by using 0.1 mg cm⁻² Pt catalyst in the present research.     

Kinetic and electrochemical analyses of a CuCI/HCl electrolyzer

An electrochemical analysis is carried out from a kinetic electrochemistry perspective of a CuCl/HCl electrolysis cell, within the CuCl thermochemical water splitting process for hydrogen production. The anolyte is a solution of 2 mol L^?1 CuCl(aq) and 10 mol L^?1 HCl(aq) while the catholyte solution is 11 mol L^?1 HCl(aq) . The cell current density of 0.5 A cm^?2 and voltage of 0.7 V are the desired working conditions for a CuCl/HCl electrolyzer. The current density of 0.5 A cm^?2 is assumed to occur at a 5% anolyte conversion degree. At 25°C , the activation overpotential of the anode half‐reaction is found to be 53 mV for a current density of 0.5 A cm^?2 while the activation overpotential of the cathode half‐reaction for the same condition is 87 mV. An increase in working temperature decreases the overpotential of the anode half‐reaction and increases the cathode half‐reaction activation overpotential. The ohmic overpotential of the cell membrane is almost 1000 times smaller than that of the activation overpotentials of the electrode half‐reactions for the same temperature and current density. A higher working temperature results in a lower membrane ohmic overpotential. The required voltage to trigger electrolysis for a current density of 0.5 A cm^?2 is found to be 0.53 V at 25°C and 0.59 V at 80°C and a higher temperature results in a higher electrochemical efficiency. The cell electrochemical efficiency increases linearly with working temperature while the voltage efficiency peaks at 75% at 60°C .     

Thin film electrocatalyst layer for unitized regenerative polymer electrolyte fuel cells

Thin film electrocatalyst layers with various PTFE and Nafion contents for unitized regenerative polymer electrolyte fuel cells (URFCs) were prepared by the paste method and the performance as URFC electrodes was examined. Comparing the terminal voltage versus current density curves of the URFC, it was found that the PTFE content in the electrocatalyst layer affected only the fuel cell performance; the electrode containing 5–7 wt.% PTFE was appropriate for the URFC. The Nafion content in the electrode affected both the fuel cell and water electrolysis performance; the electrode containing 7–9 wt.% Nafion showed good performance. The addition of a small amount of iridium catalyst (about 10 at.%) to the oxygen electrode layer significantly improved the URFC performance. Catalyst loadings can be reduced to <1/3 by using the electrode prepared by the paste method compared to the conventional one without degrading the URFC performance.     

Electrodeposition of self-supported transition metal phosphides nanosheets as efficient hydrazine-assisted electrolytic hydrogen production catalyst

The synthesis of electrocatalysts which used simultaneously as electrodes for the hydrazine oxidation reaction (HzOR), and hydrogen evolution reaction (HER) can significantly improve the efficiency of hydrogen production in the water splitting process. Here, Ni–Co–Fe–P binder-free nanosheets were fabricated using the electrochemical deposition method and used as an effective, stable, and cost-effective electrode for hydrazine-assisted electrochemical hydrogen production. Taking advantage of high surface area, being binder-free, and synergistic effect between the elements in the electrode composition, this electrode showed unique electrocatalytic activity and stability. When this electrode was used as a bifunctional electrode for HzOR-HER, a cell voltage of 94 mV was required to reach a current density of 10 mA cm^?2. The results of this study indicated that the Ni–Co–Fe–P electrode is an excellent candidate for the hydrogen production industry.     

Energy and exergy analyses of hybrid photocatalytic hydrogen production reactor for CuCl cycle

The present paper concerns electrochemical, energy, exergy and exergoeconomic analyses of a hybrid photocatalytic-based hydrogen production reactor which is capable of replacing the electrolysis sub-system of the CuCl thermochemical cycle. Several operating parameters, such as current density, reactor temperature, ambient temperature and electrode distance, are varied to study their effects on the hydrogen production rate, the cost of hydrogen production and energy and exergy efficiencies. The present results show that the voltage drops across the anolyte solution (sol 1), catholyte solution (sol 2), an anode, cathode, and cation exchange membrane vary from 0.005 to 0.016 V, 0.004–0.013 V, 1.67–2.168 V, 0.18–0.22 V and 0.06–0.19 V, respectively with an increase in current density from 0.5 to 1.5 A/cm². The energy and exergy efficiencies of the hybrid photocatalytic hydrogen production reactor decrease from 5.74 to 4.54% and 5.11 to 4.04%, respectively with an increase in current density.