PtCu/C合金固溶度梯度薄膜催化剂的后处理改性和析氢性能表征

通过离子束溅射(IBS)与Pt,Cu双靶移动工艺制备PtCu/C合金固溶度梯度薄膜。利用1mol/L的HNO_3对梯度薄膜进行表面刻蚀处理,得到具有大比表面积的催化剂表面结构。X射线衍射(XRD)分析结果表明:复合膜电极表层形成了PtCu置换固溶体合金,原有的Pt晶格收缩,晶面间距缩小;原子力显微镜(AFM)和高分辨透射电镜RTEMSTEM测试结果表明:后处理的样品表面具有多峰结构和沟孔状结构;采用循环伏安法(CV)和线性扫描伏安法(LSV)对样品的电化学析氢性能进行测试,结果表明:梯度材料去合金化可以有效地降低铂载量的同时,提高电化学析氢交换电流密度,后处理样品的Pt载量降低20.29%,电化学析氢交换电流密度达到0.004217A/cm~2,催化性能提高20.58%。     

多孔Ni-WC复合电极的制备及其在酸性溶液中的电催化析氢性能

目前,关于多孔Ni-WC电极的电催化析氢(HER)性能的报道较少。以多孔海绵镍为基体,采用复合电沉积制备多孔Ni-(WC)x复合电极。运用扫描电镜(SEM)和X射仪线衍射仪(XRD)表征电极的表面形貌和微观结构,通过阴极极化、电化学阻抗(EIS)、循环伏安、计时电流法研究多孔Ni-(WC)x电极在0.5 mol/L H2SO4溶液中的电催化析氢性能。结果表明:与多孔基体Ni电极相比,多孔Ni-(WC)x电极具有较低的析氢过电位、较低的电化学反应阻抗、较小的表观活化能以及较大的交换电流密度;随着镀液中WC浓度的升高,所制备的多孔Ni-(WC)x电极的电催化析氢活性增强,其中Ni-(WC)40电极的表观交换电流密度是多孔Ni基体电极的966.7倍,其表观活化能为5.95 kJ/mol,并具有较好的耐蚀性和析氢稳定性。     

纳米晶碳化钨薄膜的析氢催化性能

采用等离子体增强化学气相沉积法制备了具有纳米结构的碳化钨薄膜, 采用XRD、EDS、SEM方法表征了薄膜的表面形貌、化学组成和物相结构. 这种碳化钨纳米晶薄膜具有巨大的电化学比表面积、很好的电催化活性和电化学稳定性. 通过测试和计算表明, 几何面积为1cm²碳化钨薄膜/泡沫镍电极、碳化钨薄膜/镍电极的电化学比表面积分别为83.21和64.13cm2; 该薄膜电极材料的a值为0.422～0.452V, 接近低超电势材料; 析氢交换电流密度为4.02～4.22×10^-4A/cm²; 当超电势为263mV时, 其析氢反应的活化能为45.62～45.77kJ/mol.     

电沉积非晶态Co-W合金镀层在碱性溶液中的电催化析氢研究

利用恒电流直流电沉积方法在Cu基底表面制备了Co-W合金镀层,当镀液中WO_4~(2-)浓度≥0.075 mol/L时镀层为非晶态结构。电化学研究表明,非晶态Co-W合金镀层在1 mol/L NaOH溶液中表现出良好的电催化析氢活性,过程受Volmer-Heyrovsky路径控制。W含量约为40.1%(质量分数)的Co-W合金镀层析氢活性最强,其表观交换电流密度j_0为3.17×10~(-5)A/cm~2;当电位负于-1.464 V(相对于饱和甘汞电极电位)后该Co-W合金镀层的阴极电流密度超越了商用Pt片。结合电化学阻抗分析获知,由于镀层本征催化活性和比表面积(或电化学活性面积)均得到提升,使得非晶态Co-W合金镀层析氢活性获得提高。     

AC/Ni-Co复合电极材料的制备及其催化析氢性能

采用复合电沉积法制备了AC(活性炭) / Ni-Co 复合电极。XRD 和SEM 测试结果表明, AC 微粒的复合未改变Ni-Co 合金电极的物相结构, 但使镀层的表面粗糙度和真实表面积增大。通过稳态阴极极化曲线和电化学交流阻抗技术考察了不同电极在1 mol·L-1 NaOH 溶液中的催化析氢性能, 结果表明, 镀液中AC 含量为3 g·L-1时所制备的AC/ Ni-Co 复合电极较Ni 电极和Ni-Co 合金电极具有更高的催化析氢活性, 电流密度为30 mA·cm-2时, 析氢反应极化电位分别比Ni 电极和Ni-Co 合金电极正移230 mV 和140 mV , 表观交换电流密度分别是Ni 电极和Ni-Co 合金电极的42 倍和9 倍, 复合电极催化析氢性能的提高主要归因于电极真实表面积的增大。      

低温烧结时间对AB_5型贮氢合金电极电化学动力学性能的影响

在流动Ar气氛保护下,将AB5型贮氢合金电极置于管式电阻炉中进行573K不同时间(30、60min,1、5h)烧结处理。通过恒流充放电,极化曲线和交流阻抗等测试方法研究了烧结电极的电化学性能。结果表明,0.2C(60mA/g)放电时,各合金电极最大放电容量不同程度降低,烧结时间增大到1h后,最大放电容量基本保持稳定。烧结处理电极高倍率放电性能(HRD)明显优于未处理电极,烧结时间越长,HRD值越高。1500mA/g电流放电时,烧结1h电极HRD值提高12.5%,烧结5h电极提高15%。同时各烧结电极极化电阻Rp,电荷转移电阻Rct随烧结时间增加而呈逐渐减小趋势,交换电流密度I0,极限电流密度IL以及氢扩散系数D均逐渐增大,烧结处理明显改善AB5型贮氢合金电极的动力学性能。     

氯化胆碱-尿素体系中电沉积Ni-Fe-Sm析氢催化电极研究

采用恒电位电沉积技术,在氯化胆碱-尿素体系中制备Ni-Fe-Sm/Cu稀土合金电极并研究其析氢(HER)性能。通过阴极极化曲线(LSV)、循环伏安曲线(CV)等电化学测试方法及SEM等表征技术,研究沉积条件对稀土合金电极的析氢性能及其表面形貌的影响。结果表明,添加稀土元素Sm能够有效提升合金电极的析氢性能。在-1.22 V的沉积电位下,沉积20 min制备的Ni-Fe-Sm/Cu稀土合金电极析氢性能最佳。在10 mA/cm²电流密度下,稀土合金电极的析氢过电位仅115 mV,Tafel斜率最小,析氢反应受Volmer-Heyrovsky反应控制。且该条件下制备的Ni-Fe-Sm/Cu稀土合金具备最高的双电层电容,电催化活性表面积最大。通过交流阻抗法(EIS)可知,Ni-Fe-Sm/Cu合金电极具有较高电荷转移速率。此外,Ni-Fe-Sm/Cu稀土合金电极在碱性介质中具有较好的稳定性,在经过1000圈的循环侧安测试,电催化析氢性能没有明显变化。     

Ni-S-Co涂层电极的制备及其电化学性能的研究

采用电沉积的方法以泡沫镍为基体制备出非晶Ni-S-Co合金电极.用电化学测试方法分析涂层的电化学行为.结果表明,较好的制备涂层电极条件为: CoSO4·7H2O掺杂浓度为10g/L,电流密度为50mA/cm2,温度为50℃,电沉积时间为40min,pH值为4.当电解电流密度为1200A/m2时,非晶Ni-S-Co合金电极的极化电位较非晶Ni-S合金电极低95mV,较Ni金属电极低405mV;根据Tafel曲线计算出Ni、非晶Ni-S以及非晶Ni-S-Co电极的表面活化能分别为49.5、40.3和38.6kJ/mol.Ni-S-Co电极具有更高的交换电流密度和更低的析氢活化能,因此具有更高的析氢催化活性.     

沿[111]方向择优生长Pt/Ti电极制备及析氯电催化活性

针对目前低浓度氯化钠电解过程中存在的氧化物尺寸稳定阳极(DSA)使用寿命短以及Pt电极使用量高的问题, 本研究通过磁控溅射法制备了具有沿[111]方向择优生长的Pt/Ti电极。SEM结果显示, 磁控Pt表面平整, 分散均匀, 粒度大小为10 nm; 通过XPS表征, 未见到基体Ti的特征峰, 说明其表面覆盖度好。电化学循环伏安曲线(CV)显示, 磁控Pt的电化学面积最小, 仅为1.08 cm², 接近电极表观面积; 磁控Pt氧区吸附电量和氢区吸附电量的比仅为0.83, 说明其对氧吸附能力较差, 不利于发生析氧反应。在单位电化学面积上, 当电极电势为1.6 V时, 磁控Pt的析氯电流达到0.085 A/cm², 分别是电沉积Pt和热分解Pt的3.27和49.0倍, 说明磁控Pt单位活性位点上具有很高的析氯反应活性。在此基础上, 进一步研究表明磁控Pt电极析氯反应的Tafel斜率为44.3 mV/dec, 其析氯反应机理符合Volmer-Heyrovsky机理, 速控步骤为电化学复合脱附步骤。     

复合电沉积制备（Ni-Mo）-TiO2电极及其电催化析氢性能

为开发新型廉价高效的析氢材料,用恒电流复合电沉积方法制备了(Ni-Mo)-TiO2复合电极,讨论了TiO2悬浮量和电沉积时间对电极催化析氢性能的影响.用XRD和SEM对电极的晶体结构和表面形貌进行了表征,以稳态极化曲线对电极的催化析氢特性进行了评价.结果表明,(Ni-Mo)-TiO2电极是纳米TiO2粒子相和纳米晶Ni-Mo固溶体相构成的复合电极.电极具有较高的催化析氢活性.在25℃、0.5mol.dm-3H2SO4溶液中其表观交换电流密度是Ni-Mo合金电极的2.6倍,是Ni电极的60倍.在电流密度为100mA·cm-2时,电极电势相对于Ni-Mo电极正移了120mV,相对于Ni电极正移了542mV.催化活性的提高源于反应机理的改变,表观活化吉布斯自由能相对于Ni-Mo合金电极降低了24.48kJ·mol-1.     

碳纳米管沉积铂和钌对PEMFC抗CO中毒能力的影响

通过催化裂解法制备了碳纳米管,对其进行氧化处理后,在其表面沉积了分布均匀、尺寸呈纳米级的铂和铂/钌颗粒.实验结果表明,当采用碳纳米管沉积铂为催化剂时,质子交换膜燃料电池的催化剂铂很容易受CO的毒化而失去活性,从而使电池的电压随电流密度的降低而迅速降低;当采用碳纳米管沉积铂/钌为催化剂时,钌能够使铂表面吸附的CO被氧化为CO₂,增加催化剂对CO的抵抗能力,使燃料电池的性能提高.     

以预锂化多壁碳纳米管为负极的锂离子电容器性能

采用内部短路方式对多壁碳纳米管负极进行不同程度的预嵌锂处理,预嵌锂时间为5,30,60min,以预嵌锂多壁碳纳米管极片作为负极,活性炭极片作为正极,组装成锂离子电容器。利用扫描电子显微镜(SEM)、透射电子显微镜(TEM)对多壁碳纳米管及电极极片进行表征分析,采用恒流充放电(GCD)和交流阻抗谱(EIS)研究预嵌锂多壁碳纳米管负极和未预嵌锂处理多壁碳纳米管负极锂离子电容器的性能。电化学测试结果表明,多壁碳纳米管负极预嵌锂大幅提高了电容器充放电性能,对比未嵌锂多壁碳纳米管电容器,在相同的电流密度下(100mA/g),能量密度提高400%。预嵌锂60min,电流密度100mA/g时,其比容量达到57F/g。在电流密度为100～3200mA/g范围内,其最高能量密度与功率密度分别达到90Wh/kg,4130W/kg。1000次充放电循环后,容量保持率维持在85%以上,表现出良好的超级电容器性能。     

Ultrathin Ultralow-Platinum Catalyst Coated Membrane for Proton Exchange Membrane Fuel Cells

Catalyst coated membrane (CCM) is the core component of proton exchange membrane fuel cells and is routinely fabricated by spraying Pt/C slurries onto membrane, resulting in low activity and thick catalyst layer (CL, 5–10 µm) with an unaffordable Pt loading of 0.2–0.4 mg cm⁻² and a large mass transfer resistance at cathode. Highly active ultrathin ultralow-Pt CL (UUCL) is urgently required, but remains rare. Herein, wet-chemical direct growth of UUCLs on both sides of membrane to achieve integrated ultrathin ultralow-Pt catalyst coated membranes (UUCCMs) with a cathodic CL thickness of 79.7 ± 15.0 nm and a Pt loading of 20.2 ± 1.6 µg cm⁻² is reported. The key to this unique fabrication is the release of proton from membrane to regioselectively initiate the growth of interconnected Pd nanoneedle clusters array on membrane, followed by high-density deposition of Pt nanoparticles on Pd (Pt/Pd UUCLs). The single cell of UUCCMs exhibits the highest mass peak power density of 59.9 W mg_Pt,Cathode⁻¹ in the literature. The exceptional activity originates from high electrochemically active surface area, remarkable oxygen reduction reaction activity closely correlated with strain, and electronic effect at Pt/Pd interface, as well as improved mass transfer and optimal water management.     

聚酰亚胺基活性炭的制备及其电化学性能的研究

通过炭化和进一步KOH化学活化的方法制备了聚酰亚胺基炭材料, 并将其用作双电层电容器电极材料. 采用DFT、XPS方法对其孔结构和表面化学性质进行了研究, 并通过恒流充放电等方法探讨了其电化学特性. 结果表明: 样品CPI的质量比电容是双电层电容和表面氮原子(尤其是N-5)所提供的赝电容共同作用的结果. 经活化后, 样品API比表面积达到1941m²/g, 主要形成0.7～2.0nm之间的微孔, 氮原子的影响可以忽略, 在50mA/g的放电电流密度下质量比电容达300F/g, 且电流密度达到1000mA/g时, 电容保持率仍为86.1%; 交流阻抗测试也表明样品API具有良好的双电层电容特性, 是一种新型的双电层电容器电极材料.     

PbO_2-CeO_2电极的制备及其电化学性能

为解决传统铅银合金存在的铅污染和钛基PbO2(DSA)基体易钝化、使用寿命短等问题,以不锈钢为基体,用稀土Ce改性,制备了PbO2-CeO2电极。分析了PbO2的形成机理,通过析氧曲线、Tafel曲线、EDS能谱及扫描电镜考察了温度、电流密度、稀土Ce等对电极性能的影响及所制备电极的元素分布及表面形貌。结果表明:最佳制备工艺为190 g/L Pb(NO3)2,15 g/L Cu(NO3)2,0.5 g/L NaF,30 g/L CeO2,pH值为2～3,机械搅拌,温度70℃,电流密度10～20 mA/cm2,时间30 min;所制备的镀层平整、均匀,电化学性能优良,镀层中CeO2质量分数约为4%～6%;PbO2-CeO2电极析氧电位1 500 mV左右,节能性能明显优于传统惰性阳极。     

循环伏安电沉积制备Pt-Fe合金催化剂及其性能

为提高质子交换膜燃料电池(PEMFC)电催化剂的催化活性,并降低其成本,利用循环伏安法电沉积制备Pt-Fe合金催化剂,并以其作为PEMFC阴极。通过X射线衍射仪(XRD)、循环伏安法(CV)、能谱仪(EDS)、扫描电子显微镜(SEM)测试技术对催化剂样品进行性能表征。通过循环伏安线性扫描法确定Pt-Fe合金的沉积电位,并探究了电沉积过程中电解液温度、电位和扫描速率对催化剂样品形貌以及电催化性能的影响。结果表明:电解液温度主要对催化剂沉积量及分散性起作用,对形貌影响不大,扫描速率主要对晶体生长产生影响;电位扫描范围为-0.4~0.6 V、扫描速率为100 m V/s,电解液温度为50℃时,电沉积得到的Pt-Fe合金催化剂的颗粒在碳布表面呈空心球状且分散均匀,与其他沉积电位制得的样品相比较,合金中Pt/Fe原子比相对较高,其具有最大的电化学活性表面积,为64.30 m2/g,电催化活性最佳。     

Electrospun carbon nanofibers as low-cost counter electrode for dye-sensitized solar cells

Electrospun carbon nanofibers (ECNs) have been explored as an electrocatalyst and low-cost alternative to platinum (Pt) for triiodide reduction in dye-sensitized solar cells (DSCs). The results of electrochemical impedance spectroscopy (EIS) and cyclic voltammetry measurements indicated that the ECN counter electrodes exhibited low charge-transfer resistance (Rct), large capacitance (C), and fast reaction rates for triiodide reduction. Although the efficiency (η) of ECN-based cells was slightly lower than that of Pt-based cells, their short circuit current density (Jsc) and open circuit voltage (Voc) were comparable. The ECN-based cells achieved an energy conversion efficiency (η) of 5.5 % under the AM 1.5 illumination at 100 mW cm(-2). The reason for lower cell performance using the ECN electrode was because of its lower fill factor (FF) than that of Pt-based cells, probably caused by high total series resistance (RStot) at ～15.5 Ω cm2, which was larger than that of ～4.8 Ω cm2 in the Pt-based devices. Simulated results showed that the fill factor (FF) and η could be substantially improved by decreasing RStot, which might be achieved by using thinner and highly porous ECNs to reduce the thickness of the ECNs counter electrode.     

Titanium and platinum modified titanium electrodes as catalysts for methanol electro-oxidation

Electro-oxidation of methanol was studied on titanium and platinum modified titanium electrodes (Pt/Ti). Platinum was electro-deposited on Ti by potentiostatic and galvanostatic techniques. Electrodes prepared by the galvanostatic technique showed enhanced catalytic activity towards methanol oxidation in NaOH solution compared to those prepared by the potentiostatic method. Scanning electron microscopy and energy dispersive X-ray analysis were used to characterize the surface morphology and percent composition of Pt to Ti on the electrode surface. The catalytic activity of Pt/Ti electrode is much higher than that of Pt/Pt, bulk Ti and of pure Pt, in addition to minimizing the poisoning effect. In 3.0 M NaOH and in the presence of 2.0 M MeOH, the oxidation peak current density value of methanol after the 50th cycles reached 99.4% of its value at the first cycle for electrodes prepared by the galvanostatic method compared to 94.7% for electrodes prepared by the potentiostatic method. Polarizing the modified electrode at the hydrogen evolution potential region for a certain time was found to enhance the catalytic oxidation of methanol, while the presence of thick Ti-oxide as well as Ti-hydride inhibited the process.     

Resistive Switching Properties and Failure Behaviors of(Pt,Cu)/Amorphous ZrO_2/Pt Sandwich Structures

The effect of Pt and Cu electrodes on the resistive switching properties and failure behaviors of amorphous ZrO_2 ?lms were investigated. Compared with Cu/ZrO_2/Pt structures, the Pt/ZrO_2/Pt structures exhibit better resistive switching properties such as the higher resistance ratio of OFF/ON states, the longer switching cycles and narrow distribution of OFF state resistance(Roff). The switching mechanism in the Pt/ZrO_2/Pt structure can be attributed to the formation and rupture of oxygen vacancy ?laments; while in the Cu/Zr O2/Pt structure, there exist both oxygen vacancy ?laments and Cu ?laments. The formation of Cu?laments is related to the redox reaction of Cu electrode under the applied voltage. The inhomogeneous dispersive injection of Cu ions results in the dispersive Roff and signi?cant decrease of operate voltage.Schematic diagrams of the formation of conductive ?laments and the failure mechanism in the Cu/ZrO_2/Pt structures are also proposed.     

多壁碳纳米管改性铂型IPMC的试验研究

将一种全氟磺酸树脂(Nafion)与多壁碳纳米管(MWCNTs)分别按质量比100:1、 100:3、 100:5进行配比, 采用溶剂浇铸法配合超声波分散法制备MWCNTs/Nafion型离子交换膜(IEM), 在此基础上利用化学沉积法制备铂型离子聚合物金属复合材料(Pt-IPMC), 考察三种MWCNTs负载量对IEM及Pt-IPMC性能的影响。采用SEM配合EDAX研究Pt的沉积效果, 对IEM及Pt-IPMC试样进行拉伸测试, 采用数字信号发生器为激励源测试Pt-IPMC的动态位移。结果表明: 添加MWCNTs使Pt-IPMC的内、 外电极厚度分别增加200%~250%和180%~200%, 使IEM及Pt-IPMC的弹性模量分别提高57.92%~140.85%和9.06%~52.85%; MWCNTs有效修饰了Pt-IPMC的内电极, 并明显提升其动态位移量、 动态响应及变形速度。