质子交换膜燃料电池非铂电催化剂研究进展

质子交换膜燃料电池(PEMFCs)目前主要催化剂为贵金属Pt基催化剂。然而,Pt价格高、储量低等问题严重阻碍了PEMFCs的商业化进程。发展低成本、高性能的氧还原催化剂是解决铂资源短缺、降低燃料电池成本、实现燃料电池商业化的关键。结合本课题组的研究工作,综述了最近几年非铂催化剂在燃料电池阴极氧还原方面的研究进展,着重探讨了新型氮掺杂碳基纳米材料的设计与制备,并概述了非铂催化剂面临的困难以及未来发展方向。

凝溶胶蛋白在急性放射损伤防护中的作用

采用4、8Gy137Csγ射线照射BALB/c小鼠,于照后不同时间ELISAKit检测小鼠血浆凝溶胶蛋白(gelsolin)含量变化;6Gy137Csγ射线照射小鼠,照后不同时间STAGO血液凝集仪检测血浆凝血酶原时间(PT)、活化部分凝血酶时间(APTT)、纤维蛋白原(FIB)含量;分别于照后2、7天检测血浆丙二醛(MDA)、超氧化物歧化酶(SOD)、全血谷胱甘肽(GSH)含量。实验结果表明,小鼠4、8Gy照后24h时,血浆gelsolin水平升高,24～72h持续下降,下降程度与照射剂量正相关。6Gy照射后初期及中期,gelsolin给药组血浆PT、APTT显著高于单纯照射对照组,FIB低于单纯照射对照组。6Gy照后后期,gelsolin给药组PT、APTT显著低于单纯照射对照组,FIB低于单纯照射对照组。6Gy照射小鼠2、7dgelsolin给药组GSH、SOD显著高于单纯照射对照组,MDA显著低于单纯照射对照组。说明gelsolin在急性放射损伤中对改善辐射出血损伤、清除辐射诱导自由基具有一定作用。

纳米TiO_2掺杂贵金属Pt抑制蓝藻的生长

制备并研究了纳米TiO2和Pt掺杂纳米TiO2对蓝藻生长的影响。结果表明,在太阳光照射下,Pt掺杂纳米TiO2能够破坏蓝藻藻囊;与纳米TiO2相比,Pt掺杂纳米TiO2能够更有效地使蓝藻内叶绿素含量、光合速率和呼吸速率以及超氧化物岐化酶(SOD)活性降低,超氧自由基增多;当Pt掺杂量为1%时,掺Pt纳米TiO2对蓝藻的抑制效果最好。

染料敏化太阳能电池非铂对电极研究进展

对电极作为染料敏化太阳能电池(dye-sensitized solar cell,DSSC)的重要组成部分,对电极材料性能的好坏直接影响着染料敏化太阳能电池的光电转化效率。最常使用的对电极电催化材料是贵金属铂,而铂十分稀少而且价格昂贵,并且铂很容易被碘电解液腐蚀,不利于染料敏化太阳能电池的产业化发展。本文重点综述了2010年以来染料敏化太阳能电池非铂对电极的研究成果,简要说明了对电极在染料敏化太阳能电池中的作用,详细介绍了非铂金属、碳材料、导电聚合物和无机化合物等对电极材料,分析了各类非铂对电极材料的特点、制备工艺、发展前景、优缺点和改进措施。最后提出,继续开发各种成本低、原料易得以及稳定高效的新型非金属对电极材料仍是今后染料敏化太阳能电池研究的一个重要方向。

“聚龙一号”装置上磁驱动铝飞片实验的数值模拟

采用二维磁驱动数值模拟程序MDSC2,对大电流脉冲装置"聚龙一号"上的151发次磁驱动370μm厚铝飞片实验、164发次磁驱动330μm厚铝飞片实验进行了数值模拟和分析。数值模拟表明:370μm厚铝飞片和330μm厚铝飞片的磁驱动过程中,VISAR测量的速度不是飞片自由面的速度,而是飞片中邻近自由面最近的固体反射面的速度。这是由于磁驱动飞片发射过程中,飞片自由面部分被烧蚀,密度低于固体密度状态,而飞片自由面和加载面中间的飞片还保持固体密度状态。VISAR测量的激光将穿过自由面的低于固体密度状态的飞片部分,到达飞片自由面最近的固体密度位置再反射回去,获得这一位置的飞片速度。数值模拟的飞片固体反射面速度历史和VISAR测量的速度历史相吻合。

ESR法研究Pt催化N_2H_4分解机制

采用电子自旋共振谱(ESR)法,研究了酸性条件下·NH_2的转化,HClO_4体系下反应时间对溶液中自由基产生的影响、pH值对N_2H_4断键的影响以及HNO_3中N是否对溶液中的·NH_2有贡献,确定了Pt催化N_2H_4分解的反应机理。结果表明:在酸性条件下·NH_2被DMPO捕捉时反应式为·NH_3^++HO—H+DMPO=NH_4^++DMPO(·OH),硝酸在Pt催化N_2H_4体系中不会发生断键产生·NH_2,所产生的·NH_2是由N_2H_4断键形成的;在HClO_4体系中,随着Pt催化N_2H_4反应时间的延长,N_2H_4中N—N断键的趋势逐渐减小,N—H断键的趋势逐渐增大;随pH值的增大,N_2H_4中N—N断键的速率先快速减小,pH>3后缓慢增大;Pt催化N_2H_4分解反应中N—N断键和N—H断键两种方式共存,但N—N断键占优;反应体系中N_2H_4与H^+浓度之比决定了N—N断键生成·NH_2的速率,而·NH_2与H^+的浓度又决定了·NH_2转化成产物的速率,这两方面共同决定了N_2H_4分解的速率。

Pt纳米粒子/ZnO纳米管修饰的钛片葡萄糖传感器

基于钛片载Pt纳米颗粒修饰的ZnO纳米管电极制备了葡萄糖生物传感器。用电化学沉积法制备了ZnO纳米棒阵列,并用化学腐蚀法制备了ZnO纳米管。Pt纳米颗粒采用恒电位沉积法修饰在ZnO纳米管表面。用扫描电子显微镜和X-射线衍射表征了纳米Pt-ZnO/Ti修饰电极。该修饰电极在0.05 M的NaOH中对葡萄糖的催化氧化表现出很好的响应,线性范围为1×10-5～1×10-2mol/L,响应时间小于4 s,并且具有良好的重现性。

铂单晶电极表面不可逆反应动力学(Ⅲ)

在本系列研究论文Ⅰ[1]和Ⅱ[2]报导的结果基础上，进一步发展动力学数据解析方法．通过改变反应体系的温度，首次获得甲酸在Pt（100），Pt（110），Pt（111）电极上直接氧化反应的表观活化Gibbs自由能（△G≠0）．在实验选定的标准状态下，即0．0V／SCE、298．15K和1．013×105Pa下，来算得到。还发现传递系数β在实验温度范围（283．15～303．15K）不随温度变化，但随电极表面原子排列结构变化，大小次序与△G≠0的变化一致．

组合型Pt-K-Ce/γ-Al_2O_3催化剂的邻苯基苯酚的催化合成性能

采用金属有机化合物Pt2(dba)3(dba为二亚苄基丙酮)氢气分解法制备Pt纳米颗粒,直接吸附到K-Ce/γ-Al2O3上制得组合型Pt-K-Ce/γ-Al2O3催化剂。利用透射电子显微镜、X射线衍射、差热-热重对催化剂进行表征。以邻环己烯环己酮(二聚酮)为原料,经组合型催化剂催化合成邻苯基苯酚。在LHSV为0.48 h?1、反应温度355℃、无外加氢气的条件下二聚酮的转化率为98.0%,OPP的选择性达97.7%。催化剂失活的原因有积炭、团聚、氧化铝及CeO2的结构破坏、载体比表面积下降、覆盖等,其中结构破坏和覆盖是催化剂失活的主要原因。

Ti3C2TX/Au@Pt纳米花复合膜的制备及其无酶H2O2传感器的应用

基于二维过渡金属碳化物(MXene)-Ti3C2Tx材料的导电性与Au@Pt纳米花的催化活性,组装了一种用于超灵敏和快速检测H2O2含量的Ti3C2Tx/Au@Pt纳米花无酶传感器。通过发射扫描电镜和X-射线衍射对制备的Ti3C2Tx进行表征。结果表明Ti3C2Tx材料表现出特有的手风琴结构,Ti3C2Tx/Au@Pt为以Au粒子为中心,Pt粒子环绕周围组成蒲公英状纳米球。研究了H2O2在Ti3C2Tx/Au@Pt纳米花修饰玻碳电极上的循环伏安曲线和时间电流曲线,结果显示该修饰电极检测H2O2具有线性范围良好(0.03~1100μmol/L)、灵敏度高(检出限可达0.02μmol/L)、抗干扰性和再现性好等优点。与传统滴定法相比,该新型无酶传感器能在复杂环境下快速准确检出H2O2含量。

中高温质子交换膜燃料电池催化剂研究进展

中高温质子交换膜燃料电池作为一种新型能量转换装置,具有环境友好、能量转换效率高、氢气纯度要求低等特点。催化剂作为电化学反应的核心,其性能极大影响着燃料电池的整体工作效率,目前针对中高温燃料电池催化剂的研究主要集中在电化学反应动力学较慢的阴极氧还原催化剂。磷酸掺杂的聚苯并咪唑(PA-PBI)为常用的高温质子交换膜,由于磷酸与PBI的结合力差,在长时间运行过程中磷酸容易渗透到催化剂层,造成磷酸在铂基催化剂表面的强吸附导致催化剂中毒的问题,并且氧分子在磷酸中溶解度低。基于以上问题,本文综述了铂基催化剂、非铂催化剂和非金属催化剂在中高温质子交换膜燃料电池中的应用现状,重点阐述了表面修饰、合金化、载体效应等策略对催化剂在磷酸电解液中的氧还原反应动力学的影响。最后针对目前中高温质子交换燃料电池催化剂发展方向进行了探讨和展望。

Active sites of Pt/CNTs nanocatalysts for aerobic base-free oxidation of glycerol

Understanding the nature of Pt active sites is of great importance for the structure-sensitive base-free oxidation of glycerol. In the present work, the remarkable Pt particle size effects on glycerol conversion and products formation from the oxidation of the primary and the secondary hydroxyl groups are understood by combining the model calculations and DFT calculations, aiming to discriminate the corresponding dominant Pt active sites. The Pt(100) facet is demonstrated to be the dominant active sites for the glycerol conversion and the products formation from the two routes. The insights revealed here could shed new light on fundamental understanding of the Pt particle size effects and then guiding the design and optimization of Pt-catalyzed base-free oxidation of glycerol toward targeted products.

(无金)镍铂水的研究

本文论述了一种不含黄金的具有银白色装饰效果的新型陶瓷液体装饰材料的研制方法。在研究分析了各种有关金属的晶体结构和理化性能的基础上,确定了Pt-Ni发色体系及其合理配比并选定了合适的定色剂,研制成功了含铂1～5wt％的(无金)镍铂水系列产品,并对影响产品性能的各种因素如定色剂、耐温剂等进行了讨论。

用第一性原理研究应变和Pt边缘掺杂对石墨烯氧还原能力的影响

采用基于密度泛函理论的第一性原理方法,通过计算Pt边缘掺杂石墨烯的形成能,确定了Pt的最佳掺杂位点,并研究了引入应变前后Pt掺杂石墨烯氧还原反应的催化性能。结果表明,引入应变后石墨烯基底吸附O_(2)的结构是稳定的;随着压应变的引入,费密面附近的态密度峰值向价带移动,促进了Pt边缘掺杂石墨烯作为燃料电池阴极氧还原反应电催化剂的电子转移,有利于催化反应的进行;当引入压应变为6.1%时,Pt边缘掺杂石墨烯的催化性能最佳。

基于Au-Pt NPs/IDEs的无酶谷氨酸电化学传感器

基于响应灵敏、尺寸小的叉指电极(IDEs),开发了一种新型的无酶型谷氨酸电化学传感器。通过在IDEs表面电沉积金—铂纳米粒子(Au-Pt NPs)提高传感器的检测性能,通过扫描电镜(SEM)表征了电极修饰过程的形貌变化,采用循环伏安(CV)法研究了该传感器对谷氨酸的催化性能,通过电流—时间(I-T)曲线研究了传感器的检测性能。结果显示,在最优条件下,该传感器对谷氨酸在500 nmol/L~3 mmol/L内呈良好的线性关系,检测限(LoD)为0.22μmol/L。该传感器还表现出了较高的选择性和良好的稳定性。并在味精样品的测试中获得了较好的回收率(97.70%~101.71%),表明该传感器具有较高的实际应用前景。

Advantage analysis of PMN-PT material for free-flooded ring transducers

The acoustic radiation characteristics of free-flooded ring transducers made of PZT4 and PMN-PT materials are calculated and compared. First, the theoretical formulae for free-flooded ring transducers are studied. The resonant frequencies of a transducer made of PZT4 and PMN PT materials are calculated. Then, the transmitting voltage responses of the free-flooded ring transducers are calculated using the finite element method. Finally, the acoustic radiation characteristics of the free-flooded ring transducers are calculated using the boundary element method. The calculated results show that the resonant frequencies of the free-flooded ring transducer made of PMN -PT are greatly reduced compared with those made of PZT4 with the same size. The transmitting voltage response of the transducer made of PMN-PT is much higher than that of the transducer made of PZT4. The calculated 3-dB beamwidth of the acoustic radiated far-field directivity of the free-flooded ring transducer made of PZT4 at the resonant frequency 1900 Hz is 63.6° and that of the transducer made of PMN-PT at the resonant frequency 1000 Hz is 64.6°. The comparison results show that the freepflooded ring transducer made of PMN PT material has many advantages over that made of PZT4. The PMNPT is a promising material for improving the performance of free-flooded ring transducers.

Activation methods and underlying performance boosting mechanisms within fuel cell catalyst layer

Proton exchange membrane fuel cells(PEMFCs)have been widely acknowledged as a significant advancement in achieving sustainable energy conversion.However,the activation of newly established Pt-ionomer interfaces in the catalyst layer of PEMFCs can be a time-consuming and costly process to ensure proper coupling and performance.In order to gain valuable insights into this crucial activation process,we have conducted a comprehensive analysis and comparison of the commonly employed on-line(such as current or voltage control activation,short-circuiting activation,and air interruption activation)and off-line(including boiling or steaming,acidtreatment,and ultrasonic-treatment)activation methods.Our findings shed light on the underlying mechanisms that contribute to enhanced performance within the catalyst layer,such as the reduction of Pt oxides and hydroxides,improved proton transport,and the reduction of“dead”regions.Moreover,this review emphasizes the significant challenges and future opportunities that lie in further enhancing the performance within the catalyst layer through the activation process.

Few-layered MoS_(2)anchored on 2D porous C_(3)N_(4)nanosheets for Ptfree photocatalytic hydrogen evolution

The Pt-free photocatalytic hydrogen evolution(PHE)has been the focus in the photocatalytic field.The catalytic system with the large accessible surface and good mass-transfer ability,as well as the intimate combination of co-catalyst with semiconductor is promising for the promotion of the application.Here,we have reported the design of the two-dimensional(2D)porous C_(3)N_(4)nanosheets(PCN NS)intimately combined with few-layered MoS_(2)for the high-effective Pt-free PHE.The PCN NS were synthesized based on peeling the melamine–cyanuric acid precursor(MC precursor)by the triphenylphosphine(TP)molecular followed by the calcination,mainly due to the matched size of the(100)plane distance of the precursor(0.8 nm)and the height of TP molecular.The porous structure is favorable for the mass-transfer and the 2D structure having large accessible surface,both of which are positive to promote the photocatalytic ability.The few-layered MoS_(2)are grown on PCN to give 2D MoS_(2)/PCN composites based on anchoring phosphomolybdic acid(PMo_(12))cluster on polyetherimide(PEI)-modified PCN followed by the vulcanization.The few-layered MoS_(2)have abundant edge active sites,and its intimate combination with porous PCN NS is favorable for the faster transfer and separation of the electrons.The characterization together with the advantage of 2D porous structure can largely promote the photocatalytic ability.The MoS_(2)/PCN showed good PHE activity with the high hydrogen production activity of 4,270.8μmol·h^(−1)·g^(−1)under the simulated sunlight condition(AM1.5),which was 7.9 times of the corresponding MoS_(2)/bulk C_(3)N_(4)and 12.7 times of the 1 wt.%Pt/bulk C_(3)N_(4).The study is potentially meaningful for the synthesis of PCN-based catalytic systems.

Polypyrrole-cobalt-carbon nanocomposites as efficient counter electrode materials for dye-sensitized solar cells

In this work, we demonstrate a new kind of Pt-free counter electrode for dye-sensitized solar cells(DSCs). Polypyrrole-cobalt-carbon(PPY-Co-C) nanocomposites, with the advantages of low cost and simple preparation, show favorable catalytic activity in promoting tri-iodide reduction. The DSC composed of the PPY-Co-C nanocomposite electrode exhibits an acceptable energy conversion efficiency of 6.01%, a considerable short-circuit photocurrent of 15.33 mA cm-2, and a low charge-transfer resistance of 1.5 Ω cm2. The overall performance of PPY-Co-C is superior to the carbon counterparts and comparable with the platinum reference, rendering them efficient and promising counter electrode materials for DSCs.

Constructing built-in electric field in graphitic carbon nitride hollow nanospheres by co-doping and modified in-situ Ni_(2)P for broad spectrum photocatalytic activity

The construction of built-in electric field is generally considered as an effective strategy to enhance photocatalytic performance due to its significant role in charge separation.Herein,a built-in electric field within g-C_(3)N_4 hollow nanospheres co-doped with sulfur and oxygen and modified in-situ Ni_(2)P is proposed.Ni_(2)P/SO-HC_(3)N_4 exhibits significantly enhanced board spectrum photocatalytic properties for hydrogen precipitation(5.21 mmol h^(-1)g^(-1))and photocatalytic Cr(VI)reduction without the use of noble metal.It also achieves high photocatalytic sterilization activity and remarkable stability when used to completely inactivate E.coli(10~7)in 60 min under Vis-NIR light irradiation.The enhanced performance is attributed to the formation of a curved hollow sphere structure,which promotes the electron transfer between the inner and outer layers.In addition,co-doping inhibits the recombination of photogenerated carriers,and the built-in electric field recombined with Ni_(2)facilitates the electron transfer between the composite interfaces.This design strategy demonstrates an original method of devising multifunctional photocatalysts with enhanced activity and stability.