Completely Green Synthesis of Colloid Adams’ Catalyst α‐PtO2 Nanocrystals and Derivative Pt Nanocrystals with High Activity and Stability for Oxygen Reduction

We report a first solution strategy for controlled synthesis of Adams’ catalyst (i.e., α‐PtO₂) by a facile and totally green approach using H₂PtCl₆ and water as reactants. The prepared α‐PtO₂ nanocrystals (NCs) are ultrasmall in size and have very “clean” surfaces, which can be reduced to Pt NCs easily in ethanol under ambient conditions. Such Adams’ catalysts have been applied as electrocatalysts beyond the field of heterogeneous catalysis. Noticeably, the water‐only synthesized α‐PtO₂ NCs and their derivative Pt NCs all exhibit much higher oxygen reduction reaction (ORR) activities and stabilities than that of the state‐of‐art Pt/C electrocatalysts. This study provides an example on the organics‐free synthesis of α‐PtO₂ and Pt NCs as promising cathode catalysts for fuel cell applications and, particularly, this simple, straightforward method may open a new way for the synthesis of other “clean” functional nanomaterials.     

铂/石墨烯氧还原电催化剂的共还原法制备及表征

使用硼氢化钠共还原法制备40% (w)铂/石墨烯电催化剂用于氧还原反应. 通过循环伏安测试发现, 这种方法制备所得铂/石墨烯催化剂对氧还原反应活性较铂/碳催化剂差, 但稳定性有所提高. 在稳定性测试中,铂/石墨烯电催化性能衰减为50%, 较铂/碳(79%)好. X射线衍射(XRD)和透射电子显微镜(TEM)表征发现在铂/石墨烯催化剂中两者存在明显交互作用, 这可能是阻止石墨烯再堆垛和防止铂颗粒团聚的主要原因. 通过对单电池性能测试也发现铂/石墨烯催化剂更有利于电池长期稳定.     

DMFCs用磺化聚醚醚酮/功能化二氧化硅复合质子交换膜

在磺化度(DS)为55.1%的磺化聚醚醚酮(SPEEK)中掺杂功能化二氧化硅(吸湿性SiO2溶胶及带有磺酸基团的二氧化硅(SiOx-S)粒子)制备SPEEK/SiO2和SPEEK/SiOx-S复合质子交换膜.SiO2和SiOx-S的掺杂能有效提高复合膜的抗溶胀、阻醇性能及高温低湿情况下的电导率.纯SPEEK膜在80℃溶胀为52.6%,而SiO2和SiOx-S掺杂量为15%的复合膜在此温度下分别仅有26.2%和27.3%的溶胀.在室温至80℃范围内,SPEEK/SiO2(20 wt%)和SPEEK/SiOx-S(20 wt%)复合膜的甲醇透过系数比Nafion115膜小近2个数量级.在120℃、相对湿度(RH)为40%情况下,SPEEK纯膜的电导率仅为2.6×10-4S.cm-1,SPEEK/SiO2(20 wt%)复合膜约为2.0×10-3S.cm-1,而SPEEK/SiOx-S(20 wt%)复合膜高达1.0×10-2S.cm-1,与Nafion115相当.SPEEK/SiO2(20 wt%)和SPEEK/SiOx-S(20 wt%)2种复合膜的尺寸稳定性较高,膜电极无催化剂与膜分离现象,其DMFCs单电池性能好于SPEEK膜.     

二氨基马来腈共聚合改性氮化碳光催化剂

利用二氨基马来腈(DMNA)与二聚氰胺(DCDA)的高温共聚合反应, 制备了石墨相氮化碳 (g-C₃N₄), 并通过X射线衍射(XRD)、傅里叶变换红外(FT-IR)光谱、透射电镜 (TEM)、氮气吸脱附实验 (N₂-sorption)、电子顺磁共振 (EPR)、紫外-可见漫反射光谱 (UV-Vis DRS) 和荧光 (PL) 光谱等表征手段,系统考察了共聚合改性对g-C₃N₄晶体结构、化学结构、能带结构、织构、光吸收性能和光催化性能等的影响.研究结果表明:共聚合改性后氮化碳材料仍保持石墨相晶体结构, 但其π电子的离域性增强, 并在催化剂表面产生异质结构, 进而提高了氮化碳在可见光区域的光吸收性能, 并促进了光生载流子的有效分离. 性能评价结果显示, DMNA改性的氮化碳在可见光下光催化产氢活性明显高于未改性的样品, 当DMNA用量为0.01g时, 催化剂的产氢速率最高, 达到45.0 μmol·h^-1, 为纯氮化碳样品的4.5倍.     

中温固体氧化物燃料电池的基本性质测量

介绍了固体氧化物燃料电池的工作原理,测量了中温薄膜固体氧化物燃料电池的开路电压、放电曲线及功率曲线,并分析了电池内阻随电流密度的变化.     

电感耦合等离子体质谱(ICP-MS)及其联用技术在核工业领域的应用进展

综述了电感耦合等离子体质谱(ICP-MS)及其联用分析技术的进展,论述了其在相关核工业及环境领域中分析痕量或超痕量的放射性同位素、长寿命核素、元素形态等的应用。讨论了电感耦合等离子体质谱及联用技术的发展趋势,并对目前存在的主要问题及可能的解决方案进行了讨论。     

PEMFC气体扩散层内各向异性传递过程数值模拟

质子交换膜燃料电池(PEMFC)气体扩散层(GDL)具有各向异性属性,常规数值模拟对GDL采取均匀模型,忽略了各向异性传递过程对PEMFC性能的影响。本文发展了一个三维非等温单相模型,在GDL平面内和GDL厚度方向采用不同的传递系数,模拟了各向异性传递系数对PEMFC整体和局部性能的影响。在本文计算条件下,GDL各向异性和均匀模型模拟得到的电池极化曲线几乎完全相同,但电池电流密度分布和温度分布等局部特性存在很大差异。该结果进一步证明了不能单独用极化曲线来验证电池数学模型的正确性。     

Pt/porous-IrO2 nanocomposite as promising electrocatalyst for unitized regenerative fuel cell

Pt/porous-IrO₂ composite as bifunctional oxygen electrocatalyst for unitized regenerative fuel cell has been prepared by chemical reduction of Pt on porous IrO₂ which is obtained via template-removal method. X-ray diffraction and transmission electron microscopy characterizations indicate that the Pt nanoparticles (ca. 4.4 nm) are deposited on both internal and external sites of porous IrO₂ nanoparticles. Electrochemical analyses show that the activity toward oxygen evolution reaction on Pt/porous-IrO₂ catalyst is 28% (at 1.55 V) higher than that on Pt/commercial-IrO₂ catalyst, and the activity towards oxygen reduction reaction on the former is 2.3 times (at 0.85 V) that on the latter. Oxygen reduction on Pt/porous-IrO₂ catalyst follows the first-order kinetics and the four-electron mechanism.     

A new way to increase performance of oxide electrode for oxygen reduction using grain growth inhibitor

Nickel oxide was introduced as a grain growth inhibitor into Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3 − δ (BSCF) electrode to increase its activity for oxygen reduction reaction. Small amount of NiO can effectively suppress the grain growth of BSCF by spinning the grain boundary and thus increase the electrode surface area, while the particle connection is not obviously affected. Electrochemical impedance spectra of symmetric cells indicate that the electrode activity for oxygen reduction is indeed effectively improved by introducing NiO additive. At 600 °C, area specific resistance of BSCF+5wt.% NiO is about 36.5% lower than that of pure BSCF electrode. Single cell tests also demonstrate an improved cell power output by introducing NiO additive. It implies that the adoption of a sintering inhibitor may be a facile and practical way to increase electrode activity for oxygen reduction.     

The loading of polyoxometalates compound on a biomass derived N-doped mesoporous carbon matrix,a composite material for electrical energy storage

Abstract

A polyoxometalate (POM)-based composite material (NiPW₁₂NP/NMC) was synthesized, in which the nanoparticle of a POM compound (NiPW₁₂NP) distributes on orange juice derived nitrogen doped mesoporous carbon matrix (NMC) homogenously. When employed as a cathode material, NiPW₁₂NP/NMC exhibits high specific capacitance, remarkable rate capability and long-term stability. When the current density is 4?A·g^?1, a specific capacitance as high as 547 F·g^?1 is achieved by NiPW₁₂NP/NMC. With NiPW₁₂NP/NMC serving as cathode and MnO₂ acting as anode, a high performance asymmetric supercapacitor is assembled, which possesses a high energy density of 10.88?Wh·kg^?1 at 0.64?kW·kg^?1. It also shows a good rate capability, when the current density increases from 4 to 12?A·g^?1, its specific capacitance decreases from 113 to 88 F·g^?1, with 77.9% capacitance retention. After 5000 cycles charge-discharge experiments, 92.8% of its capacitance can be maintained, which exhibits good stability.