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1.
《Electroanalysis》2017,29(2):314-318
A new method to decorate metallic nanoparticles (NPs) based on the wall‐jet configuration was developed. A homemade wall‐jet amperometric cell coupled to an electronic micropipette was used to decorate Pt NPs with Sb and Sn hydrodynamically through the injection of metallic precursor solutions onto an electrode modified with NPs under applied potential. The method allows the control of the coverage degree (θ) by changing easy handling parameters such as injection flow rate, injected volume and concentration of precursors. The decoration procedure is fast, reproducible, simple and economic, since it only uses a few microlitres of precursors to prepare each electrode composition. It is possible to prepare an average of 1000 electrodes using the same amount of precursors for each one prepared by a conventional method using a typical three‐electrode cell. Sb‐ and Sn‐decorated Pt/C NPs were first evaluated towards diluted glucose electrooxidation in buffer solution. These first insights reveal that the output current density increases with θSb and θSn; Sb‐decorated Pt/C shows the greatest improvement.  相似文献   

2.
In this study, a new glucose biosensor was fabricated by immobilizing glucose oxidase (GOx) on platinum nanoparticles (Pt NPs) decorated reduced graphene oxide (rGO)/Zn‐MOF‐74 hybrid nanomaterial. Herein, the biosensor fused the advantages of rGO with those of porous Zn‐MOF and conductive Pt NPs. This has not only enlarged the surface area and porosity for the efficient GOx immobilization and faster mass transport, but also provided favorable electrochemical features such as high current density, remarkable electron mobility through metal nanoparticles, and improved electron transfer between the components. The GOx‐rGO/Pt NPs@Zn‐MOF‐74 coated electrode displayed a linear measurement range for glucose from 0.006 to 6 mM, with a detection limit of 1.8 μM (S/N: 3) and sensitivity of 64.51 μA mM?1 cm?2. The amperometric response of the enzyme biosensor demonstrated the typical behavior of Michaelis‐Menten kinetics. The obtained satisfying sensitivity and measurement range enabled fast and accurate glucose measurement in cherry juice using the fabricated biosensor. The water‐stable Zn‐MOF‐74 demonstrated higher enzyme loading capacity and can be potent supporting material for biosensor construction.  相似文献   

3.
A controlled composition‐based method—that is, the microwave‐assisted ethylene glycol (MEG) method—was successfully developed to prepare bimetallic PtxRu100?x/C nanoparticles (NPs) with different alloy compositions. This study highlights the impact of the variation in alloy composition of PtxRu100?x/C NPs on their alloying extent (structure) and subsequently their catalytic activity towards the methanol oxidation reaction (MOR). The alloying extent of these PtxRu100?x/C NPs has a strong influence on their Pt d‐band vacancy and Pt electroactive surface area (Pt ECSA); this relationship was systematically evaluated by using X‐ray absorption (XAS), scanning electron microscopy (SEM) coupled with energy dispersive X‐ray spectroscopy (EDX), transmission electron microscopy (TEM), density functional theory (DFT) calculations, and electrochemical analyses. The MOR activity depends on two effects that act in cooperation, namely, the number of active Pt sites and their activity. Here the number of active Pt sites is associated with the Pt ECSA value, whereas the Pt‐site activity is associated with the alloying extent and Pt d‐band vacancy (electronic) effects. Among the PtxRu100?x/C NPs with various Pt:Ru atomic ratios (x=25, 50, and 75), the Pt75Ru25/C NPs were shown to be superior in MOR activity on account of their favorable alloying extent, Pt d‐band vacancy, and Pt ECSA. This short study brings new insight into probing the synergistic effect on the surface reactivity of the PtxRu100?x/C NPs, and possibly other bimetallic Pt‐based alloy NPs.  相似文献   

4.
Improving the electrocatalytic activity and durability of Pt‐based catalysts with low Pt content toward the oxygen reduction reaction (ORR) is one of the main challenges in advancing the performance of polymer electrolyte membrane fuel cells (PEMFCs). Herein, a designed synthesis of well‐defined Pd@Pt core–shell nanoparticles (NPs) with a controlled Pt shell thickness of 0.4–1.2 nm by a facile wet chemical method and their electrocatalytic performances for ORR as a function of shell thickness are reported. Pd@Pt NPs with predetermined structural parameters were prepared by in situ heteroepitaxial growth of Pt on as‐synthesized 6 nm Pd NPs without any sacrificial layers and intermediate workup processes, and thus the synthetic procedure for the production of Pd@Pt NPs with well‐defined sizes and shell thicknesses is greatly simplified. The Pt shell thickness could be precisely controlled by adjusting the molar ratio of Pt to Pd. The ORR performance of the Pd@Pt NPs strongly depended on the thickness of their Pt shells. The Pd@Pt NPs with 0.94 nm Pt shells exhibited enhanced specific activity and higher durability compared to other Pd@Pt NPs and commercial Pt/C catalysts. Testing Pd@Pt NPs with 0.94 nm Pt shells in a membrane electrode assembly revealed a single‐cell performance comparable with that of the Pt/C catalyst despite their lower Pt content, that is the present NP catalysts can facilitate low‐cost and high‐efficient applications of PEMFCs.  相似文献   

5.
The investigation of highly efficient catalysts for the electrochemical oxidation of glucose is the most critical challenge to commercialize nonenzymatic glucose sensors, which display a few attractive superiorities including the sufficient stability of their properties and the desired reproducibility of results over enzyme electrodes. Herein we propose a new and very promising catalyst: Pt cubes well‐dispersed on the porous Cu foam, for the the electrochemical oxidation reaction of glucose in neutral media. The catalyst is fabricated in situ on a homemade screen‐printed carbon electrode (SPCE) substrate through initially synthesizing the three‐dimensional (3D) porous Cu foam using a hydrogen evolution assisted electrodeposition strategy, followed by electrochemically reducing the platinic precursor simply and conveniently. Field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) proofs demonstrate that Pt cubes, with an average size (the distance of opposite faces) of 185.1 nm, highly dispersed on the macro/nanopore integrated Cu foam support can be reproducibly obtained. The results of electrochemical tests indicate that the cubic Pt‐based catalyst exhibits significant enhancement on the catalytic activity towards the electrooxidation of glucose in the presence of chloride ions, providing a specific activity 6.7 times and a mass activity 5.3 times those of commercial Pt/C catalysts at ?0.4 V (vs. Ag/AgCl). In addition, the proposed catalyst shows excellent stability of performance, with only a 2.8 % loss of electrocatalytic activity after 100 repetitive measurements.  相似文献   

6.
Tungsten carbide and graphitic carbon (WC/GC) composite has been synthesized by a simple solid-state pyrolysis method from an in situ route. The results indicate that the synthesized sample has a large specific surface area (S BET) of 198 m2 g?1, and the WC nanoparticles (NPs) with a narrow particle size are well dispersed on the graphitic carbon. After loading Pt nanoparticles, the prepared Pt/WC/GC catalyst exhibits a mass activity of 416.1 mA mg?1 Pt toward methanol electrooxidation, which is much higher than that of commercial Pt/C (JM) (231.2 mA mg?1 Pt). Moreover, the onset potential is 100 mV more negative than that on Pt/C (JM) electrocatalyst. In addition, the Pt/WC/GC catalyst has stronger resistance to CO poisoning than the commercial Pt/C (JM). Its superior electrochemical performance could be attributed not only to the synergistic effect between Pt and WC NPs but also to the excellent electrical conductivity of GC and proper porous structure for desirable mass transportation in a porous electrode.  相似文献   

7.
Mesoporous carbon (m‐C) has potential applications as porous electrodes for electrochemical energy storage, but its applications have been severely limited by the inherent fragility and low electrical conductivity. A rational strategy is presented to construct m‐C into hierarchical porous structures with high flexibility by using a carbon nanotube (CNT) sponge as a three‐dimensional template, and grafting Pt nanoparticles at the m‐C surface. This method involves several controllable steps including solution deposition of a mesoporous silica (m‐SiO2) layer onto CNTs, chemical vapor deposition of acetylene, and etching of m‐SiO2, resulting in a CNT@m‐C core–shell or a CNT@m‐C@Pt core–shell hybrid structure after Pt adsorption. The underlying CNT network provides a robust yet flexible support and a high electrical conductivity, whereas the m‐C provides large surface area, and the Pt nanoparticles improves interfacial electron and ion diffusion. Consequently, specific capacitances of 203 and 311 F g?1 have been achieved in these CNT@m‐C and CNT@m‐C@Pt sponges as supercapacitor electrodes, respectively, which can retain 96 % of original capacitance under large degree compression.  相似文献   

8.
To reduce the over-dependence on Pt, Pd-based catalysts have become one of the most effective candidates for oxygen reduction reaction (ORR). In order to further accelerate the ORR kinetics and strengthen the catalytic performance of Pd catalysts, component optimization and morphology design have been adopted. Although great progress has been made, it is still difficult to obtain porous ultrathin nanosheets with excellent performance by a simple method. Here, ultrathin PdCuMo porous nanosheets (PdCuMo NSs) were successfully prepared. This structure possessed a large specific surface area with rich cavities and structural defects, significantly enhancing its ORR performance. In special, the mass activity of PdCuMo NSs was 1.46 A mg−1 at 0.90 V, which was 12.2, 8.6, and 2.7 times as high as that of Pd/C, Pt/C, and PdCuMo nanoparticles (PdCuMo NPs), respectively. In addition, it had an excellent ability to resist CO poisoning and exhibited remarkable long-term stability.  相似文献   

9.
采用离子交换-电沉积的方法(Ion-exchange/electrodeposition,IEE)制备了一种高Pt利用率催化电极,对所制备电极的表面形貌、催化活性及单电池性能用线性扫描伏安(LSV)、扫描电镜(SEM)、透射电镜(TEM)和单电池测试进行了表征. 结果表明,通过电极制备工艺和离子交换-电沉积参数的调控,能够消除碳载体表面官能团的影响,使铂阳离子只与全氟磺酸树脂(Nafion)上的H+进行交换. 在无铂离子的电解质中,将被交换的铂阳离子还原到与Nafion接触的碳载体上,使每一个铂纳米粒子都处于气体多孔电极的三相界面上,有效地调控铂纳米粒子的尺寸和分散度. 单电池测试表明,以铂载量为0.014 mgPt•cm-2的IEE电极组装的电池的输出功率与铂载量为0.3 mgPt•cm-2的Nafion粘接Pt/C电极相当.  相似文献   

10.
Pt‐based nanostructures serving as anode catalysts for the methanol oxidation reaction (MOR) have been widely studied for many years. Nevertheless, challenging issues such as poor reaction kinetics and the short‐term stability of the MOR are the main drawbacks of such catalysts and limit their applications. Herein, we have developed a facile approach to encapsulate Pt nanoparticles (NPs) inside the nanochannels of porous carbon nanotubes (CNTs; Pt‐in‐CNTs) as a new enhanced electrocatalytic material. The as‐prepared CNTs offer simultaneously ordered diffusion channels for ions and a confinement effect for the NPs, which both facilitate the promotion of catalytic kinetics and avoid the Ostwald ripening of Pt NPs, thus leading to high activity and durable cycle life as an anode catalyst for MOR. This work provides a new approach for enhancing the stability and activity by optimizing the structure of the catalyst, and the Pt‐in‐CNTs represent the most durable catalysts ever reported for MOR.  相似文献   

11.
An intermediate‐template‐directed method has been developed for the synthesis of quasi‐one‐dimensional Au/PtAu heterojunction nanotubes by the heterogeneous nucleation and growth of Au on Te/Pt core–shell nanostructures in aqueous solution. The synthesized porous Au/PtAu bimetallic nanotubes (PABNTs) consist of porous tubular framework and attached Au nanoparticles (AuNPs). The reaction intermediates played an important role in the preparation, which fabricated the framework and provided a localized reducing agent for the reduction of the Au and Pt precursors. The Pt7Au PABNTs showed higher electrocatalytic activity and durability in the oxygen‐reduction reaction (ORR) in 0.1 M HClO4 than porous Pt nanotubes (PtNTs) and commercially available Pt/C. The mass activity of PABNTs was 218 % that of commercial Pt/C after an accelerated durability test. This study demonstrates the potential of PABNTs as highly efficient electrocatalysts. In addition, this method provides a facile strategy for the synthesis of desirable hetero‐nanostructures with controlled size and shape by utilizing an intermediate template.  相似文献   

12.
We have designed a new Pt/SnO2/graphene nanomaterial by using L ‐arginine as a linker; this material shows the unique Pt‐around‐SnO2 structure. The Sn2+ cations reduce graphene oxide (GO), leading to the in situ formation of SnO2/graphene hybrids. L ‐Arginine is used as a linker and protector to induce the in situ growth of Pt nanoparticles (NPs) connected with SnO2 NPs and impede the agglomeration of Pt NPs. The obtained Pt/SnO2/graphene composites exhibit superior electrocatalytic activity and stability for the ethanol oxidation reaction as compared with the commercial Pt/C catalyst owing to the close‐connected structure between the Pt NPs and SnO2 NPs. This work should have a great impact on the rational design of future metal–metal oxide nanostructures with high catalytic activity and stability for fuel cell systems.  相似文献   

13.
In this work, hollow Au/Pt alloy nanoparticles (NPs) with porous surfaces were synthesized in a two-step procedure. In the first step, tri-component Ag/Au/Pt alloy NPs were synthesized through the galvanic replacement reaction between Ag NPs and aqueous solutions containing a mixture of HAuCl4 and H2PtCl4. In the second step, the Ag component was selectively dealloyed with nitric acid (HNO3), resulting in hollow di-component Au/Pt alloy NPs with a porous surface morphology. The atomic ratio of Au to Pt in the NPs was easily tunable by controlling the molar ratio of the precursor solution (HAuCl4 and H2PtCl6). Hollow, porous Au/Pt alloy NPs showed enhanced catalytic activity toward formic acid electrooxidation compared to the analogous pure Pt NPs. This improved activity can be attributable to the suppression of CO poisoning via the “ensemble” effect.  相似文献   

14.
Conductive polymeric [NiII(teta)]2+ (teta=C‐meso‐5,5,7,12,12,14‐hexamethyl‐1,4,8,11‐tetra‐azacyclotetradecane) films (poly(Ni)) have been deposited on the surface of glassy carbon (GC), Nafion (Nf) modified GC (GC/Nf) and Nf stabilized Ag and Au nanoparticles (NPs) modified GC (GC/Ag‐Nf and GC/Au‐Nf) electrodes. The cyclic voltammogram of the resulting electrodes, show a well defined redox peak due to oxidation and reduction of poly(Ni) system in 0.1 M NaOH. They show electrocatalytic activity towards the oxidation of glucose. AFM studies reveal the formation of poly(Ni) film on the modified electrodes. Presence of metal NPs increases electron transfer rate and electrocatalytic oxidation current by improving the communication within the Nf and poly(Ni) films. In the presence of metal NPs, 4 fold increase in current for glucose oxidation was observed.  相似文献   

15.
An electrochemical biosensor was developed using Pt‐nanoparticles (Pt‐NPs) dispersed graphene based on a boron‐doped diamond thin film electrode. To compare its performances with those of other biosensors, glucose was used as a target analyte. This biosensor exhibited a wide linear range, a low detection limit and a higher sensitivity compared to other amperometric biosensors using graphene‐based electrodes. In addition, the biosensor promotes a direct electron transfer between the redox enzymes and the electrode surface and detects low concentration analytes. The excellent performance of the biosensor is attributed to the synergistic effect of the Pt‐NPs, graphene sheet and the BDD thin film. Therefore, it can be a promising application for electrochemical detection of analytes.  相似文献   

16.
直接甲醇燃料电池(DMFCs)作为一种环境友好、高效的新能源,对解决世界目前面临的“能源危机”与“环境危机”这两大问题有着至关重要的意义,具有较广阔的应用前景.目前,甲醇氧化催化剂仍然以 Pt基为主,但是 Pt价格昂贵,且容易受甲醇氧化中间产物的毒化,从而影响了 DMFCs的商业化进程.碳化钨(WC)作为非贵金属催化剂,在催化方面具有类铂的性能.在 WC上负载适量的 Pt,可以通过两者的协同效应加强催化剂的抗 CO中毒能力.但是,由于 WC的导电性能不佳,比表面积较小,因此寻找合适的载体显得尤为必要.在碳载体中,石墨烯(RGO)具有优良的导电性以及独特的片层结构,是电催化剂的理想载体.以 RGO为载体, WC为插层物质制备的 WC-RGO插层复合物具有化学稳定性好、电导率高且电化学活性面积大等优势.但是,由于石墨烯表面光滑且呈惰性,同时使用传统的碳化方法制备的碳化钨颗粒较大,因此,制备较小颗粒且分散均匀的 WC-RGO插层复合物具有较大难度.一般以偏钨酸铵和氧化石墨烯(GO)为前驱体制备 WC-RGO插层复合物,但是由于偏钨酸根和 GO都带负电,因此不能成功地将偏钨酸根引入到石墨烯的片层结构中,造成 WC-RGO插层复合物组装上的困难.本文采用硫脲成功地合成了具有高分散性 WC纳米颗粒插层在少层 RGO里的 WC-RGO插层复合物.硫脲((NH2)2CS)作为阴离子接受器,具有较强的结合阴离子形成稳定复合物的能力,同时它也是合成具有片层结构的过渡金属硫化物的原料之一.因此在 WC-RGO插层复合物组装过程中,硫脲既作为锚定及诱导剂,又是制备片层二硫化钨(WS2)的硫源.材料具体制备方法如下:首先利用浸渍法,将偏钨酸根阴离子([H2W12O40]6?)牵引到(NH2)2CS改性过的 GO上形成[H2W12O40]6?-(NH2)2CS-GO前驱体;然后将前驱体放入管式炉中还原碳化,前驱体先反应生成 WS2;由于 WS2自身的2D片层结构,反应中可以得到 WS2-RGO插层复合物,接着原位碳化生成 WC-RGO插层复合物.碳化钨-石墨烯负载铂电催化剂(Pt/WC-RGO)通过微波辅助法制得,并采用 X射线衍射、扫描电子显微镜、透射电子显微镜及激光拉曼光谱等手段对其结构与形貌进行了表征.结果显示,在 WC-RGO插层复合物中, WC的平均粒径为1.5 nm, RGO的层数约为5层.在甲醇电氧化反应中,相比于商用 Pt/C催化剂, Pt/WC-RGO插层复合物催化剂具有更高的电化学活性面积(ECSA)和较高的峰电流密度(246.1 m2/g Pt,1364.7 mA/mg Pt),分别是 Pt/C的3.66和4.77倍.我们分别利用 CO溶出伏安法、计时电流法及加速耐久性试验法验证了 Pt/WC-RGO催化剂优秀的抗 CO中毒能力及稳定性. Pt/WC-RGO催化剂特殊的插层结构,在增加 WC与 Pt接触机会以加强协同作用的同时,促进了催化过程中质量及电荷的转移,因而具有比 Pt/C更高的催化活性.可见,通过制备WC-RGO插层复合物可降低 Pt用量,从而大大地降低燃料电池中电催化剂的成本.同时,我们使用的是一种高效,可大批量生产纳米材料的方法,有助于催化剂的商业化.  相似文献   

17.
铂纳米线(Pt NWs)由于其独特的结构特点,比商业Pt/C具有更高的氧还原反应(ORR)比活性。在本工作中,我们将预先制备好的铂纳米颗粒(Pt NPs)引入到碳基体中,用于诱导生长Pt NWs,获得了均匀分布Pt NWs的阴极。通过改变Pt NP载量(0~0.015 mg·cm-2)和Pt NP来源(不同Pt含量的Pt/C)研究了所制备阴极的结构和性能。用扫描电镜对阴极表面进行了表征,并用透射电镜和X射线衍射分析了Pt NW的形貌和晶体结构。在单电池中分别进行了极化曲线和循环伏安曲线测试。当Pt NP来源为40% Pt/C且其载量为0.005 mg·cm-2时,制备的Pt NW阴极具有最佳的单电池性能和最大的电化学表面积(ECSA)。最后,提出了预制Pt NP影响Pt NWs分布的可能机制。  相似文献   

18.
《中国化学》2018,36(4):287-292
Developing nonprecious carbon electrocatalysts as alternatives to platinum for cathodic oxygen reduction reaction in fuel cells is of significance. Herein, an efficient precursor‐controlled synthesis strategy based on extremely rapid nucleation and deposition process assisted by the liquid nitrogen freeze drying method is explored to anchor cheap iron‐EDTA complex evenly dispersed on graphene to realize microstructural homogeneity of the derived Fe‐N‐C oxygen reduction electrocatalyst. The prepared electrocatalyst possesses excellent performance including high activity with more positive onset and half‐wave potential, such long‐term stability, and anti‐poisoning effect compared to commercial Pt/C. The activity correlates well with the unique sheet‐shaped morphology, high surface area, hierarchical porous structure, and the introduction of Fe‐Nx/C species. Especially, both the assembled practical alkaline and acid fuel cells based on the synthesized cathode catalysts reveal excellent performance with high open‐circuit voltage and power density.  相似文献   

19.
The chemical state and formation mechanism of Pt-Ru nanoparticles (NPs) synthesized by using ethylene glycol (EG) as a reducing agent and their stability have been examined by in situ X-ray absorption spectroscopy (XAS) at the Pt LIII and Ru K edges. It appears that the reduction of Pt(IV) and Ru(III) precursor salts by EG is not a straightforward reaction but involves different intermediate steps. The pH control of the reaction mixture containing Pt(IV) and Ru(III) precursor salts in EG to 11 led to the reduction of Pt(IV) to Pt(II) corresponding to [PtCl4](2-) whereas Ru(III)Cl3 is changed to the [Ru(OH)6](3-) species. Refluxing the mixture containing [PtCl4](2-) and [Ru(OH)6](3-) species at 160 degrees C for 0.5 h produces Pt-Ru NPs as indicated by the presence of Pt and Ru in the first coordination shell of the respective metals. No change in XAS structural parameters is found when the reaction time is further increased, indicating that the Pt-Ru NPs formed are extremely stable and less prone to aggregation. XAS structural parameters suggest a Pt-rich core and a Ru-rich shell structure for the final Pt-Ru NPs. Due to the inherent advantages of the EG reduction method, the atomic distribution and alloying extent of Pt and Ru in the Pt-Ru NPs synthesized by the EG method are higher than those of the Pt-Ru/C NPs synthesized by a modified Watanabe method.  相似文献   

20.
An area‐selective atomic layer deposition (AS‐ALD) method is described to construct oxide nanotraps to anchor Pt nanoparticles (NPs) on Al2O3 supports. The as‐synthesized catalysts have exhibited outstanding room‐temperature CO oxidation activity, with a significantly lowered apparent activation energy (ca. 22.17 kJ mol−1) that is half that of pure Pt catalyst with the same loading. Furthermore, the structure shows excellent sintering resistance with the high catalytic activity retention up to 600 °C calcination. The key feature of the oxide nanotraps lies in its ability to anchor Pt NPs via strong metal–oxide interactions while still leaving active metal facets exposed. Our reported method for forming such oxide structure with nanotraps shows great potential for the simultaneous enhancement of thermal stability and activity of precious metal NPs.  相似文献   

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