Electrocatalytic Activity Of Pt Nanoparticles Research Articles

Enhancing Intrinsic Electrocatalytic Activity of Pt/C Nanoparticles for Oxygen Reduction Reaction in Acidic Media by Microwave-Assisted Synthesis

Abstract: This study is focused on the enhancement of the intrinsic electrocatalytic activity of Pt nano-particles supported on C (Pt/C NPs) towards Oxygen Reduction Reaction (ORR) in acidic media. The goal was to investigate the effect of microwave-assisted synthesis on the electrocatalytic performance of Pt/C NPs towards ORR. Thus, Pt/C NPs were synthesized using a microwave-assisted method and by a conventional heating method; structural and morphological characteristics were analyzed by X-ray dif-fraction (XRD) and transmission electron microscopy (TEM). Electrochemical studies were performed using the rotating disk electrode technique to evaluate the ORR performance. Microwave-assisted syn-thesis produced Pt/C NPs with a smaller particle size (6.3 ± 0.2 nm) than conventionally synthesized nanoparticles (8.6 ± 0.3 nm). Electrochemical analysis showed that the microwave-synthesized Pt/C NPs exhibited higher mass activity (4.6 ± 0.8 mA･g-1Pt) for ORR compared to conventionally synthesized nanoparticles (1.9 ± 0.4 mA･mA･g-1Pt). These results demonstrate that microwave-assisted synthesis en-hances the intrinsic electrocatalytic activity of Pt/C NPs for ORR in acidic media. These findings have important implications for the development of efficient electrocatalysts for fuel cell applications. Background: The synthesis and characterization of platinum nanoparticles on C are crucial for advancing electrocatalysis, particularly in the context of potential applications in fuel cells. This study builds on previous research, focusing on two distinct synthesis methods to enhance our understanding of their im-pact on nanoparticle properties and electrocatalytic performance. Objective: To investigate the synthesis efficiency, structural characteristics, and electrocatalytic activities of platinum nanoparticles on C using microwave-assisted heating and conventional synthesis reactor heating. The objective is to discern any significant differences in particle size, structure, and electrocata-lytic performance between the two synthesis methods. Methods: The synthesis involved a comparative analysis of platinum nanoparticles using microwave-assisted and conventional heating methods. Chemical composition analysis verified the synthesis efficiency, and structural and morphological characterizations were performed using X-ray Diffraction and Transmission Electron Microscopy. Electrochemical studies employed the rotating disk electrode technique, with activation and evaluation conducted through cyclic voltammetry, and the oxygen reduction reaction studied via linear sweep voltammetry in an acidic media (0.5 mol⋅L-1 H2SO4). Results: Well-supported platinum nanoparticles with a face-centered cubic structure were obtained on C using both synthesis methods. However, microwave-synthesized particles (6.3 ± 0.2 nm) exhibited a smaller size compared to conventionally synthesized particles (8.6 ± 0.3 nm). Electrochemical assess-ment revealed superior mass activity for microwave-synthesized material (4.6 ± 0.8 mA･g-1Pt), outper-forming commercial Pt nanoparticles (3.0 ± 0.3 mA･g-1Pt) and conventionally synthesized material (1.9 ± 0.4 mA･mA･g-1Pt). Conclusion: This study concludes that microwave-assisted synthesis yields platinum nanoparticles on C with enhanced electrocatalytic performance, as evidenced by the smaller particle size and superior mass activity compared to conventionally synthesized material and commercial Pt nanoparticles. These findings highlight the potential of microwave-synthesized Pt nanoparticles for applications in fuel cells.

Amperometric Sarcosine Biosensor Based on a Bi-Functional Platinum-Loaded Organic-Inorganic Hybrid Tungsten Phosphonate Material

Sarcosine has been identified as an effective biomarker for prostate cancer. However, the rapid and accurate determination of sarcosine has been a challenge due to its low concentration and the presence of interfering substances in human serum. Here we depict an amperometric sarcosine biosensor by using organic-inorganic hybrid mesoporous tungsten phosphonate (MTP) material. The MTP was synthesized by using a soft-template method, and platinum (Pt) nanoparticles were loaded onto it by using the ethylene glycol reduction method. Due to the excellent anti-interference performance of the mesoporous tungsten phosphonate and the high electrocatalytic activity of Pt nanoparticles, the as-prepared material exhibited both anti-interference function and electrocatalytic function. A simple biosensor was obtained by modifying a glassy carbon electrode (GCE) with the bi-functional material and sarcosine oxidase (SOx). The biosensor had a linear detection range of 1–71 μM with a limit of detection (LOD) of 0.4 μM, and had good ability to exclude interference signals from common interfering substances. Compared with our previous work about nickel phosphonate and molybdenum phosphonate, though the mechanism that the metal ions affects the anti-interference performance of the biosensor is not clear yet, it is reasonable to expect better anti-interference performance by replacing the metal ions in the phosphonate materials.

Carbon Nanotubes-Supported Pt Electrocatalysts for O₂ Reduction Reaction-Effect of Number of Nanotube Walls.

Carbon nanotubes (CNTs) are one of the most common catalysts supports for the development of electrocatalysts for O₂ reduction reaction (ORR) of electrochemical devices such as polymer electrolyte membrane fuel cells (PEMFCs) and metal-air batteries due to their high electrical conductivity and high stability. In addition to the electrical conductivity and stability, the number of inner tubes or walls also influence the electrocatalytic activity of the supported catalysts. Here we study the electrocatalytic activity of Pt nanoparticles (NPs) supported on CNTs (Pt/CNTs) as a function of number of walls towards ORR in both alkaline and acid solutions. The results indicate that the mechanism of ORR on Pt/CNTs does not change with the number of walls of CNTs support but the number of walls of CNTs supports has a significant effect on the electrocatalytic activity of supported Pt NPs. Pt NPs supported on double-walled CNTs (DWCNTs) exhibit a much better activity for ORR, as compared with that supported on single-walled and multi-walled CNTs (SWCNTs and MWCNTs). The high electrocatalytic activity of DWCNTs-supported Pt NPs is contributed to the fast electron transfer between the outer wall and inner tubes of DWCNTs for ORR through electron tunnelling process under the electrochemical polarization driving force.

4A Zeolite Support for Pt Nanoparticles towards Methanol Oxidation

The effect of 4A zeolite as a support on the electrocatalytic activity of Pt nanoparticles for the oxidation of methanol has been investigated. Pt/4A zeolite and Pt/C catalysts with the same mass of Pt are prepared by loading the Pt nanoparticles stabilized by PEG-400 on 4A zeolite and carbon black, respectively. Physical analyses reveal unevenly distributed but no large agglomerates of the Pt nanoparticles on the surface of 4A zeolite due to PEG-400 attached to the Pt nanoparticles, while the Pt nanoparticles on carbon black show a uniform distribution and a lesser degree of agglomeration. However, Pt/4A zeolite shows a much more negative onset potential and a significantly higher peak current density than Pt/C in methanol oxidation in both acidic and alkaline solutions. Pt/4A zeolite also shows high resistance to the poisoning caused by CO-like species formed in the reaction. The results indicate that 4A zeolite is superior to carbon black as a support for the Pt nanoparticles toward methanol oxidation, and further suggest that some types of zeolites could be used as efficient support materials in electrocatalysis.

Statistical analysis of the electrocatalytic activity of Pt nanoparticles supported on novel functionalized reduced graphene oxide-chitosan for methanol electrooxidation

The purpose of this study is to statistically analyze the anodic current density and peak potential of methanol oxidation at Pt nanoparticles supported on functionalized reduced graphene oxide (RGO), using design of experiments methodology. RGO is functionalized with methyl viologen (MV) and chitosan (CH). The novel Pt/MV-RGO-CH catalyst is successfully prepared and characterized with transmission electron microscopy (TEM) image. The electrocatalytic activity of Pt/MV-RGOCH catalyst is experimentally evaluated for methanol oxidation. The effects of methanol concentration and scan rate factors are also investigated experimentally and statistically. The effects of these two main factors and their interactions are investigated, using analysis of variance test, Duncan’s multiple range test and response surface method. The results of the analysis of variance show that all the main factors and their interactions have a significant effect on anodic current density and peak potential of methanol oxidation at α = 0.05. The suggested models which encompass significant factors can predict the variation of the anodic current density and peak potential of methanol oxidation. The results of Duncan’s multiple range test confirmed that there is a significant difference between the studied levels of the main factors.

Electrocatalytic activity of Pt nanoparticles supported on novel functionalized reduced graphene oxide-chitosan for methanol electrooxidation

Here, graphene oxide (GO) was synthesized by a modified Hummers’ method and was functionalized with 1,1′-dimethyl-4,4′-bipyridinium dichloride (MV) accompanied by chitosan (CH) to prepare a novel MV-RGO-CH support. Pt/MV-RGO-CH catalyst was prepared by immobilization of the Pt nanoparticles on MV-RGO-CH support. The microstructure and morphology of the prepared catalyst was characterized by transmission electron microscopy and X-ray powder diffraction analysis. The electrocatalytic activity of Pt/MV-RGO-CH catalyst was investigated for methanol electrooxidation through cyclic voltammetry (CV), COads stripping voltammetry, chronoamperometry, and electrochemical impedance spectroscopy (EIS) techniques. The effects of some experimental factors for methanol electrooxidation such as methanol concentration, scan rate and temperature were studied at the prepared catalyst. Durability of the catalyst was also investigated. Comparing the catalytic activity of the Pt/MV-RGO-CH nanocatalyst with Pt/CH and Pt/MV-RGO catalysts indicated that Pt/MV-RGO-CH has a very good catalytic activity for methanol electrooxidation.

Electrocatalytic Activity of Pt Nanoparticles Prepared in Biocompatible Ionic Liquids By Accelerated Electron Beam Irradiation

A number of papers on the metal nanoparticle synthesis method have been reported to date because metal nanoparticles are expected to be key materials for further development of science and technology.1 Of these, from a practical application standpoint, the accelerated electron beam irradiation method,2 which can be conducted at existing industrial plants for sterilizing medical kits, has been attracting attention. In this decade, several approaches to synthesize metal nanoparticles in ionic liquid (IL) have been proposed by several research groups, too.3 Some scientists point out that IL behaves as an excellent medium for formation and stabilization of the metal nanoparticles. Recently we have succeeded in the metal nanoparticle preparation by the approach with combination of the accelerated electron beam irradiation method and the IL, which is called ionic liquid-accelerated electron beam irradiation (IL-AEBI) method.4However the past ILs used for the method are not green and expensive price. The aim of this study is to design the biocompatible and cost-effective ILs suitable for metal nanoparticle, especially Pt nanoparticle, preparation by the IL-AEBI method. After supporting the resulting Pt nanoparticles onto untreated multi-walled carbon nanotubes (Pt-MWCNTs), oxygen reduction reaction (ORR) electrocatalytic activity of the Pt-MWCNTs was also examined. Biocompatible and cost-effective ILs were prepared by a neutralization method. Carboxylic acids, e.g., propionic acid, hexanoic acid, levulinic acid, were slowly added into a choline bicarbonate aqueous solution to avoid unexpected thermal decomposition of the carboxylic acids by heat of neutralization. The crude IL solutions were purified prior to use. Solutions of 5.0 mM platinum acetylacetonate (Pt(acac)2) in biocompatible ILs were encapsulated in perfluoroalkoxyethylene container in a dry Ar gas-filled glove box with O2 and H2O <1 ppm. Accelerated electron beam irradiation experiments were carried out at an existing common industrial plant for sterilizing medical kits (accelerated energy: 4.8 MeV; beam current: 10 mA; absorbed dose: 6 kGy; irradiation time: ca. 2 sec.). Pt-MWCNTs were prepared by reference to our previous paper.5The resulting Pt nanoparticles supported on MWCNT was rinsed by acetonitrile. Characterization of all the samples prepared in this study was conducted by TEM, EDX, ICP, electrochemical measurements, etc. Solvated electrons and radicals are readily produced in various solvents by quantum beam irradiation including gamma-ray and electron beam. The generated reactive species are directly related to preparation of metal nanoparticles.2 However, as is often the case with ILs, it is hard to produce metal nanoparticles since usual ILs show a better radiation stability than conventional aqueous and organic solvents. Many years ago we revealed that only 1,3-dialkylimidazolium cation-based ILs yield a sufficient number of metal nanoparticles by the IL-AEBI because such ILs can release a limited amount of reactive species.4 It is important to know the radiation stability of biocompatible ILs in light of the application to the IL-AEBI method. NMR measurements for the neat ILs after the accelerated electron beam irradiation suggested the production of the reactive species during the irradiation. In fact, after the accelerated electron beam irradiation to the solutions of 5.0 mM Pt(acac)2 in the biocompatible ILs, existence of monodispersed Pt nanoparticles in the ILs was identified by TEM observation. Mean particle size of the Pt nanoparticle was ca. 2 ~ 3 nm. Possibility of the Pt nanoparticles as the electrocatalysts was investigated after preparing the Pt-MWCNTs.4 Surprisingly the mean particle size remained even after the preparation process at 473 K and the Pt nanoparticles were immobilized onto a basal plane of the MWCNTs. Electrocatalytic activity was examined by typical electrochemical analyses using the Pt-MWCNTs coated on a glassy carbon rotating disk electrode.5 As given in Table I, the characteristics are strongly dependent on the ionic liquid species. Given the variation in the mass activity, it is possible that the d-band center of Pt nanoparticles is influenced by the carboxylate anions. In conclusion, our designed biocompatible and cost-effective ILs are suitable reaction media for metal nanoparticle preparation by the IL-AEBI method. Acknowledgement Part of this research was supported by the Grant-in-Aid for Scientific Research, Grant Numbers 15H03591, 15K13287, and 15H2202 from the Japanese Ministry of Education, Culture, Sports, Science and Technology. References Nanoparticles: From Theory to Application, G. Schmid, ed., Wiley-VCH, Weinheim, 2004. J. Belloni, Cat. Today, 113, 141 (2006). J. Dupont and J. D. Scholten, Chem. Soc. Rev., 39, 1780 (2010). T. Tsuda, S. Seino, and S. Kuwabata, Chem. Commun.,6792 (2009); ibid, 48, 1925 (2012). K. Yoshii, T. Tsuda, T. Arimura, A. Imanishi, T. Torimoto, and S. Kuwabata, RSC Adv., 2, 8262 (2012). Figure 1

Enhanced electrocatalytic activity of Pt nanoparticles supported on functionalized graphene for methanol oxidation and oxygen reduction

Reduced graphene oxide (RGO) is modified with 1,1′-dimethyl-4,4′-bipyridinium dichloride (methyl viologen, i.e. MV) by a π–π interaction, and further used as support for immobilization of Pt nanoparticles to prepare a Pt/MV–RGO catalyst for direct methanol fuel cells. Transmission electron microscopy, X-ray powder diffraction, Raman spectroscopy and X-ray photoelectron spectroscopy are used to characterize the morphology and microstructure of the prepared catalyst. Electrocatalytic performance of the as-prepared Pt/MV–RGO hybrid is investigated by cyclic voltammetry, linear scan voltammetry, COads stripping voltammetry and electrochemical impedance spectroscopy. The Pt/MV–RGO hybrid exhibits much higher catalytic activities than Pt/RGO toward both methanol oxidation and oxygen reduction, suggesting that Pt/MV–RGO hybrid could be a promising electrocatalyst for high-performance direct methanol fuel cells applications.

Cerium oxide as a promoter for the electro-oxidation reaction of ethanol: in situ XAFS characterization of the Pt nanoparticles supported on CeO2 nanoparticles and nanorods.

In this study we probe the electrocatalytic activity of Pt nanoparticles supported on ceria nanoparticles (NPs) and nanorods (NRs) in the ethanol oxidation reaction (EOR) in alkaline media. The goal of this study was to relate morphology, support structure and composition to the EOR catalytic activity by using in situ X-ray absorption fine structure (XAFS) studies. Cyclic voltammetry experiments showed that both ceria supported catalysts (NP vs. NR) had similar peak current densities at fast scan rates, however at slow scan rates, the ceria NR catalyst showed superior catalytic activity. In situ XAFS studies in KOH showed that both ceria supported catalysts had more electron density in their d-band (with the ceria NR having more electron density overall) than ceria - free Pt/Vulcan standard. However, in an ethanol solution the ceria NR catalyst had the least electron density. We propose that this change is due to the increased charge transfer efficiency between the ceria nanorod support and platinum. In the KOH solution, the increased electron density makes the platinum less electrophilic and hinders Pt-OH bond formation. In the EtOH solution, platinum's increased nucleophilicity facilitates the bond formation between Pt and the electron deficient carbon in ethanol which in turn withdraws the electron density from platinum and increases the white line intensity as observed in the XAS measurements.

Size Effect of Pt Nanoparticles Deposited By Plasma-Enhanced Atomic Layer Deposition on the Electrocatalytic Activity Toward the Methanol Oxidation Reaction

Platinum is the most important catalyst used for direct methanol fuel cells (DMFC) because its excellent electrocatalytic activity toward the methanol oxidation reaction (MOR). Most of recent research on DMFC focuses on the size minimization of the Pt catalyst, which can reduce the use of the precious Pt catalyst and increase the electroactive surface area. Moreover, nanosized Pt catalyst can significantly enhance the electrocatalytic activity toward MOR. In this study, we used plasma-enhanced atomic layer deposition (PEALD) to deposit Pt nanoparticles of different sizes on the TiO2substrate, and studied the electrocatalytic activity of Pt nanoparticles toward MOR as a function of the particle size. Pt nanoparticles were deposited on the TiO2 substrate by PEALD with a plasma power of 5W at 200oC using (methylcyclopentadienyl) trimethyl platinum (MeCpPtMe3) as the Pt precursor. Due to the self-limiting growth kinetics of ALD reactions, the size of Pt nanoparticles can be controlled by the number of the PEALD cycle, which was varied from 8 to 50 cycles in this study. The TiO2 was the nature oxide layer on a 100 nm thick Ti thin film sputter-deposited on the Si(100) wafer. Transmission electron microscopy (TEM) reveals that Pt nanoparticles has a size in the range between 3 nm and 7 nm depending on the number of the PEALD cycle. Cyclic voltammetry (CV) and CO stripping analysis were performed to study the electrocatalytic activity of the Pt/TiO2 electrode toward MOR in acidic media. The Pt/TiO2 electrode prepared with 15 PEALD cycles has a Pt particle size distribution peaking at ~4 nm, and has the best electrochemical performance, including electrocatalytic activity and CO tolerance. With the PEALD cycle number increased to 50, Pt nanoparticles trend to coalesce, and the electrode exhibits an electrochemical performance similar to a continuous Pt thin film. The better electrocatalytic activity of Pt nanoparticles prepared with a smaller number of the PEALD cycle can be ascribed to the synergistic effect of the nanosized Pt catalyst and the electronic interaction between Pt nanoparticles and the TiO2support. A schematic model describing the role of Pt nanoparticle size in the synergistic effect will be presented at the meeting. Keywords: direct methanol fuel cells, DMFC, plasma-enhanced atomic layer deposition, PEALD, methanol oxidation reaction, Pt nanoparticles, TiO2.

Highly selective and sensitive adenosine aptasensor based on platinum nanoparticles as catalytical label for amplified detection of biorecognition events through H2O2 reduction

Based on a combination of aptamer and platinum nanoparticles a new sensitive and selective adenosine aptasensor was fabricated. Functionalized thiol-terminated adenosine aptamer (5'-AGAGAACCTGGGGGAGTATTGCGGAGGAAGGT-SH-3') with Pt Nanoparticles (Pt-NPs) was employed as highly catalytic label for electrochemical detection of adenosine based on electrocatalytic activity of Pt-NPs toward H2O2 reduction. Multiwalled carbon nanotubes/ionic liquid/chitosan (MWCNTs/IL/CHIT) nanocomposite was applied as the interface for covalent attachment of 3'-amine-terminated capture probe (3'-NH2-(CH2)6-TCTCTTGGACCC-5'). The presence of Pt nanoparticles improvement the conductivity and performance characteristics of the biosensor as well as incensement in the loading amount of the aptamer DNA sequence. The interaction of adenosine with the aptamer causes the releasing of aptamer with PtNPs into solution which resulted in a decreasing of hydrogen peroxide reduction peak current. Sensitive quantitative detection of adenosine was achieved by monitoring the decrease of voltammetric responses of H2O2 peak current. The peak current of H2O2 decreased with increase in the concentration of adenosine over a range of 1–750nM with detection limit 1nM. In addition the proposed aptasensor showed excellent selectivity toward adenosine in compared to some other nucleosides such as guanosine, cytidine and uridine. The proposed aptasensor was successfully used to detect adenosine in human serum samples. The elimination of enzymes or antibodies for the amplified detection of adenosine and the use of platinum nanoparticles as inorganic catalytic label, are the advantage of the proposed aptasensor.

Methanol electrocatalytic oxidation on Pt nanoparticles on nitrogen doped graphene prepared by the hydrothermal reaction of graphene oxide with urea

A facile hydrothermal reaction of graphene oxide with urea was used to produce nitrogen doped graphene, and Pt nanoparticles were deposited on the obtained nitrogen doped graphene by the NaBH4 reduction route. The morphology and microstructure of the synthesized catalysts were characterized by transmission electron microscopy, X-ray powder diffraction and X-ray photoelectron spectroscopy, while the functional groups on the surface of the catalysts were investigated by the Fourier transform infrared spectroscopy and ultraviolet-visible absorption spectra. Cyclic voltammetry, chronoamperometry and electrochemical impedance techniques were carried out to evaluate the methanol electrocatalytic oxidation activity and durability of Pt catalysts supported on the nitrogen doped graphene. The results showed that nitrogen doping and reduction of GO were achieved simultaneously by the facile hydrothermal reaction, which had beneficial effects for the deposition process and electrocatalytic activity of Pt nanoparticles. The Pt catalysts supported on the nitrogen doped graphene substrate presented excellent activity and durability of methanol oxidation reaction, which might be promising for application in direct methanol fuel cells.

Nonenzymatic hydrogen peroxide electrochemical sensor based on carbon-coated SnO2 supported Pt nanoparticles

We describe a simple method for preparing the hybrid material of Pt nanoparticles (NPs) supported on carbon-coated SnO2 nanospheres (Pt–SnO2@C). The as-prepared Pt–SnO2@C nanocomposite was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The presence of carbon-coated SnO2 nanospheres (SnO2@C) remarkably improves the electrocatalytic activity of Pt NPs towards hydrogen peroxide (H2O2) oxidation. The Pt–SnO2@C nanocomposite modified glassy carbon (GC) electrode exhibited enhanced amperometric response to H2O2, with detection limit of 0.1μM and sensitivity of 241.1μAmM−1cm−2.

Ligand-Mediated Electrocatalytic Activity of Pt Nanoparticles for Oxygen Reduction Reactions

High-performance electrocatalysts for oxygen reduction reactions (ORR) are crucial for the development of proton exchange membrane fuel cells (PEMFCs). In this study, a novel method was developed by which the ORR activity of Pt nanoparticles was deliberately manipulated by selective organic capping ligands. By coreduction of diazonium salts and H2PtCl4, a series of Pt nanoparticles (core size 2.0–2.5 nm) stabilized by para-substituted (R = −CH3, −F, −Cl, −OCF3, and −CF3) phenyl groups were synthesized. The experimental results demonstrated that the electron-withdrawing capability of the substituent moieties, as manifested by the Hammet substituent constant (σ), plays a key role in controlling the ORR activity, where the higher σ, the higher ORR activity. Within the present experimental context, Pt nanoparticles stabilized by trifluoromethylphenyl groups (Pt–Ar–CF3) exhibit the highest catalytic activity among the series, with an ORR specific activity 3.2 times higher than that of commercial Pt/C catalysts...

Effects of the PdO nanoflake support on electrocatalytic activity of Pt nanoparticles toward methanol oxidation in acidic solutions

We prepared PdO nanoflake thin films on carbon cloths by reactive sputtering deposition, and studied electrocatalytic performance of Pt nanoparticles electrodeposited on the PdO thin film in methanol oxidation reaction (MOR) in acidic media. The PdO nanoflake thin film exhibits a cyclic voltamperometric (CV) behavior similar to metallic Pd electrodes because a metallic Pd surface layer is formed on the PdO thin film electrode under the CV measurement condition. The nanoflake morphology of the PdO electrode provides a large surface area for Pt nanoparticle loading, resulting in a large electrochemical active surface area (ESA). The Pt/PdO electrode has a high electrocatalytic activity toward MOR, and the good electrocatalytic performance of the Pt/PdO electrode is ascribed to a high CO tolerance and the large ESA. We suggest that the high CO tolerance of the catalyst on the Pt/PdO electrode is a result of the synergism of the bifunctional mechanism and the electronic effect. XPS analyses indicate that negative charge transfer occurs from the PdO support to the Pt nanoparticles, indicating the presence of the electronic effect. Pt nanoparticles on the PdO support can greatly alleviate the nanoflake damage during the CV measurement, which results from anodic dissolution of metal Pd from the PdO support in acidic media.

Enhancement of the electrocatalytic activity of Pt nanoparticles in oxygen reduction by chlorophenyl functionalization

Chlorophenyl-stabilized platinum nanoparticles (1.85 nm) exhibited electrocatalytic activity for oxygen reduction up to 3 times higher than that of commercial Pt/C catalysts. Similar enhancement was observed with naked Pt/C functionalized by the same chlorophenyl fragments, suggesting the important role of organic capping ligands in the manipulation of nanoparticle electrocatalytic performance.

Enhanced electrocatalytic activity of Pt nanoparticles modified with PPy-HEImTfa for electrooxidation of formaldehyde

A facile approach to improve the electrocatalytic properties of Pt nanoparticles (nm-Pts) has been developed. nm-Pts are deposited on substrate electrode Pt sheet using cyclic voltammetry in sulfuric acid containing H 2PtCl 6 to get nm-Pt electrode, and then are modified with polypyrrole in an ionic liquid 1-ethylimidazolium trifluoroacetate (PPy-HEImTfa) to obtain the electrode PPy-HEImTfa/nm-Pt. The electrocatalytic performance of PPy-HEImTfa/nm-Pt towards the oxidation of formaldehyde in acidic solution has been studied by cyclic voltammetry and in situ FTIR spectroscopy. Results show that PPy-HEImTfa/nm-Pt exhibits high electrocatalytic activity and stability, as compared with nm-Pt electrode or PPy-HEImTfa modified with nm-Pts (nm-Pt/PPy-HEImTfa) under the similar preparation conditions. In situ FTIR spectroscopic measurements confirm that PPy-HEImTfa film on the surface of nm-Pts help to catalyze the oxidation of the adsorbed CO and reduced the poisoning effect of CO on nm-Pt catalyst.

Enhancement of activity of platinum towards oxidation of ethanol by supporting on titanium dioxide containing phosphomolybdate-modified gold nanoparticles

A new concept of utilization of titanium dioxide matrix in electrocatalysis by admixing it with polyoxometallate modified gold nanoparticles is described here. The approach utilizes Keggin-type phosphododecamolybdate (PMo 12O 40 3−) adsorbates capable of modifying, activating and stabilizing Au nanoparticles of the sizes of 30–40 nm. Ultra-thin films of phosphomolybdates on nanostructured gold are characterized by well-defined fast (reversible) multi-electron electrochemical reactions. By dispersing platinum black over the Au-containing TiO 2, the electrocatalytic activity of Pt nanoparticles towards oxidation of ethanol has been enhanced. Remarkable increases of electrocatalytic currents measured under voltammetric and chronoamperometric conditions have been observed. The most likely explanation takes into account improvement of overall conductivity (due to the presence of nanostructured gold) at the electrocatalytic interface (including TiO 2-support), as well as and possibility of specific Pt–TiO 2 or Pt–Au electronic interactions and existence of active hydroxyl groups (on titanium dioxide or polyoxometallate surfaces) in the vicinity of catalytic Pt sites.

Electrocatalytic activity of Pt nanoparticles on a karst-like Ni thin film toward methanol oxidation in alkaline solutions

The study prepared rugged Ni thin films for the study on electrocatalytic methanol oxidation reaction (MOR) in alkaline solutions. The rugged Ni thin film has a karst-like morphology, which provides a large surface area for Pt nanoparticle loading by pulse electrodeposition. Cyclic voltammetry measurements showed that the Pt/karst-Ni electrode had a high electrocatalytic activity toward MOR and CO tolerance in the KOH electrolyte. Ni(OH)2 formed on the Ni support during the potential scan can enhance CO tolerance of Pt nanoparticles via the bi-functional mechanism. The Langmuir–Hinshelwood and the Eley–Rideal mechanisms are used to elucidate the role of OH surface groups on the Ni support and OH− ions in the electrolyte, respectively, in the enhancement of the CO tolerance. XPS analysis indicates that negative charges transfer from the Ni support to Pt nanoparticles. The electronic interaction may modify adsorption properties of CO adspecies on the Pt catalyst; the modification allows easy CO electro-oxidation by OH species surrounding the Pt nanoparticles, either from the Ni support or from the alkaline solution. The synergistic effect of the bifunctional mechanism and the electronic interaction makes the Pt/karst-Ni structure a good catalytic electrode for MOR in the KOH solution.

Electrocatalytic Activity of Pt Nanoparticles on Karst-Rock Shaped Ni Thin Films toward Methanol and Ethanol Oxidation in Alkaline Solutions

We prepared Ni thin films with a karst-rock topography on the Si substrate and used the thin film as the electrocatalyst support for the study of methanol and ethanol oxidation in alkaline media. Well-dispersed Pt nanoparticles were pulse-electrodeposited on the rugged Ni thin film, which provided a very large surface for the Pt loading. The cyclic voltammertry (CV) showed that the Pt/Ni electrode had a high electrocatalytic activity toward methanol oxidation compared with blanket Pt. Nanosized Pt particles electrodeposited on the rugged surface of the Ni thin film provide a large amount of electrocatalytic sites for methanol oxidation. Hydroxyl surface groups bound on the Ni karst-rock nanostructures in the alkaline solution may greatly enhance CO electro-oxidation in terms of the bifunctional mechanism. The study demonstrates that the karst-rock shaped Ni thin film is a potential candidate as the Pt electrocatalyst support for direct methanol alkali fuel cells.