Oxidation State Of Platinum Research Articles

Tuning the Bifunctional Properties of Cell Reversal-Tolerant Ir-Pt Electrocatalysts for HOR and Oer

Hydrogen starvation is still a big problem in PEM fuel cells [1]. In order to provide protons and electrons to the cathode during H2 starvation, the carbon oxidation reaction (COR) takes place at the anode [2]. To solve this issue, there are three main strategies: (i) utilization of corrosion resistant support materials, (ii) integration of extensive and complex system mitigation strategies and finally (iii) the addition of co-catalyst to promote the oxygen evolution reaction(OER) instead of COR. [3, 4]In this work, platinum-iridium (PtIr) nanoparticles (NPs) have been designed as a novel bifunctional electrocatalysts to accelerate either the hydrogen oxidation reaction (HOR) or the OER depending on the reaction conditions. Our catalyst concept is the combination of both functionality (HOR and OER) in single Pt-Ir alloy nanoparticles (NPs) deposited on the same support material. The Pt-Ir NPs with Pt:Ir ratios of 1:1 and 3:1 were prepared by two different (colloidal and wet-impregnation) routes. Very interestingly, the oxidation states of platinum and iridium as well as the particle size strongly vary depending on the synthesis route. More precisely, the wet-impregnation enables preparing Pt-Ir NPs of 3 – 4 nm size and mainly in the metallic state, while strongly oxidized NPs with ~2 nm size are produced by colloidal route. Despite the different oxidation states and particle sizes, the Pt-Ir NPs show considerable activity for HOR and OER compared to pure commercial Pt/C and IrOx catalysts. Very interestingly, the bifunctionality of these Pt-Ir is highly reversible and is robust during accelerated stress tests. Operando Quick-X-ray Absorption Near Edge Structure (XANES) spectroscopy were performed to provide fundamental insights into the reversibility and catalytically active states of these bifunctional catalysts under the working conditions by jumping with the potential between HER and OER within few seconds. The combination of operando XANES, RDE and MEA data show that the bifunctional approach is a promising way to improve the cell reversal-tolerant properties of anode catalyst materials compared to the state-of-the-art Pt-IrOx catalyst materials.

Carbon Corrosion Induced by Surface Defects Accelerates Degradation of Platinum/Graphene Catalysts in Oxygen Reduction Reaction.

Graphene supported electrocatalysts have demonstrated remarkable catalytic performance for oxygen reduction reaction (ORR). However, their durability and cycling performance are greatly limited by Oswald ripening of platinum (Pt) and graphene support corrosion. Moreover, comprehensive studies on the mechanisms of catalysts degradation under 0.6-1.6V versus RHE (Reversible Hydrogen Electrode) is still lacking. Herein, degradation mechanisms triggered by different defects on graphene supports are investigated by two cycling protocols. In the start-up/shutdown cycling (1.0-1.6V vs.RHE), carbon oxidation reaction (COR) leads to shedding or swarm-like aggregation of Pt nanoparticles (NPs). Theoretical simulation results show that the expansion of vacancy defects promotes reaction kinetics of the decisive step in COR, reducing its reaction overpotential. While under the load cycling (0.6-1.0V vs.RHE), oxygen containing defects lead to an elevated content of Pt in its oxidation state which intensifies Oswald ripening of Pt. The presence of vacancy defects can enhance the transfer of electrons from graphene to the Pt surface, reducing the d-band center of Pt and making it more difficult for the oxidation state of platinum to form in the cycling. This work will provide comprehensive understanding on Pt/Graphene catalysts degradation mechanisms.

Aqueous Phase Reforming over Platinum Catalysts on Doped Carbon Supports: Exploring Platinum-Heteroatom Interactions.

A series of platinum catalysts supported on carbon nanofibers with various heteroatom dopings were synthesized to investigate the effect of the local platinum environment on the catalytic activity and selectivity in aqueous phase reforming (APR) of ethylene glycol (EG). Typical carbon dopants such as oxygen, nitrogen, sulfur, phosphorus, and boron were chosen based on their ability to bring acidic or basic functional groups to the carbon surface. In situ X-ray absorption spectroscopy (XAS) was used to identify the platinum oxidation state and platinum species formed during APR of EG through multivariate curve resolution alternating least-squares analysis, observing differences in activity, selectivity, and platinum local environment among the catalysts. The platinum-based catalyst on the nitrogen-doped carbon support demonstrated the most favorable properties for H2 production due to high Pt dispersion and basicity (H2 site time yield 22.7 h-1). Direct Pt-N-O coordination was identified by XAS in this catalyst. The sulfur-doped catalyst presented Pt-S contributions with the lowest EG conversion rate and minimal production of the gas phase components. Boron and phosphorus-doped catalysts showed moderate activity, which was affected by low platinum dispersion on the carbon support. The phosphorus-doped catalyst showed preferential selectivity to alcohols in the liquid phase, associated with the presence of acid sites and Pt-P contributions observed under APR conditions.

Microwave-Assisted Synthesis of Pt/SnO2 for the Catalytic Reduction of 4-Nitrophenol to 4-Aminophenol.

In this study, we present a new approach for the synthesis of Pt/SnO2 catalysts using microwave radiation. Pt(IV) and Sn(IV) inorganic precursors (H2PtCl6 and SnCl4) and ammonia were used, which allowed the controlled formation of platinum particles on the anisotropic SnO2 support. The synthesized Pt/SnO2 samples are mesoporous and exhibit a reversible physisorption isotherm of type IV. The XRD patterns confirmed the presence of platinum maxima in all Pt/SnO2 samples. The Williamson-Hall diagram showed SnO2 anisotropy with crystallite sizes of ~10 nm along the c-axis (< 00l >) and ~5 nm along the a-axis (< h00 >). SEM analysis revealed anisotropic, urchin-like SnO2 particles. XPS results indicated relatively low average oxidation states of platinum, close to Pt metal. 119Sn Mössbauer spectroscopy indicated electronic interactions between Pt and SnO2 particles. The synthesized samples were used for the catalytic reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) in the presence of excess NaBH4. The catalytic activity of the Pt/SnO2 samples for the reduction of 4-NP to 4-AP was optimized by varying the synthesis parameters and Pt loading. The optimal platinum loading for the reduction of 4-NP to 4-AP on the anisotropic SnO2 support is 5 mol% with an apparent rate constant k = 0.59 × 10-2 s-1. The Pt/SnO2 sample showed exceptional reusability and retained an efficiency of 81.4% after ten cycles.

Development of Novel Pt(IV)-Carbohydrate Derivatives as Targeted Anticancer Agents against Osteosarcoma

Despite the enormous importance of cisplatin as a chemotherapeutic agent, its application is impacted by dose-limiting side effects and lack of selectivity for cancer cells. Researchers can overcome these issues by taking advantage of the pro-drug nature of the platinum(IV) oxidation state, and by modifying the coordination sphere of the metal centre with specific vectors whose receptors are overexpressed in tumour cell membranes (e.g., carbohydrates). In this paper we report the synthesis of four novel carbohydrate-modified Pt(IV) pro-drugs, based on the cisplatin scaffold, and their biological activity against osteosarcoma (OS), a malignant tumour which is most common in adolescents and young adults. The carbohydrate-targeting vectors and Pt scaffold are linked using copper-catalysed azide-alkyne cycloaddition (CuAAC) chemistry, which is synonymous with mild and robust reaction conditions. The novel complexes are characterised using multinuclear 1D-2D NMR (1H, 13C and 195Pt), IR, HR-MS, Elem. Analyses, and CV. Cytotoxicity on 2D and 3D and cell morphology studies on OS cell lines, as well as non-cancerous human foetal osteoblasts (hFOBs), are discussed.

Heterobimetallic 21,23-dimetallaporphyrin: activation of metal-metal interactions within the porphyrinoid macrocycle.

Two core-modified porphyrins containing metal atoms, namely platinum(II) or platinum(IV) and rhodium(III), in place of two NH units, have been obtained by a post-synthetic modification of the 21,23-ditelluraporphyrin. The products of the tellurium-to-metal exchange, 21-platina-23-rhodaporphyrins, incorporate rhodacyclopentadiene and platinacyclopentadiene units with the metal atoms facing each other. The two molecules exhibit different degrees of metal-metal interaction depending on the oxidation state of platinum, with the NBO bond order being 0.04 for platinum(IV) and 0.15 for platinum(II). Consistently, the Quantum Theory of Atoms in Molecules analysis revealed the presence of the bond determinant, the bond critical point, in the platinum(II) species, in contrast to the platinum(IV) congener. The two porphyrinoids are interconvertible in redox reactions. They both exhibit fluxional behaviour in solution, studied by 1H NMR, involving alteration in the metal ion coordination sphere accompanied by the macrocyclic skeleton conformation change.

Impact of platinum loading and dispersion on the catalytic activity of Pt/SnO2 and Pt/α-Fe2O3

The Pt/SnO2 (SP-samples) and Pt/α-Fe2O3 (FP-samples) with platinum loadings between 1 and 10 mol% were synthesized mechanochemically starting from platinum(II) acetylacetonate dissolved in toluene and from SnO2 and α-Fe2O3 powders obtained from tin(II) and iron(II) acetates. The STEM results show that the ultrasmall platinum nanoparticles (PtNPs) are well dispersed on the SnO2 and α-Fe2O3 supports. The PtNPs size distributions calculated with lognormal functions ranged from 1.0 to 1.3 nm. The results of temperature programmed reduction in hydrogen showed maxima at 120–160 °C due to the reduction of PtOx to Pt0. The Pt-4f-XPS results showed that the dispersed platinum on the SnO2 and α-Fe2O3 supports consisted of all three oxidation states of platinum: Pt4+, Pt2+ and Pt0. The average oxidation state of platinum as a function of molar fraction of Pt loading in the SP samples varies from 1.69 to 2.11, whereas the oxidation state of Pt in the FP samples varies more linearly and steeply from 1.42 to 2.58. The synthesized samples showed high catalytic activity for the reduction of 4-nitropenol (4-NP) to 4-aminophenol (4-AP), which can be explained by the high dispersion of non-aggregated ultrasmall PtNPs with a size of about 1 nm on the SnOx and FeOx supports.

Berichtigung: Can an Elusive Platinum(III) Oxidation State be Exposed in an Isolated Complex?

Berichtigung: Can an Elusive Platinum(III) Oxidation State be Exposed in an Isolated Complex?

Photoelectrochemical, photocatalytic and electrocatalytic behavior of titania films modified by nitrogen and platinum species

Co-doping of titania by N and Pt species was employed to tune the electronic structure and enhance the electrocatalytic and photocatalytic activity of the films. Herein, the different approaches of synthesis procedure of Pt- and Pt,N–TiO2 films were used to investigate their effect on the platinum oxidation states. The resulting different species of Pt led to the changes in the electronic structure of TiO2, with consequent bandgap narrowing, anodic shift of the flat band potential, and cathodic shift of the valence band The quantum yield efficiency was correlated with Pt0 atomic content and the relative atomic content of Ptn+–O–Ti fragments, whereas its decrease for some samples can be caused by the presence of N and Ptn+. The highest response for N2O photocatalytic decomposition was observed over Pt,N–TiO2 films. The presence of metal and non-metal species in TiO2 structure resulted in synergistic effect including (1) inhibition of recombination of the electrons and holes and (2) narrowing of the bandgap. Electrocatalytic properties in hydrogen and oxygen evolution reactions were improved by Pt doping. The formed Pt2+–O–Ti bonds rather than Pt nanoparticles are suggested to be responsible for the highest electrocatalytic activity. The additional UV exposure of the electrodes led to Pt NPs aggregation as a result of photodeposition of Pt ions. The mechanism of the Pt2+ photoreduction in TiO2 structure is proposed.

Bioinorganic Chemistry of Platinum(IV) Complexes as Platforms for Anticancer Agents

The current review focuses on the comprehensive studies of platinum-based complexes that are known to exhibit anticancer properties. The research on metal-particle work has helped in treating sicknesses which plays an imperative part in therapeutic bioinorganic science. Understanding the biochemistry of the detoxification mechanism of metals can help in advancing as well as enhancing the anticancer property of metal complexes for several types of a tumour. The classifications of complexes discussed have been done on the basis of Platinum oxidation states and binding sites of the ligands. Further background and current status of Pt(IV) complexes are briefly explained along with a special reference to Structural Activity Relationships and Mode of Action. The coordination chemistry of Pt(IV) has been summarised and Pt(IV) complexes are reviewed on the basis of binding of Pt(IV) with Human Serum Albumin and DNA. Finally, the results were summarized and concluded emphasizing on the most important features.

The role of surface chemistry of modified MWCNT on the development and characteristics of Pt supported catalysts

The performance and stability of electrocatalysts strongly depend on the physicochemical characteristics, such as the surface area, the crystalline structure, size and shape of the particles and the interactions with the support. Platinum (Pt) is one of the most versatile elements in catalysis, efficiently mediating a multitude of chemical reactions. Reducing the demand for expensive Pt is a major driving force in catalysis research. The objective of the present study is the development of electrocatalysts with innovative features and focuses on the synthesis and characterization of highly dispersed Pt supported catalysts using functionalized Multi-Wall Carbon Nanotubes (f-MWCNT) as the substrate. The choice of the substrate was based on the unique properties of carbon nanotubes that generate strong interest for their use in many nano-material devices in catalysis, batteries, optics, gas storage, electronics, sensors and others. Various chemical pathways were used to modify the sidewalls of MWCNT and introduce several covalently attached groups like pyridine, sulfonic acid, carboxyl, benzene or zwitterion type moieties. Using these substrates, deposition of Pt nanoparticles was realized by means of the polyol synthetic procedure. The parameters of the synthetic procedure differentiate the reduction/deposition mechanism. The surface chemistry and functionalities of the support and the diverse reaction conditions resulted in differentiations of the properties, not only in terms of quantitative deposition, but also with respect to platinum oxidation state, nanoparticle size and dispersion and overall catalyst morphology. The combined characterization techniques used shed light into the fundamental understanding of the support effect on the final properties, while metal-support interactions are intensely discussed.

Can an Elusive Platinum(III) Oxidation State be Exposed in an Isolated Complex?

AbstractPlatinum(IV) complexes are extensively studied for their activity against cancer cells as potential substitutes for the widely used platinum(II) drugs. PtIV complexes are kinetically inert and need to be reduced to PtII species to play their pharmacological action, thus acting as prodrugs. The mechanism of the reduction step inside the cell is however still largely unknown. Gas‐phase activation of deprotonated platinum(IV) prodrugs was found to generate products in which platinum has a formal +3 oxidation state. IR multiple photon dissociation spectroscopy is thus used to obtain structural information helping to define the nature of both the platinum atom and the ligands. In particular, comparison of calculations at DFT, MP2 and CCSD levels with experimental results demonstrates that the localization of the radical is about equally shared between the dxz orbital of platinum and the pz of nitrogen on the amino group, the latter acting as a non‐innocent ligand.

Can an Elusive Platinum(III) Oxidation State be Exposed in an Isolated Complex?

Platinum(IV) complexes are extensively studied for their activity against cancer cells as potential substitutes for the widely used platinum(II) drugs. PtIV complexes are kinetically inert and need to be reduced to PtII species to play their pharmacological action, thus acting as prodrugs. The mechanism of the reduction step inside the cell is however still largely unknown. Gas-phase activation of deprotonated platinum(IV) prodrugs was found to generate products in which platinum has a formal +3 oxidation state. IR multiple photon dissociation spectroscopy is thus used to obtain structural information helping to define the nature of both the platinum atom and the ligands. In particular, comparison of calculations at DFT, MP2 and CCSD levels with experimental results demonstrates that the localization of the radical is about equally shared between the dxz orbital of platinum and the pz of nitrogen on the amino group, the latter acting as a non-innocent ligand.

Photocatalytic oxidation behaviors of Di-2-ethylhexyl phthalate over Pt/TiO2

Semi-volatile organic compounds (SVOCs) are ubiquitous contaminants in indoor environments that may have significant adverse effects on human health. This study investigated photocatalytic reaction behavior of Di-2-ethylhexyl phthalate (DEHP), a kind of typical semi-volatile organic compounds (SVOCs) with high boiling point (386.9 °C) and high molecular weight (390.56), over the surface platinized TiO2. The oxidation state of platinum (Pt) was found to be the most important factor in determining the photocatalytic activity of DEHP. Platinized titania with oxidized Pt species (PtOx/TiO2) showed significantly higher photocatalytic activity than titania platinized with metallic Pt (Pt0/TiO2). 1 wt% PtOx /TiO2 illustrated superior photocatalytic activity among the group of PtOx/TiO2 when substrate concentration reached at 1 %wt. Photocatalysis coupled with thermal catalysis could further strongly promote the degradation of DEHP. The Time-resolved PL indicated that photoexcited charge carrier lifetimes are longer for the PtOx/TiO2 compared with Pt/TiO2, highlighting the beneficial effects of Pt oxide, especially PtO, in promoting the separation efficiency of photo generated carriers and further improving the photocatalytic oxidation of DEHP. This work provides a facile methodology to investigate the photocatalytic reaction of SVOCs over photocatalyst which proved the validation of photocatalytic oxidation as a possible strategy to remove SVOCs from indoor atmosphere.

Influence of Titania Synthesized by Pulsed Laser Ablation on the State of Platinum during Ammonia Oxidation

A set of physicochemical methods, including X-ray photoelectron spectroscopy (XPS), X-ray diraction, electron microscopy and X-ray absorption spectroscopy, was applied to study Pt/TiO2 catalysts prepared by impregnation using a commercial TiO2-P25 support and a support produced by pulsed laser ablation in liquid (PLA). The Pt/TiO2-PLA catalysts showed increased thermal stability due to the localization of the highly dispersed platinum species at the intercrystalline boundaries of the support particles. In contrast, the Pt/TiO2-P25 catalysts were characterized by uniform distributionof the Pt species over the support. Analysis of Pt4f XP spectra shows that oxidized Pt2+ and Pt4+ species are formed in the Pt/TiO2-P25 catalysts, while the platinum oxidation state in the Pt/TiO2-PLA catalysts is lower due to stronger interaction of the active component with the support due to stronginteraction via Pt-O-Ti bonds. The Pt4f XP spectra of the samples after reaction show Pt2+ and metallic platinum, which is the catalytically active species. The study of the catalytic properties in ammonia oxidation showed that, unlike the catalysts prepared with a commercial support, the Pt/TiO2-PLA samples show higher stability during catalysis and significantly higher selectivity to N2 in a wide temperature range of 200–400 C.

Trans-Platinum(iv) pro-drugs that exhibit unusual resistance to reduction by endogenous reductants and blood serum but are rapidly activated inside cells: 1H NMR and XANES spectroscopy study.

Recent results have confirmed that protection of transplatin from reactions on the path to cancer cells substantially increases their activity, suggesting that such complexes have greater potential than previously thought. In this study we have investigated the use of the platinum(iv) oxidation state and the tetracarboxylate coordination sphere to determine whether these features could impart the same stability to trans-diammineplatinum complexes that they do to cis-diam(m)ineplatinum complexes. The cis complexes exhibit resistance to reduction by l-ascorbate and human blood serum, but are readily reduced inside cancer cells. Studies of reduction monitored by 1H NMR revealed that oxidation of trans-diammineplatinum(ii) complexes does not always result in significant stabilisation, but the complexes trans, trans, trans-[Pt(OAc)4(NH3)2] (OAc = acetate) and trans, trans, trans-[Pt(OPr)2(OAc)2(NH3)2] (OPr = propionate) exhibit second order half-lives of 33 h and 5.9 days respectively in the presence of a ten-fold excess of l-ascorbate. XANES spectroscopy studies of reduction in blood models showed that trans, trans, trans-[Pt(OAc)4(NH3)2] is stable in blood serum for at least 24 hours, but is reduced rapidly in whole blood and was observed to have a half-life of approximately 4 hours in DLD-1 colon cancer cells. Consequently, the tetracarboxylatoplatinum(iv) moiety has the properties required to enable the delivery of trans-diammine platinum complexes to cancer cells.

Selective transport and separation of charge–carriers by an electron transport layer in NiCo2S4/CdO@CC for excellent water splitting

Here, we propose an approach to inhibit interfacial charge recombination by an electron transport layer (ETL) that selectively transports electrons and simultaneously restricts the passage of holes. The ETL is embedded as a junction between a photocatalyst (NiCo2S4/CdO) and an electron collector (carbon cloth (CC)). The electron density gradient, band gap offset, and p–orbital states above the fermi level in the ETL regulate the directional flow of electrons from NiCo2S4/CdO to CC. The distinct locations of electrons and holes were confirmed based on the oxidation state and preferential deposition of platinum and lead ions on NiCo2S4/CdO@CC. The molecular orbitals and density of states and their relation to ETL’s performance were explained using first principles calculations. Reduction in recombination energy loss was supported by the Nyquist and Bode phase analyses. ETL’s inclusion resulted in a remarkable 77 % increase in H2 yield, suggesting that they have excellent potential for practical applications.

Highly dispersed platinum supported catalysts – Effect of properties on the electrocatalytic activity

This work addresses scientific issues regarding the most challenging component of PEM fuel cells, the electrocatalyst, and explores a new approach to exploit the differentiations induced to the metal by the surface chemistry of the support. The study focuses on the development of Pt based electrocatalysts supported on pyridine modified carbon nanotubes with different Pt loadings, their thorough characterization and parallel comparison with non-modified or conventional carbon supports. The aim is the interpretation of the catalyst electrochemical behavior through a structural and physicochemical characterization study. The introduction of pyridines can differentiate the metal deposition, in terms of dispersion, nanoparticle properties, platinum oxidation state and metal-support interactions. Moreover, the substrate can play a decisive role on the size and functionality of the electrochemical interface. This approach constitutes a promising route for developing materials with innovative features aiming to a serious reduction in the Pt loads through increased activity and metal utilization.

The State of Platinum and Structural Features of Pt/Al2O3 Catalysts in the Reaction of NH3 Oxidation

The work is related to the fundamental research of the process of ammonia neutralization using catalytic oxidation over Pt/Al2O3 catalysts in an excess of oxygen. The catalysts are synthesized using nitrate precursors on the supports prepared from Pural SCF-55 aluminum hydroxide by the calcination in air at 550°C or 750°C for 4 h. A number of physicochemical methods are used to study morphology, dispersion, structure, and electronic state of the catalyst active component before and after the reduction in hydrogen. It is shown that the synthesized Pt/Al2O3 catalysts are characterized by high dispersion of the active component: the size of deposited platinum particles is in the range from 0.5 nm to 2.0 nm, while the proportion of oxidized and reduced Pt forms varies. Based on the results of kinetic measurements, the catalyst activity and the selectivity to all major products (N2, N2O, NO, NO2) are determined depending on the reaction temperature. The results of the catalytic testing are discussed in relation to the data on dispersion and oxidation state of platinum.

Temperature Effect of Oxygen Reduction Reaction Activity on Pt-Pd/C Core-Shell Catalyst Investigated By X-Ray Absorption Spectroscopy

Introduction Environment and global warming issue is one of the main global issues around the world. The polymer electrolyte fuel cells (PEFCs) supposed to be one of the main devices used in the global renewable energy system and pure hydrogen energy society in the future. PEFC cathode catalyst requires an excess amount of platinum due to the degradation of oxygen reduction reaction (ORR) activity. High performance, high durability and low cost cathode catalyst is expected for the wide use of PEFC devices. Therefore, it is important to reduce the use of platinum in the catalyst and improve its catalytic activity as well as durability. Core-shell structure catalyst is one of the solutions to achieve a higher catalytic activity and less use of platinum. Compare with the common used platinum catalyst, Pd-core/Pt-shell catalyst is one of the promised catalyst to use less platinum, reduce the cost and possess high performance. However, the factor of controlling ORR activity in core-shell catalyst still has not well understood such as potential/temperature-dependent surface structures and oxidation states of platinum. Experimental In this research, we synthesized the 1 mono-layer Pt shell on carbon-supported palladium(Pd) core by copper under potential deposition (Cu-UPD) method, investigated its oxygen reduction reaction (ORR) activity at various temperatures and the oxygen coverage of platinum by rotating disk electrode (RDE) electrochemical measurements and operando X-ray absorption fine structure (XAFS, Fig. 1) respectively. Through the results of electrochemical measurements and XAFS, the relationship among ORR activity and oxygen coverage of the surface Pt shell at different temperature, the change of electronic structure and local structure of Pt atoms in Pt-Pd/C core-shell catalyst at different temperature in the same condition with electrochemical measurement (N2-saturated) and real working condition (O2-saturated) have been discussed. Results and discussion The result of electrochemical measurements shows Pt-Pd/C core-shell catalyst possess higher ORR activity and lower oxygen coverage than common Pt/C catalyst. In the high temperature (50~70°C), the ORR activity of Pt-Pd/C catalyst decrease with the increase of oxygen coverage and temperature, shows the decrease of active sites on the surface of Pt shell and the change of mechanism or structure of Pt-Pd/C catalyst. The result of XAFS shows the core-shell catalyst possess compressive strain and less Pt-Pt bond distances than common Pt/C catalyst in N2-saturated electrolyte, the expand of Pd core and Pt-Pt bond extend occurs at high temperature, explained the high ORR activity and less oxygen coverage of Pt-Pd/C core-shell catalyst in room temperature and the activity loss in the high temperature. In O2-saturated electrolyte, XAFS result shows Pt-O bond formation is dramatically increase and in the high temperature almost all the Pt shell oxidized to PtO2, Pt-Pd bond remarkable extends, shows the loss of ORR activity of the Pt-Pd/C catalyst in high temperature (60°C) in O2-saturated condition. Conclusion This research investigated ORR activity on Pd core-Pt shell with the change of temperature. The core-shell catalyst had a compressive strain and less Pt-Pt bond distances than common Pt/C catalyst in N2-saturated electrolyte, however, the expand of Pd core and Pt-Pt bond extend occurs at high temperature. Acknowledgments This research is based on results obtained from a project commissioned by the New Energy and Industrial Technology Development Organization (NEDO). Figure 1