Platinum Metals Review 

About: Platinum Metals Review is an academic journal. The journal publishes majorly in the area(s): Platinum & Catalysis. It has an ISSN identifier of 0032-1400. It is also open access. Over the lifetime, 362 publications have been published receiving 8391 citations.

Catalysis for low temperature fuel cells. Part I: The cathode challenges

Abstract: Much of the performance still to be gained in proton exchange membrane fuel cells (PEMFCs) in use today is available from improvements to the cathode, traditionally made from unsupported or carbon-supported platinum. The search for improved cathode electrocatalysts has resulted in the development of platinum alloys which if tailored to the desired stack operating conditions can double the activity for oxygen reduction. Recently, advances have been made in cathode design which have raised performance levels in PEMFCs. The new electrocatalysts and cathode designs have increased electrical efficiency and power densities to the PEMFC stack, needed for commercial use. Improvements have also been achieved at the anode, by developments in platinum-ruthenium anodes for carbon monoxide and cell reversal tolerance. In this first paper, new cathode materials and designs are discussed; a second paper to be published in the April issue will look at anode advances.

"Organic Light-Emitting Devices: Synthesis, Properties and Applications"

Abstract: 1 Inorganic Semiconductors for Light-emitting Diodes (E Fred Schubert, Thomas Gessmann, and Jong Kyu Kim) 11 Introduction 12 Optical Emission Spectra 13 Resonant-cavity-enhanced Structures 14 Current Transport in LED Structures 15 Extraction Efficiency 16 Omnidirectional Reflectors 17 Packaging 18 Conclusion References 2 Electronic Processes at Semiconductor Polymer Heterojunctions (Arne C Morteani, Richard H Friend, and Carlos Silva) 21 Introduction 22 Charge Capture at Polymer Heterojunctions 23 Exciton Dissociation at Polymer Heterojunctions 24 Morphology-dependent Exciton Retrapping at Polymer Heterojunctions 25 Summary Acknowledgments References 3 Photophysics of Luminescent Conjugated Polymers (Dirk Hertel and Heinz Bssler) 31 Introduction 32 Spectroscopy of Singlet States 33 Optically Induced Charge Carrier Generation 34 Triplet States 35 Resum Acknowledgement References 4 Polymer-Based Light-Emitting Diodes (PLEDs) and Displays Fabricated from Arrays of PLEDs (Xiong Gong, Daniel Moses and Alan J Heeger) 41 Introduction 42 LEDs Fabricated from Semiconducting Polymers 43 Accurate Measurement of OLED/PLED Device Parameters 44 Fowler-Nordheim Tunneling in Semiconducting Polymer MIM Diodes 45 Pixilated Displays 46 Thickness Dependence of Electroluminescence Efficiency 47 Limits on the Electroluminescence Efficiency 48 White-light emission 49 Conclusion Note Acknowledgement References 5 Metal/Polymer Interface Studies for Organic Light-Emitting Devices (Man-Keung Fung, Chun-Sing Lee, and Shuit-Tong Lee) 51 Review of Organic Light-Emitting Diodes and their Fundamental Interface Studies 52 Polymer Materials, their Preparations, and Experimental Details 53 Chemistry and Electronic Properties of Metal/F8BT 54 Role of Ytterbium and Ytterbium/Cesium Fluoride on the Chemistry of F8BT 55 Highly Efficient and Substrate-Independent Ytterbium/Cesium Fluoride Cathodes 56 Conclusions Acknowledgements References 6 The Synthesis of Electroluminescent Polymers (Andrew C Grimsdale) 61 Introduction 62 Poly(arylene vinylene)s 63 Poly(arylene ethynylene)s 64 Polyarylenes 65 EL Polymers with Isolated Chromophores 66 Stability of EL Polymers 67 Conclusion References 7 Charge-transporting and Charge-blocking Amorphous Molecular Materials for Organic Light-emitting Diodes (Yasuhiko Shirota) 71 Introduction 72 Amorphous Molecular Materials 73 Requirements for Materials in OLEDs 74 Amorphous Molecular Materials for Use in OLEDs 75 Charge Transport in Amorphous Molecular Materials 76 Outlook References 8 Dendrimer Light-Emitting Diodes (John M Lupton) 81 Introduction 82 The Dendrimer Concept 83 Electroluminescent Dendritic Materials 84 Electronic Properties 85 Dendrimer Devices 86 Dendronized Polymers 87 Conclusions References 9 Crosslinkable Organic Semiconductors for Use in Organic Light-Emitting Diodes (OLEDs) (Klaus Meerholz, Christoph-David Mller, Oskar Nuyken) 91 Introduction 92 Multiple-Layer Deposition 93 Patterning 94 Conclusion and Outlook Acknowledgements References 10 Hybrid OLEDs with Semiconductor Nanocrystals (Andrey L Rogach and John M Lupton) 101 Introduction 102 LEDs in the Visible based on Composites of Semiconductor Nanocrystals and Polymers or Nanocrystals and Small Organic Molecules 103 Near-infrared LEDs based on Composites of Semiconductor Nanocrystals and Polymers or Small Organic Molecules 104 Concluding Remarks References 11 Polymer Electrophosphorescence Devices (Xiaohui Yang and Dieter Neher) 111 Introduction 112 Phosphorescent Dyes 113 Transfer Processes in Polymer Hosts Doped with Phosphorescent Dyes 114 Polymer Phosphorescence Devices based on PVK 115 Phosphorescent Devices with Other Host Polymers 116 Fully Functionalized Polymers 117 Conclusion and Outlook Acknowledgement References 12 Low-threshold Organic Semiconductor Lasers (Daniel Schneider, Uli Lemmer, Wolfgang Kowalsky, Thomas Riedl) 121 Introduction 122 Fundamentals of Organic Semiconductor Lasers 123 Low-threshold Organic Lasing 124 Comparison of Organic Laser Properties 125 Electrically Driven Organic Lasers 126 Summary and Outlook References Subject Index

Metal-Ligand Exchange Kinetics in Platinum and Ruthenium Complexes

Abstract: Since the appearance of the early review on cisdiamminedichloridoplatinum(II), commonly known as cisplatin, 1, in this Journal (1), and its early successes in the treatment of a variety of tumours, the topics of metal-DNA binding and platinum antitumour chemistry have attracted considerable interest from chemists, pharmacologists, biochemists, biologists and medical researchers (2). In fact cisplatin and the later compounds carboplatin, 2, and oxaliplatin, 3, enjoy the status of the world’s best-selling anticancer drugs. This interest has stimulated much interdisciplinary scientific activity, which has already yielded quite detailed understanding of the mechanism of action of cisplatin and related drugs. This knowledge has clearly resulted in much improved clinical administration protocols, as well as motivated research on other, related drugs containing transition metals, and their applications. All chemotherapeutic drugs have drawbacks, including intrinsic or acquired resistance, toxicity, and consequent side effects. Cisplatin is no exception. Efforts to mitigate the drawbacks have prompted chemists to synthesise a variety of analogues, but only a handful of new drugs have resulted that have been shown to be suitable for clinical application. Improved understanding of the mechanism of action of cisplatin, resulting from the efforts of many research groups during the last two decades, has rationalised the design of new platinum drugs, and drugs based on other metals such as ruthenium (3–7). Nevertheless, many mechanistic questions remain, especially for the drugs containing metals other than platinum, and for the most recent derivatives of cisplatin (2, 8, 9).

Catalysis for low temperature fuel cells. Part III: Challenges for the direct methanol fuel cell

Abstract: Two of the most advanced low temperature fuel cells are the proton exchange membrane fuel cell (PEMFC) and the direct methanol fuel cell (DMFC). The DMFC directly consumes liquid fuel (methanol), while the PEMFC is fuelled by hydrogen. Operating a fuel cell with liquid fuel is considered by some to be essential for transport applications ‐ for compatibility with the existing petroleum distribution network. The DMFC also has some system-related advantages over the PEMFC, making it of interest to fuel cell developers. For instance, the DMFC has no need for a fuel processor (or reformer) to convert a liquid hydrocarbon fuel (gasoline) into a consumable source of hydrogen. This considerably reduces the complexity and cost of the system. The DMFC system does not require the complex humidification and heat management hardware modules used in the PEMFC system: the dilute methanol-water mixtures circulating around the DMFC provide the necessary humidification and heat management. If it can meet the performance required of a commercially viable device, the DMFC system will be potentially more cost effective than the PEMFC. Performance has been a major problem for the DMFC: it typically produces only one third of the PEMFC’ s power density. Hence, the DMFC community has made great efforts to bring the performance closer to that of the PEMFC, and particularly to extend the maximum operating temperature. The majority of the work has involved developing materials, such as new anode and cathode electrocatalysts and new proton conducting polymers, to promote the efficiency of the membrane electrode assemblies (MEAs) used in the DMFC stack. Advanced MEA designs have also been developed. Since most effort has been directed towards increasing the efficiency of the MEA components, the DMFC system itself has remained relatively undeveloped compared to the PEMFC ‐ particularly for transport use. However, interest in producing low temperature (< 60o C) ambient-pressure portable DMFC systems has increased recently. This is because the power densities now accessible by state-of-the-art MEAs may be enough for these systems to become competitive with leading secondary battery technologies. This area could thus become a near-term market opportunity for the DMFC, with transport uses being a longer-term goal, if further performance gains can be achieved.

The Role of Platinum in Proton Exchange Membrane Fuel Cells

Abstract: Johnson Matthey, Orchard Road, Royston, Hertfordshire SG8 5HE, UK Email: *oliver.holton@matthey.com; **joe.stevenson@matthey.com Proton exchange membrane fuel cells (PEMFCs) dominate the transportation fuel cell market and platinum (Pt) is the catalyst material used for both anode and cathode. This review sets out the fundamentals of activity, selectivity, stability and poisoning resistance which make Pt or its alloys the best available materials to use in this application. It is clear that Pt is the only element which can meet the requirements for performance while avoiding slow reaction kinetics, proton exchange membrane (PEM) system degradation due to hydrogen peroxide (H2O2) formation and catalyst degradation due to metal leaching. Some of the means by which the performance of Pt can be enhanced are also discussed.