For Pt, the best single-element catalyst for many reactions, the question of content and loading is exceedingly important because of its price and availability. Using platinum as a fuel-cell catalyst in automotive applications will cause an unquantifiable increase in the demand for this metal. This big obstacle for using fuel cells in electric cars must be solved by decreasing the content of Pt, which is a great challenge of electrocatalysis Over the last several years we inaugurated a new class of electrocatalysts for the oxygen reduction reaction (ORR) based on a monolayer of Pt deposited on metal or alloy carbon-supported nanoparticles. The possibility of decreasing the Pt content in the ORR catalysts down to a monolayer level has a considerable importance because this reaction requires high loadings due to its slow kinetics. The Pt-monolayer approach has several unique features and some of them are: high Pt utilization, enhanced (or decreased) activity, enhanced stability, and direct activity correlations. The synthesis of Pt monolayer (ML) electrocatalysts was facilitated by our new synthesis method which allowed us to deposit a monolayer of Pt on various metals, or alloy nanoparticles [1, 2] for the cathode electrocatalyst. In this synthesis approach Pt is laid down by the galvanically displacing a Cu monolayer, which was deposited at underpotentials in a monolayer-limited reaction on appropriate metal substrate, with Pt after immersing the electrode in a K2PtCl4 solution.

This book describes a science and technology of a new type of electrocatalysts consisting of a single atomic layer of platinum on suitable supports. This development helped overcome three major obstacles—catalysts‘ cost, activity, and stability—for a broad range of fuel cell applications. The volume begins with a short introduction to the science of electrocatalysis, covering four reactions important for energy conversion in fuel cells. A description follows of the properties of metal monolayers on electrode surfaces, and underpotential deposition of metals. The authors then describe the concept of Pt monolayer electrocatalysts and its implications and their synthesis by galvanic displacement of less-noble metal monolayers and other methods. The main part of the book presents a discussion of catalysts’ characterization and catalytic properties of Pt monolayers for the four main reactions of electrochemical energy conversion: oxygen reduction and oxidation of hydrogen, methanol and ethanol. The book concludes with a treatment of scale-up syntheses, fuel cell tests, catalysts’ stability and application prospects.

Due to their unique size-dependent physicochemical properties, nanostructured thin films are used in a wide range of applications from smart coating and drug delivery to electrocatalysis and highly-sensitive sensors. Depending on the targeted application and the deposition technique, these materials have been designed and developed by tuning their atomic-molecular 2D- and/or 3D-aggregation, thickness, crystallinity, and porosity, having effects on their optical, mechanical, catalytic, and conductive properties. Several open questions remain about the impact of nanomaterial production and use on environment and health. Many efforts are currently being made not only to prevent nanotechnologies and nanomaterials from contributing to environmental pollution but also to design nanomaterials to support, control, and protect the environment. This Special Issue aims to cover the recent advances in designing nanostructured films focusing on environmental issues related to their fabrication processes (e.g., low power and low cost technologies, the use of environmentally friendly solvents), their precursors (e.g., waste-recycled, bio-based, biodegradable, and natural materials), their applications (e.g., controlled release of chemicals, mimicking of natural processes, and clean energy conversion and storage), and their use in monitoring environment pollution (e.g., sensors optically- or electrically-sensitive to pollutants)

Rotating Electrode Methods and Oxygen Reduction Electrocatalysts provides the latest information and methodologies of rotating disk electrode and rotating ring-disk electrode (RDE/RRDE) and oxygen reduction reaction (ORR). It is an ideal reference for undergraduate and graduate students, scientists, and engineers who work in the areas of energy, electrochemistry science and technology, fuel cells, and other electrochemical systems. Presents a comprehensive description, from fundamentals to applications, of catalyzed oxygen reduction reaction and its mechanisms Portrays a complete description of the RDE (Rotating Disc Electrode)/RRDE (Rotating Ring-Disc Electrode) techniques and their use in evaluating ORR (Oxygen Reduction Reaction) catalysts Provides working examples along with figures, tables, photos and a comprehensive list of references to help understanding of the principles involved

Understanding oxidation/dissolution mechanisms of Pt is critical in designing durable catalysts for the oxygen reduction reaction (ORR), but exact mechanisms remain unclear. Our present work explores the oxidation/dissolution of Pt and Pt monolayer (ML) electrocatalysts over a wide range of applied potentials using cells that facilitate in situ measurements by combining X-ray absorption spectroscopy (XAS) and X-ray diffraction (XRD) measurements. Furthermore, the X-ray absorption near edge structure (XANES) measurement demonstrated that Pt nanoparticle surfaces were oxidized from metallic Pt to [alpha]-PtO2-type oxide during the potential sweep from 0.41 to 1.5 V, and the transition state of O or OH adsorption on Pt and the onset of the place exchange process were revealed by the delta mu ([Delta][mu]) method. Only the top layers of Pt nanoparticles were oxidized, while the inner Pt atoms remained intact. At a higher potential over 1.9 V, [alpha]-PtO2-type surface oxides dissolve due to local acidification caused by the oxygen evolution reaction and carbon corrosion. Pt oxidation of PtML on the Pd nanoparticle electrocatalyst is considerably hampered compared with the Pt/C catalyst, presumably because preferential Pd oxidation proceeds at the defects in Pt MLs up to 0.91 V and through O penetrated through the Pt MLs by the place exchange process above 1.11 V.