Fully ordered face-centered tetragonal (fct) FePt nanoparticles (NPs) are synthesized by thermal annealing of the MgO-coated dumbbell-like FePt-Fe3O4 NPs followed by acid washing to remove MgO. These fct-FePt NPs show strong ferromagnetism with room temperature coercivity reaching 33 kOe. They serve as a robust electrocatalyst for the oxygen reduction reaction (ORR) in 0.1 M HClO4 and hydrogen evolution reaction (HER) in 0.5 M H2SO4 with much enhanced activity (the most active fct-structured alloy NP catalyst ever reported) and stability (no obvious Fe loss and NP degradation after 20 000 cycles between 0.6 and 1.0 V (vs RHE)). Our work demonstrates a reliable approach to FePt NPs with much improved fct-ordering and catalytic efficiency for ORR and HER.

Lithium-ion batteries are widely used throughout the world for portable electronic devices and mobile phones and show great potential for more demanding applications like electric vehicles. Unfortunately, lithium-ion batteries still lack the required level of energy storage to completely meet the demands of such applications as electric vehicles. Among advanced materials being studied, silicon nanoparticles have demonstrated great potential as an anode material to replace the commonly used graphite. Silicon has been shown to have a high theoretical gravimetric capacity, approximately 4200 mAh/g, compared to only 372 mAh/g for graphite. Though silicon nanoparticles have remarkably high capacity, they suffer from rapid degradation with each cycle due to electrode volume expansion of approximately 400% during lithiation, placing a large strain on the material. With each cycle that strain creates cracks in the electrode particles and causes them to break down into smaller particles, which create void spaces between the particles and lead to poor contact as reflected in poor conductivity. In this review, we discuss exciting new research on silicon-based anodes conducted during the past couple of years. Besides stressing the importance of well-designed nanostructures of Si, we focus on optimization of the Si electrode and resulting performance enhancement by properly selecting binders and synergistically integrating them with various carbon materials during electrode design and fabrication. Importantly, although each improvement strategy has its own advantage, appropriate combination of them will yield much higher anode performance. We summarize the core issues in developing the silicon anode and effective strategies in yielding more promising results. 3 Content: 1. Introduction crystallinity of Si after cycling. (g) Initial cycling behaviors of Si particles in different conductive matrixes against lithium metal counter electrodes at C/10 rate. Reprinted with permission from Ref. [50]. Copyright 2011, Wiley-VCH.. directly on the current collector, which do not pulverize or break into smaller particles after cycling. Rather, facile strain relaxation in the nanowires allows them to increase in diameter without breaking. (c) Voltage profiles for the Si nanowires cycled at different currents. (d) Capacity versus cycle number for the Si nanowires at the C/20 rate. (e and f) SEM image of pristine Si nanowires before (e) and after (f) electrochemical cycling. Reprinted with permission from Ref. [31, 66].

5799wileyonlinelibrary.com issues associated with energy security and environmental pollution. [1][2][3][4][5] Oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER) are the most crucial electrochemical reactions to realize energy storage and conversion in these technologies. Although Pt-, Ir-, and Ru-based materials exhibit the highest activity for these electrochemical reactions, these precious-metal catalysts cannot be largely used for these clean energy because of their scarcity on earth and high cost. [ 6,7 ] Therefore, high-active, low-cost, and durable precious-metalfree catalysts from earth-abundant elements have been attracted considerable attention since last decade. [8][9][10][11] Among studied nonprecious metal catalysts, [ 12 ] nickel and cobalt are earth-abundant, low-cost, and environment-friendly materials that have widely been explored as electrocatalysts for the oxygen or hydrogen reactions in energy conversion and storage devices. [13][14][15] However, the pure cobalt and nickel oxides usually show insuffi cient electrical conductivity and low reactive surface areas, resulting in limited kinetics during these electrochemical reactions such as ORR, OER. [ 16 ] Oppositely, standalone metallic Ni or Co has good electrical conductivity, but is less active than Pt, because the formation energies of Ni-H or Co-H is lower than that of Pt-H for the HER. [ 17 ] Furthermore, combining graphene with metal or metal oxide is an effective way to improve catalytic activities due to the high surface area and excellent electrical conductivity of graphene, [18][19][20] thereby increasing number of active sites and promoting the charge transfer in electrodes. [21][22][23] For example, Co 3 O 4 /graphene, [ 24 ] Ni/graphene fi lm, [ 25 ] and NiO/rGO [ 26 ] composite catalysts have been explored showing enhanced catalytic activity, relative to single metals or metal oxides. Based on previous studies on the nickel or cobalt electrocatalysts, in this work, we synthesized a new family catalyst including Co-CoO/N-rGO and Ni-NiO/N-rGO via a pyrolysis of graphene oxide-supported cobalt and nickel salts, respectively. The possible synergetic effect among transition metals, metal oxides, and graphene was systematically studied, making them simultaneously highly active for the OER, ORR, or HER. Metal (Ni, Co)-Metal Oxides/Graphene Nanocomposites as Multifunctional ElectrocatalystsXien Liu , Wen Liu , Minseong Ko , Minjoon Park , Min Gyu Kim , Pilgun Oh , Sujong Chae , Suhyeon Park , Anix Casimir , Gang Wu , * and

This review focuses on recent developments in the last three years of various sulfur integration methods in lithium-sulfur batteries.