We report a facile strategy to synthesize the nanocomposite of Co3O4 nanoparticles anchored on conducting graphene as an advanced anode material for high-performance lithium-ion batteries. The Co3O4 nanoparticles obtained are 10−30 nm in size and homogeneously anchor on graphene sheets as spacers to keep the neighboring sheets separated. This Co3O4/graphene nanocomposite displays superior Li-battery performance with large reversible capacity, excellent cyclic performance, and good rate capability, highlighting the importance of the anchoring of nanoparticles on graphene sheets for maximum utilization of electrochemically active Co3O4 nanoparticles and graphene for energy storage applications in high-performance lithium-ion batteries.

We developed two-step solution-phase reactions to form hybrid materials of Mn 3 O 4 nanoparticles on reduced graphene oxide (RGO) sheets for lithium ion battery applications. Mn 3 O 4 nanoparticles grown selectively on RGO sheets over free particle growth in solution allowed for the electrically insulating Mn 3 O 4 nanoparticles wired up to a current collector through the underlying conducting graphene network. The Mn 3 O 4 nanoparticles formed on RGO show a high specific capacity up to ~900mAh/g near its theoretical capacity with good rate capability and cycling stability, owing to the intimate interactions between the graphene substrates and the Mn 3 O 4 nanoparticles grown atop. The Mn 3 O 4 /RGO hybrid could be a promising candidate material for high-capacity, low-cost, and environmentally friendly anode for lithium ion batteries. Our growth-on-graphene approach should offer a new technique for design and synthesis of battery electrodes based on highly insulating materials.

Flexible electrochemical energy storage (FEES) devices have received great attention as a promising power source for the emerging field of flexible and wearable electronic devices. Carbon nanotubes (CNTs) and graphene have many excellent properties that make them ideally suited for use in FEES devices. A brief definition of FEES devices is provided, followed by a detailed overview of various structural models for achieving different FEES devices. The latest research developments on the use of CNTs and graphene in FEES devices are summarized. Finally, future prospects and important research directions in the areas of CNT- and graphene-based flexible electrode synthesis and device integration are discussed.

Self-trapped excitons (STEs) in metal halide materials are attracting an increasing level of interest due to their unique light emission properties. Light emission from STEs in metal halides is usually associated with excited-state structural deformation, which lowers the symmetry of local structures, as seen for the STEs in a wide range of materials systems. Here, we reveal a prototypic STE-associated structural “distortion” that, however, enhances the symmetry of local structures, in a series of all-inorganic copper­(I)-based halides Cs3Cu2X5 (X = Cl, Br, or I). We further find that the emission peaks of Cs3Cu2X5 blue-shift when the halogen changes from Cl to Br to I, which is the opposite of the trends found in traditional halide perovskites. This phenomenon is attributed to a synergetic combination of the significant change in band gap associated with structural deformation and a strong excitonic effect. Due to the highly localized electron and hole upon photoexcitation, Cs3Cu2Cl5 shows an extremely long and temperature-sensitive photoluminescence (PL) lifetime among metal halide materials with STEs. Remarkably, strong green emission with a PL quantum yield exceeding 90% is found in Cs3Cu2Cl5, opening the way to designing light emission compounds based on local symmetry-enhancing STE mechanisms.

Structurally ordered intermetallic phases have exhibited higher and higher electrocatalytic activity and stability than disordered alloys in many reactions such as the oxygen reduction reaction (ORR) and small-molecule (hydrogen, formic acid, or ethanol) oxidation reactions. The enhanced electrocatalytic activity could be derived from the definite composition and predictable control over structural, geometric, and electronic effects. This review, based on the understanding of the catalytic mechanism of structurally ordered intermetallic nanoparticles, provides a comprehensive acknowledgment of how the particle size and morphology affect the catalytic performance. The strategy for reducing particle size and the impact of particle size on electrocatalysis will be first introduced. Then, recent developments in the synthesis and design of morphology-controlled catalysts are summarized. The structure−activity relationship between the catalytic activity and morphology including core−shell/hollow and porosity will be highlighted. Finally, the current challenges and future developments are provided. On the basis of this review, intermetallic nanoparticles will shed light on the future development of electrocatalysts for fuel cells and metal-air batteries.