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High-voltage LiNi0.5Mn1.5O4 with a spinel structure is considered as important cathode materials for high-energy density Li-ion batteries (LIBs). In this study, we investigate the size, structure, and the electrochemical performance of LiNi0.5Mn1.5O4 electrodes prepared by using two different-sized Mn3O4 nanocrystal precursors under different calcination conditions. As the calcination temperature rises, the particle sizes of the acquired LiNi0.5Mn1.5O4 cathode materials can vary from ~ 100 nm to ~ 1 µm, and the morphology changes from nano round shape to truncated octahedral shape. The content of Mn3+ is closely related to the calcination temperature and is affected by the size of Mn precursor. It is found that the LiNi0.5Mn1.5O4 sample prepared by using 50-nm-sized Mn3O4 nanocrystals under a calcination temperature of 800 C exhibits good cycling performance with a capacity retention ratio of 96.1% at 1 C after 200 cycles, while the LiNi0.5Mn1.5O4 sample prepared by using 7-nm-sized Mn3O4 nanocrystals under a calcination temperature of 800 °C shows an excellent rate performance with a capacity retention ratio of 98% after 500 cycles at 10 C. The results show that the size of Mn3O4 precursor is an important parameter that governs the final size and electrochemical performances of LiNi0.5Mn1.5O4 cathode materials. [ABSTRACT FROM AUTHOR]

Rechargeable Li–CO2 batteries contribute towards lessening fossil fuel depletion and alleviating the "greenhouse effect". However, more efforts must be made to figure out the critical problems of a high overpotential and poor cycling stability associated with this type of battery. Here, CoSnO3/RuO2−x nanocomposites were employed as an efficient air cathode for Li–CO2 batteries, which can lower the overpotential and improve their long-term cycling performance (around 145 cycles) remarkably. [ABSTRACT FROM AUTHOR]

Exploring robust and low-cost noble-metal-free co-catalysts to substitute precious noble-metal is of great importance in both fundamental research and practical applications. Herein, we employ a novel solution-phase method to synthesize highly monodisperse zero-dimensional (0D) nickel phosphide (Ni 2 P) nanoparticles, which were then anchored on two-dimensional (2D) porous g-C 3 N 4 nanosheets via a facile self-assembly route to develop the intimate 0D-2D heterojunction interface. The outstanding feature of the material is that the resultant hybrid nanocomposite exemplified efficient noble-metal-free photocatalytic H 2 production under visible light. Under optimal conditions, the Ni 2 P embedding was found to be 3.5 wt%, giving a remarkable H 2 production rate of 474.7 μmol g −1 h −1 and an apparent quantum yield (AQY) of 3.2% at 435 nm, surpassing most of the reported noble-metal-free co-catalysts-modified g-C 3 N 4 photocatalysts. The superior photoactivity of the hybrid nanostructure is attributed to the profound role of Ni 2 P as an excellent reduction co-catalyst to hamper the recombination of charge carriers from g-C 3 N 4 and also provide good electrical conductivity, which could be substantiated by photoelectrochemical (PEC) experiments, photoluminescence (PL) spectra, and electron paramagnetic resonance (EPR) spectroscopic studies. Benefitting from the intriguing properties of Ni 2 P and g-C 3 N 4 , this work presents a new platform to uncover the immense potential of noble-metal-free nanomaterials as the next generation photocatalysts in multifunctional application prospects not only in the water splitting reaction, but also in other energy-related fields such as CO 2 reduction and solar cells. It is also anticipated that the solution-phase hybridization technique could be extended to synergistically integrate g-C 3 N 4 with a myriad of nanocrystals for multitudinous chemical reactions. [ABSTRACT FROM AUTHOR]

Owing to their high energy density, lithium-oxygen batteries (LOBs) have been drawn great attention as one of the promising electrochemical energy sources. However, the sluggish kinetics of oxygen reduction/evolution reaction (ORR/OER) hamper the widespread application of LOBs. Herein, an elaborate designed catalysts which are constructed by FeN x moieties dispersed on the network-like hollow dodecahedral carbon and then decorated with Ru nanoparticles (FeN x -HDC@Ru). Since the homogeneously dispersed FeN x moieties could promote ORR performance, and the Ru nanoparticles could facilitate OER capability, the FeN x -HDC@Ru nanocomposites used as cathode catalysts can significantly improve LOBs performance. A lower discharge and charge overpotentials of 0.15 V and 0.78 V can be detected in the first cycle, respectively, and an excellent cycle performance of 90 cycles at 200 mA g -1 and 89 cycles at 500 mA g -1 can be demonstrated. Herein, the charge transfer kinetics has been enhanced with the internal network-like hollow structure and a low impedance Li 2 O 2 /catalysts contact interface could be earned by the constructed Ru nanoparticles, these factors would lead to an efficient acceleration to the formation and decomposition of Li 2 O 2 during discharge and charge process., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier Inc. All rights reserved.)