Developing low-cost, highly active, and stable bifunctional electrocatalysts is a challenging issue in electrochemical water electrolysis. Building on 3D architectured electrocatalysts through structural and compositional engineering is an effective strategy to enhance catalytic activities as well as stability and durability. Herein, 3D architectures of quaternary Co-Ni-S-P compounds coupled with graphene ((Co 1−x Ni x )(S 1−y P y ) 2 /G) electrocatalysts are proposed, in which nanosheets are self-assembled to form 3D architectures with round and flat doughnut-like shapes, toward overall water splitting. Benefiting from the 3D architectures and Ni, P substitution, (Co 1−x Ni x )(S 1−y P y ) 2 /G exhibits superior electrocatalytic activities with low overpotentials of 117 and 285 mV at 10 mA cm −2 and Tafel slopes of 85 and 105 mV dec −1 for hydrogen and oxygen evolution reactions, respectively, in alkaline media. In addition, minimal increases in overpotential are observed, even after the 10 000th voltammetric cycle and continuous chronopotentiometric testing over 50-100 h, confirming the high stability and durability of (Co 1−x Ni x )(S 1−y P y ) 2 /G. When used as both cathode and anode, (Co 1−x Ni x )(S 1−y P y ) 2 /G achieves excellent overall water splitting performance with a cell potential as low as 1.65 V, reaching a current density of 10 mA cm −2 with no obvious decay after 50 h, demonstrating that (Co 1−x Ni x )(S 1−y P y ) 2 /G is an efficient bifunctional electrocatalyst for overall water splitting.

With the development of nanotechnology, myriad types of novel materials have been discovered at the nanoscale, among which the most interesting material is graphene. However, the toxicity data available on graphene are extremely limited. In this study, we explored toxic response of commercially available graphene nanoplatelets (GNPs) in vivo and in vitro. The GNPs used in this study had a high surface area and feature considerably few defects. In mice, GNPs (2.5 and 5 mg/kg) remained in the lung until 28 days after a single instillation, and the secretion of inflammatory cytokines reached the maximal level at Day 14 and then decreased over time. In vitro study using BEAS-2B cells, a human bronchial epithelial cell line, GNPs located within autophagosome-like vacuoles 24 h after exposure. The GNPs (2.5, 5, 10, and 20 μg/mL) also dose-dependently reduced cell viability, which was accompanied by an increase in the portion of cells in the subG1 and S phases. Moreover, the GNPs down-regulated the generation of reactive oxygen species, suppressed ATP production, caused mitochondria damage, and elevated the levels of autophagy-related proteins. Based on these results, we suggest that GNPs provoked a subchronic inflammatory response in mice and that GNPs induced autophagy accompanying apoptosis via mitochondria damage in vitro.

Lithium−oxygen batteries have been considerably researched due to their potential for high energy density compared to some rechargeable batteries. However, it is known that the stability of a carbon-based oxygen electrode is insufficient owing to the promotion of carbonate formation, which results in capacity fading and large overpotential in lithium−oxygen batteries. To improve the chemical stability in organic-based electrolytes, alternative electrocatalyst support materials are required. The Ti− O crystal system appears to provide a good compromise between electrochemical performance and cost and is thus an interesting material for further investigation. Here, we investigate a carbon-free electrode with the goal of identifying routes for its successful optimization. To replace carbon materials as an electrocatalyst support, Magneĺi Ti 4 O 7 nanospheres were synthesized from anatase TiO 2 nanospheres via a controlled thermochemical reduction. The Magneĺi Ti 4 O 7 nanospheres demonstrated effective overpotential characteristics (1.53 V) compared to the anatase TiO 2 nanospheres (1.91 V) during charge−discharge cycling at a current rate of 100 mA g −1 . Additionally, RuO 2 @Magneĺi-Ti 4 O 7 nanospheres were prepared as a bifunctional catalyst-containing oxygen electrode for lithium−oxygen batteries, providing a remarkably reduced overpotential (0.9 V). KEYWORDS: Magneĺi phase, carbon-free, Ti 4 O 7 , RuO 2 , Li−O 2 batteries

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We herein present the synthesis of germanium (Ge) nanowires on Au-catalyzed low-temperature substrates using a simple thermal Ge/Sn co-evaporation method. Incorporation of a low-melting point metal (Sn) enables the efficient delivery of Ge vapor to the substrate, even at a source temperature below 600 °C. The as-synthesized nanowires were found to be a core/shell heterostructure, exhibiting a uniform single crystalline Ge sheathed within a thin amorphous germanium suboxide (GeO(x)) layer. Furthermore, these high-density Ge nanowires grown directly on metal current collectors can offer good electrical connection and easy strain relaxation due to huge volume expansion during Li ion insertion/extraction. Therefore, the self-supported Ge nanowire electrodes provided excellent large capacity with little fading upon cycling (a capacity of ∼900 mA h g(-1) at 1C rate).

Phase-pure urchin-like rutile TiO 2 (U-TiO 2 ) submicron (<1 mm) spheres composed of numerous single-crystalline nanorods are successfully synthesized using a surfactant-free wet-chemical route. In addition, a reliable mechanism for the formation of U-TiO 2 , different from the well-known ''growth-then-assembly'' mode, is suggested. To provide a highly electron-conducting network, the U-TiO 2 submicron spheres are nanopainted with a conductive amorphous carbon layer. As anodes for Li-ion batteries, the carbon-coated U-TiO 2 submicron sphere electrodes show enhanced cycling performance, maintaining a reversible capacity of 165.7 mA h g À1 after 100 cycles at a rate of 0.2 C; this is attributed to the provision of an efficient electron-transport path by the conductive carbon.

Template-driven strategy has been widely used to synthesize inorganic nano/micro materials. Here, we used a bottom-up controlled synthesis route to develop a powerful solution-based method of fabricating three-dimensional (3D), hierarchical, porous-Co3O4 superstructures that exhibit the morphology of flower-like microspheres (hereafter, RT-Co3O4). The gram-scale RT-Co3O4 was facilely prepared using one-pot synthesis with bacterial templating at room temperature. Large-surface-area RT-Co3O4 also has a noticeable pseudocapacitive performance because of its high mass loading per area (~10 mg cm−2), indicating a high capacitance of 214 F g−1 (2.04 F cm−2) at 2 A g−1 (19.02 mA cm−2), a Coulombic efficiency averaging over 95%, and an excellent cycling stability that shows a capacitance retention of about 95% after 4,000 cycles.

With the rapid development of the nano-industry, concerns about their potential adverse health effects have been raised. Thus, ranking accurately their toxicity and prioritizing for in vivo testing through in vitro toxicity test is needed. In this study, we used three types of synthesized aluminum oxide nanoparticles (AlONPs): γ-aluminum oxide hydroxide nanoparticles (γ-AlOHNPs), γ-and α-AlONPs. All three AlONPs were spherical, and the surface area was the greatest for γ-AlONPs, followed by the α-AlONPs and γ-AlOHNPs. In mice, γ-AlOHNPs accumulated the most 24 h after a single oral dose. Additionally, the decreased number of white blood cells (WBC), the increased ratio of neutrophils and the enhanced secretion of interleukin (IL)-8 were observed in the blood of mice dosed with γ-AlOHNPs (10 mg kg À1 ). We also compared their toxicity using four different in vitro test methods using six cell lines, which were derived from their potential target organs, BEAS-2B (lung), Chang (liver), HACAT (skin), H9C2 (heart), T98G (brain) and HEK-293 (kidney). The results showed γ-AlOHNPs induced the greatest toxicity. Moreover, separation of particles was observed in a transmission electron microscope (TEM) image of cells treated with γ-AlOHNPs, but not γ-AlONPs or α-AlONPs. In conclusion, our results suggest that the accumulation and toxicity of AlONPs are stronger in γ-AlOHNPs compared with γ-AlONPs and α-AlONPs owing their low stability within biological system, and the presence of hydroxyl group may be an important factor in determining the distribution and toxicity of spherical AlONPs.