The large-scale extraction of minerals generates substantial amounts of tailings, which are often discarded despite containing valuable metal oxides such as iron, titanium, and aluminum. Among them, iron oxide holds strong potential as an active material for energy storage devices. In this study, iron oxide (alpha-Fe2O3) was recovered from Korean vanadium tailings and modified via planetary milling and nitrogen thermal treatment to tune its valence state (Fe2+/Fe3+) and defect structure, particularly oxygen vacancies. The thermally treated Fe2O3-PM12-300 sample exhibited an increased Fe2+/Fe3+ ratio and higher oxygen vacancy concentration, resulting in enhanced electrochemical performance. In lithium-ion batteries (LIBs), it achieved high-capacity retention (81.2 % over 100 cycles) and improved rate capability. In lithium-oxygen batteries (LOBs), the material maintained a discharge voltage of 2.71 V and an OER charge voltage below 4.0 V over multiple cycles, demonstrating superior discharge-charge efficiency. This work presents a sustainable approach for converting mining waste into functional electrode materials through defect engineering. The study demonstrates that by tailoring defects in alpha-Fe2O3, its performance in both LIBs and LOBs can be enhanced, indicating its relevance for next-generation, environmentally considerate storage solutions.

Ruthenium phosphide is a promising catalyst for hydrogen evolution due to its cost-effectiveness compared to platinum. However it faces the challenge of having a high binding energy for hydrogen intermediates. In this study, we demonstrate that the incorporation of iridium in ruthenium phosphides lowers the binding energy of hydrogen intermediates, thereby controlling the overpotential and Tafel slope of hydrogen evolution. When the Ir content was doped at 3 at.%, the catalyst achieved an overpotential of 33 mV and a Tafel slope of 33 mV dec-1 under acidic conditions, which are similar to those of the benchmark Pt/C catalyst. In situ Raman spectroscopy and density functional theory (DFT) calculations suggest that the enhanced catalytic activity originates from the near-neutral Gibbs free energy of hydrogen adsorption on the hollow site of the iridium cluster implanted onto ruthenium phosphide.

For green-hydrogen production through a promising electrolytic water splitting, cobalt phosphide is in the spotlight as one of the new affordable materials to replace currently used noble-metal catalysts. In this study, we fabricate hollow cobalt phosphide (CoP) nanofibers with advanced nanostructure using electrospinning and phosphidation. Due to their unique architecture and oxygen-rich surface characteristics, the novel hollow-structure CoP nanofibers effectively increase hydrogen evolution reaction catalytic activity with the low overpotentials of 91 mV (for acid) and 63 mV (for alkaline). Using in situ Raman spectroscopy, it is confirmed that high-oxygen-containing CoP catalysts could transform the CoOOH phase under alkaline conditions, which offer faster water dissociation kinetics. Furthermore, CoP nanofibers exhibited excellent durability even after 30000th accelerated degradation test cycles and overall water splitting for 40 h.

The development of advanced electrodes with highly active electrocatalysts and appropriate structures is essential for sustainable hydrogen production via water electrolysis. Moreover, there is significant demand for an affordable electrocatalyst that exhibits comparable activity to that of Pt. Herein, we report Ru2P nanofibers (NFs) as an efficient electrode material for a high-performance anion exchange membrane water electrolyzer (AEMWE). The electrospinning method enables the formation of a porous catalyst layer that comprises tangled NFs, which exhibit a three-dimensional structure with abundant empty space. In a half cell test, the Ru2P NFs exhibit a high catalytic activity for the hydrogen evolution reaction, which is comparable to the activity of a commercial Pt/C. In a single cell test, an AEMWE with Ru2P NFs demonstrates a higher performance than that with a commercial Pt/C, especially in the high current density region; this is attributed to the structural advantage of the porous catalyst layer, which enhances the mass transfer of the reactant, as well as the product.

In this study, we developed iron sulfide (Fe7S8) hollow mesocrystals (HMs) for sodium-ion battery application using silk fibroin-derived iron oxide (Fe2O3) via a simple sulfidation process. The Fe7S8HM electrodes exhibited a high specific capacity of 654 mA h g(-1)at the current density of 0.5 A g(-1)over the potential window of 0.01 to 3 V during the first cycle. However, rapid capacity decay was observed during 200 cycles. Thus, to improve the cycling stability, we performed additional electrochemical measurements with a limited potential window of 0.4 to 3 V. The specific capacity of the Fe7S8HM electrodes decreased slightly to 530 mA h g(-1)over the potential window of 0.4 to 3 V. The Fe7S8HM electrodes showed excellent cycle stability with 84% retention over 300 cycles. The Fe7S8HMs exhibited excellent Na storage performance and sufficient void space, which effectively suppressed their large volume changes by the synergetic effect with the tuned voltage window.

Alkaline water electrolysis represents one of the most promising technologies for the development of environment-friendly energy cycles. Ruthenium phosphide electrocatalysts are attractive candidates for this process, and they recently showed high electrocatalytic activity for the hydrogen evolution reaction (HER) in alkaline conditions, which is even higher than that in acidic conditions; however, the origin of their activity has not been addressed to date. Here, we demonstrate that hydroxylated Ru species reconstructed by HER in a basic electrolyte are the key active sites for alkaline HER based on an in-depth X-ray photoelectron spectroscopic study. Ru phosphides with a higher Ru/P ratio in their bulk composition possess a higher ratio of hydroxylated Ru on their surface region of several nanometers with less P sites exposed, which determines the HER activity in alkaline conditions. The Ru phosphide nanofiber electrocatalysts presented here enabled almost zero overpotentials for alkaline HER with stable performance for 320 h. This work provides a deeper understanding of the origin of high HER activity in alkaline conditions.

Si is regarded as the most promising anode material for lithium-ion batteries owing to its high theoretical capacity and low working voltage. Waste glass microfiber filters (GFs) can be an optimal silica resource for nanostructured Si synthesis because they do not require crushing or acid leaching procedures, which are essential for other silica resources. In this study, benefiting from the original filter shape, fibrous yolk-shell structured Si/carbon composite freestanding electrodes are fabricated via magnesiothermic reduction (MgR) and carbon coating processes using GFs not only as the silica precursor for MgR but also as the hard template for carbon coating. The carbon shell acts as a conductive framework for the freestanding electrodes and encapsulates the Si nanoparticles (Si NPs) inside the shell with a void space. The freestanding electrodes exhibit good cycling performance and a high areal capacity of 2.2 mA h cm(-2) at the 150th cycle because of the yolk-shell structure, which accommodates the volume expansion of the Si NPs.

For the application of electric-powered vehicles, low-cost ZnCo2O4 nanofibers with large active sites and efficient electron pathways exhibit exceptional electrocatalytic activity and cycle stability as lithium-oxygen battery electrodes. This is reported by Dong-Wan Kim and co-workers in article number 1701234.

In article number 1801284, Dong-Wan Kim and co-workers propose the facile synthesis of a three-dimensional flower-like CoxP/carbon architecture composed of an assembly of nanosheets using silk fibroin as scaffolds, which enhances catalytic activity for hydrogen generation by exposing more active sites and increasing charge transport along with a high stability even after 10 000 CV cycles and a chronoamperometric test over 40 h.

Silicon has emerged as the most promising high-capacity material for lithium-ion batteries. Waste glass can be a potential low cost and environmentally benign silica resource enabling production of nanosized silicon at the industry level. Windshields are generally made of laminated glass comprising two separate glass bonded together with a layer of polyvinyl butyral sandwiched between them. Herein, silicon/carbon nanocomposites are fabricated from windshields for the first time via magnesiothermic reduction and facile carbonization process using both waste glass and polyvinyl butyral as silica and carbon sources, respectively. High purity reduced silicon has unique 3-dimensional nanostructure with large surface area. Furthermore, the incorporation of carbon in silicon enable to retain the composite anodes highly conductive and mechanically robust, thus providing enhanced cycle stability.

The use of non-noble metal-based electrocatalysts to achieve highly efficient and cost-effective water splitting has encountered major challenges, particularly with respect to catalytic activity, stability, cost, and ease of manufacture. Herein, few carbon-layers-encapsulated NiFe nanoparticles (NiFe@C) were prepared as a simple and effective facile top-down approach when used with the electrical explosion of wire process as a bifunctional electrocatalyst to achieve higher overall water splitting efficiency. Uniformly surrounding the unique structure of NiFe nanoparticles (similar to 15 nm in diameter) by a small number of carbon layers can be accomplished via one-pot synthesis by exploding NiFe wires in an ethanol media. The simply prepared NiFe@C catalyst exhibits remarkable catalytic activity and stability in alkaline solution for both OER (oxygen evolution reaction) and HER (hydrogen evolution reaction). When bifunctional electrocatalysts are utilized as electrodes for both cathode and anode reactions in a single electrolyzer, outstanding catalytic performance was achieved with an operational voltage of 1.575 V at a current density of 10 mA cm(-2). Most importantly, the electrodes displayed superior catalytic stability in the overall water splitting reaction for 200 h. Consequently, this work proposes and evaluates this effective new strategy for the synthesis of low-cost, highly efficient and stable bifunctional electrocatalysts. (C) 2018 Elsevier Inc. All rights reserved.

Water-stable Mo/MoO2 nanoink is applied directly to a fabrication of flexible anodes with textural features for high-performance Li ion batteries.Image 1

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, Magneli Ti4O7 nanospheres were synthesized from anatase TiO2 nanospheres via a controlled thermochemical reduction. The Magneli Ti4O7 nanospheres demonstrated effective overpotential...

Hybridized 1D/2D CuGeO3/graphene composites are applied as the oxygen–electrode electrocatalysts for Li–O2 batteries. The CuGeO3/graphene composites are synthesized by the crystallographic alignment of CuGeO3 nanowires on graphene, rendering strong heteroepitaxial coupling between the 1D oxide nanostructures and the 2D electrically conducting graphene. The inherited excellent electrocatalytic activity of the CuGeO3/graphene composites leads to lower overpotentials and more stable cycling performance of Li–O2 cells than CuGeO3 nanowires and graphene. The relationships between CuGeO3 nanowires and graphene are studied for the oxygen reduction and oxygen evolution activity in both aqueous and nonaqueous solutions, and the electrocatalytic activity is improved by manipulating the redox pair and sp3/sp2 via surface chemical modification.

Lithium-oxygen batteries are considered a next-generation technology owing to their extremely high theoretical energy density despite many challenges such as low round-trip efficiency and poor cyclability. The air-cathode structure and pore properties play a key role in solving these problems. In this study, we fabricate ZnCo2O4 nanofibers and design a porous nanostructure using a facile electrospinning process and selective etching of ZnO as the cathode material in lithium-oxygen batteries. First, non-porous ZnCo2O4 nanofiber electrodes accomplish high catalytic activity and good cycling stability during 116 cycles with a limited capacity of 1000 mA h g(-1) at a current density of 500 mA g(-1). For enhanced catalytic activity and cyclability, ZnO included ZnCo2O4 nanofibers are prepared using a Zn-excess electrospun solution and porous ZnCo2O4 nanofibers are fabricated via selective etching of ZnO. Porous ZnCo2O4 nanofiber electrodes exhibit excellent electrocatalytic activity and cyclability for 226 cycles with a limited capacity of 1000 mA h g(-1) at a current density of 500 mA g(-1). The exceptional catalytic properties explain the synergistic effect of the one-dimensional nanostructure and porous structure with an appropriate pore diameter, providing a large active site and an efficient electron pathway during the Li2O2 formation/decomposition process.

Developing nonprecious, highly active, and stable catalysts is essential for efficient electrocatalytic hydrogen evolution reaction in water splitting. In this study, the facile synthesis of a 3D flower-like Cox P/carbon architecture is proposed composed of an assembly of nanosheets interconnected by silk fibroin that acts as 3D scaffolds and a carbon source. This unique 3D architecture coupled with a carbon matrix enhances catalytic activity by exposing more active sites and increasing charge transport. The flower-like Cox P/carbon can facilitate a lower overpotential, Tafel slope, charge transfer resistance, and a higher electrochemically active surface than carbon-free and silk-free Cox P. The nanostructured architecture exhibits excellent catalytic performance with low overpotentials of 109 and 121 mV at 10 mA cm-2 and Tafel slopes of 55 and 62 mV dec-1 in acidic and alkaline media, respectively. Furthermore, it minimally degrades the overpotential and current density after long-term stability tests 10 000 cyclic voltammetry cycles and a chronoamperometric test over 40 h, respectively, in acidic media, which confirms the high durability and stability of the flower-like Cox P/carbon.

In article number 1601741, Yongku Kang, Dong-Wan Kim, and co-workers demonstrate highly efficient MnMoO4 electrocatalysts for Li-O2 batteries to promote surface oxygen vacancies using the redox properties of a mixed metal oxide and the anisotropic growth for phase cooperation in catalytic active sites. MnMoO4 nanowires provide a superior long-life and high-rate catalytic activity for reversible ORR/OER in the Li-O2 batteries.

The health effects of silica may depend on the inherent properties of crystalline silica or on external factors affecting the biological activity or distribution of its polymorphs. Inhaled crystalline silica is classified as a Group I carcinogen, however, information on the health effects of amorphous silica is still insufficient. Considering that alveolar macrophages play a key role in both innate and adaptive immune responses for removal of foreign bodies that enter via the respiratory system, we treated sheet-like glass particles (SGPs), a type of noncrystalline amorphous silica, to MH-S cells, an alveolar macrophage cell line. SGPs reduced the generation of ROS and NO and induced cell death via multiple pathways. Although the expression of CD80, CD86, and CD40, increased by exposure to SGPs, the expression of MHC class II molecules had not notably changed. Additionally, expression of ICAM-1 tended to decrease. In mice, SGPs were distributed in the interstitial region of the lung without notable pathological lesion on day 14 after a single intratracheal instillation. Pulmonary total cell number increased significantly with the highest dose, but the levels of all measured inflammatory cytokines and chemokines, except IL-1, were lower in BAL fluid from SGP-treated mice compared to control. More interestingly, the expression of antigen presentation-related proteins was enhanced in the lungs of SGP-exposed mice concomitant with an increase in the number of mature dendritic cells, whereas the expression of ICAM-1, an important adhesion molecule for helper T cell recruitment, was suppressed. Taken together, we suggest that SGPs may induce adverse health effects by down-regulating function of immune cells in the lungs. Furthermore, ICAM-1 may play a key role in immune response to remove pulmonary SGPs.

The development of high-performance anode materials, along with simple synthesis processes, is of main issues to replace the commercial graphite anode and to achieve practical applications of Li-ion batteries (LIBs). Herein, we report a facile, scalable preparation of multiple Mo-MoO3-graphene nanocomposites using a simple wire-explosion process, followed by heat treatment in air, and their electrochemical performance as anode materials of LIBs. In this process, Mo wire is electrically exploded in methanol containing graphene at room temperature, resulting in well-dispersed Mo nanoparticles anchored on graphene. Subsequently, partial oxidation of Mo nanoparticles to MoO3 is achieved at 300 degrees C in air, forming Mo-MoO3-graphene nanocomposites. For comparison, Mo-MoO3 nanocomposites are also prepared under the same conditions, without using graphene. Systematic phase and microstructural characterizations of both nanocomposites, as well as the as-synthesized Mo nanoparticles, are investigated by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and Raman spectroscopy. Their Li-storage performances are also evaluated and compared. Since graphene acts as a mechanical support to prevent Mo nanoparticle aggregation, and both Mo nanoparticles and graphene play an important role in providing effective electron pathways between active MoO3 nanoparticles, Mo-MoO3-graphene nanocomposites exhibit the conductivity and Li+ diffusivity enhancements (3.35 x 10 (14) cm(2) s (1)), and structural stability, resulting in not only enhanced cycling performance, with a reversible capacity of 611 mA h g (1) after 50 cycles at a constant current rate of 0.1C, but also a better rate performance than Mo-MoO3 nanocomposites. These synergistic functions are responsible for the better Li-storage performance of Mo-MoO3-graphene nanocomposite, which can lead to the promising candidates for LIB anode materials. (C) 2017 Elsevier Ltd. All rights reserved.

A hybrid catalyst system of a porous CuO nanowire/leaf mixture anchored onto graphene (p-CuO/G hybrid) was prepared as an oxygen-electrode electrocatalyst for lithiumeoxygen (LieO(2)) batteries. The p-CuO/G hybrid was prepared via the hybridization of a porous 1D/2D CuO mixture with 2D graphene. As an oxygen-electrode electrocatalyst for LieO(2) cells, the p-CuO/G hybrid exhibited high reversibility with a low voltage gap compared with a graphene electrode during 120 dischargeecharge cycles under a fixed capacity regime of 1000 mA h g(-1). We demonstrated the oxygen reduction and evolution kinetics of the p-CuO/G hybrid using electrochemical impedance spectroscopy. (C) 2016 Elsevier B.V. All rights reserved.