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Herein, 1D titanium oxynitride nanowires (TiON NWs) with different morphologies are fabricated through the step‐controlled heat treatments of electrospun nanowires, and their electrochemical performances are analyzed with regard to the physicochemical characteristics changed by post‐annealing processes. The direct‐nitridation (1step) and sequential oxidation‐nitridation (2step) procedures are performed to convert as‐prepared nanowires, consisting of titanium precursor and polymer, to TiON NWs (TiON‐1step NW and TiON‐2step NW). The TiON‐1step NW exhibits relatively high surface area and pore volume, which can be attributed to small crystallite size and amorphous carbon species formed during the direct‐nitridation step, whereas grain growth and carbon decomposition are observed in the TiON‐2step NW. When the prepared nanowires are applied to electrochemical capacitors and oxygen reduction reactions (ORRs), the TiON‐1step NW shows significantly higher performances than the TiON‐2step NW (200% higher capacitance and 0.17 V lower half‐wave potential in ORR). It is expected that the variation of electrochemical properties is mainly affected by morphological differences of the two TiON NWs. Residual carbon components in the TiON‐1step NW also contribute to improved electrical conductivity as well as structural stability in the applied electrochemical reactions. More detailed analyses are performed to clearly elucidate the experimental results from the perspective of morphology modification. [ABSTRACT FROM AUTHOR]

The selective and efficient electrocatalytic transformation of carbon dioxide (CO2) to multicarbon alcohols (e.g., C2H5OH and C3H7OH) is a challenge in renewable and sustainable energy research. Herein, a series of hybrid catalysts consisting of Cu nanoparticles supported on N-doped porous carbon (Cu/NPC) were prepared. It was demonstrated that the selectivity for C2H5OH or C3H7OH could be tuned by introducing N-doped porous carbon materials as cocatalysts with different pyridinic N contents, which could in situ produce a reactive CO intermediate from CO2. By varying the pyridinic N content, highly selective production of multicarbon alcohols was achieved using the Cu/NPC hybrid catalysts with a high faradaic efficiency for one pot production of multicarbon alcohols up to 73.3% at −1.05 V (vs. RHE). The faradaic efficiency for C2H5OH and C3H7OH was 64.6% and 8.7%, respectively. The pyridinic N species were likely the CO-producing sites and together with Cu catalytic sites acted cooperatively to produce C2H5OH and C3H7OH via a two-site mechanism for efficient CO2 reduction to multicarbon alcohols. These findings provide novel guidance for the rational design of electrocatalysts and for tuning the catalytic activity and selectivity for multicarbon alcohol production from CO2. [ABSTRACT FROM AUTHOR]

We developed a new and efficient sulfur-tolerant catalyst for application as a solid oxide electrolysis cell (SOEC) cathode designed with in situ exsolved CoNi alloy nanoparticles anchored on a Ruddlesden–Popper (R.P.) support of La1.2Sr0.8Co0.4Mn0.6O4 and evaluated its catalytic activity for CO2 electrolysis to CO under a CO2 gas stream containing H2S species. This catalyst was prepared by in situ annealing of a perovskite derivative (La0.6Sr0.4Co0.5Ni0.2Mn0.3O3) in a 20% H2/N2 gas at 800 °C. The catalyst exhibited good reversibility of structural transitions during reduction and re-oxidation processes. A high current density of 703 mA cm−2 was achieved at 1.3 V and 850 °C with a maximum faradaic efficiency of 97.8%. In situ grown CoNi alloy nanoparticles and the high oxygen vacancy content in the R.P. support were responsible for its high catalytic activity and efficiency. Importantly, no sign of performance degradation was observed in galvanostatic tests over a period of 90 h operation under H2S-containing CO2 gas conditions. Moreover, the catalyst showed no noticeable structural changes even after exposure to 100 ppm H2S/N2, indicating that the catalyst developed in this study is highly active for CO2 electrolysis with a high tolerance against sulfur-poisoning species. Therefore, this Ruddlesden–Popper material with in situ exsolved CoNi alloy nanoparticles should be a promising cathode catalyst for practical application to H2S-containing CO2 gas streams that are effluents of power stations or steel making plants. [ABSTRACT FROM AUTHOR]

This report demonstrates the modification of reduced graphene oxide (RGO) nanosheets by decorating SnO2 nanorod bundles and nanoparticles on the surface for effective use of the graphene as supercapacitor electrode materials. The shape‐ and density‐controlled SnO2 nanostructures were prepared through hydrothermal synthesis and acted as spacer materials to physically inhibit the overlapping of the RGO sheets; this is known as the restacking effect. When measuring the electrochemical properties, the electrode comprising RGO with SnO2 nanorod bundles (RGO−SnO2−NR) revealed a higher capacitance, rate capability, and cyclic stability than the RGO electrode with SnO2 nanoparticles (RGO−SnO2−NP) and the bare RGO electrode, indicating the effective role of the surface‐implanted SnO2 spacer during the electrode reactions of the double‐layer capacitor. The electrochemical superiority of RGO−SnO2−NR could be explained by the fact that wedge‐like SnO2 nanorod bundles between the RGO sheets promote fast transfer and approach of electroactive species to form the electrochemical double layer at the electrode surface. Moreover, the improved mass transfer behavior of the RGO−SnO2 composite electrodes and the role of the SnO2 nanostructures were reasonably verified by various electrochemical analyses. [ABSTRACT FROM AUTHOR]

Current lithium‐ion batteries have a low theoretical capacity that is insufficient for use in emerging electric vehicles and energy‐storage systems. The development of lithium‐sulfur batteries utilizing Li2S cathodes would be a promising option to overcome the capacity limitation. In this work, new three‐dimensional (3D) honeycomb‐like N‐doped carbon nanowebs (HCNs) have been synthesized through a facile aqueous solution route for use as a cathode material in lithium‐sulfur batteries. The Li2S@HCNs cathode delivers a high discharge capacity of approximately 815 mAh g−1 after 65 cycles at 0.1 C, along with a superior rate capacity of approximately 568 mAh g−1 even at 2 C. The outstanding electrochemical rate performance is ascribed to their unique 3D honeycomb‐like nanoweb structure, consisting of nanowires derived from polypyrrole. These properties greatly enhance the electrochemical reaction kinetics by providing efficient electron pathways and hollow channels for electrolyte transport. Nitrogen doping in the carbon nanowebs also considerably improves the chemisorption properties by tuning affinity between sulfur and oxygen functional groups on the carbon framework. The simple synthesis strategy and the resulting unique electrode structure could present a new avenue in nanostructure research for high‐performance lithium‐sulfur batteries. Electrifying nanowebs: Three‐dimensionally interconnected carbon‐nanowire composites are demonstrated as electrode for use in the lithium‐sulfur battery, and the electrochemical properties are investigated with Li2S. These electrodes can provide efficient pathways for charge transport and promote diffusion of the liquid electrolyte for the enhanced electrochemical reaction kinetics. [ABSTRACT FROM AUTHOR]

Abstract: A designed electrode material of carbon‐encapsulated tin dioxide core–shell nanowires that are synthesized directly on reduced graphene oxide substrates is reported, and its application as a positive electrode material for lithium‐ion battery is shown. Each of the individual tin dioxide nanowires is wrapped with carbon shell layers and grown on a reduced graphene oxide substrate, which gives rise to structural benefits for electrochemical performance of the lithium‐ion battery. Such carbon structures allow the electrode materials to withstand the mechanical stress during repeated charge/discharge processes and facilitate the reaction kinetics for the lithiation/delithiation processes. In the electrochemical cell tests, the synergetic effect of the proposed electrode design is explicitly verified by presenting highly enhanced rate capability and cycle durability on full‐cell batteries as well as half‐cell tests. [ABSTRACT FROM AUTHOR]

Ruthenium oxide/cobalt oxide composite nanowires (RuO2/Co3O4 NWs) have been synthesized through a simple and efficient electrospinning method for use as bifunctional electrocatalysts in rechargeable lithium-oxygen (Li-O2) battery cathodes. The as-prepared NWs have been characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and X-ray absorption near-edge structure (XANES) spectroscopy. The intrinsic activities of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) over the obtained composite NWs are studied using a rotating-disk electrode technique. The RuO2/Co3O4 NWs exhibit superior bifunctional electrocatalytic activities for both the ORR and the OER if compared to the activities of the Co3O4 NWs and only Ketjenblack (KB). If the RuO2/Co3O4 NWs are employed as cathode catalysts in Li-O2 cells, great improvements in terms of the discharge capacity, coulombic efficiency, and cycle stability with low discharge-charge overpotentials are achieved. These can be attributed to the high bifunctional catalytic activities of the RuO2/Co3O4 composite NWs. [ABSTRACT FROM AUTHOR]

In this paper, α-Fe2O3 hollow spheres in different sizes were successfully synthesized through a glycerol emulsion template method for use as efficient electrode materials in lithium-ion batteries. The sizes of α-Fe2O3 hollow sphere could be easily controlled by adjusting the amount of glycerol over the Fe precursor during the hydrothermal synthesis process. A thin carbon layer was subsequently coated on the surface of α-Fe2O3 hollow spheres through hydrothermal treatment with glucose for the carbonization process, in which the carbon phases could serve as a conductive layer for the efficient charge transfer, but also as a buffer layer for the accommodation of volume vibration of the electrode material during cycling. The carbon-coated α-Fe2O3 hollow sphere electrode showed a high discharge capacity of approximately 1452 mAh g−1 with a capacity increase of at least 32 % compared to that of α-Fe2O3 hollow spheres without the carbon coating at the 50th cycle. The stability and cycling performance were also significantly improved by the presence of the carbon layer, indicating that the C/α-Fe2O3 hollow sphere could be a promising metal-oxide anode material for lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Abstract: In this study, a highly efficient Pd catalyst supported on a conducting polymer‐carbon composite was prepared for electro‐oxidations of ethanol and formic acid. A polypyrrole‐carbon composite was synthesized and modified by doping camphor sulfonic acid (CSA) during the polymerization step of pyrrole at room temperature. The resulting CSA‐doped polypyrrole‐carbon composite (PPyCC) showed significantly increased specific surface area and enhanced electrical conductivity compared with a polypyrrole‐carbon composite without doping (PPyC). From the electrochemical tests, it was observed that the Pd‐supported on CSA‐doped polypyrrole‐carbon composite (Pd/PPyCC) exhibited much larger electrochemical surface area (ECSA), enhanced catalytic activity and high durability towards the oxidations of ethanol and formic acid. The results indicate that the camphor sulfonic acid serving as both dopant and surfactant could improve the electrical conductivity and morphology of support material with enhanced interaction between Pd nanoparticles and support material. [ABSTRACT FROM AUTHOR]