Ysea, Nadia B.Llorente, Victoria BenaventeLoiacono, AntonellaMarquez, Lucrecia Lagucik...
13页
查看更多>>摘要：It is critical to minimize the cost of materials and inputs used in hydrogen production and to create solutions for large-scale generation to reduce the cost of hydrogen produced. Seawater is a natural low-cost electrolyte with high Na+ and Cl- concentrations, among other soluble salts. Chloride ions allow a highly corrosive media to the materials typically used as electrodes. In this work, we have prepared and tested different Ni-based catalysts for hydrogen evolution in NaCl-containing solutions. NiMo alloy, Ni(WO3), and Ni(Nb2O5) composites are compared and studied from a critical point of view to find a viable solution for catalysis in seawater electrolysis. The NiMo catalyst presents a higher dissolution rate in the NaCl medium than all synthesized catalysts. Furthermore, Ni-based composites showed improved durability due to a decrease in dissolution, and an increase in catalytic activity when using Nb2O5 as the dispersed phase. The Ni(Nb2O5) electrodes presented the higher catalytic activity in NaCl solution, even higher than that found in NiMo catalyst. (C) 2022 Published by Elsevier B.V.
Stringe, MarkSpangenberg, KatharinaPinto, Manoel Wilker da SilvaPeterlechner, Martin...
9页
查看更多>>摘要：Reproducible thermodynamic sample states of a Pd40Ni40P20 bulk metallic glass are realized via differential scanning calorimetry by repeated quenching from the supercooled liquid state to temperatures well below the glass transition. Annealing treatments at 0.81 Tg and 0.96 Tg are embedded in the calorimetric method, changing the energetical state of the system. Varying the annealing times, a detailed and reproducible picture of the reversible relaxation dynamics with separated alpha- and beta-relaxation is obtained. An endothermic signature before Tg can either be provoked or depressed depending on the annealing temperature. The activation energy related to this process is obtained via Kissinger analyses yielding about 30 RTg. A large number of annealing cycles at 0.96 Tg irreversibly alters the response of the alpha-relaxation, while the mechanism of beta-relaxation is interestingly not influenced by this alternation. In order to extend the calorimetric response of the relaxation spectra to spatial resolution, the sample states were additionally analyzed using electron correlation microscopy providing information on the glass dynamics on an atomistic scale. The thus obtained kinetic parameters of local dynamics do not show an alteration of room temperature dynamics for different levels of alpha-relaxation, which is consistent with the results obtained via kinetic analyses of calorimetric data.
查看更多>>摘要：To meet the rapid development of flexible supercapacitors with both high energy density and power density, hybrid ion capacitors like lithium and sodium ion capacitors have attracted more and more at-tention. However, the hidden danger associated with the using of organic electrolytes limit their practical application. In this regard, a new configuration flexible zinc-ion hybrid supercapacitor (ZHSC) based on free-standing films of RGO-V2O5 (RGV) battery-type cathode and RGO-MXene (RGM) capacitor-type anode in aqueous electrolyte has been designed. The RGM/RGV system consists of specific layered structure, short ion diffusion pathway, high electrical conductivity and exceptional structural stability. As a result, the ZHSC based on RGM/RGV exhibits excellent electrochemical performance, including a large specific capacity of 175 F g-1 at 0.5 mV s-1, a maximum energy density up to 107.2 Wh kg-1 (321.6 W kg-1) and a high capa-citance retention of 81% of its initial capacitance (10,000 cycles). Additionally, the ZHSC displays a high specific capacity of 125 F g-1 at 0.5 mV s-1 even in an aqueous gel electrolyte. More importantly, super -capacitors based on the composite films exhibit stable flexibility electrochemical performance. The in-vestigation provides an essential strategy to synthesize composite films for application in high performance flexible hybrid supercapacitors.(c) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：Cobalt-nickel (Co-Ni) free Lithium-rich cathode material (1 - x)Li2MnO3 center dot xLiFeO(2) is more environmental friendly and cheaper than other traditional cathode materials. However, the complex synthesis method limits its large-scale practical application. This work explores a simple dry synthesis route to directly obtain 0.7Li(2)MnO(3)center dot 0.3LiFeO(2) with good electrochemical performance. Calcination temperature is a key factor controlling the phase growth. With the calcination temperature increasing, the crystallization and ordered layered structure are improved, but the LiFe5O8 spinel phase appears in X-ray diffraction (XRD) patterns from 600 degrees C. The results of selected area electron diffraction (SAED), element mapping (EDS) and vibrating sample magnetometer (VSM) demonstrate convincingly the growth progress of LiFe5O8 as the temperature rises. The spinel phase deteriorates the electrochemical performance. Furthermore, it is proved that the crystallization and activity of Li2MnO3 precursor are effective to retard the formation of LiFe5O8 and enhance the electrochemical performance. The sample calcined at 600 degrees C exhibits a high initial capacity above 200 mAh g(-1), but capacity fades quickly to 120 mAh g(-1) after 50 cycles at 0.2 C. The sample calcined at 650 degrees C with a little LiFe5O8 delivers a low initial capacity about 160 mAh g(-1), but stabilizes at 160 mAh g(-1) after 50 cycles. Therefore, how to control the formation of thermally stable phase LiFe5O8 is an important issue, and it needs further investigation to achieve Co-Ni free Li-rich cathode materials with excellent performance. Significantly, the simple synthesis and acceptable electrochemical properties make the practical application of Fe-Mn based Li-rich material possible. (C) 2022 Published by Elsevier B.V.
查看更多>>摘要：The polysulfide shuttle and uncontrollable growth of lithium dendrites are the two fatal troubles that obstruct the practical process of lithium-sulfur batteries. Herein, a composite membrane consisting of metal-organic framework (MOF) Ce-based UiO-67 and glass fiber membrane (UiO-67-GF) is proposed as a dual-functional separator for these issues. On the one hand, the introduced Ce-UiO-67 crystals are capable of efficaciously adsorbing polysulfides and catalyzing their conversion, thereby restraining their shuttle. On the other hand, this MOF provides sufficient lithium-philic functional groups for ensuring the rapid and homogeneous transport of Li ions, and thus a stable Li plating and stripping process can be acquired. Consequently, this MOF-based separator is qualified for simultaneously resolving the challenges of polysulfide shuttle and Li dendrite. The battery with the proposed separator delivers an initial capacity of 919 mAh g(-1) and a limited decay rate of merely 0.04% per cycle for 500 cycles at 1 C. Moreover, even under a lean-electrolyte condition, a high area capacity of 6.0 mAh cm(-2) is still obtained under the increased sulfur loading of 7.0 mg cm(-2). (c) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：To develop effective and low-cost enzyme-like nanomaterials in the antibacterial field, we designed an easily performed and highly specific approach to obtain novel ultrathin Ni-V mixed metal oxides (MMOs) with rich oxygen vacancy. Herein, a selenium (Se) doped novel ultrathin Ni-V MMOs were derived from Ni-V layered double hydroxide (LDHs) with Se powder in N-2 instead of direct calcination in the air successfully. After Se doped, the acquired Ni-V MMOs exhibited richer oxygen vacancy and more changeable elemental state, which can drastically promote the oxidase (OXD)/peroxidase (POD)-like activity increasing nearly 2 times compared with Ni-V MMOs. Se-doping endow 3NiV-Se-350 the unique 2D hierarchical nanostructure and the richest oxygen vacancy. More interesting, Se doped Ni-V MMOs calcinated at 350 ? with a Ni/V molar ratio of 3:1 show the best OXD/POD mimic activity among different Ni/V molar ratios, and possess a good reusability for 7 cycles. Mimic activity of 3NiV-Se-350 was attributed to the reactive oxygen species (ROS), such as center dot OH and center dot O-2(-). 3NiV-Se-350 also exhibit bactericidal rate of 71.04% without H2O2 and 98.89% in the presence of H2O2 against E. coli through generating center dot O-2(-). (C) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：The electrical conductivity and catalytic activity of the electrode materials greatly affect the photoelectric conversion performance of DSSCs. However, the commonly used Pt electrodes no longer meet the needs of long-term development at present. Herein, based on the Kirkendall effect, CoFe2O4 @C nanoparticles with core-shell structure are successfully prepared using the treatment of quasi-sol-gel method. The size of CoFe2O4 @C nanoparticles is homogenized without agglomeration through adjusting the ratio of metal salt in the precursor. The composite exhibits excellent counter electrode properties in DSSCs, which attributes to the large specific surface area and superior electro-catalytic activity. With the optimized film thickness (12 mu m) of CoFe2O4 @C, an excellent photoelectric conversion efficiency of 7.80% is finally achieved, significantly higher than that of pure carbon (PC) electrode (6.36%) and even Pt counter electrode (7.05%) under the same conditions. The composite can additionally catalyze the recycling of I-/I3- redox couple steadily, providing more possibilities for the study of Pt-free materials about DSSCs counter electrode. (c) 2022 Published by Elsevier B.V.
查看更多>>摘要：The photocatalytic hydrogen (H2) evolution of photocatalyst generally requires the assistance of cocatalysts, which are mainly centered on noble metals, such as Pt and Au. However, noble metals cocatalysts often suffer from the uneven distribution and severe aggregation, as well as scarcity. Herein, we reported nickelsalen (Ni-salen) molecules on the promotion of photocatalytic H2 evolution with polymeric carbon nitride (PCN)/CdS heterojunction, in which the noble metal free Ni-salen molecules are soluble and highly dispersed during photocatalytic H2 evolution under visible light irradiation (lambda >= 420 nm). Under optimized loading concentration of the Ni-salen molecules (0.03 mM), the highest H2 evolution rate is up to 23.3 mmol g-1 h-1, which is more than 4 times higher than that by using PCN/CdS heterojunction alone. In addition, Ni-salen molecules are highly stable and can offer a durable H2 evolution with 28 h. The enhancement on H2 evolution is the result of efficient photogenerated electrons transfer from photoexcited PCN/CdS heterojunction to the coordination unsaturated Ni active centers of Ni-salen molecules. This work demonstrates the great potential of soluble noble metal free Ni-salen molecules on the promotion of photocatalytic H2 evolution.
查看更多>>摘要：The novel La(1-x)Ca(x)Ti(1-y)TayO(3-delta) nano perovskites with high oxygen vacancies have been prepared for solid oxide fuel cells (SOFCs) by facile hydrothermal method. To enhance the oxygen vacancies, structural, thermal and chemical stability, the phase composition of the materials was varied with multiple x & y values like (0, 0.2, 0.4, 0.6, 0.8 and 1). All the as prepared compositions of La(1-x)Ca(x)Ti(1-y)TayO(3-delta) were undergone heat treatments in autoclave, calcined at 700 & DEG;C and sintered at 1000 C. These modified perovskite oxides can add in hefty point defects, such as oxygen vacancies that compensate dopants or are part of an inherent off-stoichiometry. These defects have high mobilities in La(1-x)Ca(x)Ti(1-y)TayO(3-delta) perovskites, making it most suitable for electrochemical energy conversion devices. The appropriate phase purity, structural properties, lattice parameters and morphology of the perovskite were inspected. Electrical conductivity of sintered pellets was analyzed using electrochemical impedance spectroscopy. The electrical behavior of La(1-x)Ca(x)Ti(1-y)TayO(3-delta) is enhanced at lower operating temperature and long-term structural stability, phase purity is also improved owing to the inclusion of Calcium and Tantalum (La(1-x)Ca(x)Ti(1-y)TayO(3-delta)). The enhancement in electrical conductivity, electro-catalytic activity is credited by means of partial replacement of Ca and Ta in the perovskite structure. Among them, La0.6Ca0.4Ti0.6Ta0.4O3-delta showed the maximum conductivity of 9.18 x 10(-2) S cm(-1) at 750 C. These results demonstrate that the La(1-x)Ca(x)Ti(1-y)TayO(3-delta) perovskites are capable as electrode material intermediate temperatures SOFCs fabrication. (C) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：High-valent or equivalent foreign element doping could improve the charge separation of the hematite (alpha-Fe2O3) for enhancing the photoelectrochemical (PEC) water oxidation. However, the induced extra surface states would anodically shift the onset potential. This work reported a two-step hydrothermal method to prepare the low-valent Li doped alpha-Fe2O3 that alleviated the charge recombination and partially removed the surface states. Thus, the photocurrent density of optimized Li-doped alpha-Fe(2)O(3)was 0.75 mA/cm(2) (1.23 VRHE), up to 3.6 times higher than that of pristine alpha-Fe2O3 (0.21 mA/cm(2)). Meanwhile, the onset potential also shifted negatively to 0.68 VRHE by 100 mV. The Density Functional Theory (DFT) revealed the Li atoms occupied the interstitial sites of the oxygen octahedron, and the introduced halffilled states in the bandgap can expand the light absorbance and improve the charge transport. The synergetic effects of enhanced charge separation efficiency and removal of surface states contributed to efficient PEC water oxidation. (C) 2022 Published by Elsevier B.V.
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