查看更多>>摘要：? 2022 Elsevier B.V.Structured Li anode is a strong candidate for reviving lithium metal anode in high-energy-density rechargeable batteries, suppressing the dendrite growth and stabilizing the volume change. However, the lithiophilicity chemistry and lightweight design of substrates remain a challenge to assemble composited anode. Herein, we report a N/O co-doped carbon fiber (NOCF) and its intrinsic lithiophilicity chemistry for fabricating Li structured anode (CF/Li). The experimental lithiophilicity comparison of different N-functional groups demonstrates that the increasing ratio of quaternary N and N-oxides can turn a lithiophobic surface into the lithiophilic NOCF than pyrrolic and pyridine N as previously estimated. Thanks to the lightweight NOCF, the fabricated CF/Li anode achieves 3142 mAh g?1 capacity, equivalent to 82% theoretical capacity of lithium metal. Notably, the CF/Li composited anode presents outstanding electrochemical and structural stability with inhibited dendrites during the Li stripping/plating process. Even at an ultrahigh current density of 10 mA cm?2, the CF/Li still exhibits lower polarization (141.1 mV) and a smoother voltage profile for 500 cycles. In Li-LFP cells, the CF/Li also delivers better cycling and rate performance than the commercial Li foils.
查看更多>>摘要：? 2022 Elsevier B.V.Fuel cells have emerged as a charming candidate for next-generation energy conversion devices. However, it is highly desired but challenging to engineer advanced non-precious oxygen reduction catalysts with highly actives and stability due to the sluggish kinetics of oxygen reduction reaction (ORR) on fuel cell cathode. Herein, a novel hybrid architecture with Co nanoparticles embedded in N-doped carbon nanotubes and hollow nanocarbon polyhedron (Co@N-CNT-HC) was constructed from core-shell ZIF-67@ZIF-8 via a facile epitaxial growth-pyrolysis process. With the Co@N-CNT-HC as the catalyst, a remarkable ORR performance is achieved in terms of a high half-wave potential of 0.84 V, a large limiting current density of 4.70 mA/cm2, and excellent long-term durability ( 97.8% current retention after 8 h) in alkaline medium, which outperform commercial Pt/C catalyst. Further dynamic calculations indicated that ORR follows a four-electron reaction mechanism. The enhancement activity of Co@N-CNT-HC is mainly due to the effective integration of 0D Co nanoparticles, 1D carbon nanotubes and 3D hollow nanocarbon, which synergistically strengthen the interfacial reaction kinetics of oxygen and accelerate mass/charge transfer. The strategy reported in this work provides a new insight to synthesis of low-cost and well-designed carbon hybrid electrocatalyst for ORR.
查看更多>>摘要：? 2022 Elsevier B.V.Photoelectrochemical CO2 reduction to formate offers an appealing pathway for alleviating energy and environmental problems. However, achieving high product selectivity and low overpotential in CO2 activation remains challenging. In this work, we synthesized Cu-modified Bi2Se3 catalyst with selenium vacant sites due to the mismatched oxidation states between cations. Compared with pure Bi2Se3, the Cu-modified Bi2Se3 catalyst demonstrated improved catalytic capability for CO2. When the doping ratio of Cu was 8%, the maximum Faraday efficiency of formate reached 65.31% with an overpotential as low as ~500 mV (vs. RHE). Experimental results indicated that the doping of Cu played three roles: (i) improving the adsorption of CO2, (ii) increasing the electrochemical active surface area, and (iii) modifying the electronic structure of Bi2Se3. Moreover, a photoelectrocatalysis system using solar light as energy input was constructed, and a high formate yield of 139.97 μmol h–1 cm–2 was achieved. This study provided a rational Bi2Se3-modification strategy to achieve efficient CO2 conversion.
查看更多>>摘要：? 2022 Elsevier B.V.In this study, multi-walled carbon nanotubes (MWCNTs) reinforced René104 superalloy laminated composites with sub-micron grain size were prepared by ball milling and spark plasma sintering (SPS). MWCNTs did not change the composition and distribution of oxide scale of René104 alloy, but the micropores caused by MWCNTs formed oxygen molecular channels, which accelerated the oxidation at 900 °C. Electroless nickel plating on MWCNTs can improve the compatibility between MWCNTs and René104 matrix, thus significantly reducing the influence of MWCNTs on high temperature oxidation. This work will pave the way to develop the high-temperature structural materials reinforced by carbon nanomaterials.
查看更多>>摘要：? 2022 Elsevier B.V.g-C3N4 (CN), a nonmetal semiconductor, shows tremendous potential for utilization in the field of photocatalysis owing to its physicochemical stability and good visible light response properties. In this study, the photocatalyst of O-g-C3N4 (OCN) coupled with SnO2 (SO) was synthesized and its photocatalytic performance was evaluated under simulated sunlight irradiation for rhodamine B (RhB) degradation and Cr(IV) reduction. The structure, morphology, and properties of the synthesized photocatalyst were investigated using X-ray diffraction, Brunauer–Emmett–Teller analysis, transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, ultraviolet–visible diffuse reflectance spectroscopy, and an electrochemical system. The analysis results revealed that the 30-SO/OCN nanocomposite exhibited an excellent specific surface area; moreover, O atoms were doped into CN and a heterojunction was formed between SO and OCN. The 30-SO/OCN nanocomposites exhibited more than 2.52 and 1.73 times catalytic activity than 30-SO/CN nanocomposites toward RhB and Cr(IV) degradation, respectively. Based on radical scavenger experiments, h+ and e? were confirmed to be the main active species in the photocatalysis of 30-SO/OCN nanocomposites. The excellent photocatalytic activity of 30-SO/OCN nanocomposites was attributed to the special surface of OCN as well as the formation of a heterojunction between SO and OCN. Therefore, the 30-SO/OCN nanocomposites were confirmed to be highly active and reliable water-treatment photocatalysts.
查看更多>>摘要：? 2022 Elsevier B.V.The design of non-precious metal borides electrocatalysts with high efficiency and high stability is critical but challenging for the development of electrochemical water oxidation. The morphology and electronic structure will largely determine the activity and stability for amorphous nickel-iron-based catalysts. Herein, we developed a series of amorphous borate-modulated NiFeB OER catalysts through a facile two-step method, including sodium borohydride reduction and low temperature annealing. Benefiting from the monopoly of core-shell nanoparticles and the modulation of the boron electronic structure, the obtained NiFeB NPs-300 exhibits an overpotential of 231 mV at 20 mA cm?2 in 1 M KOH as well as excellent stability. This work might provide a new way to improve the performance of metal-borate electrocatalysts by modulating the boron electronic structure.
查看更多>>摘要：? 2022 Elsevier B.V.A novel method for preparing lead-free Cu nano Bi (CNB) alloy materials by nano Bi powder and shift-speed ball milling (SSBM) flake powder metallurgy was proposed. To improve the mechanical and tribological properties of the alloy materials, the spherical CuSn10 powder was firstly extruded and sheared into flakes by low-speed ball milling (LSBM) in the SSBM system. Meanwhile, the nano Bi powder was evenly dispersed and coated on the CuSn10 flakes. The mechanical alloying between mixed powders and the cold welding of flake CuSn10 flakes containing nano Bi into layered particles were then realized through short-time high-speed ball milling (HSBM) in the SSBM system. While promoting the uniform dispersion of lubricating phase Bi, the surface area of matrix CuSn10 flake was increased so as to achieve better combination of CuSn10 matrix in the material. Results show that the mechanical properties of the CNB material prepared through nano Bi powder and SSBM flake powder metallurgy improved compared with the Cu-Bi material prepared by HSBM. In addition, the antifriction and wear resistance improved by 30% and 80%, respectively.
查看更多>>摘要：? 2022 Elsevier B.V.Oxygen-enriched smelting is accompanied by the precipitation of magnetite due to fayalite-based slag systems, which deteriorates the properties of slag and increases copper content in Cu slag. In this study, the evolution of the structure and viscosity of slag during metallization-reduction were investigated. The reduction process of the Fe-containing phase in Cu slag can be divided into two steps (Fe3O4→FeO, FeO→Fe) as coal dosage increases. In Fe3O4→FeO, the solid-phase particle content in Cu slag decreases, which simplifies the macromolecular structures, thus decreasing the viscosity of Cu slag. In FeO→Fe, the solid-phase particle content in Cu slag increases because of the formation of metallic Fe and Cu-Fe alloy particles. The macromolecular structures dominated by SiO4 and AlO4 tetrahedra become complex, increasing the viscosity of the Cu slag.
查看更多>>摘要：? 2022 Elsevier B.V.Fabricating nanocrystalline Ni-Fe alloy coatings with excellent brightness and corrosion resistance could reduce the use of Ni and benefit economically. Nanocrystalline Ni-Fe alloy coatings were electrodeposited on steel substrates and the coatings with 34.55% Fe content were achieved at the optimized conditions with the current efficiency high up to 80.30%. The electrodeposition behavior of Ni-Fe coatings was investigated by cyclic voltammetry (CV), chronopotentiometry and chronoamperometry. CV tests illustrate that Ni2+ and Fe2+ are co-electrodeposited to form single phase and the deposition of Ni is inhibited by the presence of Fe2+ while the deposition of Fe is boosted by the Ni2+ according to chronopotentiometry. The nucleation and growth of nanocrystalline Ni-Fe alloy coatings is 3D diffusion-controlled instantaneous nucleation process. Intermetallic compound, namely Ni3Fe phase, was formed according to XRD analysis and TEM analysis, while the mean grain size is 4.79 nm. SEM and AFM images demonstrate that nanocrystalline and compact surface were fabricated and the roughness is lower than 5 nm, better than pure Ni coating. Due to the nanocrystalline and compact surface, the icorr and Rct of nanocrystalline Ni-Fe alloy coating are 0.7544 μA cm?2 and 8560 Ω respectively, indicating that Ni-Fe alloy coating is of good corrosion resistance.
查看更多>>摘要：? 2022 Elsevier B.V.In the present study, the Co9Al8W superalloy was used as a binder phase for a new tungsten heavy alloy (WHA). The effects of the binder phase, nano-Y2O3 oxides, and mechanical alloying on the microstructure evolution and mechanical properties of the model WHAs were investigated. The results demonstrate that the presence of the Co9Al8W binder phase can stabilize the formation of solid phase during sintering. The dispersed oxide particles can interact with the Al element and form complex nanoscale Al-Y-O oxides, which greatly refine the microstructure, resulting in a significant impact on mechanical properties of the alloys. However, the porous microstructure related to Al-rich oxides and pores was obtained in the alloys, which caused the formation of micro-cracks, resulting in the loss of material ductility.
NSTL
Elsevier