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Epitaxy and new stray grain formation mechanism during epitaxial laser melting deposition of Inconel 718 on directionally solidified nickel-based superalloys
摘要： The epitaxy behavior and stray grains (SGs) formation in the deposit during epitaxial laser melting deposition (E-LMD) of directionally solidified (DS) superalloys were investigated. Columnar dendritic structures were obtained by epitaxial solidification on the DS substrate. The deposit also remained the orientation of the substrate. The SGs at the fusion interface, which were hardly eliminated, were attributed to different SGs formation mechanisms. The SGs were divided into GB-SGs and MC-SGs by the distribution characteristics. The GB-SGs at the low-angle and high-angle grain boundaries with a new mechanism of dynamic recrystallization induced by accumulation of thermal strain and stress under repeated spatially variable heating and cooling. The MC-SGs around the carbides were related to the misoriented cellular crystal formation caused by the varied shape of the solid-liquid interface. The columnar to equiaxed transition (CET) was another mechanism of MC-SGs formation.
关键词： Stray grain,Nickel superalloys,Laser metal deposition,Recrystallization,Dynamic,Epitaxy,Microstructure
更新于2025-11-28 14:24:20
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Conjugated Polymer–Assisted Grain Boundary Passivation for Efficient Inverted Planar Perovskite Solar Cells
摘要： Grain boundaries in lead halide perovskite films lead to increased recombination losses and decreased device stability under illumination due to defect-mediated ion migration. The effect of a conjugated polymer additive, poly(bithiophene imide) (PBTI), is investigated in the antisolvent treatment step in the perovskite film deposition by comprehensive characterization of perovskite film properties and the performance of inverted planar perovskite solar cells (PSCs). PBTI is found to be incorporated within grain boundaries, which results in an improvement in perovskite film crystallinity and reduced defects. The successful defect passivation by PBTI yields reduces recombination losses and consequently increases power conversion efficiency (PCE). In addition, it gives rise to improved photoluminescence stability and improved PSC stability under illumination which can be attributed to reduced ion migration. The optimal devices exhibit a PCE of 20.67% compared to 18.89% of control devices without PBTI, while they retain over 70% of the initial efficiency after 600 h under 1 sun illumination compared to 56% for the control devices.
关键词： halide perovskites,conjugated polymers,grain boundary passivation,nickel oxide
更新于2025-11-20 15:33:11
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Investigation of sol-gel and nanoparticle-based NiOx hole transporting layer for high-performance planar perovskite solar cells
摘要： We conduct a comprehensive study on and comparison of sol-gel and nanoparticles (NPs)-based nickel oxide hole-transporting layer (HTL) for high-performance planar perovskite solar cells (PSCs). The characteristics and film properties of sol-gel and NPs were systemically investigated using ultraviolet photoelectron spectroscopy (UPS), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and photoluminescence (PL), and its effect on device-performance was also examined using J-V characteristics, quantum-efficiency, and the VOC dependence of the light intensity. Through this comparison of two types of HTL and their device-performances, these studies can provide sufficient and robust information for nickel oxide-based PSCs, and furthermore, the overall results and discussions can be useful for high-performance PSCs.
关键词： Nickel oxide,Planar perovskite solar cells,Hole transporting layer,Sol-gel,Nanoparticles
更新于2025-11-19 16:46:39
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Conductive electrodes based on Ni–graphite core–shell nanoparticles for heterojunction solar cells
摘要： Ni–graphite core–shell nanoparticles (CSNPs), which consisted of Ni nanoparticles (NPs) wrapped with several graphene layers, were grown by the thermal reduction of NiO NPs using H2. The effect of the synthesis temperature (800, 900, 1000, and 1100 °C) on the formation of multilayer graphene shells on the Ni core NPs was investigated to evaluate the structural and electrical characteristics of the particles. The proposed chemical reactions for the formation of Ni NPs can be summarized as follows: formation of liquid Ni by the reduction of NiO, thermal decomposition of the NiO phase, and formation of multilayer graphene shell because of the supersaturation of C in the liquid Ni phase. The resistivity of the electrode pattern fabricated with the Ni–graphite CSNP paste was found to be 6.75 × 10?3 ?·cm. Further, the power conversion efficiency of bulk heterojunction solar cells fabricated with the Ni–graphite CSNPs is higher than that of cells fabricated without the Ni- graphite CSNPs. Thus, our Ni–graphite CSNPs can be employed as a highly efficient electrode material in bulk heterojunction solar cells.
关键词： Thermal reduction,Core–shell structure,Nickel oxide nanoparticle,Graphite,Graphene
更新于2025-11-14 17:04:02
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In situ synthesis of ternary nickel iron selenides with high performance applied in dye-sensitized solar cells
摘要： Comparing with the binary chalcogenides, the ternary chalcogenides may achieve higher electrical conductivity and electrochemical activity due to the synergistic effect of the different metal cations. Herein, ternary nickel iron selenide (Ni0.5Fe0.5Se2) was fabricated through a facile one-pot solvothermal method with the assistance of glucose for the first time. The dye-sensitized solar cells (DSSCs) were assembled with the as-prepared Ni0.5Fe0.5Se2 as counter electrode (CE). Electrochemical measurements indicated that the Ni0.5Fe0.5Se2 possessed small electron transfer resistance at the interface between electrode and electrolyte, great electrocatalytic activity and reaction kinetics toward the reduction of triiodide. Compared with conventional Pt CE (7.24%), the DSSCs based on Ni0.5Fe0.5Se2 CE achieved a greater power conversion efficiency of 7.89%. Furthermore, this study provides a new idea and strategy with convenient method to synthesize Pt-free alternative materials.
关键词： Counter electrode,Solvothermal method,Dye-sensitized solar cells,Ternary nickel iron selenide
更新于2025-11-14 17:04:02
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Preparation of hierarchical flower-like nickel sulfide as hole transporting material for organic solar cells via a one-step solvothermal method
摘要： In this work, nickel sulfide (NiS) with a mesoporous network was prepared through a simple solvothermal approach. The influences of various contents of the sulfur source on the morphological changes were examined. Finally, the resultant NiS doped with various contents of sulfur were used as hole-transport layers (HTLs) for the application to organic solar cells (OSCs). Based on our knowledge of the implementation of OSCs, NiS-based HTLs are used for the first time in this paper. The OSCs developed with NiS_2.0 (NiS doped with 2.0 g of thioacetamide (sulfur source)) HTL showed a higher PCE response, at 2.28% than those fabricated with NiS_1.0 (NiS doped with 1.0 g of thioacetamide), NiS_1.5, (NiS doped with 1.5 g of thioacetamide), and NiS_2.5 (NiS doped with 2.5 g of thioacetamide), which only showed 1.38%, 1.88%, and 1.96%, respectively. Besides this improved photovoltaic response, it also demonstrated a superior reproducibility with a high degree of control over the environmental stability, i.e., 360 h, as compared to the bare PEDOT:PSS HTL-based OSCs, which showed just 240 h.
关键词： Stability,Reproducibility,Synthesis,Hole transport layer,Organic solar cells,Hierarchical flower-like nickel sulfide
更新于2025-11-14 17:04:02
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Insights into the thermo-photo catalytic production of hydrogen from water on a low-cost NiOx-loaded TiO2 catalyst
摘要： Thermo-photo catalytic water splitting, where the introduction of thermal energy increases the oxidation driving force for narrow-band-gap photocatalysts (with a low valence band potential), exhibited significantly advanced performance for hydrogen production compared with general water splitting at room temperature. Herein, a low-cost NiOx-loaded TiO2 catalyst was reported for thermo-photo catalytic water splitting with methanol as the sacrificial agent. The catalyst with an optimal Ni ratio of 5 wt.% achieved a hydrogen evolution rate of 53.7 mmol/h/g under simulated AM 1.5G sunlight at 260℃, which was 2.5 times more than that without illumination, with apparent quantum efficiencies of 66.24%, 33.55%, 32.52% and 15.35% at 380, 420, 450 and 500 nm, respectively. More impressively, under the irradiation of visible light (λ>420 nm) at this temperature, and photohydrogen yield could still reach 26.9 mmol/h/g, which was 5 orders of magnitude greater than that (0.0011 mmol/h/g) conducted at room temperature. Isotope tracer experiments demonstrated that the introduction of photo energy promoted the hydrogen production mainly by enhancing hydrogen evolution from water splitting rather than methanol decomposition or reformation. Furthermore, the step-wise reaction mechanism was revealed with insights into the synergistic roles of thermo-energy and photo-energy for production of hydrogen from water. Those findings highlight the great promise of thermo-photo catalysis and should inspire more efforts for water splitting.
关键词： visible light,Hydrogen production,nickel-based catalysts,thermo-photo catalysis,titanium dioxide
更新于2025-11-14 17:03:37
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Evolution of the infrared emissivity of Ni during thermal oxidation until oxide layer opacity
摘要： The mid-infrared (3–22 μm) emissivity of high-purity Ni has been studied in its pure state, during an isothermal oxidation in air at 730 °C and in the fully oxidized state. Measurements in pure Ni were performed in Ar between 200 and 800 °C and a change of slope in the temperature dependence of the total normal emissivity around its Curie temperature (354 °C) was observed. An oxidation process was carried out at 730 °C for 33 days, when the emissivity stopped evolving and the results were representative of NiO. During the ?rst stages, the emissivity evolved forming the usual interference patterns of semi-transparent ?lms. A mixture of oscillatory and monotonic behaviours of the emissivity as a function of wavelength and oxide layer thickness was found, which manifests as a non-trivial evolution of the total normal emissivity, di?erent than that reported in previous studies. Finally, the emissivity of NiO was measured from below its Néel temperature (252 °C) to 850 °C. It showed the typical shape of a ceramic material with an extra vibrational mode due to two-phonon processes and an additional absorption band around 5 μm in the antiferromagnetic phase produced by magnons. The temperature dependence of its total normal emissivity di?ers signi?cantly from that of a lightly oxidized nickel sample from the literature. Overall, the in?uence of the surface characteristics on the thermal radiative properties of oxidized Ni is thoroughly discussed and highlights the importance of accounting for all possible sources of infrared emissivity evolution in order to make accurate radiative heat transfer calculations.
关键词： Nickel oxide,Infrared emissivity,Radiometry,Radiative heat transfer,Magnetic phase transition,Nickel,Oxidation
更新于2025-09-23 15:23:52
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Merging Photoredox PCET with Ni-Catalyzed Cross-Coupling: Cascade Amidoarylation of Unactivated Olefins
摘要： A rapid, highly diastereoselective amidoarylation of unactivated olefins was achieved to render medicinally privileged pyrrolidinone structures. Taking advantage of a photoredox proton-coupled electron transfer process, amidyl radicals were obtained from non-prefunctionalized N–H bonds under mild conditions, which were subsequently trapped by pendant olefins, delivering alkyl radicals for nickel-catalyzed cross-coupling. Mechanistic studies revealed the key balance between thermodynamically-driven radical generation and kinetically-driven cyclization, which led to expanding the scope toward urea and carbamate substrates.
关键词： urea,nickel catalysis,carbamate,unactivated olefins,proton-coupled electron transfer,amidoarylation,photoredox catalysis,pyrrolidinone
更新于2025-09-23 15:23:52
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Synthesis, characterization and DFT analysis of new phthalocyanine complexes containing sulfur rich substituents
摘要： Nine new tetrasubstituted metallophthalocyanines (MPc) bearing sulfur rich substituents on peripheral positions were synthesized and fully characterized. The new MPc compounds contain Co2+, Ni2+ and Cu2+. The photochemical and electrochemical properties of the new molecules were investigated. In addition to this investigation, a comparative study took place on the effect of the type of terminal ligand on properties of the MPc compound. Theoretical studies (DFT) were, also carried out in order to support the corresponding experimental results.
关键词： Cobalt,Copper,Nickel,Microwave synthesis,Phthalocyanines,DFT calculations
更新于2025-09-23 15:23:52