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排序方式: 共有118条查询结果,搜索用时 31 毫秒
31.
《International Journal of Hydrogen Energy》2019,44(31):16378-16386
Exploring robust, highly efficient, and cost-effective non-noble metal electrocatalysts for replacing Pt in hydrogen evolution reaction (HER) is of great significance. In this study, we skillfully synthesized binary transition-metal (i.e., nickel and iron) phosphosulfides on nickel foam (NiFeSP/NF) via a sulfuration/phosphorization treatment of bimetallic layered double hydroxides (LDH). Taking the advantage of the presence of active heterointerfaces among Ni2P, Ni3S2, and FeS2, the NiFeSP/NF catalyst, which was advantageous of the highly exposed active sites, exhibited an extraordinary catalytic activity in HER—an overpotential of 70 mV at a current density of 10 mA cm−2 and a Tafel slope of 69 mV dec−1, outperforming most of the existing counterparts. Moreover, NiFeSP/NF catalysts demonstrated favorable long-term catalytic stability for 10 h. We contributed this superior catalytic activity to the characteristic attributes of NiFeSP/NF, which could be stemmed from its exquisite catalyst design: (i) the co-occurrence of highly HER-favored crystalline Ni2P, Ni3S2, and FeS2 in bimetallic phosphosulfides and (ii) the existence of multi-functional phase interfaces among Ni2P, Ni3S2, and FeS2 in the NiFeSP/NF hierarchical structure. The present study exemplified an effective strategy for designing HER-favored bimetallic phosphosulfides and provided the scientific base for the insight into the catalytic nature of multi-metallic phosphosulfides. 相似文献
32.
33.
《Inorganic chemistry communications》2007,10(6):661-665
Two copper(II) complexes, Cu2{3,5-(NO2)2sal}2(2,2′-bipy)2 · 0.5H2O (1) and [Cu2{3,5-(NO2)2sal}2(4,4′-bipy)(H2O)2]n (2) (3,5-(NO2)2sal = 3,5-dinitrosalicylate, 2,2′-bipy = 2,2′-bipyridine, 4,4′-bipy = 4,4′-bipyridine), were synthesized by hydrothermal reactions and characterized by single crystal X-ray analysis. There are discrete cyclic binuclear structure in 1 and 2D herringbone-like network structure in 2, although bridging ligand 3,5-(NO2)2sal in 1 and 2 has same coordination model. Variable temperature magnetic measurement reveals small ferromagnetic interactions in complex 1. 相似文献
34.
《Catalysis communications》2007,8(3):329-334
Unsupported manganese oxide catalysts with amorphous phase were prepared by three methods, and their activities for SCR of NOx with ammonia were investigated in the presence of O2. The results showed the catalysts have superior low temperature activity, and the NOx conversion is about 98% at 80 °C, and nearly 100% NOx conversion between 100 and 150 °C. Due to competing adsorption with the reactant, H2O has slight impact on the activity. The activity was suppressed with coexisting of SO2, however the deactivation of SO2 is reversible. The excellent low temperature catalytic activity of amorphous MnOx catalysts is mainly due to their amorphous phase and high specific areas. 相似文献
35.
36.
Giulia Spina Guillaume Bonnefont Paola Palmero Gilbert Fantozzi Jérome Chevalier Laura Montanaro 《Journal of the European Ceramic Society》2012,32(11):2957-2964
A fine-grained (330 nm) yttrium aluminium garnet (YAG) ceramic, presenting a non-negligible transparency (66% RIT at 600 nm), was obtained by spark plasma sintering. The YAG powder was manufactured by co-precipitation, starting from a yttrium and aluminium chlorides solution. A soft precursor was obtained, whose phase evolution was studied by X-ray diffraction. Calcined powders were dispersed by either ball milling or by ultrasonication and then subjected to spark plasma sintering at several temperatures (1200–1400 °C) and for a reduced time (15 min). It is shown that the dispersion method plays a key role in enhancing the optical characteristics of YAG ceramics, in order to obtain a material with a small grain size, transparent in both the visible and the infrared range. 相似文献
37.
《Carbon》2015
At present, Pt nanoparticle catalysts in fuel cells suffer from aggregation and loss of chemical activity. In this work, graphdiyne, which has natural porous structure, was proposed as substrate with high adsorption ability to stabilize Pt nanoparticles. Using multiscale calculations by ab initio method and the ReaxFF potential, geometry optimizations, molecular dynamics simulations, Metropolis Monte Carlo simulations and minimum energy paths calculations were performed to investigate the adsorption energy and the rates of desorption and migration of Pt nanoparticles on graphdiyne and graphene. According to the comparison between graphdiyne and graphene, it was found that the high adsorption ability of graphdiyne can avoid Pt nanoparticle migration and aggregation on substrate. Then, simulations indicated the potential catalytic ability of graphdiyne-Pt-nanoparticle system to the oxygen reduction reaction in fuel cells. In summary, graphdiyne should be an excellent material to replace graphite or amorphous carbon matrix for stabilizing Pt nanoparticle catalysts. 相似文献
38.
Manickam Sasidharan Nanda Gunawardhana Masaki Yoshio Kenichi Nakashima 《Materials Research Bulletin》2012,47(9):2161-2164
Nb2O5 hollow nanospheres of average diameter ca. ~29 nm and hollow cavity size ca. 17 nm were synthesized using polymeric micelles with core–shell–corona architecture under mild conditions. The hollow particles were thoroughly characterized by transmission electron microscope (TEM), X-ray diffraction (XRD), infrared spectroscopy (FTIR), thermal (TG/DTA) and nitrogen adsorption analyses. Thus obtained Nb2O5 hollow nanospheres were investigated as anode materials for lithium ion rechargeable batteries for the first time. The nanostructured electrode delivers high capacity of 172 mAh g?1 after 250 cycles of charge/discharge at a rate of 0.5 C. More importantly, the hollow particles based electrodes maintains the structural integrity and excellent cycling stability even after exposing to high current density 6.25 A g?1. The enhanced electrochemical behavior is ascribed to hollow cavity coupled with nanosized Nb2O5 shell domain that facilitates fast lithium intercalation/deintercalation kinetics. 相似文献
39.
《Ceramics International》2017,43(14):10673-10682
The present work aims to establish a correlation between the characteristics of YAG and Er:YAG commercial powders produced by two different synthesis routes and sintered ceramic microstructures and their optical aspect by taking into account the influence of pressure applied during the Spark Plasma Sintering (SPS) process. Physical and chemical characteristics of the powders were compared using various techniques such as SEM, XRD, laser diffraction and chemical analyses. Their behaviours were evaluated through a rheological study, compressibility tests and dilatometry cycles using SPS. This paper pinpoints the most important powder features which influence the optical quality of YAG and Er:YAG ceramics. The optical quality is mainly affected by the porosity, related to powder characteristics that affect particle rearrangement, densification and grain growth. The applied pressure induces microstructural heterogeneities depending on the starting material used and resulting in core-shell aspects of sintered ceramics. 相似文献
40.
Shuguan Li Fang Chen Shengqi Chu Zeyu Zhang Jindi Huang Shengyao Wang Yibo Feng Cong Wang Hongwei Huang 《Small (Weinheim an der Bergstrasse, Germany)》2023,19(5):2203559
Photocatalytic CO2 reduction is severely limited by the rapid recombination of photo-generated charges and insufficient reactive sites. Creating electric field and defects are effective strategies to inhibit charge recombination and enrich catalytic sites, respectively. Herein, a coupled strategy of ferroelectric poling and cationic vacancy is developed to achieve high-performance CO2 photoreduction on ferroelectric Bi2MoO6, and their interesting synergy-compensation relationship is first disclosed. Corona poling increases the remnant polarization of Bi2MoO6 to enhance the intrinsic electric field for promoting charge separation, while it decreases the CO2 adsorption. The introduced Mo vacancy (VMo) facilitates the adsorption and activation of CO2, and surface charge separation by creating local electric field. Unfortunately, VMo largely reduces the remnant polarization intensity. Coupling poling and VMo not only integrate their advantages, resulting in an approximately sevenfold increased surface charge transfer efficiency, but also compensate for their shortcomings, for example, VMo largely alleviates the negative effects of ferroelectric poling on CO2 adsorption. In the absence of co-catalyst or sacrificial agent, the poled Bi2MoO6 with VMo exhibits a superior CO2-to-CO evolution rate of 19.75 µmol g−1 h−1, ≈8.4 times higher than the Bi2MoO6 nanosheets. This work provides new ideas for exploring the role of polarization and defects in photocatalysis. 相似文献