The short-range order (SRO) in Pd78Cu6Si16 liquid was studied by high energy x-ray diffraction and ab initio molecular dynamics (MD) simulations. The calculated pair correlation functions at different temperatures agree well with the experimental results. The partial pair correlation functions from ab intio MD simulations indicate that Si atoms prefer to be uniformly distributed while Cu atoms tend to aggregate. By performing structure analysis using Honeycutt-Andersen index, Voronoi tessellation and atomic cluster alignment method, we show that the icosahedron and face-centered cubic SRO increase upon cooling. The dominant SRO is the Pd-centered Pd9Si2 motif, namely the structure of which motif is similar to the structure of Pd-centered clusters in the Pd9Si2 crystal. The study further confirms the existence of trigonal prism capped with three half-octahedra that is reported as a structural unit in Pd-based amorphous alloys. The majority of Cu-centered clusters are icosahedra, suggesting that the presence of Cu is benefit to promote the glass forming ability.
Co 3 O 4 is an excellent catalyst for the thermal decomposition of ammonium perchlorate (AP) due to its spinel structure and more Co 3+ as catalytically active sites. In this work, MCo 2 O 4 (M=Fe, Cu, Ni and Zn) with different Co species substituted with transition metal ion were prepared using triblock copolymer F127 as soft template by solvothermal method. The porous MCo 2 O 4 samples have higher Co 3+ /Co 2+ ratio than Co 3 O 4 , and exhibits better catalytic performance for thermal decomposition of AP. Especially with the addition of FeCo 2 O 4 , the high decomposition temperature (HDT) of AP decreases by an amazing 196.25 °C, showing the most excellent catalytic performance. The activation energy ( E a ) decreases from 290.19 kJ·mol −1 for pure AP to 203.05 kJ·mol −1 , while the reaction rate ( k ) increases from 0.499 s −1 to 1.699 s −1 . Based on the electron transfer theory, the catalytic mechanism and active site of porous MCo 2 O 4 series cobaltate materials are discussed. The results show that the porous FeCo 2 O 4 not only has highest specific surface, but also has the highest Co 3+ / Co 2+ ratio, which suggest that the Co 3+ on octahedral coordination sites is known as the catalytic active site for AP thermal decomposition.
Abstract The development of new energy storage and conversion pathways has gradually freed people from dependence on oil, and improving conversion efficiency and safety is still the mainstream trend in the development of new energy sources, and electrode catalysts have become crucial in solving these problems. At present, precious metal catalysts have good performance, but the scarcity of resources and the high price limit commercialization. Therefore, it is very important to develop a catalyst for commercialization. In this paper, the Pt nanoparticles were successfully loaded on the mesoporous FeCo 2 O 4 nanosheet catalyst by the sodium borohydride (NaBH 4 ) reduction method. The formation of the Pt-O bond results in covalent coupling between Pt and FeCo 2 O 4 . The increase in defect sites also facilitates improved catalytic activity. According to the test results, the ORR process is mainly carried out through the "4-electron reaction" pathway, and the main product is water, and the Tafel slope of Pt-FeCo 2 O 4 (-73 mV dec -1 ) is smaller than that of Pt/C (-84 mV dec -1 ) and FeCo 2 O 4 (-76 mV dec -1 ). The stability of Pt-FeCo 2 O 4 to ORR (After 12 h, only 15.5 % current density loss) is significantly higher than that of commercial Pt/C. Meanwhile, in the OER process, Pt-FeCo 2 O 4 (28.1 mA cm -2 ) has a higher current density than RuO 2 (24.4 mA cm -2 ) and FeCo 2 O 4 (15.1 mA cm -2 ). Therefore, Pt-FeCo 2 O 4 can be used as a bifunctional catalyst to accelerate the ORR and OER processes, which has important theoretical research significance and commercial value.
Difructose anhydride I (DFA-I) can be produced from inulin, with DFA-I-forming inulin fructotransferase (IFTase-I). However, the metabolism of inulin through DFA-I remains unclear. To clarify this pathway, several genes of enzymes related to this pathway in the genome of
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