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[en] In this paper, highly dense platinum (Pt) nanocatalysts were successfully deposited on the hydrophilically-treated nano/micro carbon supports with an ethanol (EtOH) immersion pretreatment and an acidic treatment for the performance improvement of methanol oxidation reaction (MOR). In order to thoroughly immerse the three-dimensional, interwoven structures of the carbon cloth fibers with a 6 M sulfuric acid surface modification, which increasing more oxygen-containing functional groups on the surfaces of the carbon supports, the EtOH immersion pretreatment of the carbon supports was utilized prior to the sulfuric acid treatment. Subsequently, Pt catalysts were reduced on the modified carbon supports by a homemade open-loop reduction system (OLRS)  For comparisons, carbon cloth (CC) and carbon nanotube on CC (CNT/CC) supports were employed with and without EtOH immersion pretreatments before Pt catalyst reduction. In the cyclic voltammetry (CV) curves, the electrosorption charges of hydrogen ion (QH) and the peak current density (IP) of the fabricated Pt/CC and Pt/CNT/CC electrodes with the EtOH immersion pretreatments can efficiently be enhanced due to more active Pt sites for electrocatalytic reactions
[en] We report in this article a simple route for synthesizing small-sized silver/gold core–shell (Ag/Au) on multi-walled carbon nanotube (MWCNT) surfaces via galvanic replacement of Ag nanoparticles (Ag NPs). The Raman response of MWCNT decorated with Ag/Au was investigated under surface-enhanced Raman scattering. A relatively weak Raman signal enhancement of the tube was observed due to the large interparticle distance between neighboring small-sized nanostructures. Ag/Au gives better enhancing capability than the starting Ag because of the synergistic effect between the localized electric field of the Ag core, and the Au shell separated with a hollow space formed during the galvanic replacement reaction. Furthermore, the Ag/Au was removed from the CNT surfaces via sonication with 1-octanethiol (OT), releasing unreplaced Ag NPs and Au nanobowls (Au NBs) with 1.3 and 7.6 nm of mean diameter sizes, respectively. The production of these fine-sized nanocomposites (Au/Ag NCs) allowed us to investigate their luminescent property. Interestingly, the separated Au/Ag NCs (i.e., the mixture of Au NBs and unreplaced Ag NPs) exhibit fluorescence behavior that may be useful for single-molecule detection. Our technique provides the synthesis of smallest dimension of Au NBs so far simply achieved by wet-chemical process using MWCNTs as templates.
[en] Graphical abstract: Schematic diagram for Li-rich oxide (Li_1_._2Ni_0_._2Mn_0_._6_0O_2) coated with Li_0_._7_5La_0_._4_2TiO_3 (LLTO) solid ionic conductor. - Highlights: • Li_1_._2Ni_0_._2Mn_0_._6_0O_2/C composite material was prepared by one-pot solid-state method. • 1D a-MnO_2 nanowires and microsphere hollow b-Ni(OH)_2 were prepared by a hydrothermal method. • 1 wt.%LLTO-coated composite showed the best performance among samples. • LLTO layer not only improves the ionic transport of Li-rich oxide material, but also prevent Li-rich material corrosion. - Abstract: Li-rich (spray-dried (SP)-Li_1_._2Ni_0_._2Mn_0_._6_0O_2) composite materials were prepared via two-step ball-mill and spray dry methods by using LiOH, α-MnO_2, β-Ni(OH)_2 raw materials. Two raw materials of α-MnO_2 nanowires and microsphere β-Ni(OH)_2 were synthesized by a hydrothermal process. In addition, Li_0_._7_5La_0_._4_2TiO3 (LLTO) fast ionic conductor was coated on SP-Li_1_._2Ni_0_._2Mn_0_._6_0O_2 composite via a sol–gel method. The properties of the LLTO-coated SP-Li_1_._2Ni_0_._2Mn_0_._6_0O_2 composites were determined by X-ray diffraction, scanning electron microscopy, micro-Raman, XPS, and the AC impedance method. The discharge capacities of 1 wt.%-LLTO-coated SP-Li_1_._2Ni_0_._2Mn_0_._6_0O_2 composites were 256, 250, 231, 200, 158, and 114 mAh g"_−"_1 at rates of 0.1, 0.2, 0.5, 1, 3, and 5C, respectively, in the voltage range 2.0–4.8 V. The 1 wt.%-LLTO-coated Li-rich oxide composite showed the discharge capacities of up to 256 mAh g"−"1 in the first cycle at 0.1C. After 30 cycles, the discharge capacity of 244 mAh g"−"1 was obtained, which showed the capacity retention of 95.4%.
[en] Highlights: • The LiFePO4/porous graphene oxide/C was prepared by a hydrothermal method and a spray dry process. • The porous graphene oxide was prepared through an activation method. • The discharge capacity of the SP-LFP/1%PGO/C is 107 mAh g−1 after 1000 cycles at 10C rate. • The SP-LFP/PGO/C material shows promising candidate for high-power Li-ion battery in EV. - Abstract: A 3D spray-dried micro/mesoporous LiFePO4/porous graphene oxide/C (denoted as SP-LFP/PGO/C) composite material is synthesized via a three-step process, i.e., hydrothermal process, carbon coating, and spray dry method in sequence. The 2D porous graphene oxide (denoted as PGO) material is first prepared through an activation method. The galvanostatic charge-discharge measurements of LFP composites without graphene oxide, with 1 wt% graphene oxide, and 1 wt% PGO are conducted in the potential range of 2–3.8 V at various rates (0.1–10C). It is revealed that the SP-LFP/PGO/C material shows the best performance among three samples. The discharge capacities of the SP-LFP/PGO/C composites are observed to 160, 152, 151, 149, 144, 139, 127 mAh g−1 at 0.1C, 0.2C, 0.5C, 1C, 3C, 5C and 10C rate. In particular, the discharge capacity of the SP-LFP/PGO/C composite with 1 wt% PGO is 107 mAh g−1 after 1000 cycles at a 10C rate, and its capacity retention is ca. 97%. It is due to the unique structural and geometrical feature of SP-LFP/PGO/C composite, there the diamond-like (rhombus) LFP nanoparticles are embedded in porous GO matrix which forming a porous three-dimensional network for fast electronic and ionic transport channels.