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Solid-phase hot-pressing of POMs-ZIFs precursor and derived phosphide for overall water splitting
摘要： A facile solid-phase hot-pressing method was applied to prepare bimetallic phosphides on carbon cloth without binder as efficient electrocatalysts for water splitting. High-performance electrocatalyst with high performance for both hydrogen and oxygen evolution reaction is attracting considerable attention in recent years. However, most electrocatalysts are powders and require to deposit on conductive substrates with binders, leading to complicated steps and hindering the improvement of long-term stability. This work exhibits a solid-phase hot-pressing method to prepare polyoxometalates based zeolitic imidazolate frameworks (POMs-ZIFs) precursor on carbon cloth (CC) rapidly and mildly. After phosphidation treatment, nitrogen-doped graphitic carbon layers coated phosphide on CC (CoP/MoP@NC/CC) is synthesized. CoP/MoP@NC/CC has excellent electrocatalytic performance for water splitting due to the synergistic effect of CoP, MoP and as-formed oxide/hydroxide layers. It shows the low overpotentials of 94 mV for HER and 270 mV for OER at the current density of 10 mA cm-2 in alkaline medium, which is superior to most of the reported phosphide-based electrocatalysts. Notably, the ultra-high current density of 1000 mA cm-2 can be reached at the overpotentials of only 475 mV for HER and 657 mV for OER. As both cathode and anode for overall water splitting, CoP/MoP@NC can achieve the current density of 50 mA cm-2 at the cell voltage of 1.71 V. The solid-phase hot-pressing method ensures the tight and uniform growth of the fast nucleating and stable materials on substrate and applies for more electrochemical reactions.
关键词： phosphide,hot-pressing,HER,OER,metal-organic framework
更新于2025-09-23 15:23:52
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Phosphorus incorporation into graphitic material via hot pressing of graphite oxide and triphenylphosphine
摘要： It was shown, that the treatment of graphite oxide (GO) at a temperature of 1000 °C and a static pressure of 500 bar recovers the graphene layers. Addition of triphenylphosphine to GO helps in removal of oxygen during the treatment and allows introducing ca. 0.7 at% of phosphorus in the product. Most phosphorus atoms are bonded with oxygen as the 31P nuclear magnetic resonance spectrum showed. An analysis of the X-ray photoelectron P 2p spectrum additionally found the components corresponding to CeP and PeP bonding. Assembling of phosphorus atoms into nanometer clusters was con?rmed by transmission electron microscopy. Raman spectroscopy and electrical conductivity measurements revealed the n-type doping of graphitic material through the incorporation of phosphorus.
关键词： Triphenylphosphine,XPS,Phosphorus doping,NMR,Hot pressing,Graphite oxide
更新于2025-09-23 15:23:52
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Enhanced dielectric permittivity in surface-modified graphene/PVDF composites prepared by an electrospinning-hot pressing method
摘要： In the present work, the surface-modified graphene (SMG)/poly(vinylidene fluoride) (PVDF) fibrous membranes obtained from the electrospinning were treated by the hot pressing in the laminating mode to form the SMG/PVDF composites. The SMG was prepared by subjecting the graphene oxide to silane modification, NaBH4 reduction, and PVDF grafting in sequence. The successful surface modification of graphene was confirmed by TEM, XPS, Raman spectroscopy, FTIR, WAXD, and TGA. Furthermore, the structures of SMG/PVDF composites fabricated by the electrospinning-hot pressing method were studied by SEM, FTIR, and WAXD, which exhibited the well dispersion of SMG in the PVDF matrix. Finally, the investigation showed that the dielectric permittivities of SMG/PVDF composites increased with the SMG content, which were significantly higher than that of pristine PVDF. The dielectric permittivity of SMG (16 wt.%)/PVDF composite (83.8) at 1000 Hz was found to be ten-fold that of the corresponding value of pristine PVDF (8.3) with a relatively low dielectric loss factor (0.34) and a relatively high thermal conductivity (0.679 W/mK).
关键词： surface-modified graphene/PVDF composite,thermal conductivity.,electrospinning-hot pressing method,dielectric performance
更新于2025-09-23 15:22:29
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Preparation of highly thermally conductive and electrically insulating PI/BNNSs nanocomposites by hot-pressing self-assembled PI/BNNSs microspheres
摘要： Traditional polymer-based thermally conductive composites with randomly distributed fillers always yield an undesired heat removal due to the lack of efficient heat transfer pathways. Thus, realization of rational and ordered distribution of thermally conductive nanofillers in polymer matrix is believed to be significant for obtaining a desirable thermal conductivity. Herein, a series of thermally conductive polyimide/boron nitride nanosheets (PI/BNNSs) composites with a highly ordered BNNSs network have been successfully prepared. For achieving an uniform dispersion and high orientation of BN nanosheets in PI matrix, self-assembled PI/BNNSs complex microspheres were firstly prepared via the van der Waals interaction, and then these complex microspheres were further hot-pressed at the Tg of PI matrix, which rendered the alignment of BNNSs during the deformation of complex microspheres and built an efficient heat transfer pathway. As a consequence, the resultant composites possess a much higher in-plane thermal conductivity up to 4.25 W/mK with 12.4 vol% oriented BNNSs than those of pure PI and random distribution composite (0.85 W/mK for pure PI and 1.3 W/mK for the PI/random BNNSs-12.4). Meanwhile, these nanocomposites present excellent electrically insulating properties, improved dimensional stabilities and good thermal stabilities. This facile method provides a new way to design and fabricate highly thermally conductive PI-based composites for applying in heat dissipation of modern portable and collapsible electronic devices.
关键词： Boron nitride nanosheets,Polyimide,Complex microspheres,Hot-pressing,Filler orientation
更新于2025-09-23 15:19:57
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Aligning ?±a??alumina platelets via uniaxial pressing of ceramica??filled polymer blends for improved sintered transparency
摘要： Uniaxial warm pressing was used to align alumina platelet-filled polyethylene-based copolymer blends. The solids loading (30-40 vol.%) and platelet diameter (1.2 and 11 μm) were varied to compare effects on viscosity, percent reduction, and final alignment. All ceramic-filled thermoplastic polymer blends exhibited pseudoplastic behavior. Crystallographic alignment of green body samples was quantified by the orientation parameter (r) and grain misalignment angle (full width at half maximum, FWHM) obtained from rocking curve analysis. Blends with 11 μm diameter platelets displayed a higher temperature sensitivity constant, better flow properties, and higher alignment compared to blends with 1.2 μm diameter platelets. Optimal samples produced with blends containing 30 vol.% of 11 μm diameter platelets demonstrated an alignment of r = .251 ± .017; FWHM = 11.16° ± 1.16°. A sample with optimal alignment was hot-pressed to transparency and obtained an in-line transmission of 70.0% at 645 nm. The final alignment of this pre-aligned hot-pressed sample (r = .254 ± .008; FWHM = 11.38° ± 0.54°) improved when compared to a non-pre-aligned sample (r = .283 ± .005; FWHM = 13.40° ± 0.38°).
关键词： hot pressing,rheology/rheometry,alumina,optical materials/properties
更新于2025-09-19 17:13:59
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High performance carbon-based planar perovskite solar cells by hot-pressing approach
摘要： A simple yet effective method based on hot-pressing a free-standing carbon film onto adjacent hole transport layer (HTL) is used to fabricate carbon electrode for planar perovskite solar cells (C–PSCs). Due to the thermoplasticity of as-prepared carbon film, the conductivity of the carbon electrode is enhanced by over ten-fold and the adhesion to adjacent layer is dramatically strengthened via this hot-pressing process. By optimizing the pressing temperature, 15.3% of power conversion efficiency (PCE) is obtained for CuSCN based C–PSCs, which is 70% high than the device without heating at the same pressing pressure. The device demonstrates 93% performance retention after being stored in a humid environment (55–70%) without encapsulation over 80 days. This facile fabrication process of PSCs paves a way to facilitate commercialization of the new PV technology.
关键词： Carbon electrode,Hot-pressing,Perovskite solar cells,Conductivity,Temperature
更新于2025-09-19 17:13:59
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Production of a laser textured 316L stainless steel reinforced with CuCoBe + diamond composites by hot pressing: Influence of diamond particle size on the hardness and tribological behaviour
摘要： Two composite blends of CuCoBe and synthetic diamond with different particle sizes, (0.1-0.5 μm and 40-60 μm), were obtained by mechanical alloying and were used as a reinforcement of a laser textured 316L stainless steel in this work. Consolidation/sintering of the powders was conducted by hot pressing. From all the samples studied, the 316L stainless steel reinforced with the CuCoBe + diamond (40-60 μm) composite presented the lowest values of specific wear rate and coefficient of friction (5.83 x 10-7 mm3/N.m and 0.14, respectively), showing the potential of this material in applications where good tribological behaviour is required, e.g. for the fabrication of improved automotive piston rings.
关键词： laser texturing,Diamond composites,tribological behaviour,hot pressing
更新于2025-09-12 10:27:22