JOURNAL OF POWER SOURCES
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2016
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IF 6.333
Jian Xie,Liang Tong,Liwei Su,Yawei Xu,Lianbang Wang,Yuanhao Wang
Yolk-shell Si@void@C nanostructure has greatly improved the low Li + /electron conductivity and buffered the huge volume variation of Si, whereas the surface corrosion and passivation of the Si yolks in electrolytes still limit the lithium storage capability. Herein, core-shell yolk-shell Si@C@void@C nanohybrids were proposed and successfully prepared for the first time. Compared with Si@void@C, the newly-proposed structure introduced core-shell Si@C nanoparticles as the yolks instead. Such extra carbon shell can not only decrease the electrical resistance between Si yolks and hollow carbon shells but also effectively protect Si yolks from electrolyte corrosion, i.e. , the formation of Li 2 SiF 6 layers on Si surface confirmed by X-ray diffraction and transmission electron microscopy . As a result, the Si@C@void@C electrodes exhibited remarkably enhanced reversible capacity, cycling stability (∼1366 mA h g −1 after 50 cycles at 500 mA g −1 , with a capacity retention of ∼71% with respect to the initial reversible capacity of 1910 mAh g −1 at 100 mA g −1 ), and rate performance (with a capacity retention of ∼60% at 4000 mA g −1 ). This work shows the paramount role of the inner carbon shell of Si@C@void@C in limiting the electrolyte corrosion and probably improving the electronic conductivity .
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SEPARATION AND PURIFICATION TECHNOLOGY
·
2015
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IF 3.091
Lixin Xing,Ningning Guo,Yatao Zhang,Haoqin Zhang,Jindun Liu
Silica spheres in nanoscale were prepared via sol–gel method and then sodium 4-styrene sulfonate was grafted onto the surfaces of SiO 2 (PSS-SiO 2 ) by surface-initiated atom transfer radical polymerization (SI-ATRP). Then, a negatively charged loose SiO 2 -PSS/polyethersulfone (PES) nanofiltration membrane with high flux was fabricated via phase inversion method. FT-IR and TEM results showed that SiO 2 nanoparticles were synthesized and modified successfully. GPC results further proved the “living”/controlled behavior of SI-ATRP. The morphology, hydrophilicity of the membranes were investigated by SEM, static water contact angle and water ratio. The results revealed that the surface hydrophilicity and water permeability of hybrid membranes were greatly improved after adding SiO 2 -PSS and thus may enhance fouling resistance to a certain extent. The salt permeation and separation of dye/salt mixture of the hybrid membranes were significantly superior to the pure PES membrane, and the order of permeation for different salt solutions was NaCl > MgCl 2 > MgSO 4 > Na 2 SO 4 . When the content of SiO 2 -PSS was 3.0 wt%, the hybrid membrane showed optimal performance with IEC value of 0.07 mmol/g and pure water flux of 269.5 L m −2 h −1 and the rejections for all types of salts declined to under 11%. The above results indicated that SiO 2 -PSS incorporated into PES matrix played an important role in enhancing the performance of NF membranes, which may possess a significant impact on the application in dye purification and desalination.
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APPLIED CATALYSIS B-ENVIRONMENTAL
·
2024
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IF 20.2
Jingyi Wang,Guangzhi He,Chunying Wang,Xudong Chen,Xiaofeng Liu,Yaobin Li,Wenpo Shan,Hong He
Modulating the electronic metal-support interaction (EMSI) is one of the effective means to promote catalytic activity because it can adjust the electron occupancy of the d -band of noble metals, further facilitating the activation of reactants. Herein, we prepared a Pt/SiO 2 catalyst with an ultralow Pt loading of 0.05% and found that its catalytic activity in HCHO oxidation outperformed that of the Pt/TiO 2 counterpart, owing to the EMSI effect between Pt and SiO 2 . On this basis, the alkali metal Na was used as a promoter, and the formation of highly active Pt-O x (OH)-Na clusters enabled the complete oxidation of HCHO at room temperature. With ultralow Pt loading, the Pt-Na/SiO 2 catalyst reduces the cost of practical application remarkably. In situ DRIFTS and DFT calculations confirmed that the reaction pathways were distinct on Pt/SiO 2 and Pt-Na/SiO 2 . Specifically, on Pt-Na/SiO 2 , the reaction follows the mechanism of the direct degradation of formate species with the assistance of active hydroxyls; while on Pt/SiO 2 , CO is the only intermediate formed by the dehydrogenation of HCHO, due to the lack of active hydroxyls. These findings provide new insights into the reaction pathway of HCHO oxidation.
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CERAMICS INTERNATIONAL
·
2024
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IF 5.1
Xuan Hou,Shuhua Ma,Xiaohui Wang,Ruiping Liu,Muhammad Ibrahim
In the study of hydrothermal conversion of fly ash to calcium silicate hydrates (C–S–H), the concentration of Ca and Si in the liquid phase plays a vital role in determining the hydrothermal transformation results. This paper selected a fly ash as a research object, which can leach a high Si concentration into the solution in the hydrothermal process even in a slight alkaline solution, based on a new finding when studying the alkali dissolution kinetics of different fly ashes. To explore the effects of Ca and Si concentrations in the liquid phase on the hydrothermal transformation of fly ash to tobermorite or katoite, Na 2 SiO 3 (Na 2 O·xSiO 2 ·yH 2 O) and CaSO 4 were used to change the concentration of Si and Ca in the liquid in the hydrothermal system. Characterization methods such as XRD, SEM, infrared spectroscopy, and solid-state nuclear magnetic resonance indicated that a little more concentration of Si can promote the transformation from fly ash to tobermorite and persuade the conversion of the Si–O tetrahedron in C–S–H from Q 2 to Q 3 and Q 4 . However, too high a liquid Si concentration made the hydrothermal product change to colloidal calcium silicate. On the other hand, a high Ca concentration in the liquid was found to lead to the conversion of the hydrothermal product from tobermorite to katoite. According to the above results, the deep transformation from fly ash to tobermorite under the conditions of a low temperature of 160 °C and no extra alkali addition was achieved by the induction of a small quantity of Na 2 SiO 3 .
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JOURNAL OF THE ELECTROCHEMICAL SOCIETY
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2025
·Vol. 172
·期 3
·030507
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IF 3.3
Junchao Sun,Jing Jiang,Jianjiang He,Lan Cao,Qingfu Wang
The silicon-carbon (Si/C) anode offers a significantly higher theoretical specific capacity compared to conventional graphite anodes, while also demonstrating reduced volume expansion and enhanced cycling stability compared to pure silicon anodes. Consequently, Si/C anodes have attracted considerable attention as promising candidates for next-generation high-energy lithium-ion battery anode materials. However, volume expansion remains a critical challenge, leading to the detachment of active materials from the current collector (copper foil) and adversely affecting cycling performance. In this study, we introduce diglycidyl ether (EG) as a cross-linking agent to synthesize a novel three-dimensional cross-linked carboxymethyl chitosan (CCS-EG) binder for Si/C600 anodes (theoretical specific capacity of 600 mAh g−1 at 0.1 C). Electrochemical testing reveals that the CCS-EG binder significantly improves the cycling stability of the Si/C anode, achieving a capacity retention rate of 88.68% after 400 cycles at a current density of 0.5 C, compared to only 67.71% for the anode using the linear carboxymethyl chitosan binder. Furthermore, CCS-EG offers advantages such as low cost, ease of preparation, and environmental sustainability, making it a promising candidate for commercialization as a binder in next-generation high-energy lithium-ion batteries.
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Journal of Materials Research and Technology-JMR&T
·
2024
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IF 6.2
Taehyeob Im,Kwiyoung Lee,Jonghyeok Ahn,Minjong Kim,Dongsup Lee,Jai-Sung Lee,Jongryoul Kim,Caroline Sunyong Lee
Fe-4.5Si-based soft magnetic composite (SMC) cores suitable for high-frequency applications were studied using ball milling and furnace sintering. Through ball milling, Fe-4.5Si powder was coated with Mg(OH) 2 nanoparticles to form a uniform insulation layer, introducing a novel method to optimize the furnace sintering process by adding H 3 BO 3 and SiO 2 to the insulation layer. Mg(OH) 2 nanoparticles effectively coated on Fe-4.5Si powder through ball milling formed MgO and Mg 2 SiO 4 double insulation layers after heat treatment, which provided stable insulation layer and minimized core loss in high-frequency regions up to 1 MHz. Furthermore, applying a 7% MgO–B 2 O 3 –SiO 2 insulation for sintering at 1100 °C resulted in an increase in permeability to 68, starting from its initial value of 28 at 100 kHz, while porosity decreased from 18.1% to 9.3%, minimizing the degradation of the insulation layer. After sintering, phase analysis of the MgO–B 2 O 3 –SiO 2 insulation revealed the presence of Mg 2 B 2 O 5 , MgSiO 3 , and a liquid phase, indicating densification of the cores owing to the diffusion reaction and liquid phase sintering among MgO–B 2 O 3 –SiO 2 . Therefore, the ball-milling and furnace sintering processes shown in this study provide an effective solution for increasing density of Fe-4.5Si powder-based SMC cores to develop magnetic cores suitable for high-frequency applications.
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COMPOSITES PART A-APPLIED SCIENCE AND MANUFACTURING
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2025
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IF 8.9
Wei-Chen Zhou,Shuang He,Ze-Yong Zhao,Cong Deng,Yu-Zhong Wang
The intrinsic flammability of polypropylene (PP)—a pivotal thermoplastic in automotive engineering—poses a significant safety challenge amid the accelerating shift toward new energy transportation. However, achieving high flame retardancy without compromising mechanical performance remains a critical challenge due to the poor compatibility between non-polar PP and polar flame retardants—a dilemma known as the “performance paradox.” In this study, we report the design of a novel flame retardant, BAPPAM, featuring adaptive interfaces, constructed through the ionic complexation of hyperbranched semi-aromatic polyamide-amine (BA-PAMAM) with phytic acid, followed by sol–gel-based silane encapsulation to yield a phosphorus–nitrogen–silicon hybrid architecture. Benefiting from the synergistic effects among P, N, and Si elements, BAPPAM endows PP composites with outstanding flame retardancy—achieving a limiting oxygen index of 28.5 %, UL-94V-0 rating, and effective suppression of heat release (86 % reduction in peak heat release rate and 69 % decrement in total heat release) and smoke emission (72 % decline in peak smoke production rate and 67 % slippage in total smoke production) at a 20 wt% loading. Remarkably, the adaptive interfaces formed by BAPPAM accommodate mechanical deformation under stress, affording a high elongation at break (up to 453.4 %) comparable to pure PP, along with enhancements of 41.2 % in Young’s modulus (1440 MPa) and 11.2 % in impact strength (3.9 kJ/m 2 ). This work pioneers a novel interfacial engineering strategy that reconciles fire safety with mechanical robustness, offering a solution for the next generation of high-performance, flame-retardant polyolefin composites.
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CHEMICAL ENGINEERING JOURNAL
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2025
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IF 13.2
Yu Huang,Guoping Zhu,Zhennan Wang,Yadong Wang,Zongmin Zhu
This study designed and synthesized a novel phosphorus silicon synergistic flame retardant PDD. Only adding 1 wt% PDD can achieve excellent UL-94 V-0 flame-retardant rating for PLA composite, and the limit oxygen index (LOI) can be increased to 26.8 %. At the same time, the thermal stability and crystallinity of composites are significantly improved. The results of the cone calorimeter test show that compared with pure PLA, PLA/1 % PDD reduces the peak heat release rate (pHRR), total heat release (THR), and peak of CO 2 release rate (pCO 2 P) by 38.2 %, 42.9 %, and 26.6 %, respectively. It is worth noting that PDD not only enhances the tensile strength and impact toughness of PLA composites, but also accelerates their chemical degradation process in alkaline environments through ester bond hydrolysis promoted by phosphorus silicon synergy. This work has achieved a multifunctional integration of mechanical properties, efficient flame retardancy, and chemical degradation, providing new ideas for the development of multi-functional biodegradable polymers.
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JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
·
2021
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IF 8.067
Chaoye Zhu,Yao Zhang,Ziqiang Wu,Zhihong Ma,Xinli Guo,Fuyi Guo,Jiakun Zhang,Yushu Li
Both silicon and tin are promising anodes for new generation lithium ion batteries due to high lithium storage capacities (theoretically 4200 mA h g −1 and 992 mA h g -1 , respectively). However, their large volumetric expansions (both are above 300 %) usually lead to poor cycling stability. In this case, we synthesized closely packed Si@C and Sn@C nano-particles anchored by reduced graphene oxide (denoted as Si@C/Sn@C/rGO) by the way of solution impregnation and subsequent hydrogenation reduction. Sn particles with a diameter of 100 nm are coated by carbon and surrounded by Si@C particles around 40 nm in average diameter through the high-resolution transmission electron microscopy. Expansions of Si and Sn are alleviated by carbon shells, and reduced graphene oxide sheets accommodate their volume changes. The prepared Si@C/Sn@C/rGO electrode delivers an enhanced initial coulombic efficiency (78 %), rate capability and greatly improved cycle stability (a high reversible capacity of nearly 1000 mA h g −1 is achieved after 300 cycles at a current density of 1000 mA g −1 ). It can be believed that packing Sn@C nano-particles with Si@C relieves the volume expansion of both and releases the expansion stresses. Sn@C particles enhance anode process kinetics by reducing charge transfer resistance and increasing lithium ion diffusion coefficient . The present work provides a viable strategy for facilely synthesizing silicon-tin-carbon composite anode with long life.
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GEOCHIMICA ET COSMOCHIMICA ACTA
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2009
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IF 4.235
Sean A. Shaw,Derek Peak,M. Jim Hendry
Although widely investigated in relation to acid mine drainage systems at pH > 1.0, we know little about the impact of sulfuric acid (H 2 SO 4 ) on the geochemistry and mineralogy of clays at pH < 1.0 (including negative pH values). Thus, laboratory batch experiments were conducted on three mixed clay samples with different mass ratios of phyllosilicates (smectite, illite , and kaolinite) to investigate the impact of H 2 SO 4 from pH 1.0 to −3.0 for exposure periods of 14, 90, 180, and 365 days. Si and Al K- and L 2,3 -edge X-ray absorption near edge structure (XANES) spectroscopy were employed on these samples to determine the chemical and structural changes that occur during acidic dissolution of phyllosilicates that cannot be distinguished using X-ray diffraction analyses. A series of silicate, phyllosilicate, and Al-bearing standard compounds were also studied to provide an explanation for the observed changes in the clay samples. The Si XANES results indicated the preferential dissolution of the phyllosilicates (pH ⩽ 1.0, t ⩾ 14 d), the persistence of quartz even at pH ⩾ −3.0 and t ⩾ 365 d, and the formation of an amorphous silica-like phase that was confined to the surface layer of the altered clay samples at pH ⩽ 0.0 and t ⩾ 90 d). Al XANES results demonstrated dissolution of Al-octahedral layers (pH ⩽ 1.0, t ⩾ 14 d), the persistence of four-fold relative to six-fold coordinated Al, and the precipitation of an Al-SO 4 -rich phase (pH ⩽ −1.0, t ⩾ 90 d). An existing conceptual model of phyllosilicate dissolution under extremely acidic conditions was modified to include the results of this study.
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Environmental Science-Nano
·
2020
·Vol. 7
·期 10
·2982-2994
·
IF 7.683
Weijian Duan,Jinglei He,Ziliang Wei,Zongren Dai,Chunhua Feng
The heteroatom-doped, carbon-activated peroxymonosulfate (PMS) system proceeding via the non-radical oxidation pathway involving singlet oxygen (1O2) represents a promising advanced oxidation process (AOP) due to the resistance of 1O2 to background anions in solution. However, the performance level of pollutant removal is not yet satisfied, and the mechanism of 1O2 generation remains elusive. Herein, we report the development for the first time of a unique Si-engaged heteroatom (i.e., N)-doped carbon (Si/N–C) nanomaterial for PMS activation, which exhibits outstanding performance in the removal of various kinds of pollutants and an appreciably wide working pH range of 2.5 to 11. Taking rhodamine B (RhB) as an example, the Si/N–C@PMS system achieved a much higher reaction rate (0.64 min−1) than the Si–C (0.047 min−1), N–C (0.017 min−1), SiO2 (0.021 min−1), and Co3O4 (0.026 min−1; a standard catalyst) systems. In addition, the results of electron spin resonance (ESR) and scavenging experiments solidly support the conclusion that the mechanism of 1O2 generation in this system is via the recombination of superoxide radicals O2˙−, a pathway seldom reported for metal-free, catalyst-activated PMS systems. More importantly, we observed apparent inhibition effects of the anions (e.g., HCO3−, HPO42−, and PO43−) on the degradation performance, inconsistent with many previous reports suggesting that the 1O2-mediated oxidative system possesses a high selectivity toward pollutant degradation in the presence of these anions. Further studies with the anions, including Cl−, HCO3−, and HxPO4(3−x) (x = 0, 1, 2), suggest that the reaction between O2˙− and these anions is the main reason for the abnormal salt effect. This work will deepen the understanding of 1O2 formation via the intermediate of O2˙− and provide a new insight into its salt resistance capacity.
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RSC Advances
·
2017
·Vol. 7
·期 58
·36697-36704
·
IF 3.108
Lingzhi Qian,Jin-Le Lan,Mengyao Xue,Yunhua Yu,Xiaoping Yang
SiOx-based anodes have attracted tremendous attention owing to their low cost, higher theoretical capacity than graphite and lower volume expansion than pure silicon. In this work, a simple and cost-effective two-step ball-milling method was proposed to fabricate Si/SiOx/C composites by using commercial SiO and graphite carbon as raw materials. The two-step ball-milling synthesis of the Si/SiOx/C composites can avoid the generation of an inert SiC phase and realize the uniform dispersion of Si/SiOx in graphite carbon, which offers good electrical conductivity and relieves the volume expansion of the Si/SiOx phase. Owing to the synergistic effect of the Si/SiOx phase and the graphite carbon, the typical Si/SiOx/C electrode exhibits a stable and high capacity of 726 mA h g−1 after 500 cycles at a current density of 0.1 A g−1 with a capacity retention of 82%. The two-step ball-milling preparation of the Si/SiOx/C composite provides a facile approach to fabricate high-performance SiOx-based anode materials.
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危险品化学品经营许可证（带存储）