Three-dimensional graphene network is a promising structure for improving both the mechanical properties and functional capabilities of reinforced polymer and ceramic matrix composites. However, ...direct application in a metal matrix remains difficult due to the reason that wetting is usually unfavorable in the carbon/metal system. Here we report a powder-metallurgy based strategy to construct a three-dimensional continuous graphene network architecture in a copper matrix through thermal-stress-induced welding between graphene-like nanosheets grown on the surface of copper powders. The interpenetrating structural feature of the as-obtained composites not only promotes the interfacial shear stress to a high level and thus results in significantly enhanced load transfer strengthening and crack-bridging toughening simultaneously, but also constructs additional three-dimensional hyperchannels for electrical and thermal conductivity. Our approach offers a general way for manufacturing metal matrix composites with high overall performance.
Although they are widely used as cocatalysts in promoting photocatalysis, practical application of noble metals is limited by their high cost and rarity. Development of noble‐metal‐free cocatalysts ...is thus highly demanded. Herein titanium carbide (Ti3C2) MXene is shown to be a highly efficient noble‐metal‐free cocatalyst with commercial titania (P25) for photocatalytic CO2 reduction. Surface alkalinization of Ti3C2 dramatically enhances the activity; the evolution rates of CO (11.74 μmol g−1 h−1) and CH4 (16.61 μmol g−1 h−1) are 3‐ and 277‐times higher than those of bare P25, respectively. The significantly enhanced activity is attributed to the superior electrical conductivity and charge‐carrier separation ability, as well as the abundant CO2 adsorption and activation sites of surface‐alkalinized Ti3C2 MXene, indicating its promise as a highly‐active noble‐metal‐free cocatalysts for photocatalytic CO2 reduction.
Ti3C2 MXene is used as a cocatalyst to boost the photocatalytic activity of titania (P25) for CO2 reduction into hydrocarbon solar fuels. Surface alkalinization of Ti3C2 dramatically enhances the activity and, especially, the selectivity for CH4 evolution. The high intrinsic electrical conductivity and strong CO2 adsorption/activation capability of this MXene could account for its enhanced photocatalytic activity.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
In the past few decades, great effort has been made toward the preparation and development of advanced transition metal dichalcogenide (TMD) materials for anodes of alkali metal ion batteries ...(AMIBs). However, their electrochemical performance is still severely impaired by structural aggregation and fracture during the conversion reaction. To address these issues, various methodologies for the fabrication of hierarchical and hybrid nanostructures, with optimization of materials and electrodes, have been fully investigated and reviewed. As regards tuning the TMD-based materials, extensive efforts have been undertaken toward optimization of their intrinsic structure at the atomic level, including surface defects, interlayer spacing expansion, phase control, alloying, and heteroatom doping. However, the design strategies and methods to manipulate the intrinsic structures and electrochemical mechanisms in AMIBs have not been fully summarized. This review provides a well-timed and critical appraisal of recent advances in the engineering of TMDs at the atomic level for AMIBs, by combining computational and experimental approaches. The correlation between these strategies and electrochemical performance is highlighted. The challenges and opportunities in this research field are also outlined. We expect that this review would be beneficial for improving the overall knowledge on the charge storage mechanisms in TMDs and for pointing out the importance of intrinsic structure engineering for enhancing the performance of TMDs in energy storage.
This review provides enriched information for understanding the charge storage mechanisms of transition metal dichalcogenides (TMDs), as well as the importance of intrinsic structure engineering for enhancing the performance of TMDs in energy storage.
A facile and scalable in situ synthesis strategy is developed to fabricate carbon-encapsulated Fe3O4 nanoparticles homogeneously embedded in two-dimensional (2D) porous graphitic carbon nanosheets ...(Fe3O4@C@PGC nanosheets) as a durable high-rate lithium ion battery anode material. With assistance of the surface of NaCl particles, 2D Fe@C@PGC nanosheets can be in situ synthesized by using the Fe(NO3)3·9H2O and C6H12O6 as the metal and carbon precursor, respectively. After annealing under air, the Fe@C@PGC nanosheets can be converted to Fe3O4@C@PGC nanosheets, in which Fe3O4 nanoparticles (∼18.2 nm) coated with conformal and thin onion-like carbon shells are homogeneously embedded in 2D high-conducting carbon nanosheets with a thickness of less than 30 nm. In the constructed architecture, the thin carbon shells can avoid the direct exposure of encapsulated Fe3O4 to the electrolyte and preserve the structural and interfacial stabilization of Fe3O4 nanoparticles. Meanwhile, the flexible and conductive PGC nanosheets can accommodate the mechanical stress induced by the volume change of embedded Fe3O4@C nanoparticles as well as inhibit the aggregation of Fe3O4 nanoparticles and thus maintain the structural and electrical integrity of the Fe3O4@C@PGC electrode during the lithiation/delithiation processes. As a result, this Fe3O4@C@PGC electrode exhibits superhigh rate capability (858, 587, and 311 mAh/g at 5, 10, and 20 C, respectively, 1 C = 1 A/g) and extremely excellent cycling performance at high rates (only 3.47% capacity loss after 350 cycles at a high rate of 10 C), which is the best one ever reported for an Fe3O4-based electrode including various nanostructured Fe3O4 anode materials, composite electrodes, etc.
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Currently, seldom studies have paid close attention to the impact of the defects and oxygen-containing functional groups on the surface of the graphene for composite applications. In this work, two ...typical graphene materials, namely graphene nanosheets synthesized by an in situ catalytic reaction and reduced graphene oxide (RGO), were adopted to fabricate reinforced copper matrix composites by spark plasma sintering. A harmful transitional interfacial layer made up of Cu/CuOx/amorphous carbon/RGO, resulted from interfacial reaction between Cu and RGO, were observed in the RGO/Cu composite. In contrast, the in situ synthesized graphene with fewer defect and lower oxygen level can realize clean graphene–Cu interface with Cu–O–C bonding and thus lead to much improved interface bonding and superior yield strength and tensile ductility. These results imply that the in situ synthesized graphene is more favorable for achievement of robust interfacial bonding for enhancing the mechanical properties of the graphene-Cu composites.
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A general ultrathin‐nanosheet‐induced strategy for producing a 3D mesoporous network of Co3O4 is reported. The fabrication process introduces a 3D N‐doped carbon network to adsorb metal cobalt ions ...via dipping process. Then, this carbon matrix serves as the sacrificed template, whose N‐doping effect and ultrathin nanosheet features play critical roles for controlling the formation of Co3O4 networks. The obtained material exhibits a 3D interconnected architecture with large specific surface area and abundant mesopores, which is constructed by nanoparticles. Merited by the optimized structure in three length scales of nanoparticles–mesopores–networks, this Co3O4 nanostructure possesses superior performance as a LIB anode: high capacity (1033 mAh g−1 at 0.1 A g−1) and long‐life stability (700 cycles at 5 A g−1). Moreover, this strategy is verified to be effective for producing other transition metal oxides, including Fe2O3, ZnO, Mn3O4, NiCo2O4, and CoFe2O4.
A general ultrathin‐nanosheet‐induced strategy is introduced for producing 3D mesoporous network of transition metal oxides (TMOs). An N‐doped carbon network serves as the sacrificed template, which can be applied to many kinds of TMOs. The obtained material exhibits an interconnected mesopore architecture and possesses superior performance as a lithium ion anode.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Engineering of 3D graphene/metal composites with ultrasmall sized metal and robust metal–graphene interfacial interaction for energy storage application is still a challenge and rarely reported. In ...this work, a facile top‐down strategy is developed for the preparation of SnSb‐in‐plane nanoconfined 3D N‐doped porous graphene networks for sodium ion battery anodes, which are composed of several tens of interconnected empty N‐graphene boxes in‐plane firmly embedded with ultrasmall SnSb nanocrystals. The all‐around encapsulation (plane‐to‐plane contact) architecture that provides a large interface between N‐graphene and SnSb nanocrystal not only effectively enhances the electron conductivity and structural integrity of the overall electrode, but also offers excess interfacial sodium storage, thus leading to much enhanced high‐rate sodium storage capacity and stability, which has been proven by both experimental results and first‐principles simulations. Moreover, this top‐down strategy can enable new paths to the low‐cost and high‐yield synthesis of 3D graphene/metal composites for applications in energy‐related fields and beyond.
The all‐around encapsulation (plane‐to‐plane contact) architecture that provides a large interface between N‐graphene and SnSb nanocrystal not only effectively enhances the electron conductivity and structural integrity of the overall electrode, but also offers excess interfacial sodium storage, thus leading to much enhanced high‐rate sodium storage capacity and stability, which is proven by both experimental results and first‐principles simulations.
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A facile and scalable 2D spatial confinement strategy is developed for in situ synthesizing highly crystalline MoS2 nanosheets with few layers (≤5 layers) anchored on 3D porous carbon nanosheet ...networks (3D FL-MoS2@PCNNs) as lithium-ion battery anode. During the synthesis, 3D self-assembly of cubic NaCl particles is adopted to not only serve as a template to direct the growth of 3D porous carbon nanosheet networks, but also create a 2D-confined space to achieve the construction of few-layer MoS2 nanosheets robustly lain on the surface of carbon nanosheet walls. In the resulting 3D architecture, the intimate contact between the surfaces of MoS2 and carbon nanosheets can effectively avoid the aggregation and restacking of MoS2 as well as remarkably enhance the structural integrity of the electrode, while the conductive matrix of 3D porous carbon nanosheet networks can ensure fast transport of both electrons and ions in the whole electrode. As a result, this unique 3D architecture manifests an outstanding long-life cycling capability at high rates, namely, a specific capacity as large as 709 mAh g–1 is delivered at 2 A g–1 and maintains ∼95.2% even after 520 deep charge/discharge cycles. Apart from promising lithium-ion battery anode, this 3D FL-MoS2@PCNN composite also has immense potential for applications in other areas such as supercapacitor, catalysis, and sensors.
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•Mo2C submicron layer was coated on diamond particles by a molten salts route.•Mo powder was used as the Mo source for preparing Mo2C coating.•Mo2C coating plays diverse roles on ...diamond/Cu or diamond/Al composites.•Mo2C coating increases the thermal conductivity of diamond/Cu composites.
Mo2C submicron layer coated diamond particles prepared by a molten salts route with Mo powder as the starting material were used as the filler in Cu- and Al- matrix composites. The microstructure and thermal property of the composites prepared by a vacuum pressure infiltration method were investigated. When introducing a 500nm thick Mo2C layer, the thermal conductivity of the composites with different matrix presented different performance. A high thermal conductivity (657Wm−1K−1) was obtained in diamond/Cu composites owing to the improved interfacial bonding and lower interfacial thermal resistance, while the thermal conductivity of diamond/Al composites decreased from 553Wm−1K−1 to 218Wm−1K−1 when introducing the Mo2C layer, which can be attributed to the formation of harmful granule-phase (Al12Mo) at the interface of diamond and aluminum. This work provides a promising approach to improve performance of diamond reinforced metal matrix composites by selecting carbide as an interface modifier.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Lithium-rich layered cathode Li1.2Mn0.54Ni0.13Co0.13O2 is synthesized by a co-precipitation method followed by high-temperature treatment and surface coated with different amount of amorphous FePO4. ...The microstructure and electrochemical performance of the as-prepared cathode materials are investigated systematically. It is demonstrated that the Li1.2Mn0.54Ni0.13Co0.13O2 particles are uniformly coated with amorphous FePO4. With proper amount of amorphous FePO4 coating layer, significant improvements in discharge capacity, initial Coulombic efficiency, rate capability, cycle performance, and thermal stability are achieved at room temperature. Specifically, the 3 wt.% FePO4-coated cathode exhibits the highest discharge specific capacities (271.7 mAh g−1 at C/20), improved initial Coulombic efficiency (85.1%), and best cyclability (discharge capacity of 202.6 mAh g−1 at C/2 after 100 cycles), while the 1 wt.% FePO4-coated cathode displays the best rate capability (194.3 mAh g−1 at 1 C rate and 167.9 mAh g−1 at 2 C rate). The charge–discharge curves and electrochemical impedance spectra reveal that the improved electrochemical performances are due to the suppression of both the oxygen vacancy elimination at the end of the first charge and side reactions of the cathode with the electrolyte, as well as the decrease in charge transfer polarization by the FePO4 coating layer.
► Li1.2Mn0.54Ni0.13Co0.13O2 coated with a uniform layer of FePO4 was synthesized. ► Electrochemical performance was significantly improved by FePO4 coating. ► FePO4 coating layer suppresses the side reactions with the electrolyte. ► FePO4 coating enhances kinetics of Li1.2Mn0.54Ni0.13Co0.13O2 material.
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