Thermal properties of graphene/metal composites with aligned graphene

Chu, Ke; Wang, Xiao hu; Li, Yu biao; Huang, Da; Geng, Zhong rong; Zhao, Xi; Liu, Hong; Zhang, Hu

doi:10.1016/j.matdes.2017.11.048

Cited by 229 publications

(72 citation statements)

References 53 publications

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“…The effect was reported previously for copper-graphite composites [10,14] and for composites with aluminum and magnesium alloys as matrix, for various graphite powders and production parameters [11]. The same results for copper-graphite composites were later perfectly reproduced by Chu et al [15] on nearly identical samples, whereby the CTE was measured by SEM instead of dilatometry, and attributed to a strain of the graphite flakes which will be discussed below. A similar effect was reported by Hutsch et al [16] for composites with tungsten matrices and above 70°C for copper matrices, later for iron matrices [17].…”

Section: Introductionsupporting

confidence: 78%

Understanding the negative thermal expansion in planar graphite–metal composites

2018

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The addition of graphitic fibers and flakes as fillers is commonly used to control the thermal expansion of metals. Sintered metal matrix composites with a planar distribution of graphite flakes show a low or negative thermal expansion coefficient perpendicular to the orientation plane of the graphite (z-CTE). Since the metal matrix has a positive isotropic expansion and graphite has a high z-CTE, this effect cannot be explained by a simple model of stapled metalgraphite layers. Instead, a mechanical interaction between graphite and matrix must be considered. With neutron scattering measurements we show that there is little or no strain of the graphite flakes caused by the matrix, which can be explained by the high modulus of graphite. Instead, we suggest that a macroscopic crumpling of the flakes is responsible for the low z-CTE of the composite. The crumpled flakes are thicker at low temperature and get stretched and flattened by the expanding matrix at high temperature, explaining the reduction in the thermal expansion across the orientation plane.

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Section: Introductionsupporting

confidence: 78%

Understanding the negative thermal expansion in planar graphite–metal composites

2018

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“…The representative SEM image ( Figure 1d) of N-NiO/CC depicts a high density nanosheet array that is vertically and uniformly attached on the surface of CC [34][35][36][37] . The TEM image ( Figure 1e) further confirms the nanosheet structure of N-NiO that is translucent and wrinkled [38,39] . In the HRTEM image (Figure 1f), the specific lattice spacing of 0.24 nm can be identified, which correspond to (111) plane of NiO.…”

Section: Nitrogen-doped Nio Nanosheet Array For Boosted Electrocatalymentioning

confidence: 52%

Nitrogen‐Doped NiO Nanosheet Array for Boosted Electrocatalytic N₂ Reduction

Wang

et al. 2019

ChemCatChem

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Electrocatalytic N2 reduction reaction (NRR) provides a sustainable approach for ambient N2 fixation. Non‐noble transition metal‐based electrocatalysts (TMEs) are emerging as the most promising NRR catalysts, but commonly exhibited limited NRR activity. Heteroatom doping is an effective method to improve the electrocatalytic activity of TMEs by finely modulating the electronic structures. Herein, as a proof‐of‐concept, nitrogen‐doped NiO nanosheet array on carbon cloth (N‐NiO/CC) was investigated as model heteroatom‐doped TMEs for NRR. The N‐NiO/CC exhibited the considerably enhanced NRR performance with a NH3 yield of 22.7 μg h−1 mg−1 and an FE of 7.3 % in 0.1 M LiClO4 at −0.5 V (vs. RHE), far superior to those of undoped counterpart. Density functional theory (DFT) calculations revealed that the N‐doping could induce the enhanced surface conductivity and upraised d‐band center, leading to promoted *NNH stabilization, reduced reaction energy barrier and thus improved NRR performance.

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“…[36,37] Furthermore, Raman spectra of the samples (Figure 2d) show two characteristic bands at around 1350 cm À 1 (D-band) and 1580 cm À 1 (G-band), which are related to the defects and graphic carbon, respectively. [38] The intensity ratio of D-band to G-band (I D /I G ), as a defect level indicator, is 0.82, 1.04 and 0.92 for GO, bare RGO and CuO/RGO, respectively. The increased I D /I G of RGO and CuO/RGO compared to that of GO is attributed to the increased number and reduced size of sp 2 domains when converting GO to RGO.…”

Section: Cuo/graphene Nanocomposite For Nitrogen Reduction Reactionmentioning

confidence: 99%

CuO/Graphene Nanocomposite for Nitrogen Reduction Reaction

et al. 2019

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Electrochemical conversion of N 2 to NH 3 offers a clean and energy-saving solution for artificial NH 3 production, but requires cost-effective, steady and highly efficient catalysts to promote N 2 reduction reaction (NRR). Herein, CuO employed as a new non-noble-metal NRR catalyst was investigated both experimentally and theoretically. When supporting the CuO nanoparticles on reduced graphene oxide (RGO), it was demonstrated that the resulting CuO/RGO nanocomposite could effectively and robustly catalyze NRR under ambient conditions. At À 0.75 V versus reversible hydrogen electrode, the CuO/RGO exhibited a high NH 3 yield of 1.8 × 10 À 10 mol s À 1 cm À 2 and Faradaic efficiency of 3.9 %, along with the excellent selectivity and high stability. Density functional theory (DFT) calculations revealed that the "Suf-end" was the most effective mode for N 2 adsorption on catalytic Cu atoms. In NRR process, the alternating associative route was the preferable pathway with *N 2 ! *NNH being the rate-determining step.Ammonia (NH 3 ) is an essential nitrogen chemical for manufacturing fertilizers, dyes, medicaments, explosives, etc. [1] Besides, NH 3 is also deemed as the next-generation liquid fuel and highefficiency energy carrier owing to its high energy density (4.32 kWh L À 1 ) and hydrogen capacity (17.6 wt%). [2] However, at present, the artificial ammonia production depends primarily on the Haber-Bosch process that operates under high pressure (150~300 bar) and high temperature (300~550°C), [1] leading to the significant energy consumption and enormous CO 2 emission. This motivates us to develop an alternative approach for sustainable and economical NH 3 synthesis under ambient conditions.Electrochemical conversion of N 2 to NH 3 at ambient conditions offers a clean and energy-saving solution for largescale NH 3 production, but requires efficient and stable electrocatalysts to accelerate the N 2 reduction reaction (NRR) rate. [1] The noble metals such as Au, [3] Ag [4] and Ru [5] are currently recognized as excellent catalysts for NRR. Nevertheless, the scarcity and high cost of noble metals greatly hinder their large-scale applications. Recent advances demonstrate the earth-abundant transition-metal sulfides, [6,7] carbides, [8,9] nitrides [10] and oxides [11] are the cost-effective alternatives towards NRR. Of these transition-metal-based catalysts, the metal oxides have attracted the most attention due to their facile preparation, favorable catalytic activity and high stability. Sun and coworkers recently reported a series of metal oxides, including Fe 3 O 4 , [12] VO 2 , [13] Cr 2 O 3 , [14] TiO 2 , [15] Nb 2 O 5 , [16] MoO 3 [17] and β-FeOOH [18] which were found to exhibit comparable or superior NRR activities to most noble metals. Nonetheless, the potentially high NRR performance of metal oxides is greatly limited by their poor conductivity, which lowers the electron-transfer efficiency unfavourable for NRR kinetic process. The most efficient way to tackle this problem is anchoring the metal oxides onto rob...

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Thermal properties of graphene/metal composites with aligned graphene

Cited by 229 publications

References 53 publications

Understanding the negative thermal expansion in planar graphite–metal composites

Understanding the negative thermal expansion in planar graphite–metal composites

Nitrogen‐Doped NiO Nanosheet Array for Boosted Electrocatalytic N₂ Reduction

CuO/Graphene Nanocomposite for Nitrogen Reduction Reaction

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Thermal properties of graphene/metal composites with aligned graphene

Cited by 229 publications

References 53 publications

Understanding the negative thermal expansion in planar graphite–metal composites

Understanding the negative thermal expansion in planar graphite–metal composites

Nitrogen‐Doped NiO Nanosheet Array for Boosted Electrocatalytic N2 Reduction

CuO/Graphene Nanocomposite for Nitrogen Reduction Reaction

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Product

Resources

About

Nitrogen‐Doped NiO Nanosheet Array for Boosted Electrocatalytic N₂ Reduction