An <i>ab initio</i> study of the nickel-catalyzed transformation of amorphous carbon into graphene in rapid thermal processing

Chen, Shuang; Xiong, Wei; Zhou, Yun Shen; Lu, Yong Feng; Zeng, Xiao Cheng

doi:10.1039/c5nr08614k

Cited by 26 publications

(26 citation statements)

References 53 publications

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“…In a wider context, our study also contributes to the elucidation of the recently debated role of Ni 3 C as a possible intermediate bulk catalyst phase in Ni-catalyzed graphene 35 − 44 and carbon nanotube (CNT) 45 − 60 growth. Taking our Ni 3 C/a-C nanocomposites as a model system for graphitization from Ni 3 C, our in situ derived findings suggest that fcc Ni with interstitial carbon dissolved (Ni(-C)), rather than bulk Ni 3 C, is the active catalyst phase during graphitic nanostructure growth under typical chemical vapor deposition (CVD) conditions.…”

Section: Introductionmentioning

confidence: 84%

In Situ Observations of Phase Transitions in Metastable Nickel (Carbide)/Carbon Nanocomposites

Bayer¹,

Bosworth²,

Michaelis³

et al. 2016

J. Phys. Chem. C

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Nanocomposite thin films comprised of metastable metal carbides in a carbon matrix have a wide variety of applications ranging from hard coatings to magnetics and energy storage and conversion. While their deposition using nonequilibrium techniques is established, the understanding of the dynamic evolution of such metastable nanocomposites under thermal equilibrium conditions at elevated temperatures during processing and during device operation remains limited. Here, we investigate sputter-deposited nanocomposites of metastable nickel carbide (Ni3C) nanocrystals in an amorphous carbon (a-C) matrix during thermal postdeposition processing via complementary in situ X-ray diffractometry, in situ Raman spectroscopy, and in situ X-ray photoelectron spectroscopy. At low annealing temperatures (300 °C) we observe isothermal Ni3C decomposition into face-centered-cubic Ni and amorphous carbon, however, without changes to the initial finely structured nanocomposite morphology. Only for higher temperatures (400–800 °C) Ni-catalyzed isothermal graphitization of the amorphous carbon matrix sets in, which we link to bulk-diffusion-mediated phase separation of the nanocomposite into coarser Ni and graphite grains. Upon natural cooling, only minimal precipitation of additional carbon from the Ni is observed, showing that even for highly carbon saturated systems precipitation upon cooling can be kinetically quenched. Our findings demonstrate that phase transformations of the filler and morphology modifications of the nanocomposite can be decoupled, which is advantageous from a manufacturing perspective. Our in situ study also identifies the high carbon content of the Ni filler crystallites at all stages of processing as the key hallmark feature of such metal–carbon nanocomposites that governs their entire thermal evolution. In a wider context, we also discuss our findings with regard to the much debated potential role of metastable Ni3C as a catalyst phase in graphene and carbon nanotube growth.

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Section: Introductionmentioning

confidence: 84%

In Situ Observations of Phase Transitions in Metastable Nickel (Carbide)/Carbon Nanocomposites

Bayer¹,

Bosworth²,

Michaelis³

et al. 2016

J. Phys. Chem. C

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“…In fact, it has been shown that Ni particles can catalyze the conversion of amorphous to graphitic carbon at temperatures of 550 C resulting in disordered graphite layers on the particle surface. 29,30 Indeed, in the present study, bacterial cellulose in presence of Ni(OH) 2 decomposed about 70 C below the decomposition temperature of pure bacterial cellulose, which is a strong indication of the catalytic activity of the in situ formed nickel species, i.e. NiO and Ni.…”

Section: Synthesis and Characterization Of Carbon-nickel Hybrid Matermentioning

confidence: 46%

Nanostructured carbon–metal hybrid aerogels from bacterial cellulose

et al. 2017

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“…Amorphous carbon is a type of carbon that does not have any crystalline structure and contains a random distribution of sp 2 , sp 3 , and dangling bonds, so it is considered a completely isotropic material . Unlike anisotropic carbon materials such as CNTs, graphene, or graphite, the thermal conductivity of amorphous carbon in all directions is approximately the same .…”

Section: Carbon‐based Materials For Photothermal Actuator Designmentioning

confidence: 99%

Carbon‐Based Photothermal Actuators

Han

Zhang

Chen

et al. 2018

Adv Funct Materials

394

265

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Actuators that can convert environmental stimuli into mechanical work are widely used in intelligent systems, robots, and micromechanics. To produce robust and sensitive actuators of different scales, efforts are devoted to developing effective actuating schemes and functional materials for actuator design. Carbon-based nanomaterials have emerged as preferred candidates for different actuating systems because of their low cost, ease of processing, mechanical strength, and excellent physical/chemical properties. Especially, due to their excellent photothermal activity, which includes both optical absorption and thermal conductivities, carbon-based materials have shown great potential for use in photothermal actuators. Herein, the recent advances in photothermal actuators based on various carbon allotropes, including graphite, carbon nanotubes, amorphous carbon, graphene and its derivatives, are reviewed. Different photothermal actuating schemes, including photothermal effect-induced expansion, desorption, phase change, surface tension gradient creation, and actuation under magnetic levitation, are summarized, and the light-to-heat and heat-towork conversion mechanisms are discussed. Carbon-based photothermal actuators that feature high light-to-work conversion efficiency, mechanical robustness, and noncontact manipulation hold great promise for future autonomous systems. and most have high photothermal conversion efficiencies. [55][56][57][58] With excellent thermal conduction characteristics, carbon materials can transfer the as-obtained thermal energy to the heat-sensitive materials, achieving effective photothermal actuation. [59,60] In addition, carbon materials have many advantages, such as excellent physical and chemical stability, high mechanical strength, conductivity, as well as tunable light absorption properties, which allow for broad application of carbon-based actuators. [61] In this review, we focus on the recent advancements in carbon-based photothermal actuators and highlight their unique advantages, good performance, and potential for future applications. Specific light-to-heat conversion mechanisms and strategies that enable photothermal actuation are discussed. The performance of various photothermal actuators focusing on energy conversion, response/recover time, stability, mechanical strength, and actuating manners has been reviewed in details. Figure 1 shows a summary of typical actuators constructed of different carbon-based materials and their possible light-to-work mechanisms, including photothermal expansion, desorption, phase change, Marangoni effect, and magnetic susceptibility change. In addition, the advantages and limitations of carbon-based photothermal actuators and the current challenges in this field are discussed in Section 4. The development of carbon-based photothermal actuators may stimulate rapid progress in various smart devices for cutting-edge applications.

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An ab initio study of the nickel-catalyzed transformation of amorphous carbon into graphene in rapid thermal processing

Cited by 26 publications

References 53 publications

In Situ Observations of Phase Transitions in Metastable Nickel (Carbide)/Carbon Nanocomposites

In Situ Observations of Phase Transitions in Metastable Nickel (Carbide)/Carbon Nanocomposites

Nanostructured carbon–metal hybrid aerogels from bacterial cellulose

Carbon‐Based Photothermal Actuators

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