Publication details
Gas-phase microwave plasma synthesis of few-layer graphene from pure acetylene and the influence of reactive gas admixtures
| Authors | |
|---|---|
| Year of publication | 2026 |
| Type | Article in Periodical |
| Magazine / Source | Journal of Physics D: Applied Physics |
| MU Faculty or unit | |
| Citation | |
| web | https://iopscience.iop.org/article/10.1088/1361-6463/ae627c |
| Doi | https://doi.org/10.1088/1361-6463/ae627c |
| Keywords | few-layer graphene; acetylene; reactive gases; graphene yield; microwave plasma |
| Description | The efficiency and selectivity of gas-phase synthesis of few-layer graphene (FLG) are governed by the balance between the carbon growth species and competing reaction pathways in a microwave plasma environment. Acetylene (C2H2) decomposition in an atmospheric-pressure dual-channel microwave plasma torch in Ar was used to systematically examine how hydrogen, nitrogen and oxygen admixtures modify these pathways. Under a highly stable plasma formed by the dual-channel configuration, the structural transition of solid state material from disordered carbon nanoparticles to FLG could be observed for a wide range of C2H2 (13 sccm)/(H2, O2, N2) (6.5–26 sccm) conditions in dependence on delivered microwave power of 130–350 W. Selective synthesis of FLG was achieved for all types of gas admixture, as determined by electron microscopy and Raman spectroscopy, and the required power decreased with increasing flow rate of reactive gas. Oxygen strongly suppressed solid carbon formation, whereas hydrogen and nitrogen preserved carbon availability; however, when using nitrogen a substantially higher power was required to obtain FLG. The yield of the synthesis increased monotonically with increasing delivered microwave power, up to 68% at 350 W, and slightly decreased with decreasing C/H(N) ratio. Experiments using a reduced flow rate of pure C2H2 (6.5 sccm) demonstrated that selective FLG synthesis can be achieved even without reactive gas admixtures at a high power of 350 W. Complementary experiments using methane (CH4) at 13–38 sccm achieved the best selectivity and lowest structural disorder of FLG for a low flow rate of CH4 over the whole range of delivered microwave power. This work defines a unified process window for selective high-yield FLG synthesis governed by the interplay between delivered microwave power and the C2H2/reactive gas ratio, identifying carbon availability as a necessary but not sufficient, controlling parameter. Selective FLG synthesis with pure C2H2, and analogous power–flow dependences observed for CH4, confirm the generality of the process framework. |
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