Unveiling the relationship between graphene formation and carbonaceous species (C, C2 and C2H2) via CH4 cracking in Ar/CH4/H2 microwave plasma: A global model investigation
A global model on microwave Ar/CH4/H2 plasma is developed. The number density of C, C2 and C2H2 at low pressure, reduced pressure and atmospheric pressure are compared. Atmospheric pressure is favorable for graphene growth, and our simulation shows that high C2/C and C2H2/C ratios are achieved under...
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| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Elsevier
2025-06-01
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| Series: | Results in Engineering |
| Subjects: | |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S2590123025014355 |
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| Summary: | A global model on microwave Ar/CH4/H2 plasma is developed. The number density of C, C2 and C2H2 at low pressure, reduced pressure and atmospheric pressure are compared. Atmospheric pressure is favorable for graphene growth, and our simulation shows that high C2/C and C2H2/C ratios are achieved under this condition. Ratio analysis incorporating C2/C, C2H2/C and C2H2/C2 and selectivity analysis are introduced for conducting parametric studies including microwave power (200 to 600 W), flow rate (1 to 5 slm), CH4 percentage (1 to 35 %) and H2 percentage (1 to 30 %) systematically. C2/C, C2H2/C, and C2H2/C2 ratios decrease with increasing microwave power; 200 W is chosen ideal microwave power. High selectivity of C, C2, and C2H2 is observed at 400 W, corresponding to a gas temperature of 3000 K. A flow rate of 5 slm ensures sufficient residence time for sp² growth, as indicated by elevated C2/C and C2H2/C ratios. The analysis shows that while higher CH4 levels enhance C2/C, C2H2/C, and C2H2/C2 ratios, the sharp decline in the selectivity of C, C2, and C2H2 increases the risk of amorphous carbon. The analysis indicates that 10 % H2 offers balanced C2/C, C2H2/C, and C2H2/C2 ratios while 1 to 10 % H2 achieves the highest C2H2 selectivity. Experimental validation confirmed 2 to 5 % H2 and 16 to 22 % CH4 as optimal, which is in agreement with simulated values. As such, this work casts a robust framework for optimizing reactor design and operation through ratio and selectivity analyses, enabling efficient and scalable graphene production. |
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| ISSN: | 2590-1230 |