Graphene and g-C₃N₄-Based Gas Sensors

Table 1

Comparison of various Gr preparation methods.

Method	Exfoliation	SiC epitaxy	CVD on Ni	CVD on Cu
Layers	1–10 [36]	1–4 [37]	1–4 [38]	Single [39]
Size	1 mm [36]	50 µm [37]	1 cm [38]	65 cm [40]
Mobility (cm^2V^−1s^−1)	1500–10^6 [41]	2000–11,000 [37]	3700 [38]	16,000–65,000 [40]
Synthesis temperature (°C)	Room temperature	1000–1500	1000	1000
Cost	High	High	Low	Low
Scalability	Not possible	Good	Good	Good
Advantages	(i) Easy and low cost; (ii) No special equipment is needed; (iii) SiO2 thickness is tuned for better optical contrast used for visual localization; (iv) Large-scale area	(i) Graphene sheets of even thickness; (ii) Large-scale area	(i) Morphology can be controlled by maintaining process parameters; (ii) Large-scale production is easy	(i) Morphology can be controlled by maintaining process parameters; (ii) Large-scale production is easy
Disadvantages	(i) Serendipitous; (ii) Uneven films; (iii) Nonscalable	(i) Difficult control of morphology; (ii) High processing temperatures	(i) Uniform thickness is difficult; (ii) Low deposition rates	(i) Uniform thickness is difficult; (ii) Low deposition rates