Trace gas sensing is critical for monitoring environmental pollution and detecting volatile organic compounds released from the human body. As a powerful analytical tool for identifying trace molecules, surface-enhanced Raman spectroscopy (SERS) enables remarkable amplification of normal Raman signals by using the surface plasmon resonance effect and charge-transfer effect with excellent sensitivity, noninvasive detection capability, and unique fingerprint effect, and it has been widely used in the field of analysis, especially for gas sensing.