triboelectrification and electrostatic induction, it enables to convert the mechanical energy into electrical signal. [4] When triggering in a gaseous ambient, a dipole layer is formed after contact-electrification between two triboelectric materials. [5] The surface triboelectric charge density is greatly influenced by the surface alteration of certain chemisorption of the molecular oxygen species. During the chemisorption process of some gas molecules, the additional free electrons acquired by triboelectric material would screen the triboelectric charge generated on the surface of the triboelectric layer, thus resulting in the variation of electrical output signal. [6] In this case, TENG can be treated as a self-powered gas sensor simply without any external power source. [7] However, the ambient environment, including temperature, humidity, motion frequency, and amplitude all affect the output electric signals and disrupt the sensing signals, resulting in a poor selectivity, stability, and reliability.To improve the performance of TENGbased gas sensors, the concept of impedance matching effect induced triboelectric gas sensing systems have been proposed. [8] As well known, the sensing mechanism of semiconductor gas sensor is based on varied resistance of the sensing materials in response to the gas concentration. When connecting a TENG with a traditional semiconductor gas sensor, the output of TENG would vary with the working status of the load sensor due to the impedance matching effect. [9] Every part in such a system works independently and does not interfere with each other, providing a strong theoretical basis and technical support for self-powered triboelectric gas sensors (SPTGS). However, due to the large internal impedance of TENG (≈GΩ level), the fluctuation of electrode resistance induced slight change on electrical signal usually was negligible. [10] Therefore, the previous works generally employed metal as electrode and did not take into account the impedance matching effect in the construction of triboelectric sensors. [11] In actual fact, when triboelectric gas sensors utilize sensitive materials as triboelectric layer and electrode, the oxygen species absorbed on both triboelectric layer and electrode would react with the target gas molecule, leading to a change of surface state, electrical properties, or work function. [12] Thus, the variation in impedance
