Most resistance-type humidity sensors exhibit negative humidity sensitivity, i.e., their resistance decreases with a corresponding increase in humidity. This is primarily attributed to the dominant role of ionic conduction in adsorbed water. In this work, a humidity sensor based on a p-type reduced graphene oxide (p-rGO) with positive humidity sensitivity is proposed. Moreover, its positive humidity sensing response is further enhanced by n-type WS 2 nanoparticles modification. The results show that both rGO and rGO/WS 2 humidity sensors have good linear response in the relative humidity (RH) range of 0%-91.5%. The sensitivity of the rGO/WS 2 humidity sensor is 1.87 times that of rGO humidity sensor, which is mainly attributed to p-n heterojunction between rGO and WS 2. Besides, the rGO/WS 2 humidity sensor has small humidity hysteresis (* 3% RH) and good repeatability. This work demonstrates a humidity sensor based on rGO/ WS 2 composite film and provides a facile route for fabricating humidity sensor with positive humidity sensing properties.

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