Superhydrophobic and Electrochemical Performance of CF2-Modified g-C3N4/Graphene Composite Film Deposited by PECVD

The physicochemical properties of functional graphene are regulated by compositing with other nano-carbon materials or modifying functional groups on the surface through plasma processes. The functional graphene films with g-C₃N₄ and F-doped groups were produced by controlling the deposition steps and plasma gases via radio frequency plasma-enhanced chemical vapor deposition (RF-PECVD). The first principles calculation and electrochemistry characteristic of the functional graphene films were performed on Materials Studio software and an electrochemical workstation, respectively. It is found that the nanostructures of functional graphene films with g-C₃N₄ and F-doped groups were significantly transformed. The introduction of fluorine atoms led to severe deformation of the g-C₃N₄ nanostructure, which created gaps in the electrostatic potential of the graphene surface and provided channels for electron transport. The surface of the roving fabric substrate covered by pure graphene is hydrophilic with a static contact angle of 79.4°, but the surface is transformed to a hydrophobic state for the g-C₃N₄/graphene film with an increased static contact angle of 131.3° which is further improved to 156.2° for CF₂-modified g-C₃N₄/graphene film exhibiting the stable superhydrophobic property. The resistance of the electron movement of CF₂-modified g-C₃N₄/graphene film was reduced by 2% and 76.7%, respectively, compared with graphene and g-C₃N₄/graphene.

High Sensitivity, Humidity-Independent, Flexible NO2 and NH3 Gas Sensors Based on SnS2 Hybrid Functional Graphene Ink

Here, a high sensitivity gas sensing ink based on sulfonated rGO (S-rGO) decorated with SnS₂ is synthesized for room temperature NO₂ and NH₃ detection. This sensing ink demonstrated an excellent sensitivity to ppb-level NO₂ (17% response to 125 ppb) and sub-ppm-level NH₃ (11% response to 1 ppm). The unique absorption properties of SnS₂ improve the sensitivity of S-rGO 4.2 and 55 times to NO₂ and NH₃, respectively. Besides, the superhydrophobicity of the SnS₂ endows the sensor with exceptional immunity to high relative humidity (RH). Furthermore, the sensors exhibit negligible degradation to NO₂ and less than 15% degradation to NH₃ in a wide range of RH from 30 (ambient humidity) to 90%. More importantly, the obtained full-written ink can be applied to common substrates, such as glass, clothes, and paper, and maintain excellent performance after being bent and twisted by 180°.