The design of CN/C3N2 heterostructures and the potential as gas sensor and scavenger for SF6 decomposed gases

The design, electronic and gas-sensing properties of the CN/C3N2 heterostructures with and without the adsorption of H2S, SO2, HF, SOF2, and SO2F2 were systematically investigated by using DFT calculations. All SF6 decomposition gases can physically adsorb on both sides of the CN/C3N2 heterostructure with significant adsorption strength and charge transfer. Although the adsorption of these gases, in general, hardly affects the electronic properties, but can remarkably tune the work function (Phi) of the heterostructure. The CN/C3N2 heterostructure as Phi-type gas sensors has an ultra-high sensitivity for SF6 decomposed gases (at least over 71.2 %), especially for the C3N2 side (at least over 568.7 %), and has relatively low recovery times for HF, H2S, SOF2, and SO2F2 gases at 300 K, indicating the reusability of the heterostructure at room temperature, but much more favorable at 350 similar to 400 K for SO2 gas. Further, the heterostructure as adsorbents for the capture and scavenging of SF6 decomposition gases has high adsorption capacity and strength. Therefore, our findings reveal that the CN/ C3N2 heterostructure is a promising candidate as Phi-type gas sensors with high sensitivity and reusability for the detection of SF6 decomposition gases, while as an optimal scavenger for removing these toxic gases.