First-Principles Insight into Pd-Doped C(3)N Monolayer as a Promising Scavenger for NO, NO(2) and SO(2)

The adsorption and sensing behavior of three typical industrial toxic gases NO, NO(2) and SO(2) by the Pd modified C(3)N monolayer were studied in this work on the basic first principles theory. Meanwhile, the feasibility of using the Pd doped C(3)N monolayer (Pd-C(3)N) as a sensor and adsorbent for industrial toxic gases was discussed. First, the binding energies of two doping systems were compared when Pd was doped in the N-vacancy and C-vacancy sites of C(3)N to choose the more stable doping structure. The result shows that the doping system is more stable when Pd is doped in the N-vacancy site. Then, on the basis of the more stable doping model, the adsorption process of NO, NO(2) and SO(2) by the Pd-C(3)N monolayer was simulated. Observing the three gases adsorption systems, it can be found that the gas molecules are all deformed, the adsorption energy (E(ad)) and charge transfer (Q(T)) of three adsorption systems are relatively large, especially in the NO(2) adsorption system. This result suggests that the adsorption of the three gases on Pd-C(3)N belongs to chemisorption. The above conclusions can be further confirmed by subsequent deformable charge density (DCD) and density of state (DOS) analysis. Besides, through analyzing the band structure, the change in electrical conductivity of Pd-C(3)N after gas adsorption was studied, and the sensing mechanism of the resistive Pd-C(3)N toxic gas sensor was obtained. The favorable adsorption properties and sensing mechanism indicate that the toxic gas sensor and adsorbent prepared by Pd-C(3)N have great application potential. Our work may provide some guidance for the application of a new resistive sensor and gas adsorbent Pd-C(3)N in the field of toxic gas monitoring and adsorption.