DFT calculation on p-xylene sensing mechanism of (C4H9NH3)2PbI4 single crystal based on physisorption

P-xylene (p-C8H10) is extremely harmful and dangerous to human health due to high toxicity and strong carcinogenicity. Exploring sensitive material to effectively detect p-xylene is of importance. In this paper, perovskite single crystal (C4H9NH3)(2)PbI4 has been successfully synthesized via solution method. The obtained product was analyzed by single crystal X-ray diffraction. With the space group Pbca, orthorhombic (C4H9NH3)(2)PbI4 layered perovskite structure consists of an extended two-dimensional network of corner-sharing PbI6 octahedron. Single layer perovskite sheets of distorted PbI6 octahedron alternated with protonated n-butylammonium cation bilayers, which offers many advantages and provides the possibility of forming a gas sensor device based on the change of resistances. Density functional theory (DFT) simulations regarding the adsorption energy revealed that this organic-inorganic hybrid perovskite compound has excellent selectivity toward p-xylene compared with other gases including C2H5OH, C6H6, CH2Cl2, HCHO, CH3COCH3 and C7H8. The calculation of electron density, density of states and electron density difference showed the sensing mechanism of p-C8H10 is mainly derived from physical adsorption-desorption in view of electron transfer.

Automated summary

In this study, a perovskite single crystal (C4H9NH3)(2)PbI4 was successfully synthesized and analyzed. The unique structure offers the potential for gas sensor devices, with excellent selectivity towards p-xylene compared to other gases. The sensing mechanism of p-xylene is mainly attributed to physical adsorption-desorption involving electron transfer.