Experimental and theoretical comparative analysis of modified graphene (G-O, Pd-G, Pd-G-O) sensing performance toward SO2 in agricultural greenhouse

Sulfur dioxide (SO2) is one of the main harmful gas in agricultural greenhouse. Its concentration can effectively reflect the health status of plants in agricultural greenhouse. In this paper, the adsorption characteristics of SO2 on modified graphene-based were studied in comparison. The adsorption models of epoxy grouped graphene (G-O), palladium doped graphene (Pd-G) and epoxy and palladium co-doped graphene (Pd-G-O) to SO2 were established based on the first-principles, analyzing in terms of adsorption energy, density of states, orbitals, charge density and desorption time of the adsorption models. The results showed that Pd-G-O exhibited strong chemisorption with adsorption energy of -1.237 eV. Furthermore, three modified graphene-based sensing materials were prepared via the redox method in this paper, and their crystal morphology and chemical elemental composition were investigated by transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS), respectively. The response performance of the graphene-based sensor to SO2 was tested by a gas-sensitive testbed. The test results confirmed that the response of the Pd-G-O sample to 50 ppm SO2 at room temperature was 10.5 (1.567 and 1.235 times than that of G-O, Pd-G). Pd-G-O provides theoretical basis and experimental support for the development of a highly sensitive and fast response sensor for the detection of harmful gases in agricultural greenhouse.