Improved NO2 gas-sensing performance of PPy by hydrogen plasma treatment: Experimental study and DFT verification

Abstract

Improving gas selectivity and stability poses a challenge for gas sensors based on polypyrrole (PPy). Radio frequency hydrogen plasma was employed to modify the surface of PPy nanosheet. PPy treated with hydrogen plasma owns a larger specific surface area and an increased concentration of surface hole carriers due to the dispersion of hydrogen plasma, which results in excellent nitrogen dioxide (NO2) gas sensing performance for the PPy sensor. Furthermore, the increased electronic transfer ability and NO2 adsorption capacity of the PPy treated by hydrogen plasma were confirmed based on the calculations of Density Functional Theory (DFT). The stronger interaction of PPy treated with hydrogen plasma between PPy and NO2 have happened comparing to untreated PPy. PPy/H sensor shows a magnificent NO2 gas sensing performance (sensitivity and selectivity) due to the strong interaction (strong adsorption ability and electron transfer) between PPy and NO2 caused by the hydrogen plasma treatment. Organic semiconductor treatment with hydrogen plasma offers a novel method for surface modification of PPy applied to gas sensing.