Regulating the energy band-gap, UV-Vis light absorption, electrical conductivity, microwave absorption, and electromagnetic shielding effectiveness by modulating doping agent

Conductive polymers were abundantly used to design the microwave absorbers meanwhile, the influence of energy band-gap on their microwave absorbing ability has been the main challenge. In this work, the energy band-gap of polyaniline (PANi) was tailored by tuning the ratio of doping agent, and then its effect on the microwave characteristics was scrupulously dissected. PANi was synthesized by a novel complementary method using dodecylbenzenesulfonic acid (DBSA) as a doping agent and characterized by Fourier transform infrared (FTIR), X-ray powder diffraction (XRD), diffuse reflection spectroscopy (DRS), four-point probe conductometer (FPPC), field-emission scanning electron microscopes (FE-SEM), and vector network analyzer (VNA) analyses. The results attested that the amount of doping agent has a clear compromise with the energy band-gap, DC electrical conductivity, and microwave features. Interestingly, PANi nanofibers were obtained by adjusting the amount of doping agent. It can be seen that the energy band-gaps of the architected PANis were modulated from 1.04 to 2.08 eV by regulating the ratio of the doping agent, as well as the obtained results confirmed the significant influence of the doping agent on light absorption. The maximum reflection loss (RL) was 84.48 dB at 9.63 GHz related to PANi(2.5)/polyacrylonitrile (PAN) with a thickness of 2.75 mm, meanwhile, the aforementioned composite brought an efficient bandwidth as wide as 7.05 GHz (RL < -10 dB) with only 2.25 mm in thickness. As well as, PANi(5.0)/PAN illustrated 2.47 GHz (RL < -20dB) bandwidth with 1.75 mm thickness. Interestingly, PANi(2.5) and PANi(10.0)/PAN composites illustrated more than 9 dB total electromagnetic shielding effectiveness (SET) from 8.2 to 18 GHz.