Manipulating Polyaniline Fibrous Networks by Doping Tetra-β-carboxyphthalocyanine Cobalt(II) for Remarkably Enhanced Ammonia Sensing

Manipulating the morphology and protonic acid doping of polyaniline (PANI) is significant for optimizing its NH 3 -sensing. Herein, tetra-β-carboxyphthalocyanine cobalt(II) (TcPcCo) acted as the dopant and structure-directing agent simultaneously to fabricate the uniform fibrous network-like PANI (PANI-TcPcCo hybrids) by a one-step polymerization at low temperature. During the reaction process, the protonic acid groups in TcPcCo not only induced the aniline monomers polymerizing into one-dimensional nanofibers (consist of both solid and hollow cylinders) with abundant tiny protuberances on the surface but also successfully doped into PANI. The resulting PANI-TcPcCo hybrids displayed the enhancement in terms of the good conductivity, the large gas adsorption capacity, and the unobstructed channels for the electron and gas transport. The central metal atoms of TcPcCo present the strong and selective affinity to NH 3 . Meanwhile, the deep-seated conversion of PANI’s molecular structure after exposure in NH 3 could occur due to the presence of TcPcCo. Thus, the PANI-2.5TcPcCo sensor showed the excellent NH 3 -sensing performance at room temperature, including an ultrahigh and fast response (802.7% and ∼17.0 s for 100 ppm of NH 3 ), a very low detection limit of 10 ppb (about 5000 parts of human olfaction limit of detection, 55 ppm), and superior NH 3 -sensing stability and selectivity. The strategy developed here provides a reliable and valid way to synthesize functional PANI-based hybrids with unique morphology and appropriate doping, which are able to be extended to other areas.