A tungsten disulphide–polypyrrole composite-based humidity sensor at room temperature

An electrically conductive polypyrrole–tungsten disulphide (PPy/WS 2) composite was synthesized by a chemical polymerization technique. The composite was characterized by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR) and energy dispersive X-ray spectroscopy (EDX). FESEM images showed the grainy morphology with permeable nature. XRD and FTIR characteristic peak analysis exhibited semi-crystalline behaviour and confirming the interfacial interaction of the as-synthesized composite. EDX confirmed the presence of carbon, nitrogen, oxygen, tungsten and sulphur in the composite. The humidity sensing property of the PPy/WS 2-50% composite was tested and an approximate linear decrease in resistance was observed with an increase in relative humidity, along with a maximum sensing response of 97% and a response-recovery time of 52 and 58 s, respectively. The sensing ability of the composite was observed to be stable, when monitored for a period of two months. © 2019, Indian Academy of Sciences.