Changing the morphology of polyaniline from a nanotube to a flat rectangular nanopipe by polymerizing in the presence of amino-functionalized reduced graphene oxide and its resulting increase in photocurrent

Amino-functionalized reduced graphene oxide (a-RGO) is used to change the morphology of polyaniline (PANI) and to increase the photocurrent in the PANI–a-RGO hybrid. The PANI morphology is changed from a nanotube to a flat rectangular nanopipe (FRNP) by the polymerization of aniline with a-RGO in acetic acid. Scanning (SEM) and transmission electron microscopy show the formation of FRNP morphology which varies by changing the PANI/a-RGO ratio in the hybrid. Time dependent SEM and Fourier transform infrared spectroscopy were used to investigate the mechanism of FRNP formation. Efficient (∼500 times) improvement in photocurrent is observed in FRNP over PANI nanotubes on irradiation with white light. The photoresponse is quite reproducible even after several cycles with a time interval of 100 s and in both the negative and positive bias photocurrent increases. A donor–acceptor based ‘electron–hole’ pair mechanism is proposed for the photocurrent behavior of FRNP. Using the PANI–a-RGO FRNP hybrid a dye sensitized solar cell with Rose Bengal dye is constructed yielding a power conversion efficiency of 2.012%.