Hierarchically porous hybrids of polyaniline nanoparticles anchored on reduced graphene oxide sheets as counter electrodes for dye-sensitized solar cells

Hierarchically porous polyaniline-reduced graphene oxide hybrids have been developed viaoxidative polymerization of aniline by MnO sub(2) on reduced graphene sheets under acidic conditions (named M-PANIGO). The formation mechanism of the above hybrids indicates that the MnO sub(2) undergoes oxidative disintegration and results in the porous structure of polyaniline (PANI) nanoparticle formation on the reduced graphene oxide (rGO) surface. The scanning electron microscopy (SEM) images and Brunauer-Emmett-Teller (BET) nitrogen sorption-desorption measurement clearly showed the nanoporous nature of the M-PANIGO hybrids. TEM-EDX confirmed the complete removal/degradation of MnO sub(2) during the oxidative polymerization of aniline. Just for comparison, PANI-rGO hybrids have also been prepared viaconventional polymerization using (NH sub(4)) sub(2)S sub(2)O sub(8) as the oxidant (named C-PANIGO). When these different architectural PANIGO hybrids were applied as the counter electrode for dye-sensitized solar cells (DSSCs), the short-circuit current density (J sub(sc)) and power-conversion efficiency ( eta ) of the DSSCs with C-PANIGO hybrids are measured to be 11.64 mA cm super(-2) and 5.62%, respectively, while the corresponding values are 12.88 mA cm super(-2) and 6.15% for the DSSCs with M-PANIGO hybrids, which is comparable to 6.73% for the cell with a Pt counter electrode under the same experimental conditions. The hierarchically porous M-PANIGO hybrid is thus a promising candidate to replace platinum as a counter electrode for DSSCs.