Synthesis of carbonized-cellulose nanowhisker/FeS2@reduced graphene oxide composite for highly efficient counter electrodes in dye-sensitized solar cells

摘要

Iron pyrite (FeS2) is one of the most promising materials for solar energy technology owing to its abundance and optical properties. In this work, a carbonized-cellulose nanowhisker/FeS2@reduced graphene oxide (C-CW/FeS2@RGO) composite is synthesised through a facile hydrothermal method with CW as the bio-template. In this method, the carbon matrix formed by high-temperature carbonization of CW is coated with FeS2 nanocrystals to form hollow, porous nanorods, which are randomly dispersed over the surface of the RGO sheets. The C-CW/FeS2@RGO composite presents the following structural advantages for application as a counter electrode (CE) for dye-sensitized solar cells (DSSCs): its hollow and porous structure, the rod-like morphology inside the continuous carbon matrix, and the two-dimensional continuous conducting pathway created by the RGO sheets. According to the cyclic voltammetry, impedance spectroscopy, and Tafel polarization analyses, the electrocatalytic activity of the C-CW/FeS2@RGO CE for the reduction of triiodide ions is higher than that of Pt CE. The DSSC assembled with the C-CW/FeS2@RGO CE delivers a photoconversion efficiency (eta = 7.38%) higher than that of Pt CE (eta = 6.24%). Owing to its excellent performance, C-CW/FeS2@RGO CE is expected to replace the expensive Pt electrode in DSSCs.