Fluorine-free synthesis of reduced graphene oxide modified anatase TiO_2 nanoflowers photoanode with highly exposed {001} facets for high performance dye-sensitized solar cell

摘要

A facile, fluorine-free and non-toxic one-pot solvothermal technique was adopted to synthesis TiO2 nanoflowers with anatase phase having 98% highly exposed {0 0 1} facets (TiO2 {0 0 1} NFs). The morphology, grain size and crystallinity of pure TiO2 {0 0 1} NFs and reduced graphene oxide (RGO) sheets modified TiO2 {001} NFs (RGO-TiO2 {0 0 1} NFs) were inspected by diffuse reflectance spectroscopy (DRS), X-ray diffractometry (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). TEM images showed the development of anatase TiO2 {0 0 1} NFs with high crystallinity and uniform shape. The influence of RGO on the performance of the TiO2 {0 0 1} NFs as a photoanode material in dye-sensitized solar cell (DSSC) was examined. High energy conversion efficiency (eta) was observed for the DSSC based on a photoanode made of RGO-TiO2 {0 0 1} NFs when compared to DSSCs based on photoanodes fabricated using pure TiO2 {0 0 1} NFs and commercial Degussa P25 TiO2, which exhibited eta of 6.78, 4.59 and 2.71%, respectively. The improved performance of the DSSC based on a photoanode composed of RGOTiO(2) {0 0 1} NFs was due to its good crystallinity, high dye intake and enhanced light-harvesting properties. Moreover, the presence of RGO greatly hindered the recombination of photogenerated electrons and increased their lifespan. This work discloses a novel efficient photoanode design for improving performance of the DSSCs.