Wet chemical synthesis of S doped Co3O4 nanosheets/reduced graphene oxide and their application in dye sensitized solar cells

• Published in: Applied surface science 2018-08, Vol.450, p.219-227
• Main Authors: Jiang, Tongtong, Yin, Naiqiang, Bai, Zhiman, Dai, Peng, Yu, Xinxin, Wu, Mingzai, Li, Guang
• Format: Article
• Language: English
• Subjects: Cobalt oxide nanosheet; Counter electrode; Doping; Dye sensitized solar cells; Graphene oxide
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2018.04.148

[Display omitted] •S was simultaneously doped into Co3O4 and graphene with wet chemical method.•After doping S, the electrocatalytic activity of Co3O4 shows dramatic improvement.•S-Co3O4/rGO possesses excellent cycle stability.•S-Co3O4/rGO-DSSC displays power conversion efficiency as high as 8.24%. Despite the fact that Co3O4 nanomaterials have gained much attention due to their excellent electrochemical properties, the poor conductivity and catalytic reduction ability for I3− ion hinder their application as counter electrode (CE) of dye sensitized solar cells (DSSCs). Herein, a facile ion exchange approach is developed to prepare S-doped Co3O4 nanosheet. S doping strategy significantly improves the catalytic activity of Co3O4 nanosheets for the reduction of I3− ion and their charge transport ability. For the sake of doping S into Co3O4 and rGO simultaneously, the similar wet chemical process is adopted in the presence of graphene oxide (GO) to synthesize S-doped Co3O4/reduced graphene oxide (rGO) composites. The power conversion efficiency (PCE) of Co3O4-DSSC is only 1.98%. Using S-doped Co3O4 as CE, the PCE can be dramatically improved to 6.76%. Moreover, the S-doped Co3O4/rGO-DSSC shows higher PCE (8.24%) than that of Pt (7.79%). Electrochemical measurement results indicate that the S-doped Co3O4/rGO composites not only show excellent electrocatalytic activity, but also show high cycling stability. The outstanding improved performance of DSSCs with S-doped Co3O4 nanosheet and S-doped Co3O4/rGO composite as CEs demonstrates that the surface atomic configurations of CE materials have significant influence on their electrocatalytic activity.