Enhanced Electrocatalytic Performance of a Porous g-C3 N4 /Graphene Composite as a Counter Electrode for Dye-Sensitized Solar Cells.

Abstract

A porous graphitic carbon nitride (g-C3 N4 )/graphene composite was prepared by a simple hydrothermal method and explored as the counter electrode of dye-sensitized solar cells (DSCs). The obtained g-C3 N4 /graphene composite was characterized by XRD, SEM, TEM, FTIR spectroscopy, and X-ray photoelectron spectroscopy. The results show that incorporating graphene nanosheets into g-C3 N4 forms a three-dimensional architecture with a high surface area, porous structure, efficient electron-transport network, and fast charge-transfer kinetics at the g-C3 N4 /graphene interfaces. These properties result in more electrocatalytic active sites and facilitate electrolyte diffusion and electron transport in the porous framework. As a result, the as-prepared porous g-C3 N4 /graphene composite exhibits an excellent electrocatalytic activity. In I(-) /I3 (-) redox electrolyte, the charge-transfer resistance of the porous g-C3 N4 /graphene composite electrode is 1.8 Ω cm(2) , which is much lower than those of individual g-C3 N4 (70.1 Ω cm(2) ) and graphene (32.4 Ω cm(2) ) electrodes. This enhanced electrocatalytic performance is beneficial for improving the photovoltaic performance of DSCs. By employing the porous g-C3 N4 /graphene composite as the counter electrode, the DSC achieves a conversion efficiency of 7.13 %. This efficiency is comparable to 7.37 % for a cell with a platinum counter electrode.