Catalytic mechanism and design principles for heteroatom-doped graphene catalysts in dye-sensitized solar cells

Abstract

Doped carbon nanomaterials are promising candidates to replace expensive Pt counter electrode for catalyzing triiodide reduction reaction (IRR) in dye-sensitized solar cells (DSSCs), but trial-and-error approaches have been used to develop better catalysts. Here, design principles are developed for p-block heteroatom-doped graphene as efficient IRR catalysts through density functional theory (DFT) calculations. The descriptors based on the intrinsic properties of dopant elements are identified to establish a quantitative relationship that correlates the doped structures to catalytic activities. Moreover, a quantitative relationship is also established between the catalytic performance and the extrinsic factors such as the number of exposed active sites for a particular mass loading. It is predicted that most p-block element doped graphene catalysts have better performance than Pt, and that doping at graphene edges enhances catalytic activities. These predictions are consistent with experimental results. The proposed design principles enable us to rationally design and search for highly active catalysts based on earth-abundant, cost-effective materials.