Ultrathin Ni–Ni3Se2 nanosheets on graphene as a high-performance counter electrode for dye-sensitized solar cells

Abstract

Ultrathin nanostructures of metal chalcogenides have exhibited excellent electrocatalytic activity due to the high percentage of surface atoms and many exposed interior atoms, which inevitably induce the formation of defects serving as highly efficient active sites. Here we report for the first time a high-performance electrocatalyst of ultrathin Ni–Ni₃Se₂ nanosheets on graphene nanosheets. Specifically, the thickness of the obtained nanosheets is in the range of 1.5–2.5 nm. Furthermore, the specific surface area of the ultrathin Ni–Ni₃Se₂/graphene nanosheets was as much as ∼162.5 m² g⁻¹. The electrocatalytic activity of Ni–Ni₃Se₂/graphene nanosheets was measured as a counter cell of dye-sensitized solar cells. Ni–Ni₃Se₂/graphene nanosheets exhibited high performance for the reduction of I₃⁻ to I⁻, and achieved higher power conversion efficiency (7.76%) compared with that of the Pt-based reference electrode (7.42%).