Nano-scaled hierarchical porous ZnO nanostructures: fabrication and application in dye-sensitized solar cells

Abstract

Three-dimensional (3D) hierarchical porous ZnO architectures constructed by sheet-like structures were prepared through calcination of a bilamellar basic zinc citrate intermediate. The molar ratio of citrate anion/Zn²⁺ and the pH value of the reaction solution play crucial roles in the formation of the 3D hierarchical nanostructures. On the basis of the synthetic experimental results, a growth mechanism is proposed in the case of citrate as the organic ligand. The resulting nano-scaled porous ZnO structures exhibit a high specific surface area up to 55.6 m² g⁻¹ with a pore size of 5.1 nm. A light-to-electricity conversion efficiency of 4.46% was achieved of the dye-sensitized solar cells with the porous ZnO as the photoanode.