Hierarchical forest-like photoelectrodes with ZnO nanoleaves on a metal dendrite array

Abstract

Hierarchical forest-like photoelectrodes were prepared by assembling nano-ZnO on an array of micro-metal dendrites, aiming to demonstrate the idea of highly efficient photon-harvesting inside a biomimetic dendrite structure. Via a facile aqueous electrochemical deposition process, the metal dendrites were deposited on both flat and wire substrates with different alignments, showing wide adaptability. A strong, broadband anti-reflection effect was observed, owing to the diffuse reflection inside the microdendrites. By increasing the dendrite height, the overall reflectivity of the metal electrode can be reduced from 75% to 45%, which could be further reduced to 12% after combining with acicular-leaf-like ZnO nanoarrays. Its applications in light-driven water splitting were successfully demonstrated. Taking advantage of the forest-like photoelectrode, we have artificially constructed an efficient photo-electrochemical system similar to plants in a forest, with photons harvested by the crown-like photoanodes in the sunshine, and synthetic reactions driven by the root-like electrode in the shadow.