A Study of Morphology-Dependent Cu2O Nanocrystals for Hydrogen Evolution Under Visible Light

Controllable Cu2O nanoflowers with petal structure were successfully synthesized via a novel method. The key growth mechanism involving concentrated ripening process was also proposed to extend the fabrication of special structured materials in traditional solution synthesis. During the shape evolution process, three different morphologies, i.e., Cu2O nanoparticles, nanocubes and nanoflowers were obtained. A morphology-related study on their photocatalytic activity for hydrogen evolution under visible light illumination was carried out. Among three morphologies, Cu2O nanoflowers with petal-like structure exhibited the highest activity and stability in hydrogen evolution. The excellent photocatalytic activity of Cu2O nanoflowers was attributed to their unique petal-like sheet structure with relatively bigger BET surface area and the quantum effect arose from the tiny petals and the secondary small nanoparticles. These petal-like structures revealed high separation efficiency and suppression of recombination of the photo-excited carriers by electrochemical measurements. The results of cycling experiments also confirmed that the H-2 evolution rate of Cu2O nanoflower only decreased by 2% after the four circles, which showed a relatively higher stability compared with other morphologies.