Since using sunlight to generate hydrogen by water splitting is an environment friendly route, great efforts have been focused on developing photocatalysts to convert water into hydrogen using light, especially visible-light-driven photocatalysts. From a biomimetic point of view, to synthesise a photocatalyst with a shape close to that of natural leaves is interesting in terms of morphology control and performance enhancement. But few studies on this fieldwere reported.

Researchers with Institute of Process Engineering (IPE) synthesized artificial CdS micro/nano leaves on a large scale by controlled hydrothermal reactions.. The resulting structure resembles a type of pinnate leaves. The surface of CdS micro/nano leaves was found to be dominated by the high energy (0001) plane.

The dimension of the leaves was in the range of 4–6μm and the thickness of the leaves was 30–50 nm. The surface of the leaves was smooth and composed of several parallel laminar layers with multi-steps. The SAED and HRTEM images indicated that the surface of the leaves was mainly composed of (0001) plane and all the leaves had single-crystallinity.

The efficiency of micro/nano leaves was more than 6 times greater than normal CdS microparticles.

In their work, the function of hydroflouric acid (HF) as a capping agent on the growth of hexagonal CdS single-crystalline dendrite was investigated, and a possible formation mechanism was proposed based on the intrinsic crystal structure and selected adsorption processes.

In addition, the as-prepared CdSpinnate leavesshowed enhanced photocatalytic activity for hydrogen production from water. In the absence of any noble metal co-catalyst, excellent photocatalytic activity was obtained using the CdS micro/nano leaves with a hydrogen production rate of 740.9 μmol h？1 under visible light irradiation, which was about 6.2 times higher than that of CdS spheroidal particles.

The enhanced photocatalytic activity of CdS micro/nano leaves can be attributed to its high crystallinity, the exposed (0001) high surface energy plane and wider bandgap, as well as the thin flake-like morphology. As the material resembled natural leaves in both shape and function, this work provides a good example of bionics in materials science and may provide a new way to synthesise novel photocatalysts with enhanced activities.

The paper was published in Journal of Materials Chemistry.