A cation exchange strategy to construct Rod-shell CdS/Cu2S nanostructures for broad spectrum photocatalytic hydrogen production.

Herein, Cu2S as the outer shell is grown on CdS nanorods (NRs) to construct rod-shell nanostructures (CdS/Cu2S) by a rapid, scalable and facile cation exchange reaction. The CdS NRs are firstly synthesized by a hydrothermal route, in which thiourea as the precursor of sulfur and ethylenediamine (EDA) as the solvent. And then, the outer shells of CdS NRs are successfully exchanged by Cu2S via a cation exchange reaction. The obtained CdS/Cu2S rod-shell NRs exhibit much enhanced activity of hydrogen production (640.95 μmol h-1 g-1) in comparison with pure CdS NRs (74.1 μmol h-1 g-1) and pure Cu2S NRs (0 μmol h-1 g-1). The enhanced photocatalytic activity of CdS/Cu2S rod-shell NRs owns to the following points: i) the photogenerated electrons generated by CdS quickly migrate to Cu2S without any barrier due to rod-shell structure by the in-situ cation exchange reaction, a decreased carrier recombination is achieved; ii) Cu2S as outer shells broaden the light absorption range of CdS/Cu2S rod-shell NRs into visible or even NIR light, which can produce more electrons and holes. This work inspires people to further study the rod-shell structured photocatalyst through the cation exchange strategy to further solar energy conversion.