Noble-metal-free Z-Scheme MoS2–CdS/WO3–MnO2 nanocomposites for photocatalytic overall water splitting under visible light

To fabricate an efficient two-component Z-scheme system for visible light induced overall water splitting, CdS/WO 3 nanocomposites , with cubic CdS nanoparticles grown on the surface of hexagonal WO 3 nanorods , were prepared via a facile precipitation of Cd 2+ with S 2− in the presence of pre-obtained hexagonal WO 3 nanorods. MnO 2 and MoS 2 , the co-catalysts for O 2 and H 2 generation respectively, were selectively deposited on WO 3 and CdS in the CdS/WO 3 nanocomposites. The resultant MoS 2 –CdS/WO 3 –MnO 2 composites show photocatalytic activity for overall water splitting under visible light, with an optimized performance observed over 2.0%MoS 2 -0.2 CdS/WO 3 -1.0%MnO 2 . The visible light induced overall water splitting over MoS 2 –CdS/WO 3 –MnO 2 nanocomposites can be attributed to the presence of a Z-scheme charge transfer pathway in the CdS/WO 3 nanocomposites, ie, the transfer of the photo-generated electrons from the CB of WO 3 to the VB of CdS to recombine with the photo-generated holes through an efficient interface between cubic CdS and hexagonal WO 3 . The left photo-generated holes in VB of WO 3 and the photo-generated electrons in CB of CdS therefore can accomplish the water oxidation and water reduction simultaneously, with the assistance of the surface deposited cocatalysts (MnO 2 and MoS 2 ). This work demonstrated the great potential of fabricating the two-component direct Z-scheme photocatalytic systems for overall water splitting from two semiconductors with a staggered band structure .