Synthesis of Particulate Hierarchical Tandem Heterojunctions toward Optimized Photocatalytic Hydrogen Production

Abstract

Abstract Photocatalytic hydrogen production using semiconductors is identified as one of the most promising routes for sustainable energy; however, it is challenging to harvest the full solar spectrum in a particulate photocatalyst for high activity. Herein, a hierarchical hollow black TiO 2 /MoS 2 /CdS tandem heterojunction photocatalyst, which allows broad‐spectrum absorption, thus delivering enhanced hydrogen evolution performance is designed and synthesized. The MoS 2 nanosheets not only function as a cost‐effective cocatalyst but also act as a bridge to connect two light‐harvesting semiconductors into a tandem heterojunction where the CdS nanoparticles and black TiO 2 spheres absorb UV and visible light on both sides efficiently, coupling with the MoS 2 cocatalyst into a particulate photocatalyst system. Consequently, the photocatalytic hydrogen rate of the black TiO 2 /MoS 2 /CdS tandem heterojunction is as high as 179 µmol h −1 per 20 mg photocatalyst under visible‐light irradiation, which is almost 3 times higher than that of black TiO 2 /MoS 2 heterojunctions (57.2 µmol h −1 ). Most importantly, the stability of CdS nanoparticles in the black TiO 2 /MoS 2 /CdS tandem heterojunction is greatly improved compared to MoS 2 /CdS because of the formation of tandem heterojunctions and the strong UV‐absorbing effect of black TiO 2 . Such a tandem architectural design provides new ways for synthesizing particulate photocatalysts with high efficiencies.