Formation of ZnO@CuS nanorods for efficient photocatalytic hydrogen generation

It is imperative to design integrated functional composites that simultaneously facilitate efficient optical absorption, charge separation, and surface redox reactions for efficient photocatalytic hydrogen generation. Herein, we present a strategy for efficient hydrogen evolution by developing tunable ZnO nanorods and the hybrid ZnO nanorods decorated with CuS composite. The hierarchical nanostructured ZnO@CuS heterojunction is prepared via a simple hydrothermal reaction. While characterizations of its optical and photophysical properties, less is known about its charge carrier dynamics and photocatalytic activity in aqueous systems generating hydrogen. Time-correlated single photon counting (TCSPC) decay spectra of ZnO and ZCS2 clearly showed that the rate constant of electron transfer for ZCS2 is 8.35 x 10(9)s(-1) and the average lifetime of ZnO decreases than ZCS2 which indicate fast electron transfer happens within the heterostructure through the CB of CuS to ZnO. Enhanced absorption of solar energy upon precise CuS concentration led to remarkably high photocatalytic H-2 production (10113.59 mu mol.g(-1)h(-1)) and an apparent quantum efficiency of 22.3% nm which is nearly similar to 35 times as high as that of pristine 287.96 mu mol.g(-1)h(-1). To our best knowledge, the obtained hydrogen evolution rate is among the maximum reported value in the literature under similar reaction systems. The excellent photocatalytic activity of the hybrid composite (ZnO@CuS) is attributed to the increase in light harvesting capability and efficient charge separation during the photocatalytic process as well as the synergistic role of CuS and ZnO in the nanostructured assembly. The work opens up new fundamental insights in designing hierarchical non-noble photocatalysts for solar applications.