Efficient, recyclable, and affordable daylight induced Cu/Cu2O/CuI photocatalyst via an inexpensive iodine sublimation process

Highlights: • A facile and inexpensive iodine sublimation process is used to prepare a freestanding and flexible Cu/Cu₂O/CuI sheet as daylight photocatalyst. • Multiple sheets are introduced to investigate photodegradation of the RhB dye. • The formation of CuI nanoparticles (20–30 nm) self-assembled into the ∼400–500 nm sized CuI nanoclusters. • An excellent ∼92% of RhB dye degradation was achieved with eight sheets of Cu/Cu₂O/CuI within 60 min. • In contrast with the conventional nanoparticle photocatalysts, the free-standing and flexible Cu/Cu₂O/CuI sheets demonstrated excellent recyclability and versatility of handling. The invention of an efficient, recyclable, and affordable daylight induced photocatalyst is highly desirable, for example to enhance the sustainability in industrial sectors requiring wastewater treatments. In the present paper, a facile and inexpensive iodine sublimation process was developed to prepare freestanding and flexible Cu/Cu₂O/CuI sheets to use as daylight photocatalysts capable to degrade toxic pollutants continuously without creating secondary pollution issues. The structural, chemical, and electronic properties of the Cu/Cu₂O/CuI nanostructures were systematically investigated. In particular, intriguing hierarchical structures were observed in form of the 20–30 nm CuI nanoparticles self-assembled into the ∼400–500 nm sized CuI nanoclusters. Indeed, ∼92% of the Rhodamine B – often referred as RhB - dye degradation was readily achieved, and the efficiency was controlled simply by adjusting the number of sheets used. Importantly, in contrast with the conventional nanoparticle photocatalysts, the free-standing and flexible Cu/Cu₂O/CuI sheets demonstrated excellent recyclability and versatility of handling. Moreover, potential mechanisms for suppressing the recombination of the photogenerated carriers were discussed. As a result, combining the fundamental data and the practically achieved results, the freestanding and flexible Cu/Cu₂O/CuI nanostructures are suitable candidates for an industrial upscaling as daylight activated photocatalysts for the wastewater treatment.