Magnetic template-assisted construction of 2D PCN/TiO₂ heterostructures for efficient photocatalytic hydrogen generation

Two-dimensional (2D) heterostructures with large interfacial area have great potentials as highly efficient photocatalysts. In this work, we report fabrication of 2D heterostructures of TiO₂ and polymeric carbon nitride (PCN) by using Fe₃O₄ microplates as the template and sequentially growing very thin layer of PCN and TiO₂ on the microplate surface followed by removal of Fe₃O₄. The magnetic Fe₃O₄ templates provide unique advantages for convenient magnetic separation of the grown 2D heterostructures from other by-products in solution. The obtained 2D PCN/TiO₂ heterostructures with an average total thickness of 25 nm showed excellent photocatalytic hydrogen generation rate (11.1 μmol h⁻¹), which was much higher than that of individual PCN and TiO₂ nanosheets as well as the bulk PCN/TiO₂ heterojunctions. The high photocatalytic activities could be attributed to the large contacting area between PCN and TiO₂ that enable effective separation and transport of photogenerated electrons and holes through the PCN/TiO₂ interfaces. Our studies provide a new and general approach to fabricate 2D heterostructures for high efficiency photocatalysis.