Multifunctional 2D porous g-C₃N₄ nanosheets hybridized with 3D hierarchical TiO₂ microflowers for selective dye adsorption, antibiotic degradation and CO₂ reduction

Seeking effective strategy to design multifunctional materials for pollutant removal and solar fuel production is of great significance for solving the worldwide environment and energy problems. In this work, two-dimensional porous graphite-like carbon nitride (p-g-C₃N₄) nanosheets (NSs) decorated with three-dimensional (3D) hierachical TiO₂ microflowers (MFs) were constructed through a facile acid hydrothermal route. 3D TiO₂ MFs originating from K₂Ti₆O₁₃ nanobelts were combined with p-g-C₃N₄ NSs via solid interfacial connections. By chemical exfoliation and etching, the surface area of g-C₃N₄ was significantly increased along with the formation of porous structures and C vacancies. Interestingly, the hydrothermally produced two-dimensional (2D) p-g-C₃N₄ NSs showed extraordinarily selective adsorption towards anionic methyl orange via strong electrostatic attraction. More importantly, such 3D/2D TiO₂/p-g-C₃N₄ micro-nano heteroarchitectures exhibited remarkably improved visible-light photocatalytic properties for antibiotic degradation and CO₂ reduction, mainly attributed to the enlarged surface areas and pore volumes, increased adsorption/active sites, improved light absorption and higher separation efficiency of photogenerated charge carriers. This one-pot synthesis method opens new possibilities for rational design of multifunctional g-C₃N₄-based photocatalysts towards environmental purification and solar energy conversion.