Synchronization iodine surface modification and lattice doping porous carbon nitride for photocatalytic hydrogen production

Reaction active surface area and energy band structure determine the visible-light photocatalytic property of semiconductor catalyst such as graphitic carbon nitride (CN). Herein, synchronization iodine surface modified and doped porous carbon nitride (CNI) was prepared. The self-assembly precursors from urea and ammonium iodide were firstly obtained by liquid nitrogen-assisted rapid re-crystallization and lyophilization technology. After the heat treatment of above precursors, CNI was easily synthesized. Compared with bulk CN, CNI shows large specific surface area (57.59 m² g⁻¹), due to freeze-drying treatment and thermal decomposition of ammonium iodide. As electron donors, iodine species can enrich the electron density in the carbon nitride network and tune the electronic band structure. It is important the surface iodine modification can bound the positive charge holes to inhibit the recombination of photogenerated carriers. As a result, CNI exhibits prompted photocatalytic hydrogen evolution rate of 114.0 μmol h⁻¹ under visible-light irradiation (λ > 420 nm), better than that of bulk CN. This work may provide a promising rapid method for designing another porous and effective semiconductor photocatalysts.