Ionic liquid-assisted synthesis of porous boron-doped graphitic carbon nitride for photocatalytic hydrogen production.

This work presents a simple way to prepare boron-doped graphitic carbon nitride (B/g-CN), exhibiting an enhanced photocatalytic performance to split water for hydrogen production. B/g-CN was synthesized via the pyrolysis of urea and 1-ethyl-3-methylimidazolium tetrafluoroborate ([Emim]BF), which was adopted as the boron source. The aggregate of B/g-CN nanosheets shows a porous structure since some bubbles are generated under the heat decomposition of ionic liquids. The porous structure is conducive to the exposure of more active sites. Moreover, B-doping will form some localized electronic energy levels in the band gap of g-CN, thereby extending its visible light response. As impacted by the porous structure of B/g-CN aggregate and the narrow the band gap, the photocatalytic hydrogen generation rate (901 μmol h g) is increased, almost 3 times faster than g-CN (309 μmol h g). This work proposed a simple method to prepare the aggregate of B/g-CN nanosheets exhibiting pores under ionic liquid assistance. It can be a novel method to design porous polymer photocatalysts.