Fabrication of porous TiO₂/g-C₃N₄heterojunction and investigation on its photocatalytic performance of coenzyme regeneration

Photocatalytic coenzyme regeneration holds great significance for bio-redox reactions. Porous TiO₂-60 was prepared via sol-gel method. After calcined at 300℃, TiO₂-300 was obtained and then mixed with melamine and calcined again to get a porous TiO₂/g-C₃N₄ heterojunction. The effects of TiO₂ calcination and melamine dosage on the structure and performance of catalyst were studied, and the catalyst dosage was optimized. The results showed that TiO₂ calcination engendered the crystal phase to transform from rutile to anatase. The as-prepared TiO₂/g-C₃N₄ featured high specific surface area, broad absorption edge, narrow band gap, and better charge separation efficiency. With increasing melamine dosage, the specific surface area and pore volume first increase and then decreased, while the light absorption and charge separation properties first increase and then decreased. After optimization, the catalytic activity and yield reached 4.8 mmol/(L·g·min) and 72% respectively, about 7.4 and 5.3 times those of g-C₃N₄. Moreover, the catalyst showed stable performance over five cycles.