Fabrication Of C₃N₄/por Modified Titanium Dioxide Photocatalysts And The Study Of Photocatalytic Activity Under Visible Light Irradiation

Photocatalytic degradation is one of the promising methods for organic pollutants treatment.It can convert solar energy to chemical energy and achieve degradation of organic pollutants to CO₂ and H₂O.Among various semiconductor photocatalysts,TiO₂ has attracted a great deal of attention due to its superior properties,including good photoelectric performance,chemical stability,abundance and non-toxicity.Nevertheless,its further applications are limited by inherent drawbacks,especially wide band gap,which leads to low solar energy utilization efficiency and low quantum efficiency.Therefore,recent studies have focused on the enhancement of photocatalytic activity by different modifications.In this paper,TiO₂nanoparticles and TiO₂ microspheres were modified by various modifications respectively,such as element doping,iron ion grafting and formation of heterojunction,to improve their photocatalytic performance.The contents were listed as below:?1?Here,we prepared composite of Ti³⁺-TiO₂-C₃N₄/por.Ti³⁺self-doped TiO₂(Ti³⁺-TiO₂),fabricated by microemulsion method,showed particle structure with about 20 nm in diameter.It was confirmed by electron spin resonance?ESR?that Ti³⁺was incorporated into the crystal lattice of TiO₂.Ti³⁺doping was beneficial to reduce the bandgap and extend the photo response range of TiO₂ from ultraviolet to visible light.What's more,the quantum efficiency of TiO₂ was greatly enhanced by coupling with porphyrin-sensitized carbon nitride?C₃N₄/por?.Compared with Ti³⁺-TiO₂-C₃N₄,Ti³⁺-TiO₂-C₃N₄/por showed higher generation of hydroxyl radicals and better photocatalysis ability under visible light irradiation.?2?TiO₂-Fe-C₃N₄/por was prapared by following procedures.Solvothermal method was used to fabricate TiO₂ microspheres,then Fe³⁺was grafted on the surface of TiO₂ by impregnation method,and finally C₃N₄/por was coupled with TiO₂-Fe.Fe³⁺clusters grafted on the surface of TiO₂ could provide transition sites for electrons in the valence band of TiO₂,and then Fe³⁺was reduced to Fe²⁺.The photoresponse range of TiO₂ was extended from ultraviolet to visible light due to the interfacial charge transfer?IFCT?.Besides,because of the excellent photocatalytic production of H₂O₂ over C₃N₄/por,Fe²⁺could be oxidized to Fe³⁺by H₂O₂ and a large amount of hydroxyl radicals were generated,which promoted the photo-Fenton-like process.As for TiO₂-Fe-C₃N₄/por,it was unnecessary to introduce extra H₂O₂ for the photo-Fenton-like process,which improved photocatalytic performance greatly.