In situ formation of defect-engineered N-doped TiO 2 porous mesocrystals for enhanced photo-degradation and PEC performance.

N-Doped oxygen defective N/TiO 2- x mesocrystal nanocubes were successfully prepared by a facile strategy in our system. Crystal topotactic transformation from NH 4 TiOF 3 mesocrystals facilitated the formation of a porous structure of TiO 2 . Meanwhile, the introduction of N dopants and oxygen vacancies (OVs) was also achieved during this process. The as-prepared products exhibit much higher photoelectrochemical (PEC) and photocatalytic degradation performance under visible light illumination. It is suggested that the promising catalytic properties result from the synergistic effect of doping, OVs and the amazing porous mesocrystal structure of N/TiO 2- x .