Dual modification of TiNb2O7 with nitrogen dopants and oxygen vacancies for selective aerobic oxidation of benzylamine to imine under green light

Abstract

TiNb₂O₇ powder was prepared by a simple hydrothermal method and subsequent heat treatment. V_o–N–TiNb₂O₇ was generated by NH₃ and ethanol dual treatments. The NH₃ treatment produced a new N 2p orbital band above the O 2p valence band and oxygen vacancy (V_o) levels were formed by the ethanol treatment. The photocatalytic performance of modified V_o–N–TiNb₂O₇ towards selective aerobic oxidation reactions under green light (475–600 nm, peaked at 525 nm) was measured. It exhibits a high conversion of benzylamine (above 90%) at 80 °C over 24 h with selectivity for N-benzylidenebenzylamine greater than 95% under green light, which is much better than the unmodified and mono-modified TiNb₂O₇. It is suggested that the dual modification alter the electronic band structure of TiNb₂O₇ and result in a narrower band gap which should be responsible for the enhanced photocatalytic activity.