Phosphorus-doped TiO2 for visible light-driven oxidative coupling of benzyl amines and photodegradation of phenol

Abstract

A kind of phosphorus-doped TiO2 (P-TiO2) is fabricated by boric acid-induced hydrolysis of tetrabutyl titanate in ethanol solution of triphenylphosphine, then calcination and removal of boron oxide resulted from boric acid. Under the irradiation of blue light-emitting diode (LED), P-TiO2 can successfully realize the oxidative coupling of benzylamine (conversion >95%, selectivity >99%) with air as an oxidant. The photocatalyst exhibits excellent recycling stability and broad applicability for various benzylamine derivatives. Besides, the photodegradation of phenol can also be conducted smoothly with the photocatalyst under the irradiation of Xenon lamp. Control experiments demonstrate that boric acid-induced hydrolysis and calcination temperature determine the size-distribution and surface area of TiO2 nanoparticles, which further impact the photocatalytic performance. Density Functional Theory (DFT) calculations demonstrate that the orthophosphate species covalently bonding to the titania surface facilitates the adsorption of oxygen molecule on the surface of P-TiO2 by forming P–O bond.