Heterojunctions in g-C3N4/B-TiO2 nanosheets with exposed {001} plane and enhanced visible-light photocatalytic activities

Abstract

Herein, an anatase boron-doped TiO2 (B-TiO2) with exposed {001} facets was synthesized for the first time via a solvothermal synthetic route using NaBF4 as the morphology controlling agent, and composited with the g-C3N4 formation of B-TiO2-001/g-C3N4 heterojunctions. The structure and optical properties of the B-TiO2-001/g-C3N4 were characterized by scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, UV–vis diffuse reflectance spectroscopy and photoluminescence spectroscopy. The results show that g-C3N4 uniformly covered on anatase B-TiO2, exposing the {001} facets. A red shift in the absorption edge and a strong absorption in the visible light range were observed due to the formation of Ti–O–B bonds and composite with g-C3N4, resulting in the narrowing of the band gap from 3.13 to 2.7 eV. The photocatalytic activity of the B-TiO2-001/g-C3N4 heterojunctions was evaluated by hydrogen evolution reaction under visible light irradiation (λ > 400 nm). The B-TiO2-001/g-C3N4 heterojunctions exhibited the greatest photocatalytic activity, approximately 25-fold higher than that of TiO2-001. The enhancement of photocatalytic performance was ascribed to the efficiently reduced charge recombination, high absorption of visible light range and higher catalytic activity of {001} facets relative to the {101} facets.