Maximizing the visible light photoelectrochemical activity of B/N-doped anatase TiO2 microspheres with exposed dominant {001} facets

Abstract

Anatase TiO2 microspheres with exposed dominant BBBBB001BBBBB facets were doped with interstitial boron to have a concentration gradient with the maximum concentration at the surface. They were then further doped with substitutional nitrogen by heating in an ammonia atmosphere at different temperatures from 440 to 560°C to give surface N concentrations ranging from 7.03 to 15.47 at%. The optical absorption, atomic and electronic structures and visible-light photoelectrochemical water oxidation activity of these materials were investigated. The maximum activity of the doped TiO2 was achieved at a nitrogen doping temperature of 520°C that gave a high absorbance over the whole visible light region but with no defect-related background absorption.