Understanding Photoelectrochennical Properties of B-N Codoped Anatase TiO2 for Solar Energy Conversion

Understanding the band gap narrowing of anatase TiO2 induced by B-N codoping is attractive and significant for their potential applications in renewable energy by converting sunlight to electricity or fuels. In this work, we use hybrid density functional calculations to investigate the electronic structures of B-N codoped TiO2 and further explore the mechanism of band gap narrowing of anatase TiO2 induced by B-N codoping. It is found the band gap narrowing of anatase TiO2 induced by the B-assisted N-O coupling effect (i.e., the substitution of Ti by B and the substitution of O by N, marked as (B-[sub], N) codoping) is more effective than the compensation effect between the interstitial B donor and the substitutional N acceptors on O site (marked as (B-[int], 3N) codoping). Results indicate that the (B-[sub], N) codoped anatase TiO2 is an intrinsic semiconductor with a band gap of 1.762 eV, exhibiting a figure-of-merit for photoelectrochemical (PEC) catalysis in the visible light region. By considering the formation energy, we suggest adopting the strong O-rich environment to synthesize the (B-[sub], N) codoped anatase TiO2. Actually, the B-assisted N-O coupling effect could significantly improve the visible light PEC performance of anatase TiO2. It is expected that this work can provide valuable information for design of new TiO2-based photocatalysts.