Novel precursor-reforming strategy to the conversion of honeycomb-like 3DOM TiO2 to ant nest-like macro-mesoporous N-TiO2 for efficient hydrogen production

Three-dimensional ordered macroporous (3DOM) materials play an important role in improvement of photocatalytic activity owing to their unique porous structures. However, how to further enhance photocatalytic performance based on 3DOM structure is still a huge challenge. In this paper, for the first time, a novel precursor-reforming strategy is utilized to modify 3DOM TiO2 by introducing urea into precursor of TiO2. Owing to the porogen effect of urea, the morphology of prepared material changes from honeycomb-like 3DOM structure to ant nest-like macroporous-mesoporous (macro-mesoporous) architecture after the precursor-reforming treatment, which largely increases the visible light absorption ability. Urea could also act as nitrogen source to form nitrogen doped TiO2 (N-TiO2), which decreases the band gap and enlarges the light response extent. Under visible light irradiation, the ant nest-like N-TiO2 sample exhibits improved photocatalytic hydrogen evolution rate, with more than 4.1 times higher than that of honeycomb-like pure TiO2. Under solar light irradiation, photocatalytic activity of ant nest-like sample is also enhanced and hydrogen production rate is about 1.8 times higher than that of TiO2. The strengthened photocatalytic activity is ascribed to synergy effect of morphology control and nitrogen ion doping.