In situ synthesis of C-doped TiO2@g-C3N4 core-shell hollow nanospheres with enhanced visible-light photocatalytic activity for H2 evolution

Developing photocatalysts with high charge separation and transfer efficiency remains a key challenge for photocatalytic water-splitting reaction. In this work, a facial approach was explored to successfully realize the in situ growth of g-C3N4 on the surface of C-doped TiO2 hollow nanospheres (C-TiO2). The as-obtained heterogeneous photocatalyst, C-TiO2@g-C3N4 (TCN), presented core-shell hollow nanosphere structure. Systematic studies disclose that the TCN photocatalysts exhibit remarkably enhanced visible light photocatalytic activity for water splitting to produce H-2 compared with the pristine C-TiO2 and g-C3N4. The TCN-2 photocatalyst (the weight ratio of initial urea and C-TiO2 is 2:1) presents the highest H2 generation rate of 35.6 mu mol g(-1)h(-1) which is 22.7 and 10.5 times higher than that of C-TiO2 and g-C3N4, respectively. The enhanced photocatalytic performance can be attributed to the formation of the heterojunction between the two semiconductors, which effectively promotes the separation of photo-generated carriers. Meanwhile, the intimate contact between the C-TiO2 and g-C3N4 resulted from the in situ growth greatly improves the separation and transfer efficiency of photo-generated carries. Besides, the enhancement in the utilization efficiency of light energy due to the unique hollow structure also exhibits a positive contribution. (C) 2017 Published by Elsevier B.V.