Assemble of Bi-doped TiO2 onto 2D MoS2: an efficient p-n heterojunction for photocatalytic H2 generation under visible light

Fabrication of noble-metal-free, efficient and stable hybrid photocatalyst is essential to address the rapidly growing energy crisis and environmental pollution. Here, MoS2 has been used as the co-catalyst on Bi-doped TiO2 to form a novel heterostructure to increase the utilization of the photogenerated charge carriers for improving photocatalytic H-2 evolution activity through water reduction. Significantly increased photocatalytic H-2 generation has been achieved on the optimized MoS2/Bi-TiO2 nanocomposite (similar to 512 mu mol g(-1)) after 4 h of visible light illumination, which is nine times higher than that of the pristine TiO2 (similar to 57 mu mol g(-1)). The measurements of photocurrent, charge transfer resistance and photo-stability of MoS2/Bi-TiO2 photoanode imply that charge separation efficiency has been improved in comparison to the pure MoS2 and TiO2 photoanodes. Further, the Mott-Schottky study confirmed that a p-n heterojunction has been formed between n-type MoS2 and p-type Bi-doped TiO2, which provides a potential gradient to increase charge separation and transfer efficiency. On the basis of these experimental results, this enhanced photocatalytic activity of MoS2/Bi-TiO2 heterostructures could be ascribed to the significant visible light absorption and the efficient charge carrier separation. Thus, this work demonstrates the effect of p-n junction for achieving high H-2 evolution activity and photoelectrochemical water oxidation under visible light illumination.