Nanostructured p-TiO2/n-GaN heterostructure as a potential photoelectrode for efficient charge separation

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 H₂ evolution activity through water reduction. Significantly increased photocatalytic H₂ generation has been achieved on the optimized MoS₂/Bi-TiO₂ nanocomposite (∼512 μmol g^-1) after 4 h of visible light illumination, which is nine times higher than that of the pristine TiO₂ (∼57 μmol 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 H₂ evolution activity and photoelectrochemical water oxidation under visible light illumination.