S-scheme heterojunction of MoO3 nanobelts and MoS2 nanoflowers for photocatalytic degradation

This project presents the fabrication of an efficient heterojunction photocatalyst through combining 3D MoS₂ nanoflowers with 2D MoO₃ nanobelts, both having highly prominent photocatalytic features. The prepared MoS₂@MoO₃ heterojunction exhibited superior photocatalytic activity towards the degradation of Azo dye under visible light irradiation and attained about 96% degradation within four hours. Such a high photocatalytic activity might be associated with the high BET surface area, and especially with the S-scheme mechanism that occurs between p-type MoS₂ and p-type MoO₃, probably due to the fact that this offers effectively separated and transitioned photogenerated electron-hole pairs, while the recombination rate is reduced. The addition of MoO₃ increased the bandgap of MoS₂ and consequently enhanced the photoinduced electron transfer rate and prolonged the lifetime of the charge carriers. In a word, the generation of hole and ^•O₂^- radicals in the whole process of degradation, which have been proved by scavenger tests and Mott-Schottky analysis, proved the MoS₂@MoO₃ p-p heterojunction to be photocatalytically active. This work underlines the successful application of bandgap and morphological engineering in the design of photocatalysts and points out the 3D/2D MoS₂@MoO₃ heterojunction structure as the basis for further development of transition metal chalcogenide (TMC)/transition metal oxide (TMO) photocatalysts with a view to tackling important environmental problems by means of sustainable technologies.