Constructing oxide/sulfide in-plane heterojunctions with enlarged internal electric field for efficient CO2 photoreduction

The internal electric field (IEF) has recently attracted intense attention in photocatalysis due to its extraordinary ability in accelerating charge separation and migration. In this work, it is found that IEF intensity can be effectively enhanced by constructing oxide/sulfide in-plane heterojunction from the pristine two-dimensional (2D) metal sulfides. Taking 2D In2S3 nanosheet as a model, In2O3/In2S3 in-plane heterojunction has been obtained via O2 plasma technique, the IEF of which has been dramatically increased by 2.7 times. Benefitting from its enlarged IEF, In2O3/In2S3 exhibits a 6.2 times improvement in terms of charge separation efficiency, reaching up to 5.6 %, accompanied by much faster charge migration. Thus, it has achieved a 6.4-fold increase of CH4 yield in CO2 photoreduction. Furthermore, the concept of IEF-induced better performance in oxide/sulfide in-plane heterojunction has been proved to be feasible toward other 2D sulfides, such as SnS2 and ZnIn2S4. Overall, this work throws light on enhancing the IEF via in-plane heterojunction construction to improve the photocatalytic performance of 2D metal sulfides.