Facile one-pot in-situ hydrothermal preparation of 0D/2D Mn3O4/CdS heterojunctions for improved photocatalytic H2 production and degradation of methylene blue

Developing heterojunction photocatalysts is a critical method to augment the photocatalytic activity of single semiconductors. However, the instability of their heterostructure poses a significant challenge. Herein, a unique 0D/2D Mn 3 O 4 /CdS p-n photocatalyst has been prepared by a simple one-pot in-situ hydrothermal approach for H 2 production and methylene blue (MB) degradation. The optimized MC-0.18 (18 at% Mn) nanocomposite showed remarkable photocatalytic properties, producing a significantly higher H 2 generation rate of 1291 μmol· g −1 · h −1 , which was 13.7 and 9.2 times higher than that of pristine CdS and ex-situ synthesized MC-0.18-ex photocatalysts, respectively. MC-0.18 displayed the highest reaction rate at 0.0435 min −1 for MB degradation, which was approximately 2.6 and 6.3 times higher than CdS and Mn 3 O 4 , respectively. Active species capture experiments and ESR identified •OH and •O 2 − as the main substances involved in MB degradation. Importantly, MC-0.18 demonstrated excellent stability and reusability in photocatalytic H 2 production and MB degradation cycle tests. The formation of unique p-n heterostructures results in enhanced photoactivity due to the matched band alignment between ultrafine Mn 3 O 4 nanoparticles and CdS nanosheets , leading to a high charge separation capacity. This study offers a facile route to design p-n heterojunctions that have remarkable charge transfer abilities to promote H 2 production and degrade organic dyes.