Ultrathin CdS@BDC nanosheets derived from 2D metal–organic frameworks for enhanced photoinduced-stability and photocatalytic hydrogen production

Abstract

Two-dimensional metal–organic framework materials have attracted much attention due to their large surface area, porous structure and high carrier separation efficiency. Herein, we innovatively proposed a facile in situ vulcanization method, in which 2D Cd-MOF was used as the precursor and template to prepare a novel ultrathin CdS@1,4-benzenedicarboxylic (CdS@BDC) nanosheet in Na₂S/Na₂SO₃ solution. The obtained CdS@BDC nanosheet has the overall morphology of a 1.46 nm average thickness nanosheet skeleton, and is uniformly in situ embedded with CdS nanoparticles with an average size of 6 nm. Due to the two-dimensional skeleton structure, the efficiency of capture, separation and migration of photogenerated carriers was significantly improved. The hydrogen evolution rate (HER) of ultrathin CdS@BDC nanosheet photocatalysts is up to 13 081 μmol h⁻¹ g⁻¹, which is 65 times higher than that of traditional CdS nanoparticles (199 μmol h⁻¹ g⁻¹). The excellent photocatalytic performance of CdS@BDC nanosheets can be attributed to the inherited structural and functional advantages of 2D Cd-MOF. For example, the efficiency of photo-generated carrier capture, separation and migration is significantly improved. For another example, the surface of the photocatalyst can adsorb a large amount of S²⁻ ions, which not only consumes photogenerated holes as effective hole scavengers, but also accelerates the interfacial H₂-production reaction due to the effective H⁺-capturing active sites. Thus, a tentative S²⁻-mediated mechanism for the enhanced photoinduced-stability of CdS@BDC nanosheets was also proposed. The present work provides a facile and fascinating strategy for the synthesis of highly efficient photocatalysts.