Rationally designed ternary CdSe/WS_2/g-C_3N_4 hybrid photocatalysts with significantly enhanced hydrogen evolution activity and mechanism insight

摘要

Excellent light harvest, efficient charge separation and sufficiently exposed surface active sites are crucial for a given photocatalyst to obtain excellent photocatalytic performances. The construction of two-dimensional/two-dimensional (2D/2D) or zero-dimensional/2D (0D/2D) binary heterojunctions is one of the effective ways to address these crucial issues. Herein, a ternary CdSe/WSsub2/sub/g-Csub3/subNsub4/sub composite photocatalyst through decorating WSsub2/sub/ g-Csub3/subNsub4/sub 2D/2D nanosheets (NSs) with CdSe quantum dots (QDs) was developed to further increase the light harvest and accelerate the separation and migration of photogenerated electron-hole pairs and thus enhance the solar to hydrogen conversion efficiency. As expected, a remarkably enhanced photocatalytic hydrogen evolution rate of 1.29 mmol g(-1) h(-1) was obtained for such a specially designed CdSe/WSsub2/sub/g-Csub3/subNsub4 /subcomposite photocatalyst, which was about 3.0, 1.7 and 1.3 times greater than those of the pristine gCsub3/subNsub4 /subNSs (0.43 mmol g(-1) h(-1)), WS2/g-(CN4)-N-3 2D/2D NSs (0.74 mmol g-1 h-1) and CdSe/g-(CN4)-N-3 0D/2D composites (0.96 mmol g(sub-1/sub) h(-1)), respectively. The superior photocatalytic performance of the prepared ternary CdSe/WS2/g-(CN4)-N-3 composite could be mainly attributed to the effective charge separation and migration as well as the suppressed photogenerated charge recombination induced by the constructed type-II/type-II heterojunction at the interfaces between g-(CN4)-N-3 NSs, CdSe QDs and WS2 NSs. Thus, the developed 0D/2D/2D & nbsp;ternary type-II/type-II heterojunction in this work opens up a new insight in designing novel heterogeneous photocatalysts for highly efficient photocatalytic hydrogen evolution.& nbsp; (c) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.commentSuperscript/Subscript Available/comment