Size-dependent electron injection over sensitized semiconductor heterojunctions for enhanced photocatalytic hydrogen production

• Published in: Applied catalysis. B, Environmental Environmental, 2022-07, Vol.308, p.121218, Article 121218
• Main Authors: Xu, Wenkai, Wang, Jiansong, Yu, Hui, Liu, Peng, Zhang, Gui-Rong, Huang, Hongliang, Mei, Donghai
• Format: Article
• Language: English
• Subjects: Cadmium; Cadmium sulfide; Catalytic activity; CdS/Cd-TCPP; Conduction bands; Controllability; Electron injection; Electron transfer; Electrons; Heterojunction; Heterojunctions; Hydrogen evolution reactions; Hydrogen production; Particulate composites; Photocatalysis; Photocatalytic H2 evolution; Porphyrins; Quantum dots; Size effect; Sulfidation
• ISSN: 0926-3373; 1873-3883
• DOI: 10.1016/j.apcatb.2022.121218

Mechanistic understanding of the effect of electron transfer rate across the semiconductor heterojunction interface on its photocatalytic activity remains elusive. Herein, a series of sensitized semiconductor heterojunctions consisting of monodisperse CdS quantum dots (QDs) with controllable sizes range of 2.2–6.5 nm and cadmium tetrakis(4-carboxyphenyl)porphyrin (Cd-TCPP) nanosheets are constructed through partial sulfidation strategy. The in situ resultant CdS/Cd-TCPP composites exhibit size-dependent photocatalytic hydrogen evolution reaction (HER) activity with the highest activity of 3150 μmol·h−1·g−1 obtained at a medium CdS QD size of 4.8 nm. It is demonstrated that the interfacial electron transfer rate and the corresponding photocatalytic HER activity can be regulated by tuning the CdS QD size that determines the conduction band position of CdS relative to Cd-TCPP. This work provides a new strategy that rationally controls the interfacial electron transfer rate for developing highly efficient photocatalysts. [Display omitted] •The capping agent-free CdS QDs with controllable size distribution are prepared.•CdS/Cd-TCPP heterojunctions with intimate interface contact are constructed.•The interfacial electron transfer rate can be regulated by tuning the CdS QD size.•CdS/Cd-TCPP heterojunctions exhibit size-dependent photocatalytic HER activity.•The size-dependent electron injection mechanism in photocatalytic HER is proposed.