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

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 hetero-junctions 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 evolu-tion reaction (HER) activity with the highest activity of 3150 mu mol .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.

Automated summary

This study investigates the effect of electron transfer rate on the photocatalytic activity of semiconductor heterojunctions. By synthesizing a series of sensitized semiconductor heterojunction materials, it is found that tuning the CdS quantum dot size can regulate the electron transfer rate and photocatalytic activity. This provides a new strategy for developing highly efficient photocatalysts.