CdSe quantum dots modified thiol functionalized g-C3N4: Intimate interfacial charge transfer between 0D/2D nanostructure for visible light H2 evolution

Abstract

Abstract In this paper, a novel hybrid photocatalyst comprising of CdSe quantum dots (QDs) supported on thiol (-SH) functionalized g-C3N4 sheet (TF-g-C3N4) has been synthesized and studied for hydrogen (H2) evolution. Thiol-functional group has a strong affinity towards the CdSe QDs, which assists the uniform dispersion of 0-dimensional CdSe QDs on TF-g-C3N4 sheets. The hybrid-structure of CdSe-TF-g-C3N4 prepared by different weight % loading of CdSe QDs (6 wt %, 12 wt %, 18 wt % and 24 wt %) on TF-g-C3N4 sheets. Thiol-functional group on the g-C3N4 sheet acts as a hole quencher, which suppresses the photogenerated charge recombination. The enhanced photocatalytic rate of H2 generation was observed for the functionalized TF-g-C3N4 sheet (8.1 times) as compared to non-functionalized g-C3N4 sheet. The hybrid-structure photocatalyst with 18 wt% CdSe QDs on TF-g-C3N4 sheet shows the synergetic increase in photocatalytic H2 evolution compared to its components due to intimate interfacial attachment between CdSe QDs and –SH functional group. At an irradiation wavelength of λ ≥ 420 n m , 18 wt% CdSe-TF-g-C3N4 shows steady H2 evolution at the rate of 31,000 μmolh−1g−1, which is over 103.3 fold the rate of H2 evolution for g-C3N4 sheets and 12.3 times TF-g-C3N4. The developed heterostructure photocatalyst 18 wt% CdSe-TF-g-C3N4 shows an outstanding apparent quantum yield (AQY) efficiency of 13.86% at an irradiation wavelength of 460 nm. Hence, this novel heterostructure, CdSe -TF-g-C3N4 proves itself as one of the capable candidates for visible-light photocatalyst with optimum morphology, and bandgap.