Enhanced Photocatalytic Activity and Charge Carrier Dynamics of Hetero-Structured Organic Inorganic Nano-Photocatalysts

Abstract

P3HT-coupled CdS heterostructured nanophotocatalysts have been synthesized by an inexpensive and scalable chemical bath deposition approach followed by drop casting. The presence of amorphous regions corresponding to P3HT in addition to the lattice fringes [(002) and (101)] corresponding to hexagonal CdS in the HRTEM image confirm the coupling of P3HT onto CdS. The shift of pi* (C=C) and sigma* (C-C) peaks toward lower energy losses and prominent presence of sigma* (C-H) in the case of P3HT-CdS observed in electron energy loss spectrum implies the formation of heterostructured P3HT-CdS. It was further corroborated by the shifting of S 2p peaks toward higher binding energy (163.8 and 164.8 eV) in the XPS spectrum of P3HT-CdS. The current density recorded under illumination for the 0.2 wt % P3HT-CdS photoelectrode is 3 times higher than that of unmodified CdS and other loading concentration of P3HT coupled CdS photoelectrodes. The solar hydrogen generation studies show drastic enhancement in the hydrogen generation rate i.e. 4108 mu mol h(-1) g(-1) in the case of 0.2 wt % P3HT-CdS. The improvement in the photocatalytic activity of 0.2 wt % P3HT-CdS photocatalyst is ascribed to improved charge separation lead by the unison of shorter lifetime (tau(1) = 0.25 ns) of excitons, higher degree of band bending, and increased donor density as revealed by transient photoluminescence studies and Mott-Schottky analysis.