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

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 π* (CC) and σ* (C–C) peaks toward lower energy losses and prominent presence of σ* (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 μmol h^–1g^–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 (τ₁ = 0.25 ns) of excitons, higher degree of band bending, and increased donor density as revealed by transient photoluminescence studies and Mott–Schottky analysis

Ceria Supported Pt/PtO-Nanostructures: Efficient Photocatalyst for Sacrificial Donor Assisted Hydrogen Generation under Visible-NIR Light Irradiation

In photocatalysis, imperative photoredox behavior and narrow band gap are important properties to exploit solar light for water splitting reaction. Nanostructured ceria (cerium dioxide/CeO₂) with Ce³⁺/Ce⁴⁺ (photoredox couple) shows significant enhancement in photocatalytic activity, however, no significant activity for water splitting reaction. The present study mainly focuses on incorporation of Pt on nanostructured mesoporous ceria by wet-impregnation method and its evaluation for donor assisted photocatalytic water splitting reaction. The BET analysis shows much higher surface area (119–131 m² g^–1) for unmodified as well as Pt modified mesoceria samples as compared to commercial ceria (24.4 m² g^–1), although structure was not ordered. The incorporation of Pt on mesoceria shows remarkable influence on photocatalytic hydrogen generation activity, and 1 wt % Pt was found to be optimized content, with broader light absorption. This photocatalyst was optimized with respect to photocatalyst dose, use of different sacrificial donors and their concentrations as well as other experimental parameters, with 34 h time course evaluation, yielding cumulative 1.52 mmol of hydrogen, under visible-NIR light irradiation and using ethanol as a sacrificial donor. The XPS, BET and photoluminescence studies imply that the enhanced photocatalytic hydrogen evolution in the case of mesoceria is due to the unison of high surface area, reduced recombination of photogenerated charge carrier and lower Ce³⁺ concentration in the case of mesoceria