This study explores the preparation of Ag plasmons-sensitized magnetic-Fe 3 O 4 integrated TiO 2 (Ag−Fe 3 O 4 @TiO 2 ) ternary nanocomposites and their defectinduced electron storage properties to exploit their photocatalytic memory effect toward dye degradation and H 2 generation under light and dark conditions. The crystalline phase formation and elemental states of the individual materials and elements in the nanocomposite are analyzed using X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), respectively. The existence of Ti and Fe ions with dual oxidation states of Ti 4+/3+ and Fe 3+/2+ , respectively, is observed by XPS, which revealed the presence of defects in the system. The observed red shift along with a distinct plasmonic band (corresponding to metallic Ag nanoparticles) in the UV−visible absorption spectrum and the observed modified radiative recombination emission in the PL spectrum confirmed the plasmon-driven visible light activity along with the improved carrier separation and transfer characteristics in the synthesized ternary composite. Accordingly, the Ag− Fe 3 O 4 @TiO 2 photocatalyst degraded almost 100% of MB (methylene blue) and RhB (rhodamine B) dyes under simulated solar light in 90 min, while it is found to be around 42% and 36% in 60 min under dark conditions, respectively (which is preirradiated for 60 min). Further, it produced H 2 at the rate of 911 μmol g −1 h −1 under light conditions and is decreased to ∼96 μmol g −1 h −1 under dark conditions which is preirradiated for 1 h. However, when the composite is preirradiated for 3 h, it showed a maximum H 2 evolution of 144 μmol g −1 h −1 under dark. Further, the photocurrent and electrochemical impedance under light and dark conditions suggested the mechanism of photocatalytic charge storage and transfer process in the composite. Although the photocatalytic memory effect of the composite is meager toward H 2 production due to the insufficient potential of the stored−released electrons to reduce the protons (2H + ) to H 2 under dark conditions, their degradation efficiency is considerably good.

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CdS based nanocomposites are well reported for photocatalytic hydrogen evolution reactions because of their favorable band edge potentials. The preparation of well dispersed photocatalyst plays an important role in the enhancement of H2 production efficiency. Among all the other morphologies of CdS, nanorods gained considerable attention due to their channeled charge carrying ability and improved surface area. Herein, CdS nanocapsules, which offer short and extensive charge carrier transport and enlarged surface area, were synthesized via the solvothermal method. Poly­(vinyl pyrrolidine) was used as a capping agent for size control and better dispersion. Tungsten oxide nanosheets were synthesized via the hydrothermal route, and CdS nanocapsules were incorporated on the tungsten oxide nanosheets via the wet impregnation method. Photocatalytic hydrogen generation under solar light and simulated solar light irradiations with lactic acid as a sacrificial agent employing the prepared nanocomposite gave impressive and enhanced results, and furthermore the catayst was efficient and stable. The optimized photocatalyst showed a hydrogen production rate of about 146.2 mmol.h–1 .g–1 cat. This is the highest rate reported yet for the combination of CdS and WO3.The Z-scheme heterojunction formation between two different morphologies plays a key role in the enhancement of H2 generation.

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