Unravelling the influence of Ag{111} nanoprism on the redox characteristics of Fe2O3 for efficient photocatalytic degradation

Incorporating noble metal nanostructures onto metal oxides surface can significantly improve the photocatalytic performance towards dye degradation. Hematite (α-Fe₂O₃) is considered as a potential candidate for photocatalytic applications due to its unique optoelectronic properties. However, improving the light absorption co-efficient and the excitonic carrier lifetime in Fe₂O₃ is highly required which can be achieved through the incorporation of noble metals. Hence, in this work, different silver (Ag) nanostructures such as Ag nanospheres and Ag {111} nanoprisms are incorporated on Fe₂O₃ surface, thereby enhancing the absorption co-efficient of Fe₂O₃ through localized surface plasmon resonance (LSPR) of Ag nanostructures. Initially, a solid-state sintering technique was employed to prepare pure Fe₂O₃, then Ag nanostructures has been incorporated by constant stirring of Fe₂O₃ and Ag nanostructures in aqueous solution. The structural, morphological and vibration properties were studied by XRD, FESEM, HRTEM, XPS, and Raman analysis respectively. UV–Visible spectral analysis revealed that the optical bandgap energy of Fe₂O₃ gets decreased from 1.93 eV to 1.81 eV upon Ag nanostructures incorporation. Further, time-resolved photoluminescence measurements demonstrated an improved carrier lifetime in Ag{111}/Fe₂O₃ (2.67 ns) compared to Ag nanospheres/Fe₂O₃ (2.5 ns) and pure Fe₂O₃ (1.05 ns). Photocatalytic performance of the prepared samples were evaluated by the degradation of aqueous Rhodamine-6G dye, and the results showed a significant improvement in degradation efficiency, with a maximum photocatalytic efficiency of 87.47 % and a rate constant of 0.0482 min⁻¹. The result implies that the optoelectronic properties of Ag NSs plays a crucial role on the redox reactions involved in the photocatalytic dye degradation.