Design and Photocatalytic Evaluation of Plasmonic TiO₂–Au Nanocomposites for Enhanced Solar-Driven Hydrogen Production

Abstract

Efficient photocatalysts to be utilized in the process of hydrogen generation using solar energy are also considered to be one of the major challenges to realize the process of energy conversion into the sphere of sustainability. This paper presents the architecture, synthesis and photocatalytic study of plasmonic TiO2-Au nanocomposites that had been designed with improved ability to absorb visible-light and charge separation. The TiO2 nanoparticles were produced through a sol-gel process and also functionalized using gold nanoparticles using a limited chemical reduction method. The crystalline phase anatase of TiO2 and even dispersion of the Au was validated by comprehensive structural and morphological analysis by XRD, SEM, and TEM. Localized surface plasmon resonance (LSPR) of Au was identified by optical characterization using UV-Vis diffuse reflectance and photoluminescence spectroscopy which showed a significant red-shift of the absorption edge and lower electron-hole recombination. XPS analysis also confirmed that there was good electronic interaction between Au and TiO2, which increased interfacial charge transfer. The pace of H2 evolution was shown to increase significantly in the presence of visible light when using photocatalytic hydrogen evolution tests under visible light illumination in confirmation of the synergistic nature of plasmonic excitation and Schottky barrier formation. The accelerated charge movement and extended carrier lifetimes were identified by mechanistic information based on temporal photovoltage and electrochemical impedance spectroscopy. Experimental evidence was supported by Density Functional Theory (DFT) simulations which showed the existence of effective charge delocalization at the Au-TiO2 interface. The proposed TiO2-Au nanocomposite presents a bright future in the development of high-performance solar-active catalysts of photocatalysts in generation of green hydrogen.