Enhancing Photocatalytic H2 Production and Dye Degradation: Comparative Analysis of Gold Reduction Techniques on Au/TiO2 Nanocomposites

This study compares the impact of two reduction techniques, thermal reduction (TR) and photocatalytic reduction (PR), on Au/TiO2 photocatalysts synthesized using the deposition-precipitation with urea (DPU) method. Characterization methods, including temperature-programmed reduction (TPR), UV-Vis diffuse reflectance spectroscopy (DRS), electrochemical assessments (open-circuit potential (OCP) and linear sweep voltammetry (LSV)), and transmission electron microscopy (TEM), were employed. The 2-hour PR treatment (0.5Au-PR2) yielded a highly effective, with 93.6% of gold nanoparticles below 4 nm, outperforming the TR counterpart (76.8%). All Au-loaded samples exhibited an absorption band between 400-800 nm, indicating the localized surface plasmon resonance (LSPR) effect. Interestingly, the TR catalyst had a broader LSPR band than the PR catalyst. Additionally, the 0.5Au-PR2 sample showed higher photocurrent and superior photocatalytic activity photocatalyst in the degradation of methyl orange and hydrogen production, attributed to its smaller particle size (2.9 nm) and weaker metal-support interaction. This smaller particle size emphasizes the crucial role of reduction techniques in tailoring Au/TiO2 photocatalysts for enhanced performance.