<p>In the present study, high-purity and uniform Au₁₄₄-(SCH₂Ph)₆₀ nanoclusters with a size of 1.8&#xa0;nm were synthesized. TiO₂ and Ce^δ+ modified TiO₂ were prepared by different methods. Au₁₄₄-(SCH₂Ph)₆₀ nanoclusters were then dispersed on Ce^δ+ modified TiO₂ supports to investigate the photocatalytic degradation of methylene blue (MB) under sunlight irradiation. The photocatalytic performance results showed that after 60&#xa0;min, the degradation efficiency of MB over pure TiO₂ was 68.4%. Slight improvements were observed for (CeO₂)_0.03/TiO₂ and (CeO₂)_0.03-TiO₂, with degradation efficiencies reaching 69.8% and 70.2%, respectively. However, when the Au₁₄₄ cluster were loaded onto these supports, the degradation efficiencies were significantly enhanced to 73.3%, 81.2%, and 90.2% for Au₁₄₄/TiO₂, Au₁₄₄/ (CeO₂)_0.03/TiO₂ and Au₁₄₄/ (CeO₂)_0.03-TiO₂,. The catalysts were thoroughly characterized using X-ray powder diffraction (XRD), Matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS), Ultraviolet (UV) Raman spectroscopy, and UV–vis absorption spectroscopy. Systematic characterizations revealed that the incorporation of trace amounts of Ce^δ⁺ into the TiO₂ lattice red-shifted the absorption edge of TiO₂ into the visible portion of the solar spectrum and increased the number of oxygen vacancies. These modifications not only stabilized the Au₁₄₄-(SCH₂Ph)₆₀ nanoclusters on the support but also contributed to the enhanced photocatalytic activity for MB degradation under sunlight irradiation. Notably, compared to forming gold nanoparticles on TiO₂ and (CeO₂)_0.03/TiO₂, the Au₁₄₄ clusters exhibited superior structural stability in the Au₁₄₄/ (CeO₂)_0.03-TiO₂ catalyst, which was maintained even after storage in air at room temperature for 1&#xa0;year.</p> Graphical abstract <p></p>