CuO Nanoparticle-Loaded TiO₂ Catalyst for High-Performance Photocatalytic Hydrogen Peroxide Generation

Titanium dioxide (TiO₂) has been extensively investigated in photocatalysis due to its high stability, low toxicity, and biocompatibility. However, its application in hydrogen peroxide (H₂O₂) production is hindered by the rapid recombination of photogenerated charge carriers and the poor selectivity of the two-electron oxygen reduction reaction (2e^- ORR). Here, a CuO/TiO₂ photocatalyst is reported, in which CuO nanoparticles are anchored on the TiO₂ surface as cocatalysts to provide additional active sites and promote efficient separation of photogenerated electrons and holes. The optimized CuO/TiO₂ exhibits a remarkable photocatalytic H₂O₂ production rate of 19.48 mmol g^-1 h^-1, which is 162 times higher than that of pristine TiO₂, with excellent stability sustained over 7 h' continuous irradiation. The apparent quantum yield (AQY) of CuO/TiO₂ reaches 7.30% at 365 nm. Notably, the CuO/TiO₂ demonstrated the promising H₂O₂ production in pure water (182.31 µmol g^-1 h^-1). Femtosecond transient absorption spectra (Fs-TAS) reveal that the average lifetime of photogenerated electrons in CuO/TiO₂ is 5.8 times longer than in TiO₂, confirming the enhanced charge separation and transfer. In situ spectroscopic analyses further demonstrate that CuO/TiO₂ facilitates both oxygen reduction and water oxidation pathways. These results highlight CuO/TiO₂ as a cost-effective and efficient photocatalyst for sustainable H₂O₂ production.