The photocatalytic hydrogen peroxide production of the as-prepared photocatalysts was studied in water and 10% methanol at atmospheric pressure and saturated by oxygen. The reaction conditions were optimized with the temperature kept at 5-8°C using ice and a pH of 4, as established in previous work. Au@CloseLarge show the best activity among the catalysts studied in this work, with a yield of 1.54 mmol h -1 m -2 using simulated solar light. Pristine TiO2 yields H2O2 at a rate of only 0.22 mmol h -1 m -2 . Figure clearly shows the effect of the larger SPs on the photocatalytic performance of the composite catalyst, indicating that the use of Au@CloseLarge enhances the catalytic activity under simulated solar light by more than 7 times compared to pristine TiO2, and it is twice that of the smaller Au-TiO2 SPs. To further understand the photocatalytic mechanism of the catalysts, the difference in hydrogen peroxide production rate at wavelengths of 385 nm, 515 nm and simulated solar light was studied. Upon excitation at 385 nm, the TiO2 bandgap can be overcome, the 515 nm source corresponds to the maximal LSPR wavelength, and solar light provides a broadband source that integrates both.