To synthesize Au@ZnO core@shell nanoparticles, a 20 ml aqueous reaction mixture was prepared in a Teflon-lined hydrothermal reaction flask under stirring. This mixture included effectively templating the growth of conformal ZnO shells. The reactor is placed in an aluminum heating mantle on a heating plate and the mixture is kept at 87.5 °C for 8 h. After the heating process, the solution is collected and centrifuged at 5,000 rpm (2,739 x g) for 15 min, the supernatant is removed, and the product is redispersed in an equal volume of water to remove unreacted components and surfactant. Prior to annealing, it is crucial to thoroughly remove any remaining reactants in the centrifugation step. The product, consisting of Au@Zn(OH)2 nanoparticles, is drop-casted onto a flat Si wafer and dried in air at 150 °C for 30 min until dry, before calcination at 500 °C for 2 h in a furnace with a heating ramping time of 30 min. The product is then left to cool to room temperature. The obtained powder consisting of Au@ZnO NPs with a shell thickness of 46 nm, was then collected by scraping it off the Si wafer with plastic spatula and the powder stored in an airtight container for further characterization.