To mitigate the impact of pH on the overall hydrothermal synthesis, we also tried a different approach in which the Al 3+ dopant solution was neutralized to a pH of 6.5 using ammonium hydroxide (NH4OH) before addition to the reaction mixture prior to hydrothermal heating. Despite the formation of Au@AZO core@shell nanoparticles, we noticed a significant decrease in particle size and shell homogeneity with increasing concentrations of the dopant (Figure SI.4).