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With a focus on catalysts prepared by an excess-chloride wet impregnation procedure and supported on the zeolite ZSM-5(30), the introduction of low concentrations of tertiary base metals, in particular Cu, into supported AuPd nanoparticles can be observed to enhance catalytic activity towards the direct synthesis of H₂O₂. Indeed the optimal catalyst formulation (1%AuPd_(0.975)Cu_(0.025)/ZSM-5) is able to achieve rates of H₂O₂ synthesis (115 mol_H₂O₂kg_cat⁻¹h⁻¹) approximately 1.7 times that of the bi-metallic analogue (69 mol_H₂O₂kg_cat⁻¹h⁻¹) and rival that previously reported over comparable materials which use Pt as a dopant. Notably, the introduction of Cu at higher loadings results in an inhibition of performance. Detailed analysis by CO-DRFITS and XPS reveals that the improved performance observed over the optimal catalyst can be attributed to the electronic modification of the Pd species and the formation of domains of a mixed Pd²⁺/Pd⁰ oxidation state as well as structural changed within the nanoalloy.