Solid-solution alloying of immiscible Pt and Au boosts catalytic performance for H₂O₂ direct synthesis

Here, we propose the solid-solution alloy nanoparticles (NPs) composed of Pt and Au supported on TiO₂ as an efficient catalyst for direct H₂O₂ synthesis, although Pt and Au are entirely immiscible in the bulk phases. Pt and Au atoms were homogeneously distributed in a wide composition range of Pt_xAu_100-x NPs (10 ≤ x ≤ 80) supported on TiO₂. The most Au-rich Pt₁₀Au₉₀ NPs/TiO₂ exhibits the best catalytic performances, H₂O₂ selectivity (94.5 ± 0.6%) and productivity (959 ± 12 mmol_H2O2•g_metal⁻¹•h⁻¹), even under mild conditions (10 °C, 1 atm) and without halide-ion additives. Density functional theory calculations reveal that the introduction of inactive Au atoms strongly suppresses both O-O bond scission and OH hydrogenation, thereby enabling near unity selectivity. The Pt-Au catalyst is Pd-absent, which is noteworthy given previous efforts in direct H₂O₂ synthesis are mostly limited to prototypical Pd or Pd-based modifications. This work will stimulate active utilization of immiscible elemental combinations for the direct H₂O₂ synthesis catalyst development.