Recent work has demonstrated that, for bimetallic Au–Pd systems, the rate of catalytic alcohol and formyl dehydrogenation (DH) is intrinsically linked to the rate of oxygen reduction (ORR) within the same system.

Hydrogen peroxide (H₂O₂) is an important industrial chemical that is widely applied in many areas. The direct synthesis of H₂O₂ from H₂ and O₂ has proved to be a green and economic pathway. Pd-based bimetallic catalysts, due to their superior catalytic performances in this reaction, have attracted intensive attention. Herein, Tetrakis(hydroxymethyl)phosphonium chloride (THPC) was adopted as the protective ligand to immobilize Pd-Au alloy nanoparticles onto activated carbon (AC). The varied Pd/Au molar ratios demonstrated homogeneously distributed Pd-Au nanoalloys with average particle sizes ranging from 3.51 to 5.75 nm. The optimal ratio was observed over the Pd₃Au₁/AC-THPC catalyst with a maximum H₂O₂ productivity of 165 mol/(kg_Pd·h) and selectivity of 82.3% under ambient pressure. The relationship between the electronic structure and catalytic activity indicated Pd⁰ was the active site, while the presence of Au inhibited H₂O₂ degradation rate. This research could help in the design efficient bimetallic catalysts for the direct synthesis of H₂O₂.