Ligand-Mediated Tuning of Pd-Au Nanoalloys for Selective H2O2 Production in Direct Synthesis from H2 and O2

Hydrogen peroxide (H2O2) is an important industrial chemical that is widely applied in many areas. The direct synthesis of H2O2from H2and O2has 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 H2O2productivity of 165 mol/(kgPd·h) and selectivity of 82.3% under ambient pressure. The relationship between the electronic structure and catalytic activity indicated Pd0was the active site, while the presence of Au inhibited H2O2degradation rate. This research could help in the design efficient bimetallic catalysts for the direct synthesis of H2O2.