Promoting H2O2 direct synthesis through Fe incorporation into AuPd catalysts

Abstract

In recent years growing interest has been placed on the role of dopant concentrations of tertiary precious and base metals in modifying the performance of supported AuPd nanoalloys towards the direct synthesis of H₂O₂. Within this contribution, we expand on these earlier studies, with a focus on Fe-containing systems. Through rational catalyst design, an optimal 0.5%Au–0.5%Pd–0.02%Fe/TiO₂ formulation has been developed, which not only outperforms the parent bimetallic analogue but also offers increased reactivity compared to alternative trimetallic formulations previously reported, including those which incorporate Pt. Such observations may be surprising given the propensity for Fe to decompose H₂O₂via Fenton pathways. However, detailed analysis by CO-DRFITS and XPS reveals that the enhanced activity can be attributed to the electronic modification of Pd and the formation of domains of mixed Pd²⁺/Pd⁰ oxidation state, upon Fe introduction. Notably, the resulting improvement in catalytic performance which results from dopant Fe incorporation, is seen to result from an increase in H₂ utilisation, rather than improved catalytic selectivity towards H₂O₂.