Role of Pt atoms on Pd(1 1 1) surface in the direct synthesis of hydrogen peroxide: Nano-catalytic experiments and DFT calculations

Pd-Pt bimetallic catalysts have been studied for improvement of H₂O₂ selectivity in direct synthesis of H₂O₂; however, the role of Pt on the Pd surface has not been clearly identified. Herein, we investigated the role of Pt atoms on Pd(1 1 1) facets by realizing the surface in two different ways: nano-synthesis and density functional theory (DFT) calculation model. Pd(1 1 1) were modified into 3 kinds of Pd-Pt-alloyed surfaces, a minor Pt-substituted Pd, a major Pt-substituted Pd and a Pt-shell, covering bulk Pd. We successfully embedded Pt atoms in the octahedral Pd surface. Reaction tests showed that the minor Pt-substituted octahedral Pd catalyst had the highest H₂O₂ selectivity, production rate and the lowest H₂O₂ decomposition rate. The experimental results were consistent with our DFT calculations which predicted the lowest activation barrier for the O₂ hydrogenation step and the highest one for the H₂O₂ dissociation step on the minor Pt-substituted Pd surface.