Role of Pt atoms on Pd(111) surface in the direct synthesis of hydrogen peroxide: Nano-catalytic experiments and DFT calculations

Abstract

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 O-2 hydrogenation step and the highest one for the H202 dissociation step on the minor Pt-substituted Pd surface. (C) 2018 Elsevier Inc. All rights reserved.