Selective Dissociation of Dihydrogen over Dioxygen on a Hindered Platinum Surface for the Direct Synthesis of Hydrogen Peroxide

Abstract

To achieve high catalytic selectivity towards H2O2 from a H-2/O-2 mixture, HH bonds should be dissociated and OO bonds should be kept intact in the course of the reaction. A major dilemma in catalyst design, however, is that the metal catalysts that dissociate HH bonds have a thermodynamic preference for the dissociation of OO bonds. In this work, the selective dissociation of H-2 over O-2 was realized by the deposition of H-2-selective carbon diffusion layers on a Pt catalyst. Because O-2 cannot access the carbon-coated Pt surface, O-2 hydrogenation occurs at the carbon surface from spilt-over hydrogen rather than at the Pt surface on which OO dissociation is likely. This leads to the great suppression of OO dissociation, which allows the highly selective synthesis of H2O2. Notably, N-doping of the carbon diffusion layer could increase the selectivity towards H2O2 significantly because of the stabilization of the hydroperoxy radical on the carbon surface.