Switching the Oxygen Reduction Route on Pt Using S through d–p Hybridization

The development of electrocatalysts capable of selective two-electron oxygen reduction reactions (ORRs) has become a major obstacle in the electrochemical synthesis of H2O2. Herein, a series of platinum sulfide catalysts with different sulfur contents were synthesized by a chemical vapor deposition method. The two-electron ORR performance exhibited a "volcano" plot relationship with the sulfur content of the catalysts. The PtS1.38/C catalyst with optimal sulfur content achieved a two-electron ORR selectivity of 92% at near zero overpotential and a mass activity of 70.5 A gPt–1 [0.65 V vs reversible hydrogen electrode (RHE)]. Combined spectroscopic studies and density functional theory calculations showed that the introduction of sulfur changed the d band structure of the Pt surface and in turn the binding energy of oxygen-containing species. The PtS1.38/C catalyst was capable of stable batch electrosynthesis of hydrogen peroxide in an H-cell, maintaining a high productivity of 992 mmolH2O2 g–1cat h–1 (0.2 V vs RHE), which has great potential for practical applications.