Dimethylsulfoxide as a modifier of platinum electrocatalytic activity toward oxygen reduction reaction in aqueous solutions: Combined theoretical and experimental study

• Effect of DMSO in acidic H2O-DMSO solution on kinetics of O2 reduction.
• Coordinated experimental and DFT calculation study was applied.
• DMSO adsorption suppressed oxide formation on Pt surface.
• We offered new way to accelerate ORR on Pt, based on DMSO adsorption.

By both density functional theory calculations (DFT) and voltammetry on rotating polycrystalline platinum disc, dimethylsulfoxide (DMSO) was investigated as a modifier of platinum electrocatalytic activity toward oxygen reduction reaction in aqueous solutions. The DFT calculations evidenced that DMSO molecule interacts with Pt surface most strongly by the mediation of S atom in SO group, and the modification of the surface electronic structure of Pt is restricted to the Pt atom contacting directly with the S atom. The calculated adsorption energy on Pt surface (Pt(1 0 0)) amounted to −108 kJ mol−1. The voltammetry with polycrystalline Pt disk electrode in mixed H2O-DMSO solutions supported by 0.1 mol dm−3 H2SO4 pointed out that DMSO adsorption suppressed oxide formation on Pt surface. In O2-saturated solutions, in presence of 1 vol.% of DMSO, it was found that the rate of oxygen reduction reaction (ORR) was higher in comparison to the one measured in DMSO-free solution. It was also confirmed that adsorption of DMSO suppressed ethanol oxidation reaction in the entire potential window where ORR takes place.

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