Membrane-free selective oxidation of thioethers with water over a nickel phosphide nanocube electrode

Summary Developing a membrane-free oxidation reaction, especially using water as the oxygen source, to generate high-value chemicals with high selectivity for replacing low-value O2 over a cost-effective catalyst is significant. In this study, nickel phosphide (Ni2P) hollow nanocubes are designed and shown to enable membrane-free selective oxidation of thioethers to sulfoxides and sulfones with H2O. In situ Raman data reveal the surface reconstruction of Ni2P to NiOOH, and the resulting NiII/NiIII redox couple promotes this transformation. The 18O-labeling experiments confirm H2O as the oxygen source. A cross-coupling of the sulfur-related radical with the hydroxyl radical is proposed. Sulfoxides and sulfones with high yields and selectivity can be controlled via potential modulation, which is challenging for traditional methods. Deuterated sulfoxides and sulfones are readily synthesized via one-pot thioether oxidation and the tandem H/D exchange processes. Wide substrate scopes, good functional group compatibilities, integrating hydrogen production, and paired synthesis of deuterated sulfoxide and arene highlight the potential of this membrane-free strategy.