Adjusting accommodation microenvironment for Cu⁺ to enhance oxidation inhibition for thiophene capture

Cu⁺-containing materials have great potentials in various applications like adsorptive desulfurization. Nevertheless, their applications are severely obstructed by poor stability of Cu⁺ in air. Here, we first clarify the mechanism of Cu⁺ oxidation by first-principle calculations and demonstrate that moisture accelerates Cu⁺ oxidation dramatically. Then, the microenvironment of Cu₂O-modified HKUST-1, a typical metal-organic framework, is adjusted from hydrophilic to hydrophobic with polydimethylsiloxane coating (producing Cu₂O@HK@P). This isolates moisture from pores and enhances the stability of Cu⁺ significantly even under oxygen atmosphere. Cu⁺ in Cu₂O@HK@P preserves well after exposed to air for 6 months, while Cu₂O@HK lose almost all Cu⁺ for 2 weeks. The optimal Cu₂O@HK@P can remove 540 μmol g⁻¹ of thiophene from hydrous fuel, which is much superior to Cu₂O@HK (227 μmol g⁻¹) and most reported adsorbents. Our strategy can also be applied to stabilize Cu⁺ in various materials including zeolite, mesoporous silica, and activated carbon.