Engineering SrCuxO composition to tailor the degradation activity toward organic pollutant under dark ambient conditions

The composition of SrCu O mixed metal oxides (MMOs) was engineered via varying the amount of copper relative to strontium. As-synthesized SrCu O were highly active for degrading methyl orange (MO) pollutant at dark ambient conditions without the aid of other reagents. The catalytic activity of SrCu O demonstrated a reverse-volcano relationship with copper content. Copper-rich MMOs (SrCu O) exhibited the highest degradation activity for MO by far and degraded ca. 96% MO within 25\ua0min. MO degradation over SrCu O was a surface-catalytic reaction and fitted pseudo-first-order reaction kinetics. The contact between MO molecules and catalyst surface initiated the reaction via the catalytic-active phase (Cu /Cu redox pair), which serves as an electron-transfer shuttle (⋯ Cu → + e Cu → − e Cu ⋯) from MO to dissolved O , inducing the consecutive generation of reactive oxygen species, which resulted in MO degradation as evidenced by radical trapping experiment. XPS and XRD analysis revealed that active phases in SrCu O materials underwent irreversible transformation after reaction, contributing to the observed deactivation in the cycling experiment. The observations in this study demonstrate the significance of chemical composition tailoring in catalyst synthesis for environmental remediation under dark ambient conditions. [Figure not available: see fulltext.]