MgO nanolayering of Cu2O semiconductors enhances photoreactivity: Superoxide radicals boost

In this study, the interface effects of Cu 2 O and Au/Cu 2 O semiconductors were improved by addition of a magnesia (MgO) interface nanolayer (MIN) deposited via precipitation. The morphologies, crystal structures, chemical compositions, elemental states and optical properties of MgO/Cu 2 O and Au/MgO/Cu 2 O heterojunctions were characterized via SEM, XRD, XPS, UV–VIS–NIR and PL. It was found that the MIN has a surface passivation effect that inhibits the aggregation and oxidation of Cu 2 O. This enhances Cu 2 O semiconductors’ wettability and stability, improves crystallinity and reduces Au particle sizes. More importantly, the MIN promotes charge transfer via tunneling through the insulator, and enhances adsorption of molecular oxygen, facilitating superoxide radicals formation during photoreactivity. MgO/Cu 2 O and Au/MgO/Cu 2 O exhibited superior photodegradation of methyl orange, attributed to the boost of O 2 − and h + . This work confirmed the importance of MIN as a useful modification of semiconductor photocatalysts, and the MIN can significantly enhance the production of superoxide radicals in the photocatalytic activity with visible light.