▎ 摘　　要

The 2D/2D MgO/graphene nanosheets (MgO/GNs-x) catalysts were successfully synthesized to improve the photocatalytic efficiency of MgO under visible light. The synergistic effect of MgO, GNs, and hydrogen peroxide (H2O2) was investigated by degrading methylene blue (MB, 100 mg/L). The photocatalytic activity at 30 min of MgO and MgO/GNs-x (x = 1, 2, 3, 4, 5) under visible light were 89.0%, 99.0%, 99.4%, 98.0%, 97.8%, 84.0%, respectively. It can be found that the MgO with abound defects exhibited high photocatalytic activity. Further, the excellent electron migration of GNs was beneficial to separate photo-generated e(-)-h(+) pairs and visible light absorption. The band gap k is declined from 5.34 eV (MgO) to 4.94 eV (MgO/GNs-2). This study signifies that graphene effectively improves the photo-degradation efficiency of wide band-gap semiconductor photocatalyst.