2D/2D MgO/g-C3N4 S-scheme heterogeneous tight with Mg-N bonds for efficient photo-Fenton degradation: Enhancing both oxygen vacancy and charge migration.

Construction of S-scheme heterojunction is an efficient strategy to enhance photocatalytic efficiency. Besides the retained redox ability, the wide work function gap and intimate interface contact are essential for efficient degradation. Nontoxic magnesium oxide (MgO) with two dimensional (2D) structures and high work function is a potential material for S-scheme photocatalysts. Herein, MgO was used to in-situ grown on graphitic carbon nitride (g-C3N4) for constructing the strongly connected MgO/g-C3N4 S-scheme photocatalyst with tight Mg-N bonds. Meanwhile, the presence of Mg-N bonds induces the formation of oxygen vacancy in MgO, which enhances the Fenton-like degradation. Furthermore, the Mg-N bond promotes the charge migration between MgO and g-C3N4. Consisting of the enhanced Fenton-like process and photocatalysis, the MgO/g-C3N4 shows a higher photo-Fenton degradation activity (80.01%) for degradation of organic pollutants (Rhodamine B, 100 mg L-1) in water, than g-C3N4 (28.46%) and MgO (55.64%). Therefore, the interfacial chemical bonds in heterojunction photocatalysts provide an efficient strategy for further enhancing the photocatalysis of S-scheme photocatalysts.