Na2CO3-assisted synthesis of Na-doped crystalline/amorphous g-C3N4 S-scheme homojunction photocatalyst for enhanced H2O2 production

The construction of crystalline/amorphous g-C 3 N 4 homojunctions presents a versatile strategy to obtain all-organic homojunction photocatalysts with better interface matching and lower interface charge carrier movement resistance for optimized photocatalytic activity. However, the process entails a complex multi-step workup, which compromises its feasibility. To overcome this challenge, this work provided an innovative Na 2 CO 3 -induced crystallinity modulation strategy to construct a Na-doped crystalline/amorphous g-C 3 N 4 S-scheme homojunction photocatalyst in a single step. The approach involves the initial pre-assembling of melamine and cyanuric acid molecules, and subsequent introduction of Na 2 CO 3 before the calcination. Na 2 CO 3 plays key roles to induce in-situ crystallinity modulation during the calcination and as a source for Na-doping. The prepared g-C 3 N 4 S-scheme homojunction photocatalyst demonstrated a prominent H 2 O 2 -production rate of 444.6 μmol·L –1 ·h –1 , which is 6.1-fold higher than that of bulk g-C 3 N 4 . The enhanced activity was attributed to the synergistic effect of charge carrier separation induced by the S-scheme homojunction system, and the optimized interfacial H 2 O 2 generation kinetics. The latter was fostered by the Na-doping. This study provides an innovative approach for the one-step construction of g-C 3 N 4 S-scheme homojunction and its integration in photocatalytic applications.