Insights into Molten Salts Induced Structural Defects in Graphitic Carbon Nitrides for Piezo-Photocatalysis with Multiple H2O2 Production Channels

Recently, the production of hydrogen peroxide (H2O2) from water (H2O) and oxygen (O2) in the presence of graphitic carbon nitrides (g-C3N4) via a piezo-photocatalytic process has considerably ignited global interest in achieving sustainability. To fabricate porous g-C3N4, soft templates are frequently employed, leading to structural modifications originating from heteroatoms. However, many recent reports have ignored the roles of trace quantity of heteroatoms. Hence, to understand the impacts of the mentioned factors, we fabricated g-C3N4 containing oxygen and halogen atoms in the structures for piezo-photosynthesis of H2O2. Based on our analyzed results, oxygen atoms might be inserted into g-C3N4 in-plane structures, while halogen atoms tend to become intercalated between g-C3N4 layers. Furthermore, the presence of ammonium molten salts during the synthesis alters the concentration of mono and cluster vacancies of carbon and nitrogen in the materials. These defective contributions would meaningfully accelerate catalytic performance by providing trapping states. From the mechanistic view, different reduction and oxidation channels would play a pivotal role in generating H2O2. Thus, this study highlights the importance of modulating in-plane and out-of-plane structures of g-C3N4, benefiting catalytic properties under simultaneous irradiation.