Making heterojunctions between semiamorphous carbon nitride (CN) and other well-matched semiconductors (or even insulators) can solve many photocatalytic problems such as the recombination of charge carriers. However, many researchers encounter intrinsic problems including the lack of detailed information on contact boundaries in their heterojunctions, particularly in the amorphous/amorphous interface. In addition, the roles of contact boundaries in the photocatalytic mechanisms of many heterojunctions are still obscure. This study synthesized a novel CN/SiO2/WO3 photocatalyst having two different contact features by constructing an amorphous/amorphous (CN/SiO2) interface and a crystalline/amorphous (WO3/CN) interface to provide deep insights into heterojunction interfaces. SiO2 plays an exceptional role as a major component in the separation and migration of charge carriers. It not only modifies the texture but also transfers electrons. Surprisingly, the amorphous/amorphous interface shows an unpredicted capability for decreasing the recombination of electron-hole pairs. Based on capturing experiments and photoluminescence investigations, the amorphous/amorphous interface is unprecedently present in the production of hydroxyl radicals, while the crystalline/amorphous interface gives more superoxide radicals. This work provides a platform that opens a new perspective on the selection of mutual photocatalysts. It extends boundaries of conventional heterojunctions.
Keywords: amorphous/amorphous contact; carbon nitride; charge transitions; crystalline/amorphous contact; photocatalytic activity.