Localized surface-plasmon resonance effect as a new driver of Z-scheme electron transfer in cerium dioxide–graphitic carbon nitride heterojunctions

The intersecting interface between the two semiconductors of cerium dioxide (CeO2)–graphitic carbon nitride (g-C3N4) heterojunctions, which have demonstrated excellent photocatalytic activity, inhibits the rapid compounding of the photogenerated electron–hole pairs of g-C3N4. CeO2–g-C3N4 heterojunctions with Z-scheme and type-II electron-transfer routes were prepared via calcination in argon and air atmospheres, respectively. The built-in electric field theory cannot be used to explain the presence of a type-II electron-transfer route in CeO2–g-C3N4 heterojunctions. According the femtosecond transient absorption spectra, the localized surface-plasmon resonance (LSPR) effect of CeO2 drove the Z-scheme electron transfer in CeO2–g-C3N4 heterojunctions. The CeO2–g-C3N4 heterojunction exhibited a type-II electron-transfer route when the particle size of CeO2 increased, which attenuated the LSPR effect. The CeO2–g-C3N4 heterojunction with the Z-scheme electron-transfer route exhibited 4.4 times higher degradation efficiency for bamboo pulping wastewater than g-C3N4, and this result was attributed to the reduced complexation of photogenerated electron–hole pairs and extended photogenerated electron lifetime. Overall, this research provides a new idea for constructing Z-scheme electron-transfer heterojunctions.