PVP-assisted thermal cleavage synthesis of 3D interlocked CeO2/g-C3N4 heterojunctions with proposed Z-scheme charge transfer for efficient phenol degradation

Using a simple ‘polymer-assisted pyrolysis–co-precipitation’ strategy, a three-dimensional interlocked CeO 2 /g-C 3 N 4 Z -scheme heterojunction structure with a honeycomb-like morphology was successfully fabricated. In contrast to the morphology of conventional composites, morphological and structural characterisation in this study indicates that the thermal cracking strategy of the polymer template causes partial rupture of CeO 2 microspheres to create pores, driving g-C 3 N 4 to interpenetrate, thereby promoting the interweaving of the two to form a three-dimensional interlocked symbiotic network. Its unique structure not only increases the interfacial contact area but also creates smoother mesoporous transport channels, thereby promoting mass transfer processes. This significantly enhances the degradation kinetics in low-concentration systems. The degradation rate constant k for 5 mg/L phenol is 0.036 min −1 , which is up to 4.9 times higher than that in high-concentration systems. XPS and EIS analyses revealed strong interfacial chemical interactions between CeO 2 and g-C 3 N 4 ; this close interfacial coupling effectively reduced charge transfer resistance. Combined with characterisation methods such as ESR, this suggested that the system promotes the separation of photogenerated carriers along a proposed efficient Z -scheme path, thereby continuously generating large amounts of reactive oxygen species (•O—2 and •OH). The optimal 2–1Ce/CN composite achieved a phenol degradation rate of up to 94.5% for a 5 mg/L solution within 75 min, whilst demonstrating excellent cycling stability. This work provides novel mechanistic insights for the design and development of structurally optimised materials for highly efficient photocatalytic environmental remediation.