Improvement of separation, transfer and redox ability arising from P–N heterojuncted composite phosphate-group-intercalated g-C3N4 /Bi2WO6

Graphitic carbon (g-C3N4, CN) is a promising candidate in photosynthesis and photocatalytic fields owing to various advantages, particularly the very negative conduction band minimum. But its low transfer ability limits the application. Recently, in our early-stage work, intercalating the phosphate (P) group into the layer gap of CN resulted in better transfer properties and a transition from N- to P-type, but reduced the redox ability of the photoinduced carriers. Here, a P–N-type heterojunction-structured composite [P-group intercalated g-C3N4 (NP–CN)/Bi2WO6 (BWO), NPB] was prepared to improve redox and transfer ability in a CN-based photocatalyst. p-Nitrophenol can be photodegraded into harmless products over NPB in 120 min. The apparent constant rates (k-s) of NPB are 2.45 and 42.97 times those of pure CN and BWO, respectively. The mechanism has three effects. First, the nitrogen vacancies arising from P-group intercalation in the NP-CN layer of NPB supply a quick transfer channel for carriers. Second, the hybridization of NP-CN with BWO causes more negative ECB on the NP-CN side and more positive EVB on the BWO side, suggesting high-redox ability. Third, the generation of offsets in ECB and EVB in NPB owing to the spike offset of the energy band due to the P–N heterojunction helps maintain high-redox electrons in ECB and holes in EVB in NPB. This study provides a novel route to simultaneously improve transfer and separation ability, as well as redox ability, in a hybridized photocatalyst.