S-Scheme Homojunction Carbon Nitride for Photocatalytic Overall Water Splitting

Single semiconductor photocatalysts have disadvantages, such as low carrier separation efficiency. Although subsequent studies have effectively enhanced carrier separation by constructing heterojunction and other methods. However, due to the lattice mismatch, there is an increase in carrier complex sites at the interface between semiconductors, which hinders the further practical application of photocatalytic technology. To address the aforementioned challenges, in this study, carbon nitride nanotubes/carbon nitride nanosheets (TSCN) S-scheme homojunction with strong interfacial electric fields (IEF) and matched interfaces were constructed through an in situ one-step synthesis method. The carbon nitride photocatalysts with different photoelectrochemical properties were obtained by tuning the micronano structure. Experiments and theoretical studies demonstrate that the homojunction effectively solves the problem of interfacial mismatch. Additionally, a strong IEF effectively promotes carrier migration and separation, resulting in efficient spatial separation of carriers and thus achieving overall water splitting (OWS). This work investigated the process of carrier transfer promoted by the IEF and explained its photocatalytic mechanism. This study provides a rational idea to solve the lower performance of a single catalyst and the lattice mismatch of heterojunctions for photocatalytic OWS.