Electrostatic Self‐Assembly of NiTiO₃ on Carbon Nitride as a Photocatalyst for Visible‐Light‐Driven Overall Water Splitting

Achieving intimate interfacial contact between a hydrogen evolution photocatalyst (HEP) and an oxygen evolution photocatalyst (OEP) is crucial for efficient charge carrier transfer, which in turn enhances overall water splitting (OWS) performance. However, traditional metal oxide-based photocatalysts often possess intrinsic limitations. In this study, carbon nitride (CN) with tunable electrostatic properties is employed to form a heterostructure with metal oxides through self-assembly. As such, protonated polymeric CN nanosheets functioned as the HEP, while NiTiO₃ nanoparticles served as the OEP, resulting in a photocatalytic system for OWS, exhibiting H₂ and O₂ evolution rates of 35.6 and 17.7 μmol h^- ¹, respectively. The corresponding apparent quantum yield is 2.7% at an incident wavelength of 365 nm. These results outperform those of individual photocatalysts. This study introduces a universally applicable electrostatic self-assembly strategy for using CN to construct redox-mediator-free heterojunctions, thereby advancing applications in various fields, particularly the hydrogen evolution reaction via photocatalytic OWS.