Engineered Growth of Perovskite Nanocrystals on Graphene with Subsequent TiO₂ Integration for Enhanced Photodetection and Environmental Catalysis

Abstract In this study, a binary nanohybrid (CPEG) is first developed, consisting of exfoliated graphene (EG) integrated with CsPbBr₃ perovskite nanocrystals (CPNCs). A novel intermediate step is introduced, wherein graphene nanosheets are physically exfoliated while lead‐based seeds are simultaneously formed on the graphene surface. This approach, implemented for the first time, enables the controlled growth of CPNCs, leading to the formation of CPNC/EG nanohybrids (CPEGs). Subsequently, CPEGs are further functionalized with an optically active and protective TiO₂ interface to form a ternary nanohybrid (Ti‐CPEG). The incorporation of EG induced significant modifications in the major characteristics of CPNCs while imparting catalytic activity to CPEGs when conjugated with TiO₂. Notably, as a photodetector, CPEGs exhibit reversible and reproducible photoresponses in electrical current, with a I_on/I_off of 7.7, representing a 2.3‐fold increase compared to CPNCs alone. As a photocatalyst, Ti‐CPEGs with an S‐scheme heterojunction demonstrate superior degradation of a model organic pollutant with high reusability. Graphene modulates the self‐trapped emission of CPNCs by facilitating charge transfer and modifying the excited‐state dynamics, while TiO₂ further enhances charge separation and radiative/non‐radiative energy dissipation. These synergistic effects collectively contribute to an engineered optical response, which can be leveraged for applications requiring controlled photoluminescence and charge‐transport characteristics.