Promoting Gas Sensitivity of Graphitic Carbon Nitride via Incorporation of Platinum Nanoparticles under Blue-Light...

Research on van der Waals layered materials offers opportunities to explore diverse scientific phenomena at the nano- and atomic scales, along with their promising technological potential. Among the material family, graphitic carbon nitride (g-C₃N₄) has attracted substantial research attention due to its simple synthesis process, tunable electronic structure properties, and exceptional physicochemical properties arising from good interfacial compatibility with other materials. In this research, we investigated the potential of g-C₃N₄ as a gas sensing material. To overcome its intrinsically poor conductivity and limited surface activity, the electronic band structure of g-C₃N₄ was deliberately modulated through hybridization with Pt nanoparticles, which promotes surface conductivity and suppresses charge recombination. The formation of Pt/g-C₃N₄ heterojunctions sufficiently modulated the interfacial band structure upon gas absorption, resulting in pronounced sensitivity toward NO₂, NH₃, CO, H₂S molecules, relative to a pristine g-C₃N₄ sensor. Furthermore, sensing properties were investigated under blue-light (BL; λ = 457 nm) illumination with intensity of 1.55 W/m². The photoinduced charge excitation led to distinctively different response for oxidizing and reducing nature of the target gases, and sensitivity and selectivity to NO₂ gas molecules were significantly improved. This BL-assisted, gas-dependent response contrast provides insight into the underlying gas-sensing mechanism. Overall, this work elucidates how interfacial band engineering and photoexcited carrier dynamics govern gas sensing in g-C₃N₄-based systems, offering a mechanistic framework for advanced design of high-performance gas sensors.