Graphitic-C3N4 hybridized N-doped La2Ti2O7 two-dimensional layered composites as efficient visible-light-driven photocatalyst

• Doping perovskite structured LTO with nitrogen through facile hydrothermal method.
• Hybridization of two kinds of 2D layered materials (NLTO and g-C3N4 nanosheets) with enhanced the visible-light-driven photocatalytic activity.
• Formation of large scale of type II heterojunction by large interfacial area between 2D layered g-C3N4/NLTO composite with efficient charge transfer.
• Formation of ultrathin g-C3N4/NLTO heterostructure with shortened charge transport distance.
• Exploration of charge transfer dynamics on g-C3N4/NLTO composite using the femtosecond time-resolved diffused reflectance measurement.

Perovskite-type La2Ti2O7 (LTO), having a layered structure and the separated H2 and O2 evolution sites, is attractive as an efficient photocatalyst. However, the photocatalytic activity is often limited by the poor electron mobility. This problem can be conquered by hybridization with materials having efficient properties for the visible light absorption and charge carrier transport. Here, we report a two-dimensional (2D) layered composite hybridized by approximately 2 nm thick graphitic C3N4 nanosheets (g-C3N4) and 7 nm thick nitrogen doped LTO nanosheets (NLTO) (g-C3N4/NLTO), in which g-C3N4 and NLTO act as hole receptor and electron conductor, respectively. g-C3N4/NLTO exhibited high photocatalytic activities for H2 production via water splitting and dye degradation under the UV and visible light irradiation, due to the interfacial charge transfer between g-C3N4 and NLTO. The electrochemical measurement showed the type II band alignment with favorable charge transfer from g-C3N4 to NLTO. The 2D architecture with a maximized interfacial area allows efficient charge separation with a short interfacial distance. This efficient interfacial charge transfer is further elucidated from monitoring of charge separation and trapping processes using the femtosecond time-resolved diffused reflectance (TDR) measurement.

Figure optionsDownload high-quality image (168 K)Download as PowerPoint slideThe large interfacial area of 2D layered g-C3N4/NLTO composite results in sufficient interface for efficient charge transfer to generate an excellent type II heterojunction.