Constructing Exfoliated, Ti₃C₂T_x MXene-Dispersed, LaCoO₃ and pC₃N₄-Based Nanocomposites with In Situ Grown Titania through Etching/Oxidation for Stimulating Solar H₂ Production

The use of a well-designed Ti₃C₂ MXene with in situ embedded titania nanoparticles to construct a porous carbon nitride (pCN)/LaCoO₃ Z-scheme and S-scheme heterojunction for stimulating solar hydrogen production has been explored. A novel oxidized/etched approach was employed to produce MXene to maximize charge separation in LaCoO₃ perovskite-dispersed pCN. On increasing the HF etching time from 24 to 48 h, the amount of titania embedded over the MXene was increased, enabling 1.71 times more H₂ evolution. More importantly, integrated etched/oxidized Ti₃C₂ nanoflowers showed more reaction area with enhanced light absorption, which was more prominent with increased temperature. The H₂ evolution was significantly increased due to in situ embedded TiO₂. Comparatively, optimized 15Ti₃C₂T_x/pCN was found to be more efficient at lower temperatures, which was further increased 7-fold with a 10Ti₃C₂T_x/pCN-coupled LaCoO₃ Z-scheme heterojunction. This obvious enhancement was evidently due to utilizing the maximum redox potential with good interface interaction among the components to promote charge carrier separation. Among the sacrificial agents, TEOA was found to be more promising, with 9.1 times more H₂ production due to its strong bond with amine-based pCN, which was further confirmed by quantum analysis. In conclusion, the Z-scheme photosystem is promising for efficient mobility and separation of charges and would also be beneficial for other solar energy applications.