Investigating the Influential Effect of Etchant Time in Constructing 2 D/2D HCN/MXene Heterojunction with Controlled Growth of TiO₂NPs for Stimulating Photocatalytic H₂Production

Well-designed, two-dimensional hierarchical g-C3N4 (2D HCN) nanosheets anchored over two-dimensional exfoliated titanium carbide (2D TiC) multilayers embedded with in situ grown TiO2 were fabricated for stimulating H2 production under visible light. The Ti3C2 efficiency was directly influenced by varying the etching time ranging from 24 to 96 h. Using optimized 2D TiC multilayers embedded with TiO2 (anatase) with etchant time 48 h, the highest H2 yield of 182.5 μmol g-1 h-1 was attained, an obviously higher production rate than using etchant times of 24, 72, and 96 h, due to improved charge carrier separation efficiency through heterojunction formation. Hierarchical g-C3N4 exhibited 1.26 times more H2 yield than using bulk g-C3N4 due to efficient migration and transportation of charge carrier. The H2 production rate of the optimized 10TiC-48/HCN 2D/2D heterojunction reached 310 μmol g-1 h-1 which is ∼1.93, 2.33, and 2.95 times higher than it was produced over TiC-48, HCN, and CN, respectively. This proficient hydrogen production was due to faster transfer of electrons from HCN to TiC-MXene due to higher conductivity and formation of heterojunction between HCN and TiO2 with their synergistic effects. The continuous production of H2 with recyclability evidenced 2D/2D heterojunction advantages and provides new insight on the role of the hierarchical MXene composite and, thus, would be beneficial for solar energy applications.