Ti ₃ C ₂ MXene‐Derived TiO ₂ /g‐C ₃ N ₄ Heterojunctions for Highly Efficient Photocatalytic H ₂ Generation

Abstract Metal‐free graphite carbon nitride (g‐C₃N₄) has garnered significant attention for photocatalytic water‐splitting applications. However, its practical use is hindered by the rapid recombination of photogenerated electrons and holes, which limits its photocatalytic efficiency. In this study, series photocatalysts were designed by coupling g‐C₃N₄ with TiO 2 derived from Ti 3 C 2 MXene of varying thickness. The heterojunctions were synthesized through the calcination method, leveraging the unique properties of single‐layer and multilayer Ti 3 C 2 MXene as precursors for TiO 2 . Comprehensive characterization revealed the successful formation of g‐C₃N₄/TiO₂ type II heterojunctions, facilitating the efficient separation of photogenerated electrons and holes. The photocatalytic hydrogen production performance of the composites, with the optimal CN/S‐TO (8.26 mmol/h/g) and CN/M‐TO (11.6 mmol/h/g) samples, demonstrated hydrogen evolution rates of 2.7 and 3.5 times higher than pristine g‐C₃N₄, respectively. This enhancement is attributed to the intimate heterojunction formed between TiO₂ and g‐C₃N₄, which effectively promotes the transfer of photogenerated charges while suppressing the recombination of electrons and holes. Additionally, multilayer‐derived TiO 2 retained a more stable structure post‐calcination, offering superior electron transport channels compared to its single‐layer counterpart. These findings underscore the potential of MXene‐derived heterojunctions based on different thicknesses as efficient photocatalysts for sustainable hydrogen production.