This dissertation focuses on the design and application of two-dimensional MXene-based composite photocatalysts, aiming to address the major limitations of conventional photocatalysts, including low catalytic efficiency, poor stability, and limited visible-light utilization. By employing innovative material design strategies, a series of high-performance MXene-based composite photocatalytic systems were successfully constructed.

The three chapters of this dissertation explore the application potential of the synthesized catalysts in organic pollutant degradation, photocatalytic hydrogen evolution, and hydrogen peroxide production.

Chapter one describes the in-situ construction of a ternary Z-scheme In₂S₃/CeO₂/Ti₃C₂ MXene heterojunction and investigates its photocatalytic mechanism for degrading dyes and residual pharmaceutical compounds in water under visible light irradiation.

Chapter two introduces a novel gallium-doped polymeric carbon nitride coupled Ti₃C₂ MXene Schottky junction for hydrogen peroxide production directly from water. 

Chapter three further expands the material design strategy by integrating gallium and potassium co-doped polymeric carbon nitride with Ti₃C₂ MXene to construct a ternary heterojunction for photocatalytic hydrogen generation by water splitting. Structural characterizations and catalytic performance evaluations revealed that Ti₃C₂ MXene serves as an excellent cocatalyst. By establishing a strong internal built-in electric field, it significantly promotes efficient interfacial charge transfer within the heterojunction, effectively suppresses charge recombination, and enhances both the light-harvesting ability and quantum efficiency of the composite photocatalyst. 

In summary, this research not only provides a unique tactic for enhancing photocatalytic performance but also offers a potential clean and sustainable technological solution to address environmental pollution and energy crises.