Titanium Carbide MXenes Cocatalyst with Graphitic Carbon Nitride for Photocatalytic H2 Production, CO2 Reduction, and Reforming Applications: A Review on Fundamentals and Recent Advances

Two-dimensional (2D) titanium carbide(Ti3C2) MXenes have gained increasing attentionin photocatalytic applicationsdue to their prominent electrical conductivity, optical properties,and abundant surface functional groups. The unique layered microstructurecharacteristics of Ti3C2 provide a large surfacearea, interlayer spacing, and hydrophilic surface functional groups,contributing to their high photocatalytic efficiency. Graphitic carbonnitride is very promising among the semiconductors due to its layeredstructure and higher reduction potential. The present study discussesthe recent advances in various Ti3C2 structurescoupled with g-C3N4 for hydrogen evolution reactions(HER), photocatalytic CO2 reduction reactions (CO2 RR), and CO2 reforming of methane (CO2 RM).Initially, we provide an overview of the fundamental properties ofTi(3)C(2)-based composites and recent synthesisapproaches, including structure development, of functional group formation,and various etching agents. We further explore using Ti3C2 in different structures coupled with g-C3N4 as a binary and ternary composite with the involvementof other semiconductors and sensitizers. The performance of variouscomposites for water splitting to produce hydrogen and reforming systems,including CO2 conversion with H2O, CO2 methanation, dry reforming of CH4 (DRM), and bireformingof CH4 (BRM), is discussed in detail. The hydrophilic surfacefunctional groups and efficient electron transport pathways of Ti3C2 MXenes make them excellent candidates for catalystswith high yield rates and selectivity. Finally, this review providesvaluable insights into the potential applications of Ti3C2-based composites, and future research directions inthis field are proposed.