MXene-based composites for enhanced photocatalytic Cr(VI) removal in wastewater: A comprehensive review

The conversion of hazardous hexavalent chromium (Cr(VI)) to safer trivalent chromium (Cr(III)) is critical for mitigating industrial wastewater pollution. This review highlights the potential of photocatalytic technology in treating Cr(VI)-containing effluents, with a focus on MXenes—advanced 2D materials composed of transition metal carbides and carbonitrides. Among them, Ti₃C₂ MXene stands out for its high surface area, hydrophilic functional groups, and exceptional electrical conductivity, enabling rapid electron transfer and enhanced photocatalytic efficiency. Recent studies demonstrate Cr(VI) degradation rates of 80–100 % using MXene-based composites, primarily through mechanisms like Schottky barriers that improve electron mobility and reduce recombination rates. Particular attention is given to MXene composites combined with bismuth compounds, which exhibit enhanced performance due to synergistic effects. Despite these advancements, challenges remain regarding stability, reusability, and scalability. Future research should focus on developing innovative composites and addressing practical application challenges to fully harness MXene-based photocatalysts for environmental remediation.