MXene-based composites for adsorption and photocatalytic immobilization of U(VI): Current progress and future perspectives

Abstract

Nuclear energy is widely noted for stable power, low carbon, high energy density and cost-effectiveness. Uranium plays an important role as one of the most commonly utilized elements in nuclear energy. Nevertheless, the efficient immobilization (extraction from seawater and removal from wastewater) of uranium is still a significant challenge. Emerging as a novel class of two-dimensional materials, MXenes demonstrate exceptional potential in environmental remediation applications owing to their unique layered architecture, tunable surface chemistry, and multifunctional properties. Recent advances highlight MXene-based composites as superior adsorbents for U(VI) elimination, capitalizing on their extraordinary hydrophilicity, modifiable surface charge distribution, and synergistic redox capabilities. Moreover, their remarkable electrical conductivity, abundant catalytic sites, and sufficient surface terminations position MXenes as promising co-catalysts for photocatalytic U(VI) reduction. While significant progress has been made in understanding MXene-mediated U(VI) immobilization through adsorption and photocatalysis, systematic reviews addressing these advancements remain scarce. This comprehensive review elucidates fundamental aspects of MXenes including structural characteristics, synthesis methodologies, and basic properties. Subsequently, we critically analyze their application mechanisms in U(VI) adsorption and photocatalytic reduction, systematically evaluate recent breakthroughs in adsorption and photocatalytic reduction strategies. Finally, we identify critical challenges hindering practical implementation of MXene-based technologies in U(VI) immobilization.