Smart adsorbents with responsive self-healing ability will be promising, as they can meet the desirable requirements of sustainable and efficient usage in water treatment. Herein, a photo-induced self-healing gel adsorbent is fabricated by the combination of transition metal carbides Ti 3 C 2 T x (MXene), polyethyleneimine (PEI), and poly(N,N-dimethylacrylamide) (PDMAA) for sustainable and efficient removal of specific target Cr(VI) from water. PEI, as a potent adsorptive motif, endows the gel with high maximum adsorption capacity ( q m ) (i.e....