Ti3C2: An Ideal Co‐catalyst?

Abstract How 2D Ti 3 C 2 enhances photocatalytic efficiency remains unclear. Now, it is shown that it is graphene quantum dots (GQDs) derived from Ti 3 C 2 , rather than 2D Ti 3 C 2 itself, that play the role of co‐catalyst for La 2 Ti 2 O 7 /Ti 3 C 2 (LTC) composites during the photocatalytic reaction. After modification of Ti 3 C 2 derivatives, the photocatalytic efficiency of La 2 Ti 2 O 7 is enhanced 16 times over pure La 2 Ti 2 O 7 . Solid‐state NMR, Raman, and HRTEM results confirm the existence of GQDs in Ti 3 C 2 and LTC composites. The GQDs are formed during the chemical change from Ti 3 AlC 2 to Ti 3 C 2 via HF etching, as Ti atoms are removed and unsaturated carbon bonds are left, which react with each other to form sp 2 π‐conjugation GQDs. 2D Ti 3 C 2 is completely oxidized to CO x modified TiO x species, causing Ti 3 C 2 to lose its electrical conductivity and the role as co‐catalyst. GQDs largely suppress the photogenerated charge recombination of La 2 Ti 2 O 7 , as revealed by the photoluminescence (PL) and transient photocurrent.