Herein, a composite of in-situ grown niobium-doped TiO2 nanosheet arrays on a double transition metal MXene TiNbCTx (TiNbC@NTO) was successfully obtained via a hydrothermal pretreatment followed by in-situ partial oxidation strategy.  Furthermore, an extraordinary rate performance (148.5 mAh g-1 at 2 A g-1) was obtained based on the pseudocapacitance dominated mechanism. 
THERM