Stimulation of surface terminating group by carbon quantum dots for improving pseudocapacitance of Ti3C2Tx MXene based electrode.

Enhancing pseudocapacitance of Ti 3 C 2 T x MXene-based electrode materials induced by sufficient surface terminating groups (such as Ti–O bonding) becomes one promising way for fabricating high energy-density supercapacitors. However, most of terminating group activity cannot be excited well in the multilayer Ti 3 C 2 T x due to the layer stacking feature, which limits its further performance improvement. In this paper, a CQDs@Ti 3 C 2 T x hybrid material is synthesized by modifying few-layer Ti 3 C 2 T x MXene matrix with highly dispersed carbon quantum dots (CQDs). In this unique hybrid model, the Ti 3 C 2 T x MXene matrix with high conductivity and high specific surface area is just like the "paddy field", which not only promotes the charge rapid transfer, but also provides the high double layer capacitance by ion adsorption. More importantly, the CQDs act as "rice seedlings" firmly anchored to the Ti 3 C 2 T x matrix, and greatly stimulate the activity of the termination groups of Ti 3 C 2 T x. As expected, this hybrid achieves a harmonious coexistence of high conductivity and high pseudocapacitance. As a result, the CQDs@Ti 3 C 2 T x electrode delivers high reversible capacitances of 441.3 F g−1 at 1 A g−1 and 310.1 F g−1 at 20 A g−1, and a relatively stable cyclability with almost 100% capacitance retention after 10 000 cycles at 10 A g−1. A CQDs@Ti 3 C 2 T x hybrid is facilely designed, in which the activity of Ti–O bonding is excited well to enhance its pseudocapacitance. Consequently, this resultant CQDs@Ti 3 C 2 T x realizes a comprehensive energy storage ability. This strategy may provide a promising approach to fabricate high-performance MXene based electrode. [Display omitted] [ABSTRACT FROM AUTHOR]