Stable carbon encapsulated titanium carbide MXene aqueous ink for fabricating high-performance supercapacitors

Abstract

• A simple method to synthesize phenolic carbon encapsulated Ti 3 C 2 T x (Ti 3 C 2 T x @C) inks • Ti 3 C 2 T x @C exhibited superior oxidation resistance even after 100 days of aging • Ti 3 C 2 T x @C exhibited a specific capacitance of 736 F g –1 in a three-electrode system • A flexible interdigitated micro supercapacitor (MSC) was printed using Ti 3 C 2 T x @C inks • Ti 3 C 2 T x @C MSC device displayed high cycling stability (83% after 10,000 cycles) Ti-based MXenes have shown great promise in electrochemical applications, including (photo)electrocatalysis and energy storage. However, their practical application has been hindered by their rapid oxidation in the presence of water and O 2 . In this work, we propose a method to solve the problem through a one-step hydrothermal treatment of MXene (Ti 3 C 2 T x , where T x is –OH or –F) in the presence of agarose. The hydrothermal treatment results in the in situ capping of the phenolic carbon layer on the Ti 3 C 2 T x to form Ti 3 C 2 T x @C, which improves its chemical stability by protecting the Ti atoms from oxidation with water and O 2 , and thus enhances its electrochemical performance by avoiding re-stacking of the Ti 3 C 2 T x @C sheets. The as-prepared Ti 3 C 2 T x @C exhibits high oxidation resistance with >95% performance when stored in an aqueous medium for at least 100 days. Ti 3 C 2 T x @C provides a specific capacitance of 736 F g –1 in 1 M H 2 SO 4 electrolyte over a voltage window of 0.5 V. Having excellent water dispersibility and high electrochemical activity, Ti 3 C 2 T x @C is ideal for the preparation of stable MXene inks for the fabrication of high-performance interdigitated electrodes through inkjet printing. The flexible micro-supercapacitor constructed from Ti 3 C 2 T x @C ink exhibits excellent cyclic stability up to 10,000 charge-discharge cycles without a significant decrease in specific capacitance.