Ag-Nanoparticle-Decorated 2D Titanium Carbide (MXene) with Superior Electrochemical Performance for Supercapacitors

Two-dimensional Ti 3 C 2 T x decorated with Ag nanoparticles (NPs) has been rationally designed and successfully fabricated by filtering the mixture of Ti 3 C 2 T x nanosheet and Ag NP aqueous dispersion solution. The Ti 3 C 2 T x /Ag NP hybrid film electrode exhibits a high specific surface area (107 m 2 g –1 ), high areal capacitance (332.2 mF cm –2 at 2 mV s –1 ), good rate performance (63.2% of its initial value at 2 mV s –1 as the scan rate increases to 100 mV s –1 ), and long-term cycling stability (87% capacitance retention over 10 000 cycles). Furthermore, even when the mass loading is as high as 15.0 mg cm –2, a high areal capacitance of 1173 mF cm –2 can be obtained. In addition, an asymmetric supercapacitor (ASC) has been assembled on the basis of a Ti 3 C 2 T x /Ag NP negative electrode and MnO 2 /ESCNF positive electrode using 1 M Na 2 SO 4 as electrolyte. The integrated device not only delivers excellent capacitive performance (246.2 mF cm –2 at 2 mA cm –2, 69.4% capacitance retention at 20 mA cm –2, and 82% capacitance retention over 10 000 cycles), but also exhibits the maximum energy density of 121.4 μW h cm –2 and maximum power density of 17 395 μW cm –2 . A red light-emitting diode is lighted by the ASC, suggesting the ability of its practical application.