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

Two-dimensional Ti3C2Tx decorated with Ag nanoparticles (NPs) has been rationally designed and successfully fabricated by filtering the mixture of Ti3C2Tx nanosheet and Ag NP aqueous dispersion solution. The Ti3C2Tx/Ag NP hybrid film electrode exhibits a high specific surface area (107 m2 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 Ti3C2Tx/Ag NP negative electrode and MnO2/ESCNF positive electrode using 1 M Na2SO4 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.