In situ ice template approach to fabricate Ag modified 3D Ti3C2Tx film electrode for supercapacitors

Benefitting from the large interlayer spacing, ultrahigh conductivity and excellent electrochemical properties, Ti3C2Tx has been a promising electrode material for supercapacitors (SCs). However, it suffers from the problem of restacking, which hinders ion accessibility and leads to slow reaction kinetics. Herein, a simple two-step in situ strategy is proposed to fabricate free-standing Ag nanoparticles (AgNPs) decorated 3D Ti3C2Tx film. Ti3C2Tx as reducing agent allows firmly anchoring of the nanostructures. The obtained AgNPs are directly reduced from AgNO3 by the -OH termination, which can enhance the ion transfer rate of 3D-Ti3C2Tx/Ag. Afterwards, 3D Ti3C2Tx film is fabricated by freeze-drying. Within the process of freeze-drying, small ice grains are transformed in situ from water molecules remaining between Ti3C2Tx layers and then serve as self-sacrificing templates to construct a 3D network. As a result, the 3D-Ti3C2Tx/Ag electrode exhibits a remarkable specific capacitance of 356 F g−1 at 2 mV s−1 and ultrahigh capacitance retention of 94.7% after 40,000 cycles at 10 A g−1. The efforts and attempts made in this work provide a prototype for achieving high-performance flexible 3D MXene film electrode for SCs.