Synthesis and characterizations of solid-solution i-MAX phase (W1/3Mo1/3R1/3)2AlC (R = Gd, Tb, Dy, Ho, Er and Y) and derivated i-MXene with improved electrochemical properties

In this work, a series of new solid-solution i-MAX phase (W1/3Mo1/3R1/3)2AlC (R = Gd, Tb, Dy, Ho, Er and Y) were synthesized and characterized. From R = Gd to Er, the lanthanide contract is observed while the magnetic behaviors are varied from nonlinear antiferromagnetism-like type for R = Gd to weak ferromagnetism-like one for R = Er with gradually weakened magnetic coupling and reduced Curie-Weiss temperature. The solid-solution i-MXene W2/3Mo2/3(R)CTx was synthesized by selective etching Al and R elements and the highest specific capacitance of 120 Fg−1 at 1 Ag−1 was obtained. By further HM (Hydrazine Monohydrate, N2H4•H2O) treatment and hydrothermal composite with rGO, the specific capacitance is further elevated to 249 Fg−1. This is explained by the increament of O-/N-containing terminals and improved conductivity due to the formation of multidimensional interactive microstructure.