Synthesis, Properties, and Electrochemical Performance of ϕy-type KCu2OH(MoO4)2(H2O).

A new KCu2OH(MoO4)2(H2O) compound was synthesized via the sonochemical method. Its crystal structure was identified by powder X-ray diffraction (PXRD) and Rietveld refinement, revealing a polymorph of layered transition-metal molybdates (ϕy). The compound crystallizes in a trigonal system with R3̅ space group with lattice parameters: a = b = 6.0320(3) Å, c = 21.3445(6) Å and α = β = 90°, γ = 120°. Morphology, compositional, textural, and thermal properties were evaluated by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), N2 physisorption, and thermogravimetric analysis (TGA). Vibrational properties were investigated by FT-IR and Raman spectroscopies. Additionally, cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy (EIS) were used to characterize its electrochemical behavior. The material exhibits a specific capacitance of 967 F/g at a current density of 1 A/g. Continuous charge/discharge studies demonstrated a moderate cycling stability over the first 1,000 cycles. The findings suggest a mixed charge-storage mechanism involving both diffusion-controlled Faradaic reactions and pseudocapacitive contributions. Further studies are required to validate KCMO as a viable material for electrochemical energy-storage devices.