Biocompatible Supercapacitors with Enhanced Potassium Storage Performance: Ag-Decorated MoO3 Nanobelts as Advanced Electrode Materials

Molybdenum trioxide (MoO3), characterized by its abundant valence states and distinctive layered architecture, has emerged as a highly promising electrode material for potassium-ion (K+) storage. Nevertheless, its practical application in energy storage systems is significantly hindered by intrinsic limitations, including low electrical conductivity and inadequate electrochemical activity. In this study, we successfully synthesized silver-decorated MoO3 (Ag–MoO3) nanobelts through an innovative integration of electrochemical oxidation and hydrothermal techniques, achieving optimized morphology and structural properties. Comprehensive density functional theory (DFT) calculations revealed that the incorporation of Ag not only modified the electronic structure of MoO3 but also significantly enhanced its K+ adsorption capacity, thereby facilitating improved ion and electron transport kinetics. The engineered Ag–MoO3 electrode exhibited remarkable biocompatibility and superior energy-storage performance, demonstrating a specific capacitance of 442 F g–1 at a current density of 0.4 A g–1 in neutral aqueous electrolyte. Furthermore, the assembled asymmetric supercapacitor device achieved an extended operating voltage window of 0–1.8 V, delivering an impressive energy density of 38.4 Wh kg–1 at a power density of 182 W kg–1. These notable characteristics underscore the material’s exceptional potential for efficient K+ storage, positioning it as a promising candidate for next-generation biocompatible and environmentally sustainable electrochemical energy storage systems.