Kirkendall Effect Induced One-Step Fabrication of Tubular Ag/MnOx Nanocomposites for Supercapacitor Application

One-dimensional (1D) tubular Ag/MnOx nanocomposites were synthesized by the solvothermal method via the Kirkendall effect between potassium permanganate (KMnO4) and Ag nanowire templates. The morphology and electrochemical performance of Ag/MnOx composites were tuned by varying the pH levels. Tubular MnOx nanosheets with ultrafine Ag nanoparticles were formed in an acidic environment (pH 0.76), whereas the Ag nanoparticles entrapped in amorphous MnO2 nanotubes were prepared in a neutral environment (pH 7.00). Based on a series of volume-dependent experiments, it was confirmed that the Kirkendall effect was involved in the formation of these morphologies. When tested as an electrode for supercapacitors, the hierarchical tubular Ag/MnOx nanosheet composites prepared in an acidic environment exhibited an optimized electrochemical performance, with specific capacitance of 180 F g(-1) at current density of 0.1 A g(-1), and still maintained 80% of initial capacity after 1000 cycles at current density of 1 A g(-1). The proposed synthetic mechanism and the developed synthetic strategy may provide design guidelines for synthesizing other hierarchical transition metal/transition metal oxide nanocomposites.