Fig. 2
Microstructural characterization of the constituent KxV2O5. a XRD patterns of layered KxV2O5 (x = 0.25) that is annealed at 25, 200, and 300 °C. The line patterns show reference cards 39–0889 and 41–1426 for layered K0.25V2O5 and V2O5 according to JCPDS. b High-resolution XPS spectra of O 1s in the layered KxV2O5 (x = 0.25) that is annealed at 25, 200, and 300 °C. c HRTEM image of the layered KxV2O5 (x = 0.25) with a dual-phase nanostructure that is produced by annealing at 200 °C. d, e FFT patterns of layered KxV2O5 with crystalline region (yellow box) (d) and amorphous region (red box) (e). f HRTEM image of the layered KxV2O5 (x = 0.25) with a complete crystallization at annealing temperature of 300 °C. g FFT pattern of layered crystalline KxV2O5 (green box). Scale bar, 2 nm (c, f)
