Fig. 3
Pseudocapacitance performance of CeO2−x thin films. a Cyclic voltammograms obtained at scan rates in the range 5–500 mV s−1, plot of log i vs. log ʋ in inset. b Capacitive and diffusional contributions to the total capacitance obtained at a scan rate of 50 mV s-1. c fractions of capacitive and diffusional contributions at scan rates in the range 5–100 mV s-1. d Stability of charge-storage performance up to 1000 cycles at a scan rate of 100 mV s-1 (inset shows voltammograms obtained at cycle numbers 1, 500 and 1000). e Plot of thickness vs. volumetric and area capacitances obtained in the present work (5 mV s-1) compared to data from recently reported works for high-performance materials: ultrathin films of hybrid RuO2/PEDOT55, MnO2/graphene hybrid nanostructure56, MnO2/Au hybrid nanostructure19, ß-Ni(OH)2/graphene hybrid nanostructure57, VOPO4 thin film58, VS2 thin film59, MnO2/multiwall carbon nanotube hybrid structure28, α-MoO314
