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The vanadium pentoxide (V2O5)/graphene nanocomposite films have been synthesized by direct intercalation method using V2O5 sol and graphene. The structure of the films was investigated with X-Ray Diffraction (XRD). The electrochemical properties of the nanocomposite films were studied by cyclic voltammetry and chronoamperometry with the standard three-electrode configuration. The optical properties were characterized by UV–Visible spectrophotometer. The intercalation of graphene improves the stability and reversibility of the V2O5 xerogel films. The response rate of the V2O5/graphene nanocomposite films is enhanced. The optical modulatory range of the V2O5/graphene nanocomposite films is 1.5 times larger than that of V2O5 xerogel films. These results demonstrate that the nanocomposite films can be used potentially in fast switching electrochromic devices.

Summary Gas diffusion layer (GDL) plays an important role in the performance of membrane electrode assembly (MEA) in polymer electrolyte fuel cells. In this work, 2‐type MEAs were prepared by 2 different GDLs of 29 BC and 29‐WUT, and the performance were investigated using polarization curve methods. The performance of MEA with 29‐WUT was 120 mV higher than 29 BC at 1600 mA/cm2. Electrochemical impedance spectroscopy (EIS) was applied to measure the mass transport resistance of 2‐type MEAs under normal running condition. The results of EIS showed that the mass transport resistance of 29 BC was 3.15 times higher than that of 29‐WUT at 1600 mA/cm2. To clarify this phenomenon, limiting current methods were applied under diluting oxygen concentration, low humidity, and high flow rate conditions. The results of limiting current methods showed that both the total oxygen transport resistance and the molecular diffusion resistance in the GDL of 29 BC were larger than that of 29‐WUT due to the lower porosity of gas diffusion substrate in 29 BC. As a result, EIS can be well combined with limiting current methods to analyze oxygen transport resistance in GDLs of fuel cells.

A sodium ion-conducting polymer electrolyte based on polyvinyl pyrrolidone (PVP) complexed with NaClO(4) was prepared using the solution-cast technique. The cathode film of V(2)O(5) xerogel modified with polyvinyl pyrrolidone was prepared using the sol-gel method. Investigations were conducted using X-ray diffractometry (XRD), Fourier transformation infrared (FT-IR) spectroscopy. The ionic conductivity and transference number measurements were performed to characterize the polymer electrolyte for battery applications. The transference number data indicated that the conducting species in these electrolytes are the anions. Using the electrolyte, electrochemical cells with a configuration Na/(PVP + NaClO(4))/V(2)O(5) modified by (PVP) were fabricated and their discharge profiles studied.