Fig. 3: In-situ XRD patterns for WO3-x NWNs/FTO.

a Schematic diagram of the in situ XRD under a three-electrode mode, b Typical CV curve of the WO3-x NWNs/FTO electrode at a scan rate of 0.5 mv s−1, c In situ XRD results based on the cycling process in Fig. 3b, d Enlarged in situ XRD patterns of the WO3-x NWNs/FTO electrode at 2θ from 15° to 30°, e Interlayer distance of the WO3-x NWNs calculated from the XRD patterns during the CV processes.