Abstract This study presents the relationship between the morphology, porosity, and specific surface area in W 18 O 49 nanourchins and their effects on the specific capacitance. For this purpose, W 18 O 49 nanourchins were synthesized using tungsten hexachloride (WCl 6 ) and ethanol by controlling precursor concentration and nucleation process. These nanourchins were grown directly on carbon felt substrates through solvothermal synthesis to test them as working electrodes for pseudocapacitors. The structural characterizations of the samples were subjected to scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and Brunauer–Emmett–Teller (BET) analysis. Electrochemical studies were performed using cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), and electrochemical impedance spectroscopy (EIS) in 1 M H 2 SO 4 at a three-electrode setup with an Ag/AgCl, a Pt wire, and a synthesized working electrode. According to the results, the sample with 0.0168 molL −1 (intermediate concentration) exhibited a superior specific capacitance of 605.6 Fg −1 at 1 mVs −1 and a lower solution resistance of 1.78 Ω compared to the others. Besides, this sample with a specific surface area of 91.79 m 2 g −1 provided a 26.17% increase in specific capacitance over the sample with 101.02 m 2 g −1 . It was clear that the concentration of the precursor influenced the sample morphology and specific surface area, as it played a crucial role in determining the nucleation. In turn, morphological structure governs the effective range of pore size distribution. This phenomenon has made porosity a more dominant factor than specific surface area in enhancing the specific capacitance of W 18 O 49 nanourchins. Graphical Abstract
Kesici et al. (Mon,) studied this question.