AUTHOR=Norouzi Nazgol , Omo-Lamai Darrell , Alimohammadi Farbod , Averianov Timofey , Kuang Jason , Yan Shan , Wang Lei , Stavitski Eli , Leshchev Denis , Takeuchi Kenneth J. , Takeuchi Esther S. , Marschilok Amy C. , Bock David C. , Pomerantseva Ekaterina 

TITLE=The Dopamine Assisted Synthesis of MoO3/Carbon Electrodes With Enhanced Capacitance in Aqueous Electrolyte

JOURNAL=Frontiers in Chemistry

VOLUME=10

YEAR=2022

URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2022.873462

DOI=10.3389/fchem.2022.873462

ISSN=2296-2646

ABSTRACT=<p>A capacitance increase phenomenon is observed for MoO<sub>3</sub> electrodes synthesized <italic>via</italic> a sol-gel process in the presence of dopamine hydrochloride (Dopa HCl) as compared to α-MoO<sub>3</sub> electrodes in 5M ZnCl<sub>2</sub> aqueous electrolyte. The synthesis approach is based on a hydrogen peroxide-initiated sol-gel reaction to which the Dopa HCl is added. The powder precursor (Dopa)<sub>x</sub>MoO<sub>y</sub>, is isolated from the metastable gel using freeze-drying. Hydrothermal treatment (HT) of the precursor results in the formation of MoO<sub>3</sub> accompanied by carbonization of the organic molecules; designated as HT-MoO<sub>3</sub>/C. HT of the precipitate formed in the absence of dopamine in the reaction produced α-MoO<sub>3</sub>, which was used as a reference material in this study (α-MoO<sub>3</sub>-ref). Scanning electron microscopy (SEM) images show a nanobelt morphology for both HT-MoO<sub>3</sub>/C and α-MoO<sub>3</sub>-ref powders, but with distinct differences in the shape of the nanobelts. The presence of carbonaceous content in the structure of HT-MoO<sub>3</sub>/C is confirmed by FTIR and Raman spectroscopy measurements. X-ray diffraction (XRD) and Rietveld refinement analysis demonstrate the presence of α-MoO<sub>3</sub> and h-MoO<sub>3</sub> phases in the structure of HT-MoO<sub>3</sub>/C. The increased specific capacitance delivered by the HT-MoO<sub>3</sub>/C electrode as compared to the α-MoO<sub>3</sub>-ref electrode in 5M ZnCl<sub>2</sub> electrolyte in a −0.25–0.70 V vs. Ag/AgCl potential window triggered a more detailed study in an expanded potential window. In the 5M ZnCl<sub>2</sub> electrolyte at a scan rate of 2 mV s<sup>−1</sup>, the HT-MoO<sub>3</sub>/C electrode shows a second cycle capacitance of 347.6 F g<sup>−1</sup>. The higher electrochemical performance of the HT-MoO<sub>3</sub>/C electrode can be attributed to the presence of carbon in its structure, which can facilitate electron transport. Our study provides a new route for further development of metal oxides for energy storage applications.</p>