Morphological Control of Nanostructured VO by Deep Eutectic Solvents.

Herein, we show a facile surfactant-free synthetic platform for the synthesis of nanostructured vanadium pentoxide (VO) using reline as a green and eco-friendly deep eutectic solvent. This new approach overcomes the dependence of the current synthetic methods on shape directing agents such as surfactants with potential detrimental effects on the final applications. Excellent morphological control is achieved by simply varying the water ratio in the reaction leading to the selective formation of VO 3D microbeads, 2D nanosheets, and 1D randomly arranged nanofleece. Using electrospray ionization mass spectroscopy (ESI-MS), we demonstrate that alkyl amine based ionic species are formed during the reline/water solvothermal treatment and that these play a key role in the resulting material morphology with templating and exfoliating properties. This work enables fundamental understanding of the activity-morphology relationship of vanadium oxide materials in catalysis, sensing applications, energy conversion, and energy storage as we prove the effect of surfactant-free VO structuring on battery performance as cathode materials. Nanostructured VO cathodes showed a faster charge-discharge response than the counterpart bulk-VO electrode with VO 2D nanosheet presenting the highest improvement of the rate performance in galvanostatic charge-discharge tests.