Multifunctional hexagonal-shaped zinc vanadate nanostructures for lithium-ion battery and NH3 gas sensor applications

Vanadium-based metal oxides are used in different fields like gas sensors, supercapacitors , and lithium (Li)-ion batteries due to their availability, layered structure, and facile synthesis. Herein, we report a temperature-effective strategy to synthesize hexagonal-shaped zinc vanadate (Zn 2 VO 4 (ZVO)) nanostructures (NSs) via a facile hydrothermal method without any further doping of an element or carbon additive. The synthesized ZVO NSs provide large surface area, low energy band gap, and fast Li + diffusion. When compared with the ZVO-120 (synthesized at 120 °C) and ZVO-160 samples, the ZVO-140 sample shows a lower energy band gap value of 2.57 eV with higher surface area (37 m 2  g −1 ) and porous nature. As an anode material for Li-ion batteries, the ZVO-140 demonstrates superior rate capability (126 mA h g −1 at 1.5 A g −1 ) and excellent cycling performance (576 mA h g −1 after 100 cycles at 0.05 A g −1 and 327 mA h g −1 after 2000 cycles at 1 A g −1 ) as well as good Li + diffusion coefficient (2.61 × 10 −8  cm 2  s −1 ). Due to these synergistic benefits, ZVO NSs are used for NH 3 gas sensing application. The ZVO-140 sample exhibits excellent sensitivity (47.3%) at 190 °C with fast response/recovery time (136 s/128 s) and reliable stability towards NH 3 gas (100 ppm) at 190 °C, when compared with counterparts (ZVO-120 and ZVO-160). This preparation strategy may initiate the design of advanced ZVO-based materials for multifunctional applications.