Preparation of free-standing V2O5 nanosheets for ammonia sensing application: A potential candidate for flexible sensors

Advances in the healthcare sector have driven tremendous possibilities as well as the necessity in developing potential innovation towards smart and wearable sensors. However, the preparation and functionalization of the sensing material remain challenging for real-time application. In this regard, herein, a novel free-standing nanosheet strategy involving sputtering technique is proposed for toxic ammonia (NH3) sensing application. Radio frequency (RF) sputtered vanadium pentoxide (V2O5) film was used as the sensing layer on the biocompatible poly-l-lactic acid (PLLA) substrate of ∼130 nm. The deposited V2O5 film was carefully evaluated for its control in thickness, morphology, and topographical characteristics in addition to its elemental studies. X-ray photoelectron spectroscopy (XPS) confirmed the highly stable V+5 oxidation state with the binding energy of 516.8 and 524.2, corresponding to V2p3/2 and V2p1/2 peaks. From the chemiresistive sensing analysis, V2O5 film exhibited a sensor response (Ra/Rg) of 1.2 towards 5 ppm NH3 at room temperature. The sensing mechanism of n-type V2O5 towards reducing NH3 has been schematically explained. It is worth emphasizing that this work will pave the way for exploring novel yet facile preparation strategies for flexible sensing devices. We believe that the 2D freestanding nanosheets will provide remarkable advancements in flexible/wearable devices owing to their biocompatibility, conformability, flexibility, and light feel characteristics.