Gold Nanoparticle-Modified Tungsten Oxide Flakes as Nitric Oxide Sensor Electrodes for Fruit Quality Monitoring

Development of low-cost, handheld nitric oxide (NO) sensors is very much important due to its major role in environmental pollution, biomedical research, and food safety applications. In this study, an electrochemical NO sensor has been fabricated using gold nanoparticle (Au NP)-modified tungsten oxide (WO3) nanoflakes. WO3 nanoflakes were grown hydrothermally on fluorine doped tin oxide (FTO) substrates, and Au NPs were attached by a photoreduction method. The sensing characteristics of pristine WO3 and Au NP-coated WO3 electrodes have been studied by amperometric techniques. The sensor performance has been optimized at various Au NP loadings. The optimized sensor demonstrated a high sensitivity (∼39.37 μA cm–2 mM–1) over a wide linear range (∼10 μM to 5.78 mM) with a low detection limit (∼0.12 μM). The Au NP-coated WO3 sensing electrode demonstrated high stability. The sensor current only decreases 7.54% after 31 days of continuous measurements. The sensor also showed fast response (1.7 s) and high selectivity toward NO detection. NO detection in fruit samples (apple and orange) has been studied with the Au NP-modified WO3 electrode for fruit quality monitoring application.