Utilizing water hyacinth extract as an eco-friendly electrolyte substitute for electrochromic devices

In this study, an entirely biodegradable and cations-rich Water hyacinth (WH) (Eichhorniacrassipes) extract is used as the electrolyte in electrochromic devices. The active electrodes are fabricated by applying a layer of nanocrystalline orthorhombic WO₃ onto 5 × 5 cm² fluorinated tin oxide plates using an indigenous formulation. The electrolyte utilized is the juice derived from WH plants without any modifications. The devices exhibit a transmission contrast of around 46% and 82% at wavelengths of 600 nm and >1000 nm, respectively, between the colored and bleached states. Additionally, they have a rapid coloration/bleaching time of 10 and 4.6 s with coloration efficiency value around 52 cm²/C. Investigations have indicated that the electrolyte's sodium ion concentration is likely the key behind the electrochromic process in this system. Using pectin as a natural gelling agent results in the formation of a gel polymer electrolyte that is mechanically resilient. The electrochromic systems created utilizing this electrolyte exhibit exceptional cyclic stability, lasting for 16 000 s of uninterrupted voltage sweep.