Novel Electrochemical Coupled Three-in-One Sensing System for Transforming Organic Pollutants into Green Fuels and Their Sensing

Abstract

The organic pollutants present in wastewater produce greenhouse gas, CO₂. Effective utilization of CO₂ into valuable green fuels and its sensing is focused research area. Aiming above, this work is focused on fabrication of electrochemical coupled sensing system for degradation of 4-nitrophenol to CO₂ from wastewater samples, electrochemical reducing system for transforming CO₂ to alcohols and selective amperometric sensing system for quantifying alcohols. A graphene anchored iron oxide electrode was used as an electrocatalyst to facilitate the electrochemical oxidation process to mineralized organic pollutants into water and CO₂. The CuO film on silicon substrate was used in cathodic compartment for converting CO₂ to methanol and ethanol. Alcohol oxidase modified Au–Cu nanoparticle modified pencil graphite was selective sensing and quantifying the methanol and ethanol. The experimental results revealed that, graphene anchored iron oxide showed maximum degeneration of 4-nitrophenol 72% at 0.9 V. Furthermore, simultaneous reduction of CO₂ at cathode gave good yield of the liquid fuels CH₃OH and C₂H₅OH were 105.0 and 90.0 μmol/L respectively. In addition, Alcohol oxidase modified Au–Cu nanoparticles modified pencil graphite biosensor displays a linear response to both methanol and ethanol in the range 0.250–850 μmol/L with a detection limit of 0.07 μmol/L (S/N = 3) (RSD = 0.004 μA) and 0.7–800 μmol/L with detection limit of 0.068 μmol/L (S/N = 3) (RSD = 0.005 μA) with >40% quantitative yield. The response time is less than 50 s at ambient conditions. Consequently, the ethanol and methanol yield were obtained 30.0%. Our developed three-in-one provides a convenient, simple and reliable method to remediate polluted water and utilizing CO₂ into green fuels.