Highly Sensitive Electrochemical Detection of Hydroquinone in Wastewater Using Ionic Liquid Grafted rGO-ZrO2 Nanohybrid-Based Conducting Paper

Abstract

Herein, we envisage the fabrication of conducting paper electrode (CPE) based on ionic liquid (IL)-grafted ZrO2 nanoparticles and rGO for ultra-sensitive enzymatic detection of hazardous phenolic compounds. The rGO-ZrO2 nanohybrid has been synthesized using the one-pot hydrothermal technique, followed by the modification with IL to enhance the catalytic activity and conductivity of rGO-ZrO2 nanohybrid. CPE has been prepared by integrating ILs@rGO-ZrO2 nanohybrid with the PEDOT: PSS modified Whatsman filter paper. The ILs@rGO-ZrO2/CPE has been immersed in different solvents, and its conductivity was assessed using the four-probe method. The conductivity of the ILs@rGO-ZrO2/CPE was higher in ethanol (7.58 × 10⁻3 S/cm) compared to the electrodes without treatment with any solvent. Further, the laccase enzyme was covalently linked to the ILs@rGO-ZrO2/CPE for detecting HQ. The fabricated biosensor depicts a linear response for the detection of HQ in the concentration range of 40 μM to 0.01 μM with a detection limit of 0.01 μM and sensitivity of 0.1408 μA μM−1 cm−2. The electrochemical results indicate that integrating ILs@rGO-ZrO2 nanohybrid with the CPE enhances electron transfer and electrocatalytic performance. The validation of the fabricated biosensor with tap and lake water shows an acceptable recovery rate, indicating that the developed method is cost-effective and eco-friendly.