Deep Eutectic Solvent-Assisted Synthesis of a Strontium Tungstate Bifunctional Catalyst: Investigation on the Electrocatalytic Determination and Photocatalytic Degradation of Acetaminophen and Metformin Drugs

In this work, we propose a modified solid-state approach for the sustainable preparation of a SrWO₄ bifunctional catalyst using thymol–menthol-based natural deep eutectic green solvents (NADESs). Various spectroscopic and morphological techniques analyzed the as-synthesized SrWO₄ particles. Acetaminophen (ATP) and metformin (MTF) were selected as the model drug compounds. The electrochemical detection and photocatalytic degradation of ATP and MTF upon ultraviolet–visible (UV–vis) light irradiation in the presence of as-prepared SrWO₄ particles as an active catalyst are examined. The present study displayed that the proposed catalyst SrWO₄ has enhanced catalytic activity in achieving the optimum experimental conditions, and linear ranges of ATP = 0.01–25.90 μM and MTF = 0.01–25.90 μM, a lower limit of detection (LOD) value (ATP = 0.0031 μM and MTF = 0.008 μM), and higher sensitivity toward ATP and MTF determination were obtained. Similarly, the rate constant was found to be k = ATP = 0.0082 min^–1 and MTF = 0.0296 min^–1 according to the Langmuir–Hinshelwood model, benefitting from the excellent synergistic impact of the SrWO₄ catalyst toward the photocatalytic degradation of the drug molecule. Hence, this work offers innovative insights into the applicability of the as-prepared SrWO₄ bifunctional catalyst as an excellent functional material for the remediation of emerging pollutants in water bodies with a recovery range of 98.2–99.75%.