Enhanced Electrochemical Detection of Orthophosphate in Potable Water Using Zinc-Cobalt Oxide Nanocomposite-Modified Nickel Foam Electrodes

This study presents a novel approach to electrochemical detection of orthophosphate in potable water using hydrothermally synthesized nickel foam electrodes, modified with cobalt oxide (CoOx), zinc oxide (ZnOx), and zinc-cobalt oxide (ZnCoOx) nanocomposites. The incorporation of zinc-cobalt oxide into the electrode significantly enhances its stability and detection capability. In-situ phosphate detection was performed using voltammetric techniques in a highly alkaline environment (pH 14) facilitated by sodium hydroxide (NaOH). Comprehensive electrode characterization, including cyclic voltammetry (0 to 0.6 V at a scan rate of 50 mV s −1 ), electrochemical impedance spectroscopy (10 5 to 10 –2 Hz), scanning electron microscopy, and energy-dispersive X-ray spectroscopy, confirmed the superior performance of the synthesized electrodes. Among the tested configurations, the zinc-cobalt oxide nanocomposite on nickel foam exhibited outstanding sensitivity, with a sensitivity of 0.4 μA/μM across a concentration range of 0 to 40 μM, and an elevated sensitivity of 4.26 μA/μM within the 50 to 100 μM range. The electrode achieved a remarkably low detection limit of 0.171 μM L −1 (0 to 40 μM detection range) and 0.324 μM L −1 (50 to 100 μM, detection range), underscoring its potential for highly accurate phosphate detection. These findings highlight the sensor’s applicability for diverse practical uses in water quality monitoring.