▎ 摘　　要

Still the whole world is straggling for the pure surface water monitoring which is time consuming and expensive work. Thus, a quick, selective and authentic measuring tool is anticipated for continuous monitoring the addition of chemical contaminants, such as hydrazine (N2H4). In this study, we have developed a Co(OH)(2) nanoparticles decorated benzaldehyde-functionalized graphene (denoted as RGO/DHB/Co(OH)(2)) electrochemical sensor for selective determination of N2H4 from surface water. The electrochemical experiments are signifying its potential catalytic activity towards the oxidation of N2H4. Amperometric response suggests that this electrode can perform at the broad linear concentration range from 5 to 1700 mu M at a lower limit of detection of 0.165 mu M with good sensitivity of 1446.82 mu A mM(-1) cm(-2) by <2 s. The RGO/DHB/Co(OH)(2) exhibits nonsignificant interference during N2H4 detection in presence of several interferents such as primary amines, biomolecules and some common anions/cations. The admirable stability, repeatability, reproducibility and trace-level detection of N2H4 in various surface water samples have proven that the RGO/DHB/Co(OH)(2) is an efficient tool for real-time application towards N2H4 detection and can contribute its potentiality against the current worldwide pandemic COVID-19. Importantly, the reaction mechanism of N2H4 oxidation has revealed at the RGO/DHB/Co(OH)(2) surface by easy demonstration.