A versatile ratiometric electrochemical sensing platform based on N-Mo₂C for detection of m-nitrophenol

M-nitrophenol (m-NP) is a high priority environmental pollutant and poses a series of threats on human health. Accurate and rapid detection of m-NP in practical samples is very important as this is the key prerequisite for its effective monitoring. Eelectrochemical sensor, though long serving as highly sensitive and fast analytical tool, suffers from the bottleneck problems like low specificity, poor reproducibility, susceptibility to internal and external disturbances, etc. Herein, we developed a ratiometric electrochemical sensor (R-ECS) for m-NP detection, in which nitrogen-doped Mo₂C (N-Mo₂C) was deployed as the sensing agent and methylene blue (MB) as the internal reference. Full characterization of N-Mo₂C was carried out in the aspects of morphology, composition, chemical bonds and electrochemical behavior, and the sensing performance of the easy-to-operate R-ECS was evaluated. Complete separation of the oxidation peaks of m-NP and MB was achieved using the MB/N-Mo₂C composite modified electrode and their ratiometric signals were adopted for quantification of m-NP. The linear relation between the electrical signal and the concentration of m-NP is in the range of 1-1500 μM, with the detection limit of 0.256 μM (S/N = 3). The sensor was applied to measure m-NP in real samples from tap water and river. Experimental results demonstrate that it exhibits decent repeatability, reproducibility, stability and selectivity, which proves its great practical potential as an analytical detector.