Construction Of Electrochemical Sensors Based On Molybdenum-based Carbon Materials And Their Application In The Detection Of Phenol

Phenols are chemical intermediates or raw materials commonly used in industry and agriculture,and most of them are highly toxic compounds.They are mainly discharged into the environment through industry and cause environmental pollution.It is difficult to degrade in the environment,is persistent and cumulative,can cause endocrine disorders,reproductive and immune dysfunction,and cause carcinogenesis,teratogenicity,mutagenesis and so on.It poses a great threat to the ecological environment and human health.However,the common detection methods currently have disadvantages such as complicated operation,expensive equipment and harsh experimental conditions.Electrochemical methods are widely used because of their simple operation,speed,high sensitivity,high selectivity and low cost.In this paper,the sensitivity and selectivity of the sensor are improved by modifying the electrode with Mo based carbon material,and the repeatability and stability of the sensor are improved by introducing internal reference material.The main results are as follows.?1?Synthesis of hollow Mo₂C/carbon spheres and electrochemical detection of hydroquinone,catechol,and resorcinolIn this study,hollow molybdenum-dopamine spheres were synthesized and thermally annealed to form hollow Mo₂C/C spheres.These were characterized with respect to morphology,composition and electrochemical behavior.A glassy carbon electrode?GCE?was modified with the spheres and then used for simultaneous detection of hydroquinone?HQ?,catechol?CC?,and resorcinol?RS?.Distinct oxidation peaks can be observed for HQ,CC and RS at potentials of?0.0041 V,0.104 V and 0.440 V?vs.SCE?.The responses to HQ,CC and RS are linear in the 0.3¹000?M,2²000?M and 3⁶00?M concentration in the ranges,respectively.The corresponding detection limits are 0.12,0.19 and 1.1?M?S/N=3?.The sensor was then applied to quantify HQ,CC,and RS in genuine?spiked?tap water,river water and vegetable juice.Recoveries ranged from 93.5%to 106.5%.The modified GCE is repeatable,reproducible,stable and selective.?2?A versatile ratiometric electrochemical sensing platform based on N-Mo₂C for detection of m-nitrophenolM-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 1¹500?M,with the detection limit of 0.256?M?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.?3?A novel ratiometric electrochemical sensor based on Mo₂C for determination of acetaminophenIn this paper,MoO₂ nanoparticles were synthesized and annealed to form Mo₂C nanoparticles.A ratiometric electrochemical sensor?R-ECS?for the detection of paracetamol?AP?was developed with Mo₂C as the sensing agent and ferrocene?Fc?as the internal reference.Among them,for convenience,Fc?100?M?was directly added to the electrolyte solution.The synthesized materials were fully characterized in the aspects of morphology,composition and electrochemical behavior.The Mo₂C modified glassy carbon electrode can completely separate the oxidation peak potentials of Fc?0.196 V?and AP?0.364 V?,and quantify AP in the form of ratiometric.The peak current of AP has a linear relationship with the concentration in the range of 0.5⁶00?M,and the detection limit is 0.029?M?S/N=3?.The sensor was applied to measure AP in real samples from tap water and river.Besides,Mo₂C/GCE exhibited decent repeatability,reproducibility,stability,and anti-interference ability,which proves its great practical potential as an analytical tool.