Application Of Electrochemical Sensors Based On Novel Two-dimensional Nanomaterials For The Copper Ion Reduction Detection

Heavy metal ion pollution is a severe threat to human health and ecological safety due to its highly toxic and non-biodegradable characteristics.Heavy metal ion can accumulate in the body through the food chain,which will cause damage to the cell tissue of the human body and cause various physiological and metabolic disorders.Copper ion(Cu²⁺)is a common heavy metal ion in daily life and also is an indispensable trace element in the metabolic process of life.However,the intake of excessive Cu²⁺may lead to many diseases such as Wilson disease and Kayser’s disease.Accordingly,it is very important to choose a suitable detection method for highly sensitive detection of Cu²⁺.Electrochemical sensors have shown great application prospects in rapid detection of Cu²⁺due to their short analysis time、high sensitivity and selectivity.At present,the research of electrochemical sensors mainly focuses on sensing materials.Two-dimensional（2D）nanomaterials have been introduced as sensing materials to achieve high sensitivity towards heavy metal ion detection own to their ultra-thin structure,extreme specific surface area and other properties.However,the traditional sensors based on 2D nanomaterials have shortcomings such as high detection limit,narrow linear range,and their sensitivity needs to be further improved.In recent years,new 2D nanomaterials such as black phosphorous（BP）and graphdiyne（GDY）have attracted attention in various fields,especially in the sensing field due to their unique characteristics.In this paper,BP and GDY were used as sensing materials for the fabrication of high-performance electrochemical sensor to realize the rapid and sensitive detection of Cu²⁺and successfully used in quantitative analysis of Cu²⁺in water.The main contents are as follows:1.Due to its unique puckered structure,BP possess excellent performance such as great surface-to-volume ratio,excellent electrocatalytic activity and so on,which making it widely used in the sensing field.However,BP is mostly used to fabricate field effect crystal sensors（FET）to realize the detection of heavy metal ions,and there are few studies on the application of BP-based electrochemical sensors for the detection of Cu²⁺.In this work,we used BP as the sensing material to fabricate a novel electrochemical sensor for high selective and ultratrace detection of Cu²⁺.In order to ensure the high sensing performance of the sensor,the BP was functionalized by branched polyethylenimine（PEI）in this work to improve the stability of BP due to BP was easy to be degraded.After functionalization,the stability of the nanocomposite（BP-PEI）and the sensing performance towards Cu²⁺were obviously enhanced.The enhancement mechanism was that the stability of BP was improved after functionalization,which made its excellent catalytic reduction performance could be retained.Meanwhile,the amine functional groups in PEI could choose to chelate Cu²⁺.Therefore,BP-PEI could enhance the sensing ability towards Cu²⁺detection by the synergistic effect of BP and PEI.The BP-PEI based electrochemical sensor could detect Cu²⁺rapidly within 1.5 s and delivered an outstanding performance with a wide linear detection range（0.25～91μM,91～177μM）and a low detection limit（0.02μM）.In addition,a flexible sensing platform was established by using the screen print technology and its mechanical properties were studied.The results showed that BP-PEI/SPE still remained 97.8%of its initial response after many bending-release cycles and kept 98.2%of its initial response after different bending angles,which predicted that BP-PEI/SPE could be used for the real-time detection of Cu²⁺in real water without being affected by water flow rate.Finally,the flexible sensing platform was successfully applied to the detection of Cu²⁺in river sample,the recovery rates of BP-PEI/SPE were in the range of 90.8%～96.8%,which provided a convenient and reliable approach for expanding the practical application of BP-PEI in environment monitoring.2.GDY has a broad application potential in electrochemical sensing due to its highπ-conjugated system and excellent chemical stability.At present,there is no report on electrochemical detection of Cu²⁺by GDY.In this work,a novel electrochemical sensor based on GDY was fabricate for electrochemical reduction detection of Cu²⁺with high selectivity and low detection limit.Various characterization methods such as XRD,XPS and so on,had been used to study the physical and chemical properties of GDY.The characterization results showed that Cu²⁺could be chelated and reduced by GDY through-C≡C-.Due to the excellent chemical stability and reduction ability of GDY,the electrochemical sensor based on GDY had better sensing performance than that based on BP-PEI with wider detection linear range（0.25～10μM,10～380μM）,lower detection limit（8 n M）,lower detection limit（8 n M）,expanding the application of GDY in environmental detection.In conclusion,2D nanomaterials can improve their detection performance of heavy metal ions through functionalization or the addition of highly active functional groups.The functionalized material not only has abundant active sites,but also has the ability to specifically recognize heavy metal ions conferred by functional groups.Meanwhile,the highly active functional groups can improve the sensitivity and selectivity of the detection,which provides a feasible and effective approach for the design of electrochemical sensors based on high-performance 2D nanomaterials to realize sensitive and selective detection of heavy metal ions.