| Nitrite is a toxic and carcinogenic pollutant,which is ubiquitous in food,water and ecological environment.Excessive nitrite will cause serious harm to human health and environment.Therefore,rapid detection of nitrite becomes a very meaningful and necessary research work.In recent years,methods for detecting nitrite have emerged in an endless stream.Among them,electrochemical methods have attracted wide attention due to their advantages of rapid response,simple operation,sensitivity and low cost.Therefore,it is of great significance to construct new high-efficiency nitrite electrochemical sensors.Among many nitrite modified materials,transition metal has the advantages of good catalytic activity,large specific surface area,high chemical stability and simple preparation,but its own conductivity is poor.Therefore,in order to improve the electrocatalytic activity of modified electrode on nitrite,In this paper,based on noble metal/transition metal composite nanomaterials,a new electrochemical sensor with fast,high sensitivity and low detection limit was constructed and successfully used for nitrite detection.The research results are as follows:（1）Electrodeposition of Au/Ni nanotubes with highly improved electrochemical performance for non-enzymatic nitrite detectionAu/Ni nanotubes were fabricated on carbon papers through depositing Au nanoparticles on Ni nanotubes to construct nitrite sensors.The structure and constituent characterization of Au/Ni-60s NTs demonstrated the homogeneous distribution of Au nanoparticles on the Ni nanotubes.Due to the synergy between Ni nanotubes and Au nanoparticles,highly improved nitrite sensing performance was achieved on Au/Ni-60s NTs,which presented a very wide linear range for nitrite detection.Two linear segments have been obtained in the range of 0.4-40000μM and 40-130m M with the detection limit of 0.13μM.The sensitivity of 707.14μA·m M-1·cm-2 in lower region and339.53μA·m M-1·cm-2 in higher region was achieved.Furthermore,the obtained Au/Ni-60s NTs displayed good selectivity and high reliability for nitrite detection in real samples such as milk and peach juice.This investigation may provide a useful route and reference to construct tubular structures for efficient nitrite detection.（2）Electrodeposition hollow structure Au/Co nanocomposites for non-enzymatic nitrite detectionThe hollow Co nanomaterials were prepared by electrodeposition,and then Au nanoparticles were deposited on them.Au/Co nanocomposites were successfully prepared on carbon paper,and nitrite sensors were constructed and showed excellent sensing performance.This may be due to the synergistic effect between Co and Au.The hollow structure also makes Au nanoparticles evenly distributed on Co,providing more active sites.Au/Co showed a very wide linear range（0.1～10μM and 20～11000μM）for nitrite,the detection limit was 0.03μM,and the sensitivity in low concentration zone and high concentration zone were 463.11μA·m M-1·cm-2 and449.3μA·m M-1·cm-2,respectively.The Au/Co sensor showed a good recovery rate for nitrite detection in actual samples（milk and peach juice）.This study provides a feasible idea for the simple preparation of hollow structure nanomaterials by electrodeposition to construct efficient nitrite sensors.（3）Electrochemical sensors based on platinum coated MOF-derived nickel/N-doped carbon nanotubes（Pt/Ni/NCNTs）for sensitive nitrite detectionPlatinum nanoparticles were deposited on nickel/N-doped carbon nanotubes,which were obtained through a self-catalytically grown process with Ni-MOF as precursors.The as prepared Pt/Ni/NCNTs were applied as amperometric sensors and presented superior sensing properties for nitrite detection.Benefiting from the synergy of Pt and Ni/NCNTs,Pt/Ni/NCNTs displayed much wider detection ranges（0.5Μm～40 m M and 40～110m M）for nitrite sensing.The sensitivity is276.92μA·m M-1·cm-2 and 224.39μA·m M-1·cm-2,respectively.The detection limit is 0.17μM.The Pt/Ni/NCNTs sensors also showed good feasibility for nitrite sensing in real samples（milk and peach juice）analysis.The active Pt/Ni/NCNTs composites and facile fabrication technique may provide useful strategies to develop other sensitive nitrite sensors.（4）Polyhedral Pt/Co@C nanoporous composite derived from ZIF-67 for nitrite detectionThe Pt/Co@C polyhedral nanoparticle composite was obtained by calcining the precursor of ZIF-67 to obtain Co@C,and then the Pt nanoparticles were deposited on it.Pt/Co@C greatly improves the nitrite sensing performance,showing a very wide detection range,including0.6～2000μM and 2～75m M,detection limits of 0.2μM,corresponding to 73.91μA·m M-1·cm-2 and60.32μA·m M-1·cm-2,respectively.The Pt/Co@C sensor showed good anti-interference ability to common metal ions and some organic interferences,and showed good selectivity to the determination of nitrite in milk and peach juice.The simple preparation process of Pt/Co@C composites has good potential value in nitrite detection. |
