The Research And Application Of Nonenzyme Electrochemical Sensors Based On Noble Metal Nanoparticles

Some small molecules such as oxalic acid,hydrogen peroxide and nitrite,are affecting human health.The accurate and quick detection of these subatances is of great significance in the filed of environmental monitoring,food determination and clinical diagnosis.Electrochemical sensing technology has advantages of low cost,fast response,high sensitivity,good selectivity,which has been received attention by the researchers.The noble metal nanomaterials are widely used in electrochemical sensors on account of possessing good biocompatibility,fast electron transfer rate and high catalytic activity.In this paper,we constructed precious metal electrode materials containing Pt or Pd for detection of oxalic acid,hydrogen peroxide and nitrite.The content mainly includes the following:?1?The platinum nanoparticles modified glassy carbon electrode?PtNPs/GCE?prepared by electrochemical deposition method and bare platinum electrode without modification were used for detection of oxalic acid.Cyclic voltammograms showed the oxidation peak potential of oxalic acid were at 0.8 V on both kinds of electrodes and PtNPs/GCE had higher peak current strength.The optimal potential at the bare platinum electrode was 0.9 V by using amperometric method with good linear range of 0.57¹04.01 mM,104.01²28.75 mM and low detection limit of 0.38 mM?S/N=3,n=5?.The wider linear concentration range of PtNPs/GCE was 1.14³42.80 mM and 342.80⁵84.92 mM at the potential of 0.95 V with slightly lower detection limit of 0.28 mM?S/N=3,n=5?.Both electrodes possessed good stability,strong anti-interference ability and achieved satisfactory results in actual spinach sample.?2?We prepared hollow cubic Cu₂O@Pd/GCE core-shell nanomaterial through galvanic replacement reaction.The electrochemical tests showed that Cu₂O@ Pd/GCE contained larger electrochemical active surface area and dispiayed higher catalytic reduction activity to H₂O₂.Simultaneously,the effect of pH,scan rate and working potential were studied.Through amperometric method determining H₂O₂,the linear range was 19.9 mM².08 m M,2.08 m M⁹.27 mM with detection limit of 9.5 mM?S/N=3,n=3?.The electrochemical sensor showed good reproducibility,stability and selectivity.More importantly,the amount of precious metals was little,which effectively reduced the experiment cost.?3?The prepared hollow Cu₂O@Pd/GCE core-shell nanomaterial used to construct nitrite sensor,which revealed great oxidation catalytic activity of nitrite.The experimental conditions such as different electrolyte solutions,electrolyte concentrations and pH were optimized.Under the optima condition,the linear range was 0.2⁶1.6 mM and 61.6¹216.7mM.The limit of detection was estimited to be 42 nM?S/N=3,n=4?.We investigated that stability and selectivity of nitrite sensor were great.The recovery rate ranged from 98% to102% by determining the nitrite content of tap water.