Preparation Of Silver Nanocomposites For Electrochemical Detection Of Hydrogen Peroxide

Due to the advantages such as fast analysis,good accuracy,high sensitivity,low price and simple detection process,electrochemical sensors have important application potentials in clinical,food safety,agriculture,environmental analysis and other fields.Silver nanocomposite materials have been widely researched for efficient catalytic activity and fast electron transfer rate.In this paper,silver nanocomposite materials were successfully prepared by using electrochemical deposition and solvothermal method.The composition,microstructure,and electrochemical properties were characterized using high-resolution transmission electron microscopy,X-ray diffraction,X-ray photoelectron spectroscopy,Raman spectroscopy,in-situ Infrared,cyclic voltammetry and electrochemical impedance spectroscopy.The prepared electrodes were directly used for the electrochemical detection of hydrogen peroxide.The catalytic performance of the modified electrodes was detected as hydrogen peroxide sensor.In this paper,we mainly studied the following three aspects:Firstly,nano-silver electrode(AgNPs^-L-Pro/GCE)was available through amino acid assisted synthesis using electrochemical deposition and directly prepared on the surface of glassy carbon electrode.L-proline as a stabilizer plays the very important role in slowing the oxidation of metallic silver and makes contributions to avoid aggregations.AgNPs^-L-pro were spherical,and the particle size was about 5-10 nm.The valence of silver was Ag⁰.The conductivity and electrochemical activity of AgNPs^-L-pro/GC electrodes were significantly improved due to the morphology and chemical states.The resultant silver nanoparticles stabilized using L-proline had a higher active surface and displayed lower detection limit of 50.0 nM in the range of 0.1?M-5.1 mM.It also had excellent anti-interference,long-term stability,reproducibility and repeatability.The fabricated sensor also reliably applied in detection of H₂O₂ in milk samples,and recovery range was 97.5%¹02.1%.Secondly,silver-titanium dioxide?Ag-TiO₂?were synthesized by solvothermal method using tetrabutyl titanate,silver nitrate,ascorbic acid and ethanol as titanium source,silver source,reducing agent and solvent.Ag-TiO₂ were approximately spherical,and the particle size was about 350 nm.The surface of Ag-TiO₂ was also rough,like layer coated.The composite material had certain electric catalytic performance of H₂O₂.But due to the poor conductivity of TiO₂,catalytic performance was not strong.It could detect H₂O₂ in the linear range of 0.1?M–7.0 mM with the detection limit of 39.7 nM?S/N=3?.The sensitivity was 3.13?A?mM^-1?cm^-2.It also had long-term stability,reproducibility and repeatability.The performance could be maintained at 82.1%after a month.Thirdly,Ag-TiO₂ converted into silver-titanium nitride?Ag-TiN?by ammonia reduction.The result confirmed that the microstructure of microspheres remains at high temperature after nitriding.Ag-TiN had diameters of 150-250 nm with porous structure.While its structure became more uniform,surface roughness had increased greatly.The surface of TiN was homogeneously decorated with Ag⁰.Such structure characteristics can improve the catalytic properties of electrodes.It could detect H₂O₂ in the linear range of 0.05?M–2.1 mM with the detection limit of 7.7 nM,and excellent selectivity in the presence of interfering species.In addition,Ag-TiN nanocomposite exhibited good reproducibility,repeatability and storage stability.The performance could be maintained at 91.7%after a month.The fabricated sensor also reliably applied in detection of H₂O₂ in milk samples,and recovery range was 97.0%¹02.0%.