Investigation On Hydrogen Peroxide Sensors Fabricated Using Gold Nanomaterials

In the fields of industrial, biological, environmental, clinical diagnostic and food, H2O2 detection includes many methods such as chromatography, titrimetry, spectrometry, chemiluminescence and electrochemistry. Among them, the electrochemical method is an extremely important means bacause of its low cost, easy operation, high accuracy and practical utility. The development of nano-technology makes it possible to construct high-sensitive and robust H2O2 sensors. Three types of nanostructured films, in this thesis, were prepared based on self-assembly and electrodeposition techniques for the design of H2O2 sensors. The main research contents are as follows:1. Sensing properties of horseradish peroxidase （HRP） modified gold nanoparticle （AuNP） films: AuNP monolayer and multilayer films were fabricated by combining liquid/liquid interfacical self-assembly and organic linker-free layer by layer self-assembly, and used to study the direct electron transfer behavior of HRP and the response of HRP/AuNP films to H2O2. We found that HRP adsorbed on AuNP mulilayer films gave a more intense current signal for its direct electron transfer. This may be attributed to the increase of surface roughness of AuNP film, which not only provides more adsorption sites for HRP molecules, also effectively shortens the distance between electrode substrates and the active center of HRP molecules. Among as-prepared HRP/AuNP films, HRP adsorbed on AuNP four-layer （HRP/AuNP4） films had the most intense current signal for its direct electron transfer, and were used for H2O2 detection. The HRP/AuNP4 sensor showed the fast response and good sensitivity. The linear range and the detection limit of H₂O₂ concentration were 9.8×10-6 6.0×10-3 mol-L-1 and 4.9×10-6 mol-L^-1, respectively.2. Sensing properties of polyaniline （PANI） and gold nanoparticles composite thin-film: AuNP multilayer films were modified onto the surfaces of glassy carbon electrodes via liquid/liquid interfacial self-assembly, and used as substrates for the electrodeposition modification of PANI film. The sensing properties of PANI/AuNP films were optimized by controlling the layer number of AuNP monolayer and the time of electrodepositing PANI. The optimized PANI/Au composite nanostructured film showed a linear range of 9.8×10-5 8.0×10-2 mol-L-1, and a detection limit of 7.0×10-6 mol-L-1 for H2O2 detection.3. Sensing properties of Au/Pt alloy nanoparticle （Au/Pt NP） films. Au/Pt NP films were prepared by electrodeposition using cyclic voltammetry. We found that Au:Pt atomic ratios in Au/Pt NP films were closely associated with the concentration of AuCl4- and PtCl62- in the electrolyte, and had a remarkable effect on the response of Au/Pt NP films to H2O2 oxidation. Au/Pt NP film with the Au:Pt molar ratio of 38:62 had an intense current signal of H₂O₂ at the same condition, and showed a very broad linear range of H2O2 concentration of 1.0×10-7 4×10^-2 mol-L^-1, spanning 5 orders. Additionally, the detection limit reached 5.0×10-8 mol-L^-1, close to nmol-L^-1.