Study On The Synthesis Of Prussian Blue, Metal Oxide Composite Electrode Materials And The Application Of Electrocatalysis

Along with the rapid development of economies, the problems about energy, environment and food safety are gradually appeared and attract more and more attention. Due to their advantages such as good chemical stability, redox, excellent electrocatalytic properties, soft synthesis method, low cost and less environmental damage, transition metal hexacyanometalates are promising modified electrode materials for design and fabrication of electrochemical sensors and excellent templates for the synthesis of metal based nanomaterials. Therefore, in this paper, two kinds of electrochemical sensors were fabricated mainly based on Prussian blue?PB? and applied on electrocatalytic detection of nitrite and L-cysteine, respectively. Also, a kind of cobalt oxide based on the cobalt hexacyanocobaltates?Co-Co PBA?, which was used as a template, was synthesized and applied as a catalyst for electrocatalytic water oxidation. The main work is as follows:1. Graphene quantum dots?GQDs?, which were synthesized and grafted on the surface of graphite felt?GF?, were used to promote the synthesis process of redox reaction between Fe³⁺ and [Fe?CN?₆]^3- in aqueous solution and thus form PB@GQDs composite film on the surface of GF. The PPy film was electro-polymerized on the surface of electrode for improving the electrochemical stability, so the PPy/GQDs@PB/GF had been fabricated. Then the as-prepared electrode was characterized by scanning electron microscopy?SEM?, transmission electron microscopy?TEM?, Fourier tansform infrared spectroscopy?FTIR?, X-ray diffraction?XRD? and electrochemical methods. The promotion effect of GQDs for the formation of PB was verified by UV- vis spectrophotometry as well. It exhibited an excellent activity for the electrocatalytic detection of L-cys, with a high sensitivity, a low detection limit, a wide detection range, as well as a remarkable long-time stability and a good response to practical analytes, were also ascertained.2. A novel Prussian blue?PB?, ionic liquid 1-butyl-3- methylimidazolium tetra?uoroborate?[Bmim][BF4]? and graphite felt?GF? nanocomposite electrode?PB/[Bmim][BF4]-GF? was obtained on the substrate of GF, which was grafted with [Bmim][BF4] to accelerate redox reaction process between Fe³⁺ and [Fe?CN?₆]^3- for the synthesis of PB. The as-prepared electrode material was characterized by scanning election microscopy?SEM?, Fourier tansform infrared spectroscopy?FTIR? and X-ray diffraction?XRD? and electrochemical methods. The promotion effect of [Bmim][BF₄] for the formation of PB was verified by UV- vis spectrophotometry as well. Then the PB/[Bmim][BF4]-GF composite electrode was used to detect nitrite. The sensor displays remarkable sensitivity, extremely low detection limit, as well as a long-time stability and a good response to practical analytes.3. The Mn-Co₃O₄ nanobox with hollow porous structure was synthesized by thermal decomposition of Mn doped cobalt hexacyanocobaltates?Co-Co PBA? and characterization by scanning electron microscopy?SEM?, transmission electron microscopy?TEM?, fourier tansform infrared spectroscopy?FTIR?, X-ray diffraction?XRD? and X-ray photoelectron spectroscopy?XPS? methods. The structure of Mn-Co₃O₄ nanobox was found to be similar to Co₃O₄ nanobox. However, doping Mn is in favor of the increase of electrochemical active sites of t he nanomaterials, and thus improving the electrocatalytic water oxidation property. The as-prepared Mn-Co₃O₄ nanobox exhibits a low onset potential, a small Tafel slope and a low overpotential when the current density is 10 m A cm-2.