Synthesis Of Transition Metal (Co, Ni) Hydroxides And Their Electrocatalytic Performance

This thesis reports the fabrication of non-enzyme electrochemicalsensors for glucose and oxygen evolution reaction (OER) catalysis basedon α-Ni(OH)2nanosheets and hierarchical cobalt aluminum layereddouble hydroxide respectively. The influences of structure, elementalcomposition and the synergistic interaction between electroactive specieson the electrocatalytic performance were investigated.A electrochemical sensor was fabricated on glassy carbon electrode(GCE) through alternate assembly of positively charged α-Ni(OH)2nanosheets and negatively charged functional dye Acid Violet (AV34) viathe electrostatic layer-by-layer (LBL) technique, and its electrocatalyticoxidation for glucose was demonstrated. UV-vis absorption andelectrochemical impedance spectra indicate the uniform deposition of theLBL film, with continuous and smooth film morphology observed bySEM and AFM. The electrochemical performance of the ultrathin filmwas studied by cyclic voltammetry and chronoamperometry measurement.The (AV34/Ni(OH)2)5ultrathin film modified electrode displays a fastdirect electron transfer attributed to the Ni2+/Ni3+redox couple as well as remarkable electrocatalytic activity towards the oxidation of glucose. Thelinear response was obtained in the range0.5–13.5mM (R=0.9994) witha low detection limit (14M), high sensitivity (25.9A· mM1· cm2),rapid response (less than1s). The sensor also shows good reproducibility,long-term stability and excellent anti-interference properties to thespecies including ascorbic acid (AA), uric acid (UA), acetamidophenol(AP) and structurally related sugars. The practical application of the(AV34/Ni(OH)2)5ultrathin film modified electrode in blood serumsamples gave satisfactory results compared with the hexokinase method(relative standard deviation less than4.1%). Therefore, theAV34/Ni(OH)2ultrathin film can be potentially used as a feasibleelectrochemical sensor for the determination of glucose.Hierarchical flowerlike Co-Al layer double hydroxides (LDHs) withhigh specific surface area (63.57m2· g1) and abundant mesopores, wassynthesized via hydrothermal method with Cetyltrimethylammoniumbromide (CTAB) as soft template. Pt nanoparticles were subsequentlyimmobilized onto the surface of hierarchical Co-Al LDH via the in-situreduction of PtCl26. The direct electrochemical behavior of the Pt/LDHmodified glassy carbon electrode was studied, and its electrocatalyticperformance for the oxygen evolution reaction (OER) was alsoinvestigated. It was found that hierarchical structure of the LDH and theexcellent conductivity of Pt nanoparicles impose a significant enhancement on the electrocatalytic activity for OER, indicating asynergistic effect between Co-Al LDH and Pt nanoparticles. It is expectedthat the obtained Pt (particle size range:0.5~1.5nm)/Co-Al LDHcomposite can serve as a new type of effective Co-based electrocatalystfor OER (η=412mV (current density=10mA· cm2)) in the alkalinefuel cells.