Manganese Oxide Nanowire Arrays Applied At Electrochemistry

The boom population triggers to the increasing demand of energy,and the problem of energy shortage has become more and more serious.Meanwhile using non-renewable energy such as oil and coal will cause environmental pollution and emission of greenhouse gases.The exhaustion of energy source is the main block of the society's sustainable development.Therefore,the key solution of the problem is how to discover a renewable energy.Hydrogen is considered as the best alternative energy after the exhaustion of fossil energy.The electrolysis of water for hydrogen production is also regarded as the most mature and efficient technology at present time.However,the major obstruction that triggers to the energy-consumption problem is the higher overpotential.Therefore,the best way to tackle the problem is to find out the better anodic catalysts.As a green and environmental generating set,fuel cells are attracted a wide spread attention because of high energy efficiency.Nevertheless,the larger consumption of noble metal is the main problem of the fuel cell anodic catalyst research.So the best approach to solve the problem is discovering a new supporter to improve the efficiency of noble metal use.Electrochemical sensor has attracted lots of attentions in the world due to his abundant applications in food industry,clinical,environmental treatments and so on.Howereve,the protein-based electrochemical sensors have their own disadvantages,such as high cost of enzymes,instability and complicated immobilization procedures.Furthermore,the activity of the proteins can be easily affected by around microenvironment,containing temperature,p H,and toxic substances.Therefore,the development of enzyme-free sensors with low detectionlimit and wide response range has become a trend.Based upon the conditions described above,in this paper,manganese oxides with different morphology have been directly grown vertically on Ti foil by a simple electrochemical method without any template,which were used to study the anode oxygen evolution and cathodic oxygen reduction and electrochemical sensors performance.The results are as follows:1.Simply by the electrochemical method,at the reaction temperature of 40,70 and 901.Simply by the electrochemical method,at the reaction temperature of 40,70 and 90 oC,the MnO_x with cotton wool structure,MnO_x nanowire arrays and MnO_x nanosheet arrays were obtained on Ti foil.The weight percent of Mn₃O₄ is 77.8%using the RIR method from XRD patterns,so the weight percent of ?-MnO₂ is22.2%.2.The manganese oxides with different morphology show high activity and good stability for OER.The value of j0.7V on the MnO_x nanowire arrays is 2.4 and 1.7times as bigger as that on the MnO_x cotton wool structure and MnO_x nanosheet arrays.3.The cyclic voltammograms?CVs?of the manganese oxides with different morphology measured in 0.01 mol/L phosphate buffer?p H=7.0?shows that MnO_x nanowire arrays prepared at 70 o C show higher electro catalytic activity as compared with MnO_x nanosheet arrays and MnO_x cotton woolstructure.Using the current analysis to analysis the MnO_x nanowire arrays electrochemical activity in electrochemical sensors which containing H2O₂ with different concentrations?0.0to 1.4 mmol/L?in the range of 0 to 2 V at a scan rate of 0.02 V/s.The current sensitivity increases with increasing H2O₂ concentration,which may be applied as the quantitative analysis.From amperometry analysis manganese nanowire arrays electrode shows linear responses from 0 to 1.4 mmol/L H2O₂ with a correlation coefficient of 0.998.