Study On The Decomposition Of Hydrogen Peroxide By A New Type Of Porous Anodic Alumina Template Supported By Palladium Catalyst

Typical and traditional porous palladium based on porous substrate was used to have such large diameters that it is of great importance to investigate the nano-porous Pd which is loaded on the nano-pore substates.In this thesis the anodic aluminum oxide(AAO)templates were used to grow Pd and fabricate the nano-porous Pd materials indeed.The decomposition of hydrogen peroxide(H2O2)was investigated on the surface of Pd/AAO and explored catalytic performance.AAO were formed in 0.3 M oxalic acid solution(H2C2O4)and 20 wt%sulphuric acid(H2SO4)respectively.The Pd/AAO materials were fabricated as catalytic materials by different parameters.The microstructure and electrochemical performance of the investigated samples were examined with field emission scaning electron microscope(FE-SEM)and electrochemical impedance spectroscopy(EIS).The catalytic efficiency of catalysts was investigated by using the bubble formation in the decomposition process of H2O2.During the experiment,the parameter of AAO prepared under different parameters such as voltage,temperature and oxidation time were analyzed by Image J.The AAO templates with nanopores of approximately 200 nm in diameter in H2C2O4 and 20 nm in H2SO4 were fabricated and selected.The thickness are 1 ?m and 13 ?m respectively.The influence of the deposition process on the effect of Pd@AAO deposition was compared by means of AC impedance spectroscopy.This paper studies the process from two aspects of template modification and electrochemical deposition control parameters.The results show that the amount of Nano-palladium particles deposited in the channel of the two templates is less,and only shows the peak value reflecting the structural characteristics of AAO template.In the AAO which is fabricated in H2C2O4,the optimal reaming time was 2?3 min,when the peak phase Angle is 67°;In the AAO which was fabricated in H2SO4,the phase angle peak value after preanodic oxidation is more obvious due to the improvement of formwork order.Electrochemical deposition parameters were controled as deposition time,current waveform and voltage.Time of 30 s in the H2C2O4 template and 10 min in the H2SO4 template are optimal time in the process of alternating current deposition.In addition,the longer the DC deposition time in H2C2O4 template,the more response of the barrier layer when the deposition voltage in H2SO4 template is-0.1 V.EDX shows that Pd is mainly distributed in the upper part of the pore channel and the collected content is up to 0.9wt%and 0.7wt%,while the content in the middle and bottom of the pore channel is 0.2wt%.The images of the bubbles generated by the decomposition of H2O2 on the catalyst surface were collected with an Metalloscope and show that the bubble increasing state depends on the deposition state of Nano-palladium particles,and the growth and decrease rules conform to the shape of parabola.The bubble disappearance time in different catalysts is different.At 10 min of reaction,the largest bubbles are up to 130 ?.m in diameter,while the smallest ones are close to 0 ?m at 20 s.On the same catalyst,some of the bubbles will have s-type fluctuation when growing.A few bubble appears slowly but grows quickly,reaching 140 ?m after 10 min reaction,which is related to the diffusion of H2O2 in the channel.In addition,the deactivation test of the catalyst found that the number of bubbles decreases significantly and the rate of bubble growth rate slows down.