Preparation Of Graphene Containing Selenide And Its Application In Ethanol Oxidation

With the rapid development of human society,people are facing acute shortage-of-resources problem,for the simple reason that traditional fossil energy has been consumed in the last hundred years.Without energy,society cannot develop.However,in the current society,the development in China depends mostly on traditional energy.Therefore,it's so urgent that China needs to develop additional renewable green energy as soon as possible.The direct fuel cell is one of the most suitable resources,which is also a hot topic in electrochemistry at present.A direct ethanol fuel cell converts chemical energy directly into electrical energy through the oxidation of ethanol.Such kind of process isn't restricted to Carnot Cycle so it can enhance the ethanol fuel cell energy efficiency.As for the resources of ethanol fuel,it can be easily derived from a wide range of sources such as fermentation of agricultural byproducts.Thus,this kind of fuel can be safer and more convenient to transport while being storaged.Meanwhile,it makes more energy to ensure the power output of fuel cells.However,the anodic ethanol reaction of direct ethanol fuel cells is so complicated that a single transition metal material is hard to promote the reaction.And for now,people mostly use platinum-based catalyst as an anodic catalyst.At the same time,there are lots of intermediates in the process of electrocatalytic oxidation.Most of these reaction intermediates are toxic and can poison the noble metal catalysts,which reduce the electrochemical activity and stability of noble metal catalysts.Therefore,direct ethanol fuel cell anodic catalyst researchers are focussing mainly on how to reduce the content of noble metal in the catalyst and to improve the electrochemical activity and anti-poisoning power.All in all,this paper uses composite graphite carbon materials as carriers to carry the metal selenides and noble metal palladium.As the results,the ability of anti-poisoning and the electrocatalytic activity can be well improved through their synergistic effect.The contents of the study are as follows:?1?Prepared by modified Hümmers method and chemical reduction method,reduced graphene was used as the base as well as carbon nanotubes.After that,the hydrothermal method and chemical reduction method were used to load Co_0.85Se and Pd onto the carbon material respectively,and eventually compose the product Pd-Co_0.85Se/RGO&CNT.It shows good catalytic activity in the electrocatalytic test of ethanol electrooxidation that it has a peak potential of-0.45 V,is less than Pd/RGO&CNT by 0.105 V.After working in constant voltage-0.3 V for 30 minutes,the residual current density remains 7.2 mA/cm²,which is 6 times of Pd/rGO&CNT.What' more,the results of XPS indicate that Co_0.85Se could effectively adjust the electronic structure of Pd,thus improving the activity of the catalyst.?2?Pd-Ni_0.85Se/RGO&CNT catalysts were prepared on the surface of carbon materials by the method of hydrothermal synthesis and NaBH₄ reduction respectively using reduced graphene and carbon nanotubes as the base.And applying the catalyst to the electrocatalytic oxidation of ethanol.The results show that the Pd-Ni_0.85Se?1:5?/rGO&CNT catalyst has lower peak potential and higher peak current density than Pd/rGO&CNT.After working at constant voltage-0.3 V for 30 minutes,the residual current density of Pd-Ni_0.85Se?1:5?/rGO&CNT catalyst is 3.9 times as high as that of Pd/RGO&CNT.?3?Ni_0.75Fe_0.25-LDH and Ni_0.75Zn_0.25-LDH were prepared from nickel nitrate,ferric nitrate and zinc nitrate by a two-step synthesis method.After that,the hydrothermal synthesis method was used to load Ni_0.75Fe_0.25Se₂ and Ni_0.75Zn_0.25Se₂ onto the graphene carbon material respectively.Finally using the reduction method to synththesize Pd-Ni_0.75Fe_0.25Se₂/RGO and Pd-Ni_0.75Zn_0.25Se₂/RGO catalyst.According to the anodic ethanol oxidation test,these two catalysts both show better catalytic activity and electrochemical stability than Pd/RGO.All in all,this study effectively improves the catalytic activity of Pd-based catalysts for ethanol oxidation.And diselenide is proved that it has a good perspective application in this study.