Preparation And Electrooxidation Performance Of Ethanol Of Palladium Based Catalysts With High Stability

Direct ethanol fuel cells(DEFCs)directly convert the chemical energy of small organic molecules into electrical energy.They have the advantages of high power density,high energy conversion efficiency and environmental friendliness,and have good commercial application prospects.However,the poor long-term stability of DEFCs anode catalysts is one of the important factors hindering the commercial application.The main reason is that toxic intermediates(such as CO)generated during the ethanol oxidation process are easily adsorbed on the active sites,resulting in the catalyst being poisoned and deactivated in a short period of time.The introduction of co-catalytic metals(Sn,Ag,etc.)to form bimetallic mechanism is conducive to the formation of OHads to promote the oxidation and removal of toxic intermediate COads.In addition,the introduction of a support to form a catalyst-support interaction can not only prevent the active sites from being covered by the aggregation of metal nanoparticles,but also facilitate the rapid removal of toxic substances.The π-π effect between the layers of graphene oxide(GO)supports can easily induce self-stacking.The intercalation can effectively shield the interlayer π-π interaction,promote the uniform distribution and rapid mass transfer of metal nanoparticles,and effectively improve the long-term stability of the catalyst.This project explores the influence of the synergistic effect of GO support and metal through different intercalation methods and the coupling effect of catalytic metal on the stability of the catalyst.The main work is as follows:1)Using NaBH4 as reducing agent and PdCl2 and SnCl2 as metal precursors,PdSn/C@FrGO catalysts with high long-term stability were successfully prepared by simple impregnation reduction method.The introduction of the composite support C@FrGO makes the PdSn nanoparticles evenly distributed and the interlayer gap formed by carbon black intercalation is conducive to the rapid removal of toxic intermediate species.The bimetallic mechanism of Pd and Sn promotes electron transfer,so that the catalyst has good catalytic activity and strong resistance to CO poisoning.After the stability test of Pd1Sn1.0/C@FrGO after 5000 s,the residual current density value still retains 686 mA mgPd-1,which is 4.2 times of Pd/C(JM).2)Using dodecyldimethylammonium chloride(DODAC)as the structure directing agent,H2PdCl4 and AgNO3 as the metal precursors,the mPdAg@FrGO catalyst with uniformly distributed alloy nanospheres was prepared by the co-reduction method.The PdAg microporous alloy nanospheres can effectively separate the GO sheets and slow down the stacking.Its porous and loose structure facilitates the timely entry and separation of reactants and products.After 20000 s stability test,the residual current density value of mPd1Ag1@FrGO is 659 mA mgPd-1,which is 20 times of Pd/C(JM).After 4 cycles of 20000 s i-t test,its current density only dropped by 18.2%.In addition,the catalyst mPd1Ag1@FrGO has good regeneration ability.After six cycles of regeneration,the residual current density value is 878.1 mA mgPd-1.