Ceria Hydrate Enhancing The Electrocatalytic Performance Of Noble Metal Nanocrystals

In recent years,the direct alcohol fuel cell has attracted extensivly attention because of the energy crisis and environment pollution.However,the exploration of highly active and stable electrocatalyst is still a challenge for the direct alcohol fuel cell.At present,the precious platinum catalyst is the first choice for direct alcohol fuel cell.However,on the one hand,the catalyst was easily poisoned by the intermediate products such as carbon monoxide during alcohol electrooxidation,contributing to the recession of catalysis performance.On the other hand,the high price and low storage of Pt has hinded the wide application of the direct alcohol fuel cell.This thesis aim to exploit the electrocatalyst with low price,high activity and stability for alcohol fuel cell.We have systematically investigated the promising effect of precious metal by the introduction of CeO₂·x H₂O nanoparticles for alcohol electrooxidation and oxygen reduction reaction.Furthermore,the controlled synthesis of Pd alloy catalysts and the relation between their structure and electrocatalysis performance have been studied.The major research topics and conclusions concluded are as follows.?1?The small CeO₂·xH₂O nanoparticles with plenty of surface OH group have been prepared by a tert-butylamine assisted solvothermal method.and have been mixed with Pt/CNTs?carbon nanotube?catalyst by a facile ultrasonically method.The mass activity of Pt/CNTs+CeO₂·xH₂O catalyst is 4 times higher than that of Pt/CNTs for methanol electrooxidation reaction.Besides,the promotion effect of CeO₂·xH₂O is superior to the CeO₂ for alcohol electrooxidation including methanol,EG and glycerol.Moreover,the electrocatalytic activity and stability of commercial Pd/C,Pt/C and PtRu/C catalyst has also been improved by the introduction of CeO₂·xH₂O nanoparticles.?2?The Pd/CeO₂·xH₂O nanocatalyst have been prepared by NaBH₄reduction method assisted by L-lysine.The mass activity of ethanol electrooxidation of Pd/CeO₂·xH₂O catalyst is 4 times and 2 times than that of commercial Pd/C and Pd/CeO₂ catalysts,respectively.The half-potential of the as-prepared Pd/CeO₂·xH₂O catalyst is 0.875V,positively shifted by 25mV and18mV compared to commercial Pd/C and Pd/CeO₂ catalyst.Hence,the Pd/CeO₂·xH₂O catalyst has turned into the highly efficient bifunctional catalyst for oxygen reduction reaction and ethanol electrooxidation reaction.?3?The N-doping of CNTs and preparation of Pd_2.6Ni alloy nanoparticles has been realized by one-step solvothermal method in which DMF has been used as the solvent and reducing agents.The half-potential of the PdNi/CNT catalyst is0.875V,superior to the commercial Pt/C catalyst.Moreover,the preparation method has also been used to prepare the highly efficient Pd₃Co/CNTs and Pd₃CoNi/CNTs catalysts for oxygen reduction reaction.