| Carbon monoxide(CO)is a combustible and toxic chemical compound,which will threaten the health of human and environment.The incomplete combustion of fossil fuels and the incineration of domestic garbage are the main cause of CO emissions,inducing serious environmental problem.Supported gold catalysts exhibit good catalytic performance in CO oxidation with a low onset temperature and have become a major research hotspot due to the controllability of their chemical properties.However,owing to the technical limitations,the design of catalysts by chemists are still relying on experiment attempt.Therefore,the rational design of supported gold catalysts with high stability and activity is still one of the most challenging topics.The key point is the in-depth understanding of the structure-activity relationship of the catalysts.Therefore,this research focused on the structure-activity relationship of Au/CeO2 and its application in CO oxidation.This research used biomolecules to regulate the strength of the interaction between Au and CeO2 through theoretical calculations,and further applied them in experiments.The main works are as follows:Firstly,we focused on building catalyst model with gold clusters supported on a periodic CeO2 support and investigated the coordination of biomolecule hemin and ferrous phthalocyanine(FePc)through theoretical calculations.Biomolecules regulates the electronic structure of the catalyst,the interaction of the metal support and the catalytic behavior of Au/CeO2.Studies have shown that:(1)hemin and FePc can enhance the interaction between Au and CeO2,which not only stabilized the gold nanoparticles on the carrier well,but also made the center of the d-band of Au move deeper,thereby adjusting the electronic structure of gold;(2)both hemin and FePc can weaken the negative feedback effect of Au on CO backfilling electrons,thereby weakening the adsorption strength of CO on Au,which is beneficial to the reaction according to the Langmuir-Hinshelwood mechanism;(3)Oxygen vacancy formation energy on the CeO2 surface reduced.The calculation results show that the presence of hemin and FePc can reduce the oxygen vacancy formation energy of the carrier,which is beneficial to the CO oxidation reaction through the Mars-van Krevelen mechanism.In addition,FePc has the ability to compensate electrons which will enhance the adsorption of O2 on the Au surface,thereby increasing the activity of the catalyst to catalyze CO oxidation.Secondly,based on theoretical calculation results,hemin-Au/CeO2 and FePc-Au/CeO2 biomimetic catalysts were designed and prepared.XRD,BET,SEM,TEM,FTIR,Raman,ICP-OES and XPS were used to prove the existence of biomolecules in hemin-Au/CeO2 and FePc-Au/CeO2,and compare the effects of biomolecules on gold nanoparticles size,valence state and carrier oxygen vacancy generation.The catalytic performance evaluation results showed that the prepared biomimetic catalysts had good CO oxidation reactivity and stability.XPS results proved that the strong electronic interaction between biomolecules,Au and CeO2 promotes the adsorption of CO molecules and made them further activated.In situ Infrared research results show that the amount of CO adsorption on hemin-Au/CeO2 is about 8 times that of Au/CeO2.This research will provide references for other catalytically active biomolecules to be used as heterogeneous catalysts,and provide new ideas for the CO oxidation. |
