Synthesis And Catalytic Performance Regulation Of CeO₂-supported Noble Metal Catalysts

CeO₂-based catalysts show excellent catalytic performance in REDOX reactions,which is attributed to the excellent storage and release capacity of cerium dioxide（CeO₂）,including CO oxidation,automobile exhaust,methane reforming,hydrogenation of CO₂,fuel cells and other fields.However,the activity of single component CeO₂ in catalytic reaction is limited.Loading precious metal on CeO₂ surface is one of the important strategies to improve the catalytic activity.By regulating the strong interaction between CeO₂ carrier and precious metal,the catalytic performance of composite materials can be greatly improved.In this paper,CeO₂ was used as the carrier,and the structural characteristics of its surface defects were used.CeO₂ noble metal composite catalytic materials activated by a variety of high efficiency small molecule were synthesized.The specific research contents are as follows:1.Pt-Pd dual-site single atom catalyst supported by CeO₂ was prepared by autoredox synthesis method combined with multi-step heat treatment.The existence of PtO-Pd diatomic pairs on CeO₂ surface was verified by XAFS results and DFT calculation.Due to the strong synergy between Pt and Pd atoms in the dual-site pair,the catalytic activity in the three-way catalytic reaction,especially in the elimination of NO,showed very excellent.Under the condition of 800℃,containing 15%water vapor,the catalytic activity almost didn’t decay for 12 hours.The synchronous improvement of low temperature cold-start performance and high-temperature stability performance was realized,which effectively solved the problem of unit activity decline caused by the formation of P1O4 structure in the three-way catalytic reaction of single atom catalyst.2.A mild and universal solid phase synthesis method was developed.Atomicallymixed nanoalloys（AuPt,AuPd,PtPd,AuPdPt）were prepared by anchoring multicomponent noble metal with the oxygen defect of CeO₂,and the feasibility of the synthesis route was proved from the perspective of system energy.Through theoretical calculation,atomic-scale dispersed NAs strengthened the interaction between different components,the electrons around platinum and gold was rearranged,and the d-band center of platinum atoms in the alloy was closer to the Fermi level,which therefore could be used as an efficient active center.With CeO₂ providing reactive oxygen species,the two composes worked together to completely catalyze CO oxidation at room temperature with a low metal load,effectively controlling the cost of catalytic materials.3.Using CeO₂ as solid solvent,the catalytic material of atomically-mixed highentropy alloy with CeO₂ as carrier was synthesized,and the specific formation mechanism of atomic high entropy alloy nanoparticles was elucidate by using various characterization methods and DFT results.By controlling the element composition of high entropy alloy,the selectivity of hydrogenation of CO₂ could be controlled effectively.Combined with DFT and Machine learning,a screening method was developed to automatically search the adsorption energy of different metal single atoms on different oxide surfaces,so as to predict the possibility of metal single atoms forming alloy particles on oxide surfaces.According to the adsorption energy of 33 kinds of metal single atom and 22 kinds of metal oxide support,378 kinds of single atom catalysts are selected to form nanoparticles on the oxide surface.In this paper,a variety of CeO₂-supported noble metal catalysts were synthesized.By using the strong synergistic effect between CeO₂ and noble metals,the problem of poor catalytic performance of single active component and weakly stability of noble metal was solved,and the comprehensive optimization of catalytic activity and selectivity of composite catalytic materials was realized.It provides scientific basis and technical support for the design and synthesis of new high-performance rare earth catalytic materials.