以第一原理計算研究氧氣還原反應在鉑合金和鈷合金表面的活性和穩定度的趨勢

The Trends of Activity and Stability on Pt and Co-based Alloys for Oxygen Reduction Reaction by First Principles Calculation

周宗甫(Chou Tsung-Fu)

指導教授 ： 王禎翰

國立臺灣師範大學/理學院/化學系/碩士(2017年)

https://doi.org/10.6345/NTNU202202895

摘要

本論文主要以理論計算研究鉑合金及鈷合金的氧氣還原反應機制，透過第一原理計算氧氣還原反應(Oxygen Reduction Reaction)之所有中間吸附物，O*、O2*、OH*、 OOH*、H2O2*、 H2O*和H*的吸附能以及七種反應路徑，包含三個O-O斷鍵步驟和四個O-H生成反應步驟的反應能量以及活化能，並藉由計算乾淨表面以及表面吸附含氧中間產物(ORR的關鍵中間產物)的分離能量(segregation energy)，比較所設計的表面合金和其ORR反應上的穩定性。
在研究鉑合金的部分，PtSn擁有比Pt更良好的活性，相較於其他PtM合金(M= Ag, Au, Co, Cu, Pd)擁有較好的穩定性，PtSn在ORR反應上，由於其較易使吸附含氧中間產物(oxygen-containing species, OCS)吸附於表面上生成穩定產物，故可以有效率提升其ORR活性以及穩定性。
對於鈷合金表面氧氣還原反應研究，加入少量白金在鈷金屬中，可以有效改善ORR活性，此外，如果加入第三種元素金做為取代，則可以更進一步改善CoPt合金的穩定性。

關鍵字

氧氣還原反應 ； 密度泛函理論 ； 鉑合金 ； 鈷合金 ； 第一原理

並列摘要

In this thesis, we computationally study oxygen reduction reaction (ORR) on Pt-based and Co-based alloys. The adsorption energies for all the possible adspecies, O*, O2*, OH*, OOH*, H2O2*, H2O* and H* and reaction energy/activation barriers for all the elementary steps, including 3 O-O cleavage and 4 O-H association steps were thoroughly examined by first-principles calculation. The segregation energy for clean and oxygen-containing species (OCS), key intermediates in ORR, adsorbed alloys were computed to model the as-prepared alloys and investigate their stability during ORR operation. In the study of Pt-based alloys, PtSn shows better activity than clean Pt catalysts and its stability is better than other PtM alloys (M = Ag, Au, Co, Cu, Pd). Its better ORR activity and stability are attributable to the abundant OCS formation on PtSn. In the study of Co-based alloys, adding small amount of Pt in Co can show improved ORR activity. Also, introducing the third element of Au in the subsurface of CoPt alloy can further enhance the stability.

並列關鍵字

Oxygen Reduction Reaction ； density functional theory calculations ； Pt-based alloy ； Co-based alloy ； First principle

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