{"title":"Tailoring reactivity of small Ag/Pt bimetallic cluster for ORR: A comprehensive study using density functional theory approach","authors":"Sandeep Nigam , Chiranjib Majumder","doi":"10.1016/j.cattod.2024.115102","DOIUrl":null,"url":null,"abstract":"<div><div>Bimetallic clusters, as the name suggests, are known to act as bifunctional catalyst. Therefore, it is possible to tune the composition of the catalyst to achieve the best performance for a specific reaction. In the first part of this work, we explore the geometric and electronic structures of various Ag-Pt bimetallic clusters and find the right composition for ORR, one of the most sought-after reactions in the field of energy materials. We have considered Ag-Pt bimetallic clusters in both free and on Al<sub>2</sub>O<sub>3</sub>(0001) support. The results reveal that the equilibrium structures of the bimetallic Ag<sub>n</sub>Pt<sub>m</sub> (n+m ≤ 12 atoms) clusters are governed by a balance of competing interactions (<em>Pt-Pt vs Ag-Pt vs cluster-support interactions</em>). Whilst the isolated decamer cluster with 5:5 or 6:4 composition (Ag<sub>6</sub>Pt<sub>4</sub> and Ag<sub>5</sub>Pt<sub>5</sub>) shows atomically segregated structures, Ag rich clusters (Ag<sub>9</sub>Pt<sub>1–3</sub>) prefer to form core-shell pattern where Pt forms the core surrounded by Ag atoms. In general, these clusters adopt pseudo-planar structure on alumina support following the surface template. Analysis of the electronic structure shows that Al<sub>2</sub>O<sub>3</sub> surface induces significant broadening in the energy states of the bimetallic cluster, which in turn facilitates higher mixing between <em>d</em>-states of the Ag and Pt in the complex. Finally, the <em>d</em>-band centre descriptor model has been utilized to underscore the chemical reactivity of these bimetallic clusters. Remarkably, the Ag<sub>6</sub>Pt<sub>4</sub>@Al<sub>2</sub>O<sub>3</sub> cluster with <em>d</em>-band centre at −2.68 eV is found to be in “just right” zone for ORR. This is further corroborated by the reduction (∼ 25 %) in oxidation reaction enthalpy of the Ag<sub>6</sub>Pt<sub>4</sub>@Al<sub>2</sub>O<sub>3</sub> than standard Pt(111) catalytic surface.</div></div>","PeriodicalId":264,"journal":{"name":"Catalysis Today","volume":"445 ","pages":"Article 115102"},"PeriodicalIF":5.2000,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Catalysis Today","FirstCategoryId":"92","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0920586124005960","RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"CHEMISTRY, APPLIED","Score":null,"Total":0}
引用次数: 0
Abstract
Bimetallic clusters, as the name suggests, are known to act as bifunctional catalyst. Therefore, it is possible to tune the composition of the catalyst to achieve the best performance for a specific reaction. In the first part of this work, we explore the geometric and electronic structures of various Ag-Pt bimetallic clusters and find the right composition for ORR, one of the most sought-after reactions in the field of energy materials. We have considered Ag-Pt bimetallic clusters in both free and on Al2O3(0001) support. The results reveal that the equilibrium structures of the bimetallic AgnPtm (n+m ≤ 12 atoms) clusters are governed by a balance of competing interactions (Pt-Pt vs Ag-Pt vs cluster-support interactions). Whilst the isolated decamer cluster with 5:5 or 6:4 composition (Ag6Pt4 and Ag5Pt5) shows atomically segregated structures, Ag rich clusters (Ag9Pt1–3) prefer to form core-shell pattern where Pt forms the core surrounded by Ag atoms. In general, these clusters adopt pseudo-planar structure on alumina support following the surface template. Analysis of the electronic structure shows that Al2O3 surface induces significant broadening in the energy states of the bimetallic cluster, which in turn facilitates higher mixing between d-states of the Ag and Pt in the complex. Finally, the d-band centre descriptor model has been utilized to underscore the chemical reactivity of these bimetallic clusters. Remarkably, the Ag6Pt4@Al2O3 cluster with d-band centre at −2.68 eV is found to be in “just right” zone for ORR. This is further corroborated by the reduction (∼ 25 %) in oxidation reaction enthalpy of the Ag6Pt4@Al2O3 than standard Pt(111) catalytic surface.
期刊介绍:
Catalysis Today focuses on the rapid publication of original invited papers devoted to currently important topics in catalysis and related subjects. The journal only publishes special issues (Proposing a Catalysis Today Special Issue), each of which is supervised by Guest Editors who recruit individual papers and oversee the peer review process. Catalysis Today offers researchers in the field of catalysis in-depth overviews of topical issues.
Both fundamental and applied aspects of catalysis are covered. Subjects such as catalysis of immobilized organometallic and biocatalytic systems are welcome. Subjects related to catalysis such as experimental techniques, adsorption, process technology, synthesis, in situ characterization, computational, theoretical modeling, imaging and others are included if there is a clear relationship to catalysis.