Pub Date : 2022-02-17DOI: 10.26434/chemrxiv-2022-v76pk
Chinmay Dahale, Sriram Goverapet Srinivasan, S. Mishra, S. Maiti, B. Rai
High entropy alloys (HEAs) are emerging as a novel class of superior catalysts for diverse chemical conversions. The activity of a catalyst is intimately related to the composition and atomic structure at its surface. In this work, we used embedded atom (EAM) potential based Monte Carlo – Molecular Dynamics simulations to study surface segregation in the equimolar AuAgCuPdPt HEA, that was recently shown to be an efficient catalyst for CO2 electrochemical reduction. Firstly, EAM potentials were extensively validated against experimental segregation data for several different binary and ternary compositions. Subsequently, simulations on the HEA were carried out for four different surface orientations, spherical and cubical nanoparticles, to obtain detailed structural and concentration profiles normal to the surface. In all cases, Ag atoms were found to preferentially segregate to the surface while the subsurface layer mainly consisted of Au atoms. No Pt atoms were found on the surface layer for all systems. A detailed analysis neighborhood of each surface site revealed that the atoms formed a finite number of chemically unique clusters. The percentage of chemically unique sites were larger for elements with lower concentration at the surface. Together with the physical diversity surrounding each site, the enrichment of one or more element(s) at the surface also increased its number of unique catalytically active sites. Results from our work suggest that HEAs are prone to surface segregation and such effects must be taken into consideration while modeling the surface chemistry of these materials.
{"title":"Surface Segregation in AgAuCuPdPt High Entropy Alloy: Insights From Molecular Simulations","authors":"Chinmay Dahale, Sriram Goverapet Srinivasan, S. Mishra, S. Maiti, B. Rai","doi":"10.26434/chemrxiv-2022-v76pk","DOIUrl":"https://doi.org/10.26434/chemrxiv-2022-v76pk","url":null,"abstract":"High entropy alloys (HEAs) are emerging as a novel class of superior catalysts for diverse chemical conversions. The activity of a catalyst is intimately related to the composition and atomic structure at its surface. In this work, we used embedded atom (EAM) potential based Monte Carlo – Molecular Dynamics simulations to study surface segregation in the equimolar AuAgCuPdPt HEA, that was recently shown to be an efficient catalyst for CO2 electrochemical reduction. Firstly, EAM potentials were extensively validated against experimental segregation data for several different binary and ternary compositions. Subsequently, simulations on the HEA were carried out for four different surface orientations, spherical and cubical nanoparticles, to obtain detailed structural and concentration profiles normal to the surface. In all cases, Ag atoms were found to preferentially segregate to the surface while the subsurface layer mainly consisted of Au atoms. No Pt atoms were found on the surface layer for all systems. A detailed analysis neighborhood of each surface site revealed that the atoms formed a finite number of chemically unique clusters. The percentage of chemically unique sites were larger for elements with lower concentration at the surface. Together with the physical diversity surrounding each site, the enrichment of one or more element(s) at the surface also increased its number of unique catalytically active sites. Results from our work suggest that HEAs are prone to surface segregation and such effects must be taken into consideration while modeling the surface chemistry of these materials.","PeriodicalId":429331,"journal":{"name":"Molecular Systems Design & Engineering","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123834635","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Post-synthetic modification (PSM) is a powerful tool for introducing complex functionalities into metal-organic frameworks (MOFs). Aldehyde-tagged MOFs are particularly appealing platforms for covalent PSM due to the high reactivity of...
{"title":"Reducing defects density in UiO-68-CHO is a key for its efficient and reliable post-synthetic modification","authors":"Marcin Wiszniewski, M. Chmielewski","doi":"10.1039/d3me00071k","DOIUrl":"https://doi.org/10.1039/d3me00071k","url":null,"abstract":"Post-synthetic modification (PSM) is a powerful tool for introducing complex functionalities into metal-organic frameworks (MOFs). Aldehyde-tagged MOFs are particularly appealing platforms for covalent PSM due to the high reactivity of...","PeriodicalId":429331,"journal":{"name":"Molecular Systems Design & Engineering","volume":"74 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"119848725","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xiao-Sa Zhang, Jialin Cui, Yu Liu, Wenze Li, Yan Liu, Hong Xiang, Jian Luan
Coordination polymers (CPs) are a scientifically compelling and evolving class of highly crystalline materials. Owing to their controllable structures and morphologies, CPs can be used as a type of uniformly...
{"title":"Anion influence on synthesis of Cu(I)-based coordination polymers along with a series of derived materials for the selective photocatalysis properties","authors":"Xiao-Sa Zhang, Jialin Cui, Yu Liu, Wenze Li, Yan Liu, Hong Xiang, Jian Luan","doi":"10.1039/d3me00047h","DOIUrl":"https://doi.org/10.1039/d3me00047h","url":null,"abstract":"Coordination polymers (CPs) are a scientifically compelling and evolving class of highly crystalline materials. Owing to their controllable structures and morphologies, CPs can be used as a type of uniformly...","PeriodicalId":429331,"journal":{"name":"Molecular Systems Design & Engineering","volume":"103 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"118615245","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The growing demand for solute selective separations necessitates the development of materials and processes capable of separating species of similar charge and size. Polymeric ion pumps, which are composite membranes...
{"title":"Isolating the effects of gate layer permeability and sorbent density on the performance of solute-selective polymeric ion pumps","authors":"J. A. Ouimet, A. Dowling, W. Phillip","doi":"10.1039/d3me00073g","DOIUrl":"https://doi.org/10.1039/d3me00073g","url":null,"abstract":"The growing demand for solute selective separations necessitates the development of materials and processes capable of separating species of similar charge and size. Polymeric ion pumps, which are composite membranes...","PeriodicalId":429331,"journal":{"name":"Molecular Systems Design & Engineering","volume":"188 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"118942296","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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