Pub Date : 2024-10-24DOI: 10.1016/j.susc.2024.122634
Johanna Reich , Sebastian Kaiser , Alexander Bourgund , Matthias Krinninger , Ueli Heiz , Friedrich Esch , Barbara A.J. Lechner
Surfaces and interfaces of functional nanoscale materials are typically highly dynamic when employed at elevated temperatures. Both, lateral surface and vertical bulk exchange diffusion processes set in, which can be relevant for applications such as heterogeneous catalysis. Time-resolved scanning tunneling microscopy (STM) is being pushed to ever faster measurement modes to follow such dynamic phenomena in situ. Here, we present FastSTM movies monitoring a range of atomic-scale dynamics of a prototypical reducible oxide catalyst support, Fe3O4(001), at elevated temperatures. Antiphase domain boundaries between two domains of the reconstructed surface exhibit local mobility from around 350 K, while Fe-rich point defects, in a stable equilibrium with the bulk, appear to diffuse in a peculiar zigzag pattern above 500 K. Finally, exploiting the diffusivity of Fe interstitials, we follow the propagation of step edges in the topmost atomic layer of the Fe3O4(001) surface in an oxygen atmosphere.
功能纳米材料的表面和界面在高温条件下通常具有很强的动态性。横向表面和纵向块体交换扩散过程都会发生，这可能与异相催化等应用有关。时间分辨扫描隧道显微镜（STM）正被推向更快的测量模式，以现场跟踪此类动态现象。在这里，我们展示了在高温下监测原型可还原氧化物催化剂载体 Fe3O4(001) 的一系列原子尺度动态的 FastSTM 电影。重构表面的两个畴之间的反相畴边界从 350 K 左右开始表现出局部流动性，而与块体处于稳定平衡状态的富铁点缺陷则在 500 K 以上以奇特的之字形模式扩散。
{"title":"Exploring the atomic-scale dynamics of Fe3O4(001) at catalytically relevant temperatures using FastSTM","authors":"Johanna Reich , Sebastian Kaiser , Alexander Bourgund , Matthias Krinninger , Ueli Heiz , Friedrich Esch , Barbara A.J. Lechner","doi":"10.1016/j.susc.2024.122634","DOIUrl":"10.1016/j.susc.2024.122634","url":null,"abstract":"<div><div>Surfaces and interfaces of functional nanoscale materials are typically highly dynamic when employed at elevated temperatures. Both, lateral surface and vertical bulk exchange diffusion processes set in, which can be relevant for applications such as heterogeneous catalysis. Time-resolved scanning tunneling microscopy (STM) is being pushed to ever faster measurement modes to follow such dynamic phenomena in situ. Here, we present FastSTM movies monitoring a range of atomic-scale dynamics of a prototypical reducible oxide catalyst support, Fe<sub>3</sub>O<sub>4</sub>(001), at elevated temperatures. Antiphase domain boundaries between two domains of the reconstructed surface exhibit local mobility from around 350 K, while Fe-rich point defects, in a stable equilibrium with the bulk, appear to diffuse in a peculiar zigzag pattern above 500 K. Finally, exploiting the diffusivity of Fe interstitials, we follow the propagation of step edges in the topmost atomic layer of the Fe<sub>3</sub>O<sub>4</sub>(001) surface in an oxygen atmosphere.</div></div>","PeriodicalId":22100,"journal":{"name":"Surface Science","volume":"752 ","pages":"Article 122634"},"PeriodicalIF":2.1,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142592996","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-22DOI: 10.1016/j.susc.2024.122632
Jinfeng Xu , Chen Liu , Yuxuan Guo , Guikai Zhang , Kun Liu , Haijie Qian , Kaiqi Nie , Zhenyu Wang , Jiaou Wang
Cu2Si, a single-layer two-dimensional material with a honeycomb structure, has been proposed to have Dirac nodal line fermions. In this study, the synchrotron radiation X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy, and angle-resolved photoemission spectroscopy (SR-XPS, SR-UPS, and SR-ARPES) techniques were used to investigate the dynamic process of in situ deposition of single-layer Cu2Si on a Cu(111) crystal surface via molecular beam epitaxy (MBE). Cu2Si existed as a monolayer (ML) alloy, and there were competing mechanisms of distinct chemical states of silicon in different growth periods, according to a detailed examination of the experimental SR-XPS and SR-UPS spectra. Additionally, a weak interaction between the Cu2Si ML and Cu(111) was demonstrated via SR-ARPES and first-principles computations. The unique electronic structure of the Cu2Si ML was not destroyed by either this weak interaction or the disordered silicon produced on the surface during the growth process. The study of the Cu2Si growth kinetics provides a guarantee and a basis for the future exploration of the exotic properties of Cu2Si.
Cu2Si 是一种具有蜂巢结构的单层二维材料，被认为具有狄拉克结线费米子。本研究采用同步辐射 X 射线光电子能谱、紫外光电子能谱和角分辨光发射光谱（SR-XPS、SR-UPS 和 SR-ARPES）技术，研究了通过分子束外延（MBE）在铜（111）晶体表面原位沉积单层 Cu2Si 的动态过程。根据对 SR-XPS 和 SR-UPS 实验光谱的详细研究，Cu2Si 以单层 (ML) 合金的形式存在，并且在不同的生长时期存在硅的不同化学状态的竞争机制。此外，通过 SR-ARPES 和第一原理计算，证明了 Cu2Si ML 与 Cu(111) 之间存在微弱的相互作用。Cu2Si ML 的独特电子结构既没有被这种弱相互作用破坏，也没有被生长过程中表面产生的无序硅破坏。对 Cu2Si 生长动力学的研究为今后探索 Cu2Si 的奇异特性提供了保证和基础。
{"title":"Growth and electronic structure of the nodal line semimetal in monolayer Cu2Si on Cu(111)","authors":"Jinfeng Xu , Chen Liu , Yuxuan Guo , Guikai Zhang , Kun Liu , Haijie Qian , Kaiqi Nie , Zhenyu Wang , Jiaou Wang","doi":"10.1016/j.susc.2024.122632","DOIUrl":"10.1016/j.susc.2024.122632","url":null,"abstract":"<div><div>Cu<sub>2</sub>Si, a single-layer two-dimensional material with a honeycomb structure, has been proposed to have Dirac nodal line fermions. In this study, the synchrotron radiation X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy, and angle-resolved photoemission spectroscopy (SR-XPS, SR-UPS, and SR-ARPES) techniques were used to investigate the dynamic process of in situ deposition of single-layer Cu<sub>2</sub>Si on a Cu(111) crystal surface via molecular beam epitaxy (MBE). Cu<sub>2</sub>Si existed as a monolayer (ML) alloy, and there were competing mechanisms of distinct chemical states of silicon in different growth periods, according to a detailed examination of the experimental SR-XPS and SR-UPS spectra. Additionally, a weak interaction between the Cu<sub>2</sub>Si ML and Cu(111) was demonstrated via SR-ARPES and first-principles computations. The unique electronic structure of the Cu<sub>2</sub>Si ML was not destroyed by either this weak interaction or the disordered silicon produced on the surface during the growth process. The study of the Cu<sub>2</sub>Si growth kinetics provides a guarantee and a basis for the future exploration of the exotic properties of Cu<sub>2</sub>Si.</div></div>","PeriodicalId":22100,"journal":{"name":"Surface Science","volume":"752 ","pages":"Article 122632"},"PeriodicalIF":2.1,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142553519","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-18DOI: 10.1016/j.susc.2024.122630
K. Idczak , S. Owczarek , A. Trembułowicz , B. Rusin
This work investigates the temperature and time as key parameters for graphene formation on the silicon carbide surface during the high thermal decomposition process. Measurements were performed using various experimental techniques under ultra-high vacuum conditions. The graphitisation process was divided into various stages, after which the surface chemical composition and atomic structures were analysed in detail. It has been shown that despite the known theory of graphitisation mechanism and initial condition for occurrence of this process, the application of different temperatures and heating times affect the quality and quantity of formed graphene layers. Applying a temperature too low or annealing the sample for a too short time led to an inefficient silicon sublimation process. On the other hand, too high temperature during flashing modifies the visibility of surface structures, which may be crucial for other investigations and potential applications of such systems.
{"title":"Step-by-step silicon carbide graphitisation process study in terms of time and temperature parameters","authors":"K. Idczak , S. Owczarek , A. Trembułowicz , B. Rusin","doi":"10.1016/j.susc.2024.122630","DOIUrl":"10.1016/j.susc.2024.122630","url":null,"abstract":"<div><div>This work investigates the temperature and time as key parameters for graphene formation on the silicon carbide surface during the high thermal decomposition process. Measurements were performed using various experimental techniques under ultra-high vacuum conditions. The graphitisation process was divided into various stages, after which the surface chemical composition and atomic structures were analysed in detail. It has been shown that despite the known theory of graphitisation mechanism and initial condition for occurrence of this process, the application of different temperatures and heating times affect the quality and quantity of formed graphene layers. Applying a temperature too low or annealing the sample for a too short time led to an inefficient silicon sublimation process. On the other hand, too high temperature during flashing modifies the visibility of surface structures, which may be crucial for other investigations and potential applications of such systems.</div></div>","PeriodicalId":22100,"journal":{"name":"Surface Science","volume":"751 ","pages":"Article 122630"},"PeriodicalIF":2.1,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142532114","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-17DOI: 10.1016/j.susc.2024.122627
Sarah M. Ortiz, Steven Baldelli
Nonlinear spectroscopy has been a valuable technique for probing surfaces for many decades. Still, in the recent past, nonlinear spectroscopy has become a useful tool for imaging monolayers on surfaces. This technique of nonlinear microscopy, more specifically sum frequency generation microscopy, provides both spectral and spatial information with varying resolution, allowing for the surface activity to be monitored and imaged. The following paper highlights the history, theory, and range of experimental advantages sum frequency generation imaging provides, focusing on specific experiments that put those advantages on display.
{"title":"Imaging on surfaces with vibrational sum frequency generation microscopy","authors":"Sarah M. Ortiz, Steven Baldelli","doi":"10.1016/j.susc.2024.122627","DOIUrl":"10.1016/j.susc.2024.122627","url":null,"abstract":"<div><div>Nonlinear spectroscopy has been a valuable technique for probing surfaces for many decades. Still, in the recent past, nonlinear spectroscopy has become a useful tool for imaging monolayers on surfaces. This technique of nonlinear microscopy, more specifically sum frequency generation microscopy, provides both spectral and spatial information with varying resolution, allowing for the surface activity to be monitored and imaged. The following paper highlights the history, theory, and range of experimental advantages sum frequency generation imaging provides, focusing on specific experiments that put those advantages on display.</div></div>","PeriodicalId":22100,"journal":{"name":"Surface Science","volume":"751 ","pages":"Article 122627"},"PeriodicalIF":2.1,"publicationDate":"2024-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142532021","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-17DOI: 10.1016/j.susc.2024.122629
Dillon Dodge, Rowan Dirks, Lauren F. Hornbrook, Nazila Hamidi, Erin V. Iski
A widely studied surface phenomena on Au(111) is the formation of Au magic fingers, which were first discovered nearly 20 years ago. A variety of experimental conditions have been used to observe the formation of Au magic fingers with a slight preference to ultra-high vacuum and low temperature studies. With the advances in scanning probe techniques, it is possible to study these unique structures under more relevant conditions including in air and at room temperature. After exposure to a 0.1 M solvent solution, Au(111) displayed three types of surface disturbances, including the formation of Au magic fingers, based on the identity of the solvent. The type of disturbance was dependent on the solvent molecule's characteristics, specifically its total charge and its electrolytic behavior in aqueous environments. The mechanism of disturbance relied on a strong tip-surface interaction and the mass transport of Au atoms, which was modified by the solvent selected. Overall, the ability to form organized nanostructures, like Au magic fingers, in a repeated way in environments outside of UHV and without a protective liquid layer increases the utility of these structures into a wider array of fields and applied areas.
金（111）表面现象中被广泛研究的一种是金魔指的形成，这种现象在近 20 年前首次被发现。观测金魔指形成的实验条件多种多样，但人们更倾向于超高真空和低温研究。随着扫描探针技术的发展，我们有可能在包括空气和室温在内的更多相关条件下研究这些独特的结构。在暴露于 0.1 M 溶剂溶液后，Au(111) 显示出三种类型的表面扰动，包括根据溶剂特性形成的金魔指。扰动类型取决于溶剂分子的特性，特别是其总电荷及其在水环境中的电解行为。扰动机理依赖于针尖与表面的强烈相互作用以及金原子的质量传输，而所选溶剂则改变了这一机理。总之，能够在超高真空以外的环境中以重复的方式形成有组织的纳米结构（如金魔指），并且不需要保护液层，这提高了这些结构在更广泛领域和应用领域的实用性。
{"title":"In air STM observation of Au(111) surface disturbance including Au magic fingers as modified by solvent choice","authors":"Dillon Dodge, Rowan Dirks, Lauren F. Hornbrook, Nazila Hamidi, Erin V. Iski","doi":"10.1016/j.susc.2024.122629","DOIUrl":"10.1016/j.susc.2024.122629","url":null,"abstract":"<div><div>A widely studied surface phenomena on Au(111) is the formation of Au magic fingers, which were first discovered nearly 20 years ago. A variety of experimental conditions have been used to observe the formation of Au magic fingers with a slight preference to ultra-high vacuum and low temperature studies. With the advances in scanning probe techniques, it is possible to study these unique structures under more relevant conditions including in air and at room temperature. After exposure to a 0.1 M solvent solution, Au(111) displayed three types of surface disturbances, including the formation of Au magic fingers, based on the identity of the solvent. The type of disturbance was dependent on the solvent molecule's characteristics, specifically its total charge and its electrolytic behavior in aqueous environments. The mechanism of disturbance relied on a strong tip-surface interaction and the mass transport of Au atoms, which was modified by the solvent selected. Overall, the ability to form organized nanostructures, like Au magic fingers, in a repeated way in environments outside of UHV and without a protective liquid layer increases the utility of these structures into a wider array of fields and applied areas.</div></div>","PeriodicalId":22100,"journal":{"name":"Surface Science","volume":"751 ","pages":"Article 122629"},"PeriodicalIF":2.1,"publicationDate":"2024-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142532019","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-16DOI: 10.1016/j.susc.2024.122624
Minttu M. Kauppinen , Ewa N. Słapa , José Luis González Escobedo , Riikka L. Puurunen , Karoliina Honkala
The observed difference in the selectivity towards alkane, ketone, and alcohol hydrodeoxygenation products over Ru and Rh catalysts is explored using a combination of density functional theory and microkinetics. Using -valerolactone as a model compound, we investigate the reaction mechanism in order to identify selectivity determining species. The effect of the coadsorbed water molecule as well as the higher adsorbate surface coverage on reaction barriers and energies is explored as well. The performed calculations suggest that the desired alkane product is formed from a ketone intermediate on Ru, and through both ketone and alcohol on Rh, although the selectivity towards alkane on Rh is much lower than on Ru.
{"title":"Computational insight into the selectivity of γ-valerolactone hydrodeoxygenation over Rh(111) and Ru(0001)","authors":"Minttu M. Kauppinen , Ewa N. Słapa , José Luis González Escobedo , Riikka L. Puurunen , Karoliina Honkala","doi":"10.1016/j.susc.2024.122624","DOIUrl":"10.1016/j.susc.2024.122624","url":null,"abstract":"<div><div>The observed difference in the selectivity towards alkane, ketone, and alcohol hydrodeoxygenation products over Ru and Rh catalysts is explored using a combination of density functional theory and microkinetics. Using <span><math><mi>γ</mi></math></span>-valerolactone as a model compound, we investigate the reaction mechanism in order to identify selectivity determining species. The effect of the coadsorbed water molecule as well as the higher adsorbate surface coverage on reaction barriers and energies is explored as well. The performed calculations suggest that the desired alkane product is formed from a ketone intermediate on Ru, and through both ketone and alcohol on Rh, although the selectivity towards alkane on Rh is much lower than on Ru.</div></div>","PeriodicalId":22100,"journal":{"name":"Surface Science","volume":"751 ","pages":"Article 122624"},"PeriodicalIF":2.1,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142532023","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-14DOI: 10.1016/j.susc.2024.122628
Hannah Boeckers , Markus Rohdenburg , Petra Swiderek
Ammonia (NH3) dissociates efficiently when it interacts with an electron beam. This applies not only to single electron-NH3 collisions in the gas phase but also to electron irradiation of NH3 adsorbed on surfaces. The dissociation products include atomic hydrogen which can act as a reducing agent or NH2 radicals that can bind to suitable surfaces or to adsorbed molecules. This chemistry can be exploited in nanofabrication processes that use electron beams for deposition, etching, or modification of materials. This review describes the current state of insight regarding electron-induced reactions of NH3 adsorbed on surfaces and outlines approaches to the use of these reactions for enhancing electron beam induced nanofabrication processes. First, an overview of surface science studies on electron-induced reactions of NH3 adsorbed on single crystal surfaces is given. This is followed by a summary of studies on the use of NH3 for improving the purity of deposits prepared by electron beam induced deposition (EBID) and on the prospects of NH3 to suppress unwanted thermal surface chemistry during EBID. Finally, we discuss electron-induced reactions of NH3 that are fundamental to the modification of carbonaceous nanomaterials as well as potential application scenarios such as the functionalization of self-assembled monolayers and humidity sensing.
{"title":"Surface science studies on electron-induced reactions of NH3 and their perspectives for enhancing nanofabrication processes","authors":"Hannah Boeckers , Markus Rohdenburg , Petra Swiderek","doi":"10.1016/j.susc.2024.122628","DOIUrl":"10.1016/j.susc.2024.122628","url":null,"abstract":"<div><div>Ammonia (NH<sub>3</sub>) dissociates efficiently when it interacts with an electron beam. This applies not only to single electron-NH<sub>3</sub> collisions in the gas phase but also to electron irradiation of NH<sub>3</sub> adsorbed on surfaces. The dissociation products include atomic hydrogen which can act as a reducing agent or NH<sub>2</sub> radicals that can bind to suitable surfaces or to adsorbed molecules. This chemistry can be exploited in nanofabrication processes that use electron beams for deposition, etching, or modification of materials. This review describes the current state of insight regarding electron-induced reactions of NH<sub>3</sub> adsorbed on surfaces and outlines approaches to the use of these reactions for enhancing electron beam induced nanofabrication processes. First, an overview of surface science studies on electron-induced reactions of NH<sub>3</sub> adsorbed on single crystal surfaces is given. This is followed by a summary of studies on the use of NH<sub>3</sub> for improving the purity of deposits prepared by electron beam induced deposition (EBID) and on the prospects of NH<sub>3</sub> to suppress unwanted thermal surface chemistry during EBID. Finally, we discuss electron-induced reactions of NH<sub>3</sub> that are fundamental to the modification of carbonaceous nanomaterials as well as potential application scenarios such as the functionalization of self-assembled monolayers and humidity sensing.</div></div>","PeriodicalId":22100,"journal":{"name":"Surface Science","volume":"751 ","pages":"Article 122628"},"PeriodicalIF":2.1,"publicationDate":"2024-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142532024","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-12DOI: 10.1016/j.susc.2024.122626
Tomasz Kosmala , Phan Thanh Hai , Nguyen Thi Minh Hai , Klaus Wandelt
A detailed understanding of properties and processes at surfaces and interfaces requires at least two types of most basic information, chemical composition and –distribution as well as structure. While surface science in ultrahigh vacuum is blessed with a plethora of high sensitivity and highest spatial and temporal resolution due to the free accessibility of the surfaces by any kind of probe beams, investigations of solid surfaces under ambient conditions, i.e. in contact with gases or liquids, were for a long time restricted to the use of integral photon-based reflection-, absorption-, emission-, and diffraction methods. This “methodological gap” between UHV surface science and environmental interface research became immediately, at least partially, closed after the realization of the scanning tunneling microscope (STM) and following variants of proximity probes (SPM). The full applicability of this class of methods also under ambient conditions opened the door to structure information of solid-liquid interfaces of comparable resolution as in UHV at room temperature, a “quantum leap” for the understanding of e.g. interfacial electrochemistry. This, in turn, highlighted the need of reliable determination of the chemical composition and distribution at solid-liquid interfaces and pushed the development of in situ X-ray photoelectron spectroscopy (XPS).
The availability of both techniques, in situ SPM and in situ XPS closes the former methodological gap between the research in UHV and under ambient conditions. In particular, interfacial electrochemistry, being primarily interested in chemical processes at electrode/electrolyte interfaces benefits decisively of this development.
In this article, as an example, we present systematic in situ STM measurements and results on the interactions and self-assembly of porphyrins at anion modified metal/electrolyte interfaces, an important class of molecules for the functionalization of surfaces for various applications. Atomically and sub-molecularly resolved potentiostatic and potentiodynamic in situ STM images of such molecular layers are nowadays standard and wait for an in-depth theoretical analysis.
要详细了解表面和界面的特性和过程，至少需要两类最基本的信息：化学成分和分布以及结构。超高真空条件下的表面科学具有得天独厚的高灵敏度和最高的空间和时间分辨率，因为任何类型的探针光束都可以自由进入表面，但在环境条件下，即与气体或液体接触时，对固体表面的研究长期以来仅限于使用基于积分光子的反射、吸收、发射和衍射方法。在扫描隧道显微镜（STM）及其后的近距离探针（SPM）变体问世后，超高真空表面科学与环境界面研究之间的这一 "方法论鸿沟 "立即（至少是部分）得以弥合。这类方法在环境条件下的完全适用性为获得固液界面结构信息打开了大门，其分辨率可与室温下的超高真空相媲美，这对于理解界面电化学等问题来说是一次 "质的飞跃"。这反过来又突出了可靠测定固液界面化学成分和分布的需要，推动了原位 X 射线光电子能谱（XPS）的发展。在本文中，我们将以阴离子修饰的金属/电解质界面上卟啉的相互作用和自组装为例，介绍系统的原位 STM 测量和结果。这类分子层的原子和亚分子分辨电位静力学和电位动力学原位 STM 图像如今已成为标准图像，有待深入的理论分析。
{"title":"Electrochemical surface science: Self-assembly of Porphyrin molecules at single crystal metal electrodes","authors":"Tomasz Kosmala , Phan Thanh Hai , Nguyen Thi Minh Hai , Klaus Wandelt","doi":"10.1016/j.susc.2024.122626","DOIUrl":"10.1016/j.susc.2024.122626","url":null,"abstract":"<div><div>A detailed understanding of properties and processes at surfaces and interfaces requires at least two types of most basic information, <em>chemical composition and –distribution</em> as well as <em>structure.</em> While surface science in ultrahigh vacuum is blessed with a plethora of high sensitivity and highest spatial and temporal resolution due to the free accessibility of the surfaces by any kind of probe beams, investigations of solid surfaces under ambient conditions, i.e. in contact with gases or liquids, were for a long time restricted to the use of integral photon-based reflection-, absorption-, emission-, and diffraction methods. This “methodological gap” between UHV surface science and environmental interface research became immediately, at least partially, closed after the realization of the scanning tunneling microscope (STM) and following variants of proximity probes (SPM). The full applicability of this class of methods also under ambient conditions opened the door to structure information of solid-liquid interfaces of comparable resolution as in UHV at room temperature, a “quantum leap” for the understanding of e.g. interfacial electrochemistry. This, in turn, highlighted the need of reliable determination of the chemical composition and distribution at solid-liquid interfaces and pushed the development of in situ X-ray photoelectron spectroscopy (XPS).</div><div>The availability of both techniques, in situ SPM and in situ XPS closes the former methodological gap between the research in UHV and under ambient conditions. In particular, interfacial electrochemistry, being primarily interested in chemical processes at electrode/electrolyte interfaces benefits decisively of this development.</div><div>In this article, as an example, we present systematic in situ STM measurements and results on the interactions and self-assembly of porphyrins at anion modified metal/electrolyte interfaces, an important class of molecules for the functionalization of surfaces for various applications. Atomically and sub-molecularly resolved potentiostatic and potentiodynamic in situ STM images of such molecular layers are nowadays standard and wait for an in-depth theoretical analysis.</div></div>","PeriodicalId":22100,"journal":{"name":"Surface Science","volume":"751 ","pages":"Article 122626"},"PeriodicalIF":2.1,"publicationDate":"2024-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142532022","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-11DOI: 10.1016/j.susc.2024.122625
Lukas Ruppenthal , Zilin Ruan , Jakob Schramm , Pengcai Liu , Florian Münster , Tim Naumann , Leonard Neuhaus , Jan Herritsch , Xing-Yu Chen , Xiao-Ye Wang , Bernd Meyer , Ralf Tonner-Zech , J. Michael Gottfried
Defects play a critical role in the performance of carbon-based (opto-)electronic materials, because the materials’ interaction with metal electrodes can strongly depend on the topology of the π-electron system. However, the direct investigation of defects is difficult due to their typically low density. To address this issue, we use a molecular model system comparing the polycyclic aromatic hydrocarbon pyrene with its isomer acepleiadylene regarding their interaction with a Cu(111) surface. Acepleiadylene serves as a model defect with a nonbenzenoid nonalternant topology, while pyrene represents an ideal benzenoid alternant structure. We find that acepleiadylene forms a stronger bond to the metal surface than pyrene. This is evidenced by a higher molecule-surface bond energy, significant adsorption-induced changes in electronic structure (studied via photoelectron and X-ray absorption spectroscopies), and a potentially lower adsorption height (according to non-contact atomic force microscopy). The stronger bond of acepleiadylene is linked to its smaller gap between the highest occupied and the lowest unoccupied orbitals (HOMO-LUMO gap), bringing the LUMO closer to the metal's Fermi energy and resulting in stronger hybridization with the metal's electronic states. Density functional theory calculations support our findings, suggesting that nonbenzenoid, nonalternant structural elements can enhance the bonding between graphene-based materials and metal electrodes. Additionally, these results highlight the potential of nonbenzenoid molecular organic semiconductors as alternatives to their benzenoid counterparts.
缺陷对碳基（光）电子材料的性能起着至关重要的作用，因为材料与金属电极的相互作用在很大程度上取决于π电子系统的拓扑结构。然而，由于缺陷的密度通常很低，因此很难对缺陷进行直接研究。为了解决这个问题，我们使用了一个分子模型系统，比较了多环芳烃芘及其异构体醋楹与铜(111)表面的相互作用。醋楹是一种具有非苯类非交替拓扑结构的模型缺陷，而芘则代表了一种理想的苯类交替结构。我们发现，醋楹与金属表面形成的结合比芘更牢固。这表现在分子-表面键能更高、吸附引起的电子结构变化显著（通过光电子和 X 射线吸收光谱进行研究）以及吸附高度可能更低（根据非接触式原子力显微镜）。醋螨烯的键更强与它的最高占位轨道和最低未占位轨道之间的间隙（HOMO-LUMO 间隙）更小有关，这使得 LUMO 更接近金属的费米能，从而与金属的电子状态产生更强的杂化。密度泛函理论计算支持我们的发现，表明非苯类、非替代结构元素可以增强石墨烯基材料与金属电极之间的结合。此外，这些结果突显了非类苯分子有机半导体作为类苯分子有机半导体替代品的潜力。
{"title":"The surface chemical bond of a nonbenzenoid aromatic hydrocarbon: Acepleiadylene versus pyrene","authors":"Lukas Ruppenthal , Zilin Ruan , Jakob Schramm , Pengcai Liu , Florian Münster , Tim Naumann , Leonard Neuhaus , Jan Herritsch , Xing-Yu Chen , Xiao-Ye Wang , Bernd Meyer , Ralf Tonner-Zech , J. Michael Gottfried","doi":"10.1016/j.susc.2024.122625","DOIUrl":"10.1016/j.susc.2024.122625","url":null,"abstract":"<div><div>Defects play a critical role in the performance of carbon-based (opto-)electronic materials, because the materials’ interaction with metal electrodes can strongly depend on the topology of the π-electron system. However, the direct investigation of defects is difficult due to their typically low density. To address this issue, we use a molecular model system comparing the polycyclic aromatic hydrocarbon pyrene with its isomer acepleiadylene regarding their interaction with a Cu(111) surface. Acepleiadylene serves as a model defect with a nonbenzenoid nonalternant topology, while pyrene represents an ideal benzenoid alternant structure. We find that acepleiadylene forms a stronger bond to the metal surface than pyrene. This is evidenced by a higher molecule-surface bond energy, significant adsorption-induced changes in electronic structure (studied via photoelectron and X-ray absorption spectroscopies), and a potentially lower adsorption height (according to non-contact atomic force microscopy). The stronger bond of acepleiadylene is linked to its smaller gap between the highest occupied and the lowest unoccupied orbitals (HOMO-LUMO gap), bringing the LUMO closer to the metal's Fermi energy and resulting in stronger hybridization with the metal's electronic states. Density functional theory calculations support our findings, suggesting that nonbenzenoid, nonalternant structural elements can enhance the bonding between graphene-based materials and metal electrodes. Additionally, these results highlight the potential of nonbenzenoid molecular organic semiconductors as alternatives to their benzenoid counterparts.</div></div>","PeriodicalId":22100,"journal":{"name":"Surface Science","volume":"753 ","pages":"Article 122625"},"PeriodicalIF":2.1,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142698356","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-05DOI: 10.1016/j.susc.2024.122623
Fangliang Li , Ali S. Ahsen , Salai C. Ammal , Mengxiong Qiao , Thathsara D. Maddumapatabandi , Sumit Beniwal , Andreas Heyden , Donna A. Chen
PtSn bimetallic clusters on TiO2(110) and highly oriented pyrolytic graphite (HOPG) surfaces have been characterized by scanning tunneling microscopy, low energy ion scattering (LEIS), X-ray photoelectron spectroscopy, and temperature programmed desorption (TPD); density functional theory (DFT) calculations have also been performed to better understand adsorption of CO and D2 on the PtSn surfaces. On TiO2 at coverages of 2 ML of Pt and 2 ML of Sn, exclusively bimetallic clusters are formed for both orders of deposition because clusters of the first metal completely cover the surface such that all atoms of the second metal are incorporated into the existing clusters. In contrast, on HOPG, the high mobility and weak cluster-support interactions on HOPG result in much larger 2 ML monometallic clusters (∼30 Å high) that do not completely cover the surface, and deposition of the second metal produces larger clusters as well as smaller ones. Despite the difference in cluster morphologies for the different orders of deposition and supports, the LEIS experiments demonstrate that in all cases, the PtSn clusters are rich in Sn at the surface, as expected based on the lower surface free energy for Sn compared to Pt. Furthermore, the +0.2 eV shift in the Sn(3d5/2) binding energy observed on all surfaces in the presence of Pt is consistent with PtSn alloy formation. Deposition of 2 ML of Sn on TiO2 produces two-dimensional clusters with oxidation of Sn and reduction of titania at the cluster-support interface, but addition of Pt to the Sn clusters causes Sn to diffuse away from this interface, leaving Sn in the metallic state. TPD experiments on 2 ML Pt/TiO2 with increasing coverages of Sn show that the number of adsorption sites for D2 sharply decreases to nearly zero at 0.5 ML, while CO adsorption decreases to zero only at much higher Sn coverages of 2 ML. DFT studies for Sn modified Pt surfaces and bulk structures demonstrate that for CO adsorption at low Sn coverages (≤0.25 ML), the strong Pt-CO interactions induce diffusion of Pt to the cluster surface and the formation of a bulk Pt3Sn alloy, whereas D2 adsorption does not lead to interactions with the Pt surface that are strong enough to induce alloy formation. A single Sn adatom prevents D2 adsorption on four neighboring Pt atoms via site-blocking and the donation of electron density to Pt.
通过扫描隧道显微镜、低能离子散射 (LEIS)、X 射线光电子能谱和温度编程解吸 (TPD) 对 TiO2(110) 和高取向热解石墨 (HOPG) 表面上的铂锰双金属团簇进行了表征；还进行了密度泛函理论 (DFT) 计算，以更好地了解 CO 和 D2 在铂锰表面的吸附情况。在铂的覆盖率为 2 ML 和锡的覆盖率为 2 ML 的 TiO2 上，两种沉积阶次都能形成完全的双金属簇，因为第一种金属的簇完全覆盖了表面，这样第二种金属的所有原子都融入了现有的簇中。与此相反，在 HOPG 上，由于 HOPG 的高迁移率和微弱的簇支撑相互作用，形成了大得多的 2 ML 单金属簇（高 30 Å），这些簇并没有完全覆盖表面，而第二种金属的沉积既会产生较大的簇，也会产生较小的簇。尽管不同沉积顺序和支持物的簇形态各异，但 LEIS 实验表明，在所有情况下，PtSn 簇表面都富含 Sn，这是基于 Sn 的表面自由能低于 Pt 所预期的。此外，在有 Pt 存在的情况下，所有表面上观察到的 Sn(3d5/2) 结合能都发生了 +0.2 eV 的移动，这与 PtSn 合金的形成是一致的。在二氧化钛上沉积 2 ML Sn 会产生二维簇，在簇-支撑界面上 Sn 被氧化，二氧化钛被还原，但在 Sn 簇中添加铂会导致 Sn 从该界面扩散开，使 Sn 处于金属态。在 Sn 覆盖率不断增加的 2 ML Pt/TiO2 上进行的 TPD 实验表明，D2 的吸附位点数量在 0.5 ML 时急剧下降至近乎为零，而 CO 的吸附只有在 Sn 覆盖率高达 2 ML 时才降至零。对 Sn 修饰的铂表面和块体结构进行的 DFT 研究表明，在低 Sn 覆盖率（≤0.25 ML）条件下吸附 CO 时，强烈的 Pt-CO 相互作用会诱导铂向簇表面扩散并形成块体 Pt3Sn 合金，而吸附 D2 不会导致与铂表面产生足以诱导合金形成的相互作用。单个锡原子通过位阻和向铂提供电子密度阻止了 D2 在四个相邻铂原子上的吸附。
{"title":"Characterizing the surface compositions of supported bimetallic PtSn clusters: Effects of cluster-support interactions and surface adsorbates","authors":"Fangliang Li , Ali S. Ahsen , Salai C. Ammal , Mengxiong Qiao , Thathsara D. Maddumapatabandi , Sumit Beniwal , Andreas Heyden , Donna A. Chen","doi":"10.1016/j.susc.2024.122623","DOIUrl":"10.1016/j.susc.2024.122623","url":null,"abstract":"<div><div>PtSn bimetallic clusters on TiO<sub>2</sub>(110) and highly oriented pyrolytic graphite (HOPG) surfaces have been characterized by scanning tunneling microscopy, low energy ion scattering (LEIS), X-ray photoelectron spectroscopy, and temperature programmed desorption (TPD); density functional theory (DFT) calculations have also been performed to better understand adsorption of CO and D<sub>2</sub> on the PtSn surfaces. On TiO<sub>2</sub> at coverages of 2 ML of Pt and 2 ML of Sn, exclusively bimetallic clusters are formed for both orders of deposition because clusters of the first metal completely cover the surface such that all atoms of the second metal are incorporated into the existing clusters. In contrast, on HOPG, the high mobility and weak cluster-support interactions on HOPG result in much larger 2 ML monometallic clusters (∼30 Å high) that do not completely cover the surface, and deposition of the second metal produces larger clusters as well as smaller ones. Despite the difference in cluster morphologies for the different orders of deposition and supports, the LEIS experiments demonstrate that in all cases, the PtSn clusters are rich in Sn at the surface, as expected based on the lower surface free energy for Sn compared to Pt. Furthermore, the +0.2 eV shift in the Sn(3d<sub>5/2</sub>) binding energy observed on all surfaces in the presence of Pt is consistent with PtSn alloy formation. Deposition of 2 ML of Sn on TiO<sub>2</sub> produces two-dimensional clusters with oxidation of Sn and reduction of titania at the cluster-support interface, but addition of Pt to the Sn clusters causes Sn to diffuse away from this interface, leaving Sn in the metallic state. TPD experiments on 2 ML Pt/TiO<sub>2</sub> with increasing coverages of Sn show that the number of adsorption sites for D<sub>2</sub> sharply decreases to nearly zero at 0.5 ML, while CO adsorption decreases to zero only at much higher Sn coverages of 2 ML. DFT studies for Sn modified Pt surfaces and bulk structures demonstrate that for CO adsorption at low Sn coverages (≤0.25 ML), the strong Pt-CO interactions induce diffusion of Pt to the cluster surface and the formation of a bulk Pt<sub>3</sub>Sn alloy, whereas D<sub>2</sub> adsorption does not lead to interactions with the Pt surface that are strong enough to induce alloy formation. A single Sn adatom prevents D<sub>2</sub> adsorption on four neighboring Pt atoms via site-blocking and the donation of electron density to Pt.</div></div>","PeriodicalId":22100,"journal":{"name":"Surface Science","volume":"751 ","pages":"Article 122623"},"PeriodicalIF":2.1,"publicationDate":"2024-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142444599","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
扫码关注我们
求助内容：
应助结果提醒方式：
京公网安备 11010802042870号