Recent Progress with In Situ Characterization of Interfacial Structures under a Solid-Gas Atmosphere by HP-STM and AP-XPS.

Shen Shen,Jiang Jiang,Zhang Zhang,Hu Hu,Song Song,Sun Sun

doi:10.3390/ma12223674

Abstract

Surface science is an interdisciplinary field involving various subjects such as physics, chemistry, materials, biology and so on, and it plays an increasingly momentous role in both fundamental research and industrial applications. Despite the encouraging progress in characterizing surface/interface nanostructures with atomic and orbital precision under ultra-high-vacuum (UHV) conditions, investigating in situ reactions/processes occurring at the surface/interface under operando conditions becomes a crucial challenge in the field of surface catalysis and surface electrochemistry. Promoted by such pressing demands, high-pressure scanning tunneling microscopy (HP-STM) and ambient pressure X-ray photoelectron spectroscopy (AP-XPS), for example, have been designed to conduct measurements under operando conditions on the basis of conventional scanning tunneling microscopy (STM) and photoemission spectroscopy, which are proving to become powerful techniques to study various heterogeneous catalytic reactions on the surface. This report reviews the development of HP-STM and AP-XPS facilities and the application of HP-STM and AP-XPS on fine investigations of heterogeneous catalytic reactions via evolutions of both surface morphology and electronic structures, including dehydrogenation, CO oxidation on metal-based substrates, and so on. In the end, a perspective is also given regarding the combination of in situ X-ray photoelectron spectroscopy (XPS) and STM towards the identification of the structure–performance relationship.

Highlights

With the rapid pace of characterization technologies in surface science during the past several decades, techniques with static investigation capabilities with atomic precision and orbital resolution have been emerging [1,2,3,4,5] in applications in such as materials science, energy conversion and storage, catalysis, solar cells, and so on
We focused on ambient pressure X-ray photoelectron spectroscopy (AP-X-ray photoelectron spectroscopy (XPS)) investigations on the solid–gas interface in a gas environment
We present examples of high-pressure scanning tunneling microscopy (HP-scanning tunneling microscopy (STM)) experiments on solid/gas and solid/vapor interfaces about self-assembly and dehydrogenation processes

Summary

Introduction

With the rapid pace of characterization technologies in surface science during the past several decades, techniques with static investigation capabilities with atomic precision and orbital resolution have been emerging [1,2,3,4,5] in applications in such as materials science, energy conversion and storage, catalysis, solar cells, and so on. Measurements under relatively high pressures up to several dozens millibars [21,22,23,24,25,26] can be carried out without disturbing the electron analyzer, and more realistic results close to actual reactions can be obtained compared to UHV studies of ideal static surface/interfaces. Most AP-XPS systems have been equipped with other surface characterization tools such as low-energy electron diffraction (LEED), sputtering guns, in situ annealing treatments by either radiative heating or laser heating, various evaporation sources, and so on With such means, samples can be properly cleaned or prepared before in situ measurements. We focused on AP-XPS investigations on the solid–gas interface in a gas environment

Applications of HP-STM in Identifying Surface Catalysis Reactions

HP-STM Experiments of Single-Crystal Reactions and Reactant Gas

Reconstruction

Torr of Obecomes

STM images for onon

CO Catalytic Oxidation

HP-STM Experiments of Dehydrogenation Reactions

Investigations of Copper-Based Catalyst Reactions

Reactions on Platinum-Based Catalysts

Results showed

Conclusions