09/2013
Discover this journal online at:
wileyonlinelibrary.com
ChemCatChem is an international journal covering all fields of catalysis. It is co-owned by 16 European Chemical Societies forming together the Chemistry Publishing Society Europe (ChemPubSoc Europe), supported by the German Catalysis Society (GeCatS), and published by Wiley-VCH. Publications in ChemCatChem cover research into nanocatalysis, biocatalysis, heterogeneous catalysis, and homogeneous catalysis, as well as that at the interfaces of all three areas. ChemCatChem publishes Communications and Full Papers, Reviews and Minireviews, Highlights, Concepts, Essays, Book Reviews, and Conference Reports. Authors can submit articles to ChemCatChem online. Just go to our homepage (http://www.chemcatchem.org), click on “Submit an Article”, and follow the instructions.
All of the articles in this issue have already appeared online on wileyonlinelibrary.com See http://www.chemcatchem.org under Early View
CHEMCATCHEM EDITORIAL DOI: 10.1002/cctc.201300657
Special Issue: Advanced Electron Microscopy for Catalysis Dang Sheng Su*[a]
Nanoscience is characterized by the ability to determine the structure and composition of nanoscopic objects ranging from mesoscopic dimensions, of about 100 nm, down to individual atoms and clusters. A rational science in this dimension has to rely on analytical capabilities to “see” and control the manipulation of atoms. Catalysis at the atomic or molecular level is a major player in nanoscience. The need to understand catalysts and other functional materials (including semiconductors) has driven the development of electron microscopy into dimensions that were hardly imaginable 10 years ago.
As shown in Figure 1, electron microscopy has experienced a revolutionary development through the past 80 years, both [a] Prof. D. S. Su Shenyang National Laboratory for Materials Science Institute of Metal Research, Chinese Academy of Science Wenhua Road 72, 110016 Shenyang 110016 (P.R. China) Fax: (+) 86 24 8397 0019 E-mail:
[email protected]
2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
instrumentally and methodically.[1] From the development of Bragg diffraction contrast and column approximation, which enable us to understand TEM images of crystals and their defects, to spherical aberration correction for subangstrom scale imaging, which is capable of revealing atomic structures with unprecedented precision, and all the powerful analytic modes and affiliated detectors, such as Xrays, backscattered electrons, and electron energy loss spectroscopy (EELS), electron microscopy has shown spiraling and steady advances. The well-established methods, such as diffraction contrast and mass thickness contrast, developed around the 1950’s are still vital imaging techniques used to obtain the basic morphological information of a catalyst. A revised form of mass thickness, called HAADF-STEM (Z contrast), established around the 1990’s, has proven to be a very powerful method to study supported catalysts of high atomic number. The left ChemCatChem 2013, 5, 2543 – 2545
2543
CHEMCATCHEM EDITORIAL
www.chemcatchem.org lective and individual geometric, chemical, and electronic properties of such materials.[2]
C
atalysts, however, are complex solids and this structural complexity is associated with their ability to undergo in every catalytic cycle structural changes of their active sites that are reverted into a metastable initial state of activity. In this sense, the ex situ obtained information from a catalyst, either by using electron microscopy or any other spectroscopic method, is often irrelevant to a working catalyst. The recently developed environmental TEM Figure 1. Milestones of transmission electron microscopy. The history of TEM (from the first TEM built by Ernst (in situ TEM) and 4D electron Ruska and Max Knoll in 1931 to the spherical aberration-corrected TEM with sub-angstrom resolution after the microscopy provide the possiyear 2000), and the tendency of spatial resolution achieved with TEM (left side). bility to study dynamic behavior of a catalyst under working conditions. This could be a true revolution in catalysis, if combined side of Figure 1 shows the tendency of spatial resolution achwith other in situ spectroscopic methods, to give a full set of ieved with TEM from 10 nm to sub-angstrom. More recently, information for these catalysts and possibly access to key inforaberration-corrected TEM has achieved resolution below 0.5 mation for the reaction mechanism. at a magnification of 50 million. Not summarized in Figure 1, but equally important for materials science and electron microscopy, are electron tomography and electron holography. These technologies in association with modern electron microscopy are becoming routine methods in many laboratories.
C
atalysis plays a key role for the sustainable development of our society. The characterization of morphology, chemical composition, surface, and internal structure of catalysts is of great importance for the synthesis of materials of high selectivity and high conversion rate with long cycle times favored for their reduced environmental impact. As shown in Figure 2, modern electron microscopy with its arsenal of diffraction, imaging, and spectroscopic techniques gives access to the col-
Dang Sheng Su completed his Ph.D. at the Technical University of Vienna (Austria) in 1991, and then moved to the Fritz Haber Institute (FHI) of the Max Planck Society as a post-doctoral fellow in the Department of Electron Microscopy. After a short stay at the Hahn-Meitner Institute GmbH and the Humboldt University in Berlin (Germany), he joined the FHI in 1999, where he worked on nanomaterials in heterogeneous catalysis and energy storage. He now leads the Catalysis and Materials Division at the Institute of Metal Research, Chinese Academy of Sciences, Shenyang (P.R. China).
2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Figure 2. An illustration of electron tomography combined with EELS in the scanning transmission electron microscope, which can be used to probe the 3D crystal and electronic structure of a nano-object. GIF = Gatan imaging filter.
Apart from nanoscience and nanotechnology (but is the catalysis not a part of nanoscience?), catalysis is one of the most important areas where electron microscopy has found important application. It is said that the evolution of catalysis science is based on the ability to cope with the structural complexity of solid catalysts, which is largely made possible by the advancement of electron microscopy. Although, undeniably, the opposite is also true in that the analysis of catalysts is seen as a major driving force for the current revolution in electron microscopy. ChemCatChem 2013, 5, 2543 – 2545
2544
CHEMCATCHEM EDITORIAL
T
he manuscripts in this Special Issue include selected contributions to ChemCatChem and a large number of invited articles based on the 2nd International Symposium on Advanced Electron Microscopy for Catalysis and Energy Storage Materials, EmCat2012, organized by us in Berlin in 2012. EmCat2012 covered the most recent developments, especially those after EmCat2010, in all areas of advanced electron microscopy applied to catalysis and energy storage materials.
www.chemcatchem.org
I close by wholeheartedly thanking all the contributors to this Special Issue, the referees, and the editors of ChemCatChem. With best regards, Dang Sheng Su Keywords: electron microscopy · HAADF · heterogeneous catalysis · holography · EELS · SEM · STEM · TEM · tomography [1] B. Zhang, D. S. Su, Small 2013, DOI: 10.1002/smll.201301303. [2] D. S. Su, ChemCatChem 2011, 3, 919 – 920. [3] B. Zhang, D. S. Su, Angew. Chem. 2013, 125, 8662 – 8664; Angew. Chem. Int. Ed., 2013, 52, 8504 – 8506.
2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ChemCatChem 2013, 5, 2543 – 2545
2545
