Surface Reconstructions of Metal Oxides and the Consequences on Catalytic Chemistry

Catalysts are inherently dynamic in nature, as they respond to the environment by changing their local and extended structures. Surface reconstruction is among such dynamic behaviors of catalysts and greatly affects the physical, chemical, and electronic properties of catalysts and consequently the catalytic performances. Thus, understanding the nature of the catalytic sites of the reconstructed surfaces is essential for establishing the structure catalysis relations and has attracted much interest in catalysis research. Knowledge of the reconstruction of metal oxides has been quite limited in comparison to that of metal surfaces because the nature of oxide surfaces is generally more complex. However, significant progress has been made in recent years in oxide surfaces thanks to the advances in the ability to synthesize model oxide nanocrystals and to characterize the surface reconstruction behaviors under in situ and operando conditions with advanced spectroscopy and microscopy aided by computational modeling. In this Perspective, such advances in understanding the surface reconstruction behaviors of metal oxide nanoshapes and thin films with well-defined surface structures under as-synthesized, various pretreatment, and reaction environments will be summarized, and the catalytic consequences of these reconstructions will be highlighted. The results from these studies clearly show that the combination of model oxides and in situ/operando investigations is imperative in shaping the fundamental understanding of the dynamic reconstructions of oxide surfaces. However, it is still challenging to study the surface reconstructions of oxide catalysts with meaningful temporal and spatial resolution under operating conditions. Future opportunities are discussed on how to address the challenges and eventually help to design more efficient catalysts by taking advantages of the surface reconstructions.