Surface Reconstructions of Metal Oxides and the Consequences on Catalytic Chemistry

Abstract

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.

Designing High‐Valence Metal Sites for Electrochemical Water Splitting

“…However, it is more common and universal that high‐valence metal sites accelerate the OER kinetics according to the available literature, which can be mainly attributed to the moderate adsorption energies for OER intermediates and the oxidative environment for the OER process. [ 14c,68 ] Furthermore, compared with HER, OER is more complicated due to its multiple intermediates and different types of reaction mechanisms. [ 47a,51 ] The OER efficiency is the bottleneck of that of overall water electrolysis.…”

Bulk and Surface Properties Regulation of Single/Double Perovskites to Realize Enhanced Oxygen Evolution Reactivity

“…Additionally, the interaction between phases in a composite may influence physicochemical properties and therefore the electrochemical behavior of the material . Thanks to modern in operando and in situ characterization techniques, it is known that catalysts may undergo structural self‐reconstruction during oxidation or reduction, also impacting catalytic activity, where the generation of active surface species during the reaction (commonly metal hydroxide or oxide layers) may improve catalytic activity . For example, the OER activity of single perovskite oxides Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3−δ (BSCF) and SrCo 0.8 Fe 0.2 O 3−δ increases after only a few electrochemical cycles as a result of rapid surface amorphization, with catalytic activity deteriorating on continuous cycling owing to local structural changes as a result of excessive surface reconstruction .…”

Tuning Reconstruction Level of Precatalysts to Design Advanced Oxygen Evolution Electrocatalysts

“…In addition, factors that affect the reaction conditions such as the concentration of the electrolyte, the applied potential, and the temperature will also affect the degree of surface change [ 56 , 85 ]. Thus, much effort has been devoted to exploring advanced OER electrocatalysts based on surface reconstruction [ 63 , 79 , 86 , 87 ].…”