Developments and advances in in situ transmission electron microscopy for catalysis research

The characterization of heterogeneous catalysts is critical to their development and to understand their performance by correlating their physicochemical properties to their activity, selectivity and stability. Transmission electron microscopy (TEM) is one of the routinely used characterization techniques, and is commonly limited to investigations of catalyst samples before and after synthesis, activation, and operation. Thus only indirect information can be obtained about structural transformations undergone by the catalyst during synthesis or catalysis. Effort over the decades in developing in situ TEM is showing promising results whereby the direct, real-time observation of the structural changes of materials under reaction conditions are becoming available. In this review we provide an overview of the developments in in situ TEM techniques, focusing on their application for studies related to catalysis by loosely following the four stages of the catalyst life cycle: synthesis, activation, performance and deactivation, and regeneration.