SEM operates by scanning a focused electron beam over the surface of a sample. When the electrons interact with the sample, they produce various signals, including secondary electrons, backscattered electrons, and X-rays. Secondary electrons are typically used to create high-resolution images of the surface, while backscattered electrons can provide information about the sample's composition. Energy-dispersive X-ray spectroscopy (EDX) is often combined with SEM to analyze the elemental composition of the catalyst.
