The particle sizes and morphology of COFs and Pd@COFs were characterized using TEM images (Figure ). TEM images of COF-1 and COF-2 show particles with a size distribution of 25-110 nm and 25-55 nm, respectively. COF-1 exhibits a larger particle size than COF-2 because of the length of the tricarboxylic acid. COFs materials tend to aggregate and create inter-particle pores that were confirmed from nitrogen adsorption-desorption isotherms. TEM images for Pd-COFs materials show the presence of dark particles corresponding to the palladium particles (Figure ). The data show the homogenous distribution of Pd into COF-1 and COF-2. The particle size distribution of Pd was calculated using TEM images that show a particle size distribution of 1-5 nm with an average particle size of 2.6 nm (Figure ).