An intriguing question is whether palladium nanoparticles are formed that operate as a water splitting catalyst. Scanning electron microscopy (SEM) is an excellent tool for detecting palladium(0) nanoparticles as small as ⌀ = 8 nm in metallo-organic films. We use oxidative potentials; therefore, the formation of such metallic particles is not expected. However, it is known that palladium salts can form particles of palladium oxides under oxidative potentials in water. SEM imaging was performed on the two MAs before and after electrocatalysis for 7 h (Figure -10). These measurements show the presence of grainy, continuous coatings. After electrocatalysis, the presence of low amounts of particles has been oberved. Electrochromic cycling (×1500) does not alter the texture and such particles were not oberved owing to the use of lower potentials (vide supra). EDS mapping indicated the presence of a homogeneous distribution of the expected elements; however, the resolution does not allow the composition of these particles to be elucidated (Figure ). CV measurements of both MA1 and MA2 used for CPE measurements are consistent with the formation of palladium oxides (Figure ). These CV measurements also show that the iron complexes (1) have undergone irreversible structural changes that resulted in loss of electrochemical reversibility. Regardless of these changes, it is remarkable that the films show relatively long catalytic stability without an appreciable leakage of material to the electrolyte solutions or changes in the surface texture.