Coupling between adjacent crystal planes during CO+O-ad reaction on a defective Pd(100) surface

Spatially resolved photoemission electron microscopy (PEEM) was employed to investigate the adsorption, diffusion, and reactivity of oxygen on a defec tive Pd(100) surface. The defective region on Pd(100) exposed several diffe rent planes with low indexes, for example, (110) and (111) planes. Upon oxy gen adsorption, various types of oxygen species formed on each plane; which behaved with different reactivities toward CO. An obvious coupling between the Pd(110) plane and its adjacent planes was monitored by PEEM during CO + O-ad reaction and resulted in the appearance of the reaction-diffusion wa ves on the Pd(110) plane. The occurrence of reaction coupling had a great i nfluence on the catalytic kinetics of the crystal planes involved. However, during isothermal desorption of adsorbed oxygen on the planes, no coupling existed between adjacent planes, which implied that the reaction played a key role in the occurrence of coupling.