Role of nano in catalysis: Palladium catalyzed hydrogen desorption from nanosized magnesium hydride

► Role of nano particle size in H desorption beyond the quantum confinement regime. ► Identify two competing pathways for catalyzed H desorption from MgH2. ► Surface pathway, in the presence of Pd, enables low-barrier H desorption. ► Identify the role of gas-product entropy and self-limiting of the surface pathway.