What two types of reaction happen at the electrodes?
Electrode reactions can be classified into two groups: one in which an electron transfer takes place across the electrode interface, such as ferric–ferrous redox reaction ( Fe aq 3+ + e = Fe aq 2+ ) ; and the other in which an ion transfer takes place across the electrode interface, such as iron dissolution–deposition ...

Nanoparticles often self-assemble into hexagonal-close-packed (hcp) structures although it is predicted to be less stable than face-centered-cubic (fcc) packing in hard-sphere models. In addition to close-packed fcc and hcp superlattices, we observe formation of nonclose-packed simple-hexagonal (sh) superlattices of nearly spherical PbS, PbSe, and γ-Fe2O3 nanocrystals.