A model macroion solution next to a charged wall:: Overcharging, charge reversal, and charge inversion by macroions

We study the inhomogeneous primitive model macroion solution next to a charged wall, through an integral equations theory. We report a new class of overcharging, which refers to the adsorption of an effective charge onto a like-charged wall. In addition, macroions produce surface charge reversal, charge inversion, and layering. The role of electrostatic and excluded volume correlations, on these effects, is discussed. It is argued that electrostatic and the steric repulsive interactions give rise to depletion forces which produce macroion adsorption, even if the wall or the macroparticle are uncharged or if the wall and macroions are like charged. By consideration of two limit cases of the inhomogeneous primitive model, the role of the small ion and macroion short-range correlations is separately examined. Across the paper, the agreement is discussed of our results with computer simulations and with experimental results.