The synchronization and dependence of etching of Pt-Ni nanoparticles and precipitation of Ni-Al hydroxides in basic solutions are investigated by use of ab initio calculations. The oxidized Ni2+ from Pt-Ni nanoparticles reacts with the OH to form the Ni-(OH)(x) species on etched nanoparticles, allowing for the in situ nucleation. The resultant interface structure is the Pt-O(H)-Ni scheme. The additional Al3+ ions facilitate the growth of hydrotalcite membranes in an edge-by-edge manner. The continuous consumption of Ni2+ and OH in the membrane growth shifts the equilibria of etching reactions, which may enable the control of shape and composition of etched nanoparticles. (C) 2017 Elsevier B.V. All rights reserved.