Efficient cationic agents for exfoliating two-dimensional nickel oxide sheets

Two-dimensional catalysis is a very active research area in recent years. Water splitting catalysis may be achieved with the outstanding efficiency of the nickel oxyhydroxide (NiOOH) catalyst. NiOOH is a layered material, which constitutes of partially hydrogenated nickel oxide (NiO2) layers that are stacked together with the possible intercalation of water and electrolyte species. Recently, various studies have reported that NiO single sheets could be prepared and exhibit interesting photocatalytic properties. However, there is a lack of knowledge in developing efficient exfoliation processes adapted to such materials. We investigate with density functional theory the effect of intercalating cations, which is a strategy demonstrated recently to be efficient for exfoliation of various metal oxides. We observed that earth-alkali cations significantly increase the strength and amount of H bonds and inhibit exfoliation. Hence, we conclude that small alkali species are preferable for an exfoliation process of NiOOH.