Domain Orientated Nanoparticle Exsolution in Defect Engineered Stannate Perovskite

The exsolution, a new catalyst design method that has recently attracted attention, is to make metal nanoparticles through a single reduction heat treatment without any special process [1][2][3].This phenomenon is the specific metal component is seperated from oxide support (mainly perovskite-structured oxides such as ABO 3 ) to the surface of the support.The exsolution from the 'defectfree' perovskites has the limited number of the exsolved nanoparticles on the oxide surface [4].Recently, the exsolutions from the 'defect-structured' perovskites have received growing attention as an effective route for formation the nanoparticles [4][5][6].It is well known the density of catalyst nanoparticles is high in non-stoichiometric perovskites, leading to both A-site and oxygen deficiencies that make easier ion diffusion using the reduction by hydrogen [4][5][6].Herein, we propose the exsolution using the domain boundary in stannate perovskites (e.g., ASnO 3 ).Unlike titanate perovskties (ATiO 3 ), which has been mainly studied, stannate perovskite structure generally has a wide band gap and is a material that is manufactured as a transparent electrode due to low electron-phonon scattering [7].It is reported that, using these advantages, we demonstrate an unprecedentedly bimetallic exsolution in SrSnO 3 thin films, with domain structures.We revealed that the exsolved particles on the surface and inside of the Ni doped SrSnO 3 (SSNO) thin film were Ni-Sn alloy from a thermodynamic perspective and scanning transmission electron microscope (STEM)energy diepersive spectroscopy (EDS).Also, we confirmed the structure of the exsolved particles, Ni 3 Sn [Fm 3m], in atomic-scale structure analysis.In addition, we analyzed the planar defects enhance the exsolution using statistical analysis based on transmission electron microscopy (TEM) studies.Exsolution in SSNO film is dominant not only in the domain boundary but also in the specific domain.Based on density funtional theory (DFT) calculations, the calculated activation energy indicates that the Ni-Sn NPs preferentially exsolve on the specific domain due to the lower activation energy.Our design of the bimetallic exsolution using the planar defects in thin film proposes the effective approach to tailor catalytic particle density in nanostructure engineering.