Supplementry Figure 1 Comprtive illustrtion of the steps required to decorte n oxide support AO with ctlyst prticles M through chemicl infiltrtion or in situ redox exsolution. () chemicl infiltrtion usully requires severl deposition nd therml tretment steps followed y reduction to produce the metl prticles M on the outer surfce of the support AO. () in in situ redox exsolution M is incorported in its ction form in the crystl lttice of AO nd exsolved in one step, upon reduction. c Supplementry Figure 2 Rietveld refinement nd corresponding crystl structure of L0.4Sr0.4Ni0.03Ti0.97O3-γ. () Rietveld refinement of the room temperture powder XRD pttern using I4/mcm ( 0 0 c - ) spce group, = = 5.5067 Å, c = 7.7852 Å. Rp = 6.67%, Rwp = 8.82%, Re = 7.77%, χ 2 = 1.29 () Three-dimensionl overview of the crystl structure. (c) Projection long the z xis showing out of phse tilting long this xis.
L Sr Ti Supplementry Figure 3 XPS spectr of L, Sr nd Ti for the smples indicted in Fig. 1,, c, d. Blck lines represent experimentl dt, grey lines the ckground, ornge lines Ti 4+ pek fit, nd lue lines Ti 3+ pek fit. Supplementry Figure 4 () TEM imge of the ntive surfce of L0.4Sr0.4Ni0.03Ti0.97O3-γ similr to the one displyed in Fig. 1, in the vicinity of n exsolved prticle; scle r 1 nm. () Schemtic tomic model of the structure of L0.4Sr0.4Ni0.03Ti0.97O3-γ going from ulk to the ntive surfce sed on the XPS surfce stoichiometry presented in Fig. 1,.
c Supplementry Figure 5 () Cleved porous L0.52Sr0.28Ni0.06Ti0.94O3 smple reveling ulk-like surfces longside the lredypresent ntive surfces; scle r, 20 μm. () detil from the cleved ulk surfce region of L0.4Sr0.4Ni0.03Ti0.97O3-γ smple with microstructure similr to smple () fter reduction (5% H2/Ar, 900 C, 20 h); scle r, 1 μm. (c) detil of smple () fter reduction (5% H2/Ar, 900 C, 12 h) showing no prticles grow on the ntive surfces in this cse, lthough numerous prticles grow on the cleve surfce; scle rs, 1 μm.
c d Supplementry Figure 6 Fcet ngle mesurements y 3D AFM surfce reconstruction for the ntive surfce shown in Fig. 1. The reconstructed 3D imge is shown in Fig. 1e.
c Supplementry Figure 7 B-site ction diffusion in perovskites. () 3D view of the curved migrtion pth in the (011) plne. () Projection from the top, [001]. (c) Projection in the direction of diffusion, [100]. Adpted from reference 1.
L Sr Ti Supplementry Figure 8 XPS spectr corresponding to Fig. 1g. Blck lines represent experimentl dt, grey lines the ckground, ornge lines Ti 4+ pek fit, nd lue lines Ti 3+ pek fit.
c Supplementry Figure 9 Prticle nlysis on the surfce shown in Fig. 1d. () SEM imge corresponding to Fig. 1d. () Ni prticle mpping nd contour extrcted with ImgeJ from Supplementry Fig. 9. (c) Prticle size distriution clculted with ImgeJ sed on Supplementry Fig. 9. Scle rs, 1 μm. Supplementry Figure 10 Comprison etween () norml perovskite crystl structure nd () projection down c of hexgonl tungsten ronze ( high A-site deficient vrint of the perovskite lttice) showing units coupling A-site vcncies with the smller L 3+ ion through B site octhedron. This suggests possile defect unit tht could potentilly couple L, Ni nd n A-site vcncy consistent with the coopertive movement of L nd Ni s tungsten ronzes.
Supplementry Figure 11 Exsolved Ni prticles from the ntive surfce of L0.46Sr0.34Ni0.03Ti0.97O3 fter reduction in pure H2 t 900 C for 2.5 hours. Scle rs, 1 μm. Supplementry Figure 12 Prticle shpe nd emedding highlighted on the TEM imge shown in Fig. 3. Scle r, 10 nm.
c d e f Supplementry Figure 13 Orienttion reltionship etween exsolved prticles nd prent perovskite for the smple in Fig. 3. (), () nd (c) show selected re electron diffrction (SAED) ptterns contining reflections from the perovskite nd nickel prticle. The ptterns correspond to the [001], [112] nd [011] zone xes of the perovskite oxide, in ech cse nickel reflections corresponding to the sme zone xis re lso visile, s shown in (d), (e), (f), respectively. The presence of these reflections is consistent with the orienttion reltionship [010]P//[010]Ni (001)P//(001)Ni which we hve previously oserved in other system we investigted, ut which hve higher Ni sustitution level (L0.8Ce0.1Ti0.6Ni0.4O3, see reference 2 ), perhps suggesting tht exsolution generlly occurs epitxilly with respect to the prent perovskite. However, in this cse, not ll expected nickel reflections re visile. The sence of these reflections cn e ttriuted to the very smll volume of the nickel prticles, the sence of higher intensity low index reflections close to the centre of the diffrction pttern due to the fce centred cuic structure of nickel nd the possiility of vrition from the idel orienttion reltionship. Of the eight to ten nickel prticles present in the electron trnsprent region of the TEM smple, reflections consistent with this orienttion reltionship could only e otined for two. Whether this is due to em dmge from imging or smple preprtion or the sence of this specific orienttion reltionship could not e determined. c d e Supplementry Figure 14 AFM imges nd height profiles of: () Ni prticles exsolved from L0.4Sr0.4Ti0.97Ni0.03O3-δ (900 C, 5 h, dry H2); () smple () fter etching (HNO3) t room temperture for 20 minutes; (c) Ni prticles from Ni nitrte solution deposition (900 C, 6 h, dry H2); (d) Smple (c) fter etching t room temperture overnight showing now ovious pits; (e) further etching t 70 C for 2 hours. Scle rs, 500 nm.
c d Supplementry Figure 15 () ~20 nm Ni prticles formed y infiltrtion on L0.4Sr0.4TiO3. () 30-100 nm Ni prticles prepred y vpour-deposition on L0.4Sr0.4TiO3 (the inset shows the prticle size distriution). (c) 80-90 nm size Ni prticles exsolved from L0.52Sr0.28Ni0.06Ti0.94O3 (5% H2/Ar, 1000 C, 12 h; the inset shows the prticle size distriution). (d) Flse colour microgrph of smple (c) fter coking experiment showing prticle uplifting which leves ehind corresponding empty sockets. Scle rs, 1 μm (, c), 100 nm (, d). Supplementry Tle 1 Quntifiction of the XPS spectr in Supplementry Fig. 8 which ws used to derive the dt plotted in Fig. 1g. Pek res re given in ritrry units s clculted y CsXPS softwre nd lso include trnsmission function nd men free pth contriutions. RSF represents the corresponding reltive sensitivity fctor. L 3d5/2 Sr 3d5/2,3/2 Ti 2p3/2,1/2 Atomic rtios Ti 4+ 2p3/2 Ti 3+ 2p3/2 Temperture ( C) 20 600 700 800 900 Pek re (.u.) 6969.6 6832.1 7758.3 8888.2 8172.9 RSF 5.473 5.473 5.473 5.473 5.473 Pek re/rsf (.u.) 1273.5 1248.3 1417.6 1624.0 1493.3 Atomic % 35.2 34.9 35.4 36.8 38.2 Pek re (.u.) 1261.5 1258.3 1372.7 1426.5 1172.5 RSF 1.843 1.843 1.843 1.843 1.843 Pek re/rsf (.u.) 684.5 682.7 744.8 774.0 636.2 Atomic % 18.9 19.1 18.6 17.6 16.3 Pek re (.u.) 3321.7 3283.2 3676.5 4026.3 3561.4 RSF 2.001 2.001 2.001 2.001 2.001 Pek re/rsf (.u.) 1660.0 1640.8 1837.3 2012.1 1779.8 Atomic % 45.9 45.9 45.9 45.6 45.5 L/Ti 0.77 0.76 0.77 0.81 0.84 Sr/Ti 0.41 0.42 0.41 0.38 0.36 (L+Sr)/Ti 1.18 1.18 1.18 1.19 1.20 Pek re (.u.) 2032.2 2022.0 2214.0 2396.2 2099.0 RSF 2.001 2.001 2.001 2.001 2.001 Pek re/rsf (.u.) 1015.6 1010.5 1106.4 1197.5 1049.0 Pek re (.u.) 0.0 19.0 57.4 110.2 135.0 RSF 2.001 2.001 2.001 2.001 2.001 Pek re/rsf (.u.) 0.0 9.5 28.7 55.1 67.5 Ti 3+ /(Ti 3+ +Ti 4+ ) 0.00 0.01 0.03 0.04 0.06
Supplementry Note 1 The verge numer of Ni toms contined y the prticles shown in Supplementry Fig. 9, clculted sed on the prticle distriution shown in Supplementry Fig. 9d is given y: ( ) (1) Where: is Ni metl density, is the tomic weight of Ni, is Avogdro s numer, is the frction of prticles hving dimeter ccording to Supplementry Fig. 9d. The verge numer of Ni toms in prllelepiped perovskite volume of length width nd depth is given y: (2) Where is the pseudo-cuic perovskite unit cell prmeter nd is Ni stoichiometry in the perovskite. The verge depth of virtul perovskite prllelepiped contining imge shown in Supplementry Fig. 9: toms over n re equl to the one in the ( ) (3) In conclusion, for the microgrph shown in Supplementry Fig. 9, Ni toms pper to e depleted from ~88 nm deep eneth the surfce in order to ccount for the mount of Ni oserved on the surfce in the form of metl prticles. The verge numer of L toms in prllelepiped perovskite volume of length width nd depth is: (4) Where is L stoichiometry in the perovskite. The numer of L toms enriching the surfce during reduction through diffusion from the ulk, over n re equl to the one in Supplementry Fig. 9 is given y: ( ) (5) Where is L surfce stoichiometry in the perovskite fter reduction (from XPS, Fig. 1d) nd is L surfce stoichiometry in the perovskite prior to reduction (from XPS, Fig. 1), lso ssuming the surfce is thick (typicl XPS detection depth): (6) ( ) ( ) In conclusion, the mount of Ni metl contined in the surfce prticles shown in Supplementry Fig. 9, Ni toms, is of the sme order of mgnitude s the numer of L toms tht diffused from the ulk, L toms.
Supplementry references 1. De Souz, R. A., Islm, M. S. & Ivers-Tiffée, E. Formtion nd migrtion of ction defects in the perovskite oxide LMnO3. J. Mter. Chem. 9, 1621 1627 (1999). 2. Negu, D., Tsekours, G., Miller, D. N., Ménrd, H. & Irvine, J. T. S. In situ growth of nnoprticles through control of non-stoichiometry. Nt. Chem. 5, 916 923 (2013).