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Nasrat Hannah Shudin, [Ryuto Eguchi](https://orcid.org/0009-0003-2859-6934), [Shigenori Ueda](https://orcid.org/0000-0001-9425-0614), Ankit Singh, [Ayako Hashimoto](https://orcid.org/0000-0002-1985-7667), [Hideki Abe](https://orcid.org/0000-0002-8392-7586)

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[A heteroepitaxial interface of Pt//CeO<sub>2</sub> nanoparticles for enhanced catalysis of the oxygen reduction reaction (ORR)](https://mdr.nims.go.jp/datasets/3f065fce-180d-4930-9fcc-a230d4392cc7)

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A heteroepitaxial interface of Pt//CeO2 nanoparticles for enhanced catalysis of the oxygen reduction reaction (ORR)Journal ofMaterials Chemistry ACOMMUNICATIONOpen Access Article. Published on 21 February 2025. Downloaded on 8/22/2025 8:38:07 AM.  This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence.View Article OnlineView Journal  | View IssueA heteroepitaxiaaNational Institute for Materials Science, NJapan. E-mail: ABE.Hideki@nims.go.jp; HasbGraduate School of Science and EngineerinSaitama 338-8570, JapancUniversity of Tsukuba, 1-1-1 Tennodai, Tsu† Electronic supplementary informahttps://doi.org/10.1039/d4ta07380kCite this: J. Mater. Chem. A, 2025, 13,9660Received 16th October 2024Accepted 16th February 2025DOI: 10.1039/d4ta07380krsc.li/materials-a9660 | J. Mater. Chem. A, 2025, 13,l interface of Pt//CeO2nanoparticles for enhanced catalysis of the oxygenreduction reaction (ORR)†Nasrat Hannah Shudin,ab Ryuto Eguchi,ac Shigenori Ueda, a Ankit Singh,aAyako Hashimoto *ac and Hideki Abe *abMetal-oxide nanocomposites (MONs) have garnered significantinterest in catalysis due to their excellent performance in variouschemical reactions. A key focus of research on MONs is the hetero-epitaxial metal-oxide interface, which is known to serve as a highlyactive catalytic center. In this report, we demonstrate that nanometer-sized MONs with heteroepitaxial interfaces can be engineered toexhibit enhanced catalytic performance owing to their strong inter-facial effects. Specifically, a MON material composed of platinum (Pt)and cerium dioxide (CeO2), denoted as Pt//CeO2, can be obtained byexposing graphene-supported precursor Pt5Ce alloy nanocrystals(Pt5Ce/graphene), which are synthesized by the pyrolytic dissociationof chloroplatinic acid (H2PtCl6) and cerium trichloride (CeCl3) ina hydrogen-containing atmosphere, to a gas mixture of carbonmonoxide (CO) and oxygen (O2) at elevated temperatures. Trans-mission electron microscopy (TEM) observations revealed a sharpheteroepitaxial interface between Pt(110) and CeO2(110) planes withinthe Pt//CeO2 material. This nanometer-sized heteroepitaxial interfaceshowed superior catalytic activity of Pt//CeO2 compared to carbon-supported Pt and large-grained Pt//CeO2 bulk catalysts for theoxygen reduction reaction (ORR) in basic media.1 IntroductionCatalysts play a crucial role in the economy, with approximately90% of chemical manufacturing processes worldwide relying onhigh-performance catalysts. Among them, heterogeneousnanocatalysts comprising metal-oxide nanocomposites (MONs)are widely used due to their enhanced performance comparedto their bulk counterparts.1–4 The enhanced catalytic perfor-mance of MONs is widely attributed to strong interfacial effectsthat improve electronic transfer and atomic exchanges at theamiki 1-1, Tsukuba, Ibaraki 305-0044,himoto.Ayako@nims.go.jpg, Saitama University, 255 Shimo-Okubo,kuba, Ibaraki 305-8577, Japantion (ESI) available. See DOI:9660–9664metal-oxide interface.5–9 The interfacial effects are particularlystrengthened at the heteroepitaxial interface, where a pair of themetal-oxide phases is conjugated sharing one or more crystalaxes. This heteroepitaxial interface with fewer atomic defectsand lattice-mismatch distortions facilitates charge and atomictransfers across the interface, further improving their catalyticperformance.10–12Heterogeneous catalysts comprising MONs are typicallysynthesized as nanoparticles smaller than 100 nanometers tomaximize the exposure of active sites for catalysis, usingconventional wet chemistry processes involving impregnationmethods or co-precipitation methods.13,14 In both methods, thebuilding blocks for the desired MON nanoparticles, consistingof small molecules and/or nanoparticles, are initially dissolvedor highly dispersed in a solvent to form a solution. The solutionis then dried, and the resulting solid sediment is typicallyheated in a controlled atmosphere to produce the desired MONnanoparticles.15–17 However, a technical challenge arises insynthesizing MON nanoparticles with a catalytically activemetal-oxide heteroepitaxial interface via wet chemistryapproaches where these methods oen yield randomly orientedheterointerfaces rather than the desired atomically orientedheteroepitaxial interfaces.We propose here a hybrid approach for synthesizing MONnanoparticles with metal-oxide heteroepitaxial interfaces. Gra-phene nanoplatelets are dispersed in an aqueous solutioncontaining chloroplatinic acid (H2PtCl6) and cerium trichloride(CeCl3), and subsequently dried to form a solid-state sediment.This sediment is then heated in a stream of hydrogen (H2) andargon (Ar) gases at 900 °C to precipitate Pt5Ce alloy nanocrystalson the surface of graphene nanoplatelets, yielding graphene-supported Pt5Ce nanocrystals. The Pt5Ce nanocrystals arefurther treated in a gas mixture of carbon monoxide (CO) andoxygen (O2) at 600 °C to selectively oxidize Ce atoms, formingthe desired Pt–CeO2 MON nanoparticles with a heteroepitaxialinterface (Pt//CeO2). Transmission electron microscope (TEM)observations reveal that the Pt metal and CeO2 phases of the Pt//CeO2 nanoparticles contact at a heteroepitaxial interface.This journal is © The Royal Society of Chemistry 2025http://crossmark.crossref.org/dialog/?doi=10.1039/d4ta07380k&domain=pdf&date_stamp=2025-03-28http://orcid.org/0000-0001-9425-0614http://orcid.org/0000-0002-1985-7667http://orcid.org/0000-0002-8392-7586https://doi.org/10.1039/d4ta07380khttp://creativecommons.org/licenses/by-nc/3.0/http://creativecommons.org/licenses/by-nc/3.0/https://doi.org/10.1039/d4ta07380khttps://pubs.rsc.org/en/journals/journal/TAhttps://pubs.rsc.org/en/journals/journal/TA?issueid=TA013014Fig. 1 Schematic of the synthesis route. (a) The materials, (b)impregnation of molecular precursors over graphene nanoplatelets,(c) development of precursor alloy Pt5Ce nanocrystals, and (d)formation of Pt//CeO2 nanoparticles through promoted nanophaseseparation of Pt5Ce nanoparticles. The (110) planes of Pt and CeO2 areepitaxially oriented.Communication Journal of Materials Chemistry AOpen Access Article. Published on 21 February 2025. Downloaded on 8/22/2025 8:38:07 AM.  This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence.View Article OnlineCatalytic tests for the oxygen reduction reaction (ORR) inaqueous electrolytes have further demonstrated that the Pt//CeO2 nanomaterial exhibits superior ORR activity compared tothe bulk counterpart, Pt//CeO2 bulk catalyst. This enhancementis attributed to strengthened interfacial effects at the hetero-epitaxial interface. The ndings of this study highlight thesimple approach in obtaining a heteroepitaxial interface innanomaterials via oxidation-triggered nanophase separation.2 Materials and methods2.1 Synthesis of Pt5Ce/graphene nanoplateletsPt5Ce nanocrystals supported on graphene nanoplatelets havebeen synthesized via a two-step approach: impregnation fol-lowed by hydrogen reduction. In the rst step, chloroplatinicacid hexahydrate (H2PtCl6$6H2O; Sigma-Aldrich) and cerium(III)chloride heptahydrate (CeCl3$7H2O; Kishida Chemical) wereused as precursors. An aliquot of 100 mg graphene nano-platelets (Sigma-Aldrich) and 50 ml ultrapure water were addedas the support material. The mixture was placed in a sealed100 ml round bottom ask and sonicated with a magneticstirrer overnight. This was followed by sonication in a bathsonicator for one hour. The mixture was then transferred toa beaker and placed in an oil bath to dry using the double bowlmethod. In the second step, the dried powder was placed ona graphite boat and transferred into a glass tube for hydrogenreduction. A 5% H2/Ar gas mixture was supplied, and thereaction was conducted at 900 °C to obtain Pt5Ce nanocrystalssupported on graphene nanoplatelets.2.2 Synthesis of Pt5Ce bulkThe Pt5Ce bulk sample was prepared to explore the effect ofdimensionality on catalytic performance. Pt5Ce alloy wasprepared by melting Pt and Ce metals at a mole ratio of 5 : 1using an arc torch in an argon environment.5 The obtainedingot was subsequently crushed and sieved to collect particleswith an average size of approximately ∼50 mm.2.3 Phase separation in a CO–O2 gas environmentThe graphene-supported Pt5Ce nanocrystals were placed ina ceramic crucible and heated at 600 °C in a stream of a mixedgas of CO and O2 (CO : O2= 2 : 1 by volume ratio) for 1 minute toinduce phase separation of Pt5Ce, forming the desired Pt//CeO2nanoparticles. A similar procedure was applied to the bulkPt5Ce alloy but extended to 12 hours, ensuring complete phaseseparation across its large grain size of 50 mm to produce the Pt//CeO2 bulk catalyst. Fig. 1 shows the schematic of the syntheticroute for Pt//CeO2 nanoparticles.2.4 CharacterizationThe synthesized Pt5Ce nanocrystals and Pt//CeO2 nanoparticlessupported on graphene nanoplatelets were characterized usingpowder X-ray diffraction (pXRD; PANalytical X'Pert Pro (Cu Ka,45 kV, 30 mA)) over a 2q range of 0° to 90°. The elementalcomposition and structure were observed using an aberration-corrected TEM (JEM-ARM200F, JEOL Ltd, Japan) with anThis journal is © The Royal Society of Chemistry 2025energy-dispersive X-ray spectrometer (EDS, JED-2300, JEOL Ltd,Japan). Hard X-ray photoemission spectroscopy (HAXPES) withsynchrotron radiation X-rays (5.95 keV) was performed atBL09XU of SPring-8 (Super Photon Ring 8, Hyōgo Prefecture,Japan).2.5 Electrochemical measurementsElectrochemical measurements were conducted using a three-electrode cell connected to a potentiostat (CHI 842B). A 5 mmdiameter glassy carbon electrode was used as the workingelectrode, an Ag/AgCl electrode was used as the reference elec-trode and a 1 mm diameter Pt electrode was used as the counterelectrode. A mixture of ultrapure water (370 mL), isopropanol(100 mL), Naon solution (5 mL), and the catalyst powder (2.5 mgPt content) was prepared and sonicated to obtain ink, whichwas subsequently dropped onto the working electrode. Theloading weight of the catalysts was approximately 0.0316 mgmm−2 over the glassy carbon electrode. Electrochemical testswere carried out in 0.1 M KOH solution at room temperature.The electrolyte was rst purged with Ar gas for 30 minutes, andcyclic voltammetry (CV) was conducted at a scanning rate of 20mV s−1. The electrolyte was later purged with O2 gas for30 minutes, and linear sweep voltammetry (LSV) for the ORRwas conducted at a scanning rate of 1 mV s−1.3 Results and discussion3.1 Nanoparticles of Pt5Ce and Pt//CeO2 supported ongraphene nanoplateletsThe pXRD pattern in Fig. 2a(i) represents Pt5Ce nanocrystalssupported on graphene nanoplatelets, which show peaks thatmatch closely with those of the atomically ordered Pt5Ce phase(ICDD 01-071-7052), indicating a successful synthesis of thedesired phase. Aer the post-treatment in a CO–O2 atmospherefor 1 minute, all the peaks corresponding to Pt5Ce diminished(Fig. 2a(ii)). Instead, the peaks for Pt are clearly observed, sug-gesting a phase transformation from Pt5Ce to Pt//CeO2 hascompleted within the exposure time.The HAXPES spectrum in the Pt 4f region for the Pt5Cenanocrystals is similar to that for Pt5Ce bulk in peak positionsand intensities (Fig. 2b). The Pt 4f emission peaks for the Pt//CeO2 nanoparticles show shis towards lower binding energycompared to the nanocrystals and bulk of Pt5Ce. The Pt 4fJ. Mater. Chem. A, 2025, 13, 9660–9664 | 9661http://creativecommons.org/licenses/by-nc/3.0/http://creativecommons.org/licenses/by-nc/3.0/https://doi.org/10.1039/d4ta07380kFig. 2 (a) pXRD of Pt5Ce nanocrystals and Pt//CeO2 nanoparticlessupported on graphene nanoplatelets. (b) HAXPES spectra of the Pt 4fregion (blue, red, green, and black curves represent Pt nanoparticles,Pt//CeO2 nanoparticles, Pt5Ce nanocrystals, and Pt5Ce bulk, respec-tively). (c) HAXPES spectra of the Ce 3d region (blue, red, green, andblack curves represent CeO2, Pt//CeO2 nanoparticles, Pt5Ce nano-crystals, and Pt5Ce bulk respectively).Fig. 3 (a) TEM image of a Pt5Ce nanocrystal. Inset shows a structuralmodel. The red and black spheres in the inset correspond to the Ceand Pt atoms, respectively. (b) HAADF-STEM image of a Pt5Ce nano-crystal. Inset shows a filtered STEM image, clearly showing crystalstructures. (c) STEM image and EDSmapping of the Pt5Ce nanocrystal.(d) STEM image and EDS mapping of Pt//CeO2 nanoparticles afterphase separation. The red and green regions in the mapping corre-spond to Pt and Ce, respectively.Journal of Materials Chemistry A CommunicationOpen Access Article. Published on 21 February 2025. Downloaded on 8/22/2025 8:38:07 AM.  This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence.View Article Onlinespectrum for the Pt//CeO2 nanoparticles is similar to that forpure Pt bulk instead of the Pt5Ce bulk, indicating the chemicalenvironment for Pt in the Pt//CeO2 nanoparticles is close to thatin pure Pt instead of Pt5Ce. The HAXPES spectrum in the Ce 3dregion for the Pt//CeO2 is similar to that for pure CeO2, unlikeany of the spectra for the nanocrystals and bulk Pt5Ce, indi-cating that the Ce atoms in Pt//CeO2 are situated in a similarenvironment in pure CeO2 instead of Pt5Ce (Fig. 2c). There arerecognized Ce3+ 3d emissions from the nanocrystals and bulkPt5Ce at 884.5 and 903.8 eV, which are absent in the Ce 3dspectrum for the Pt//CeO2 nanoparticles and pure CeO2. Ce inPt5Ce bulk and nanocrystals primarily exhibits photoelectronpeaks at binding energy positions corresponding to Ce3+species, whereas the Ce in Pt//CeO2 and CeO2 primarily showspeaks at binding energy positions corresponding to Ce4+species. However, in the case of Pt5Ce nanocrystals, photoelec-tron peaks corresponding to Ce4+ species are also observed.These peaks most likely originated from an impurity containingCe4+ within the Pt5Ce nanocrystals. (see ESI Table S1†).Summarizing the results of pXRD and HAXPES, we concludethat the Pt5Ce nanocrystals were fully phase-separated into thePt//CeO2 nanoparticles by the atmosphere treatment.Pt5Ce nanocrystals with a size of approximately 10 nm wereobserved using a TEM and a high-angle annular dark-eld(HAADF) scanning TEM (STEM), as shown in Fig. 3a and b,respectively. Elemental mapping with an EDS in Fig. 3c showsspatially overlapped regions of Pt and Ce, conrming thesuccessful synthesis of the desired Pt5Ce nanocrystals. ESIFig. S1† shows the corresponding Fast Fourier Transformation(FFT) patterns and the calculated interplanar distance furtherconrmed Pt5Ce nanocrystals. STEM-EDS in Fig. 3d show thefull phase separation of Pt5Ce nanocrystals into Pt//CeO2nanoparticles, showing a clear contrast between Pt and Ceregions aer exposure to an oxidative atmosphere containingO2. FFT patterns and EDS spectra in ESI Fig. S2† show areas9662 | J. Mater. Chem. A, 2025, 13, 9660–9664corresponding to Pt and CeO2 phases further proving that phaseseparation has completed. Note that a longer duration of 12hours was required for the bulk Pt5Ce to achieve completephase separation (see a cross-sectional STEM image of the fullynanophase-separated Pt//CeO2 bulk material, ESI Fig. S3†).Oxygen species from the atmospheric O2 likely need more timeto diffuse into the inner regions of the Pt5Ce bulk alloy, whichexplains the extended exposure time to ensure full phaseseparation.3.2 Heteroepitaxial interface of nanosized Pt//CeO2supported on graphene nanoplateletsAn epitaxial interface was observed in the heterostructure of thePt//CeO2 nanoparticles, as shown in Fig. 4a. All the Pt//CeO2nanoparticles exhibited an asymmetrical structure with sharpfacets (see ESI Fig. S4†). Phase separation initiated by thespontaneous oxidation of the oxyphilic component, in this case,Ce, resulted in distinct regions of Pt and CeO2.18 The white linesin Fig. 4a highlight the crystal facets and lattice planes of the Ptand CeO2 phases. The congurational relationship between thetwo phases was veried from the FFT patterns (Fig. 4b–d). ThePt- and CeO2 phases are both on the [01�1] zone axis, where thePt(111) plane is parallel to the CeO2(002) plane (see Fig. 1d).Fig. 4e depicts a congurational model of the Pt//CeO2 nano-particle along the [01�1] direction at the heterointerface. The Pt-and CeO2 phases are conjugated at their (01�1) planes to form anepitaxial interface, perpendicular to their [01�1] axes.This journal is © The Royal Society of Chemistry 2025http://creativecommons.org/licenses/by-nc/3.0/http://creativecommons.org/licenses/by-nc/3.0/https://doi.org/10.1039/d4ta07380kFig. 4 (a) TEM image of a Pt//CeO2 particle showing a heteroepitaxialinterface. (b–d) FFT patterns from the blue and red squares, and theinterface in (a), respectively, demonstrating the configurational rela-tionship between the Pt- and CeO2 phases. (e) Schematic illustratingthe epitaxial (110) interface between the Pt- and CeO2 phases.Fig. 5 (a) CV and (b) LSV measurements performed at 1200 rpm ina 0.1 M KOH solution, (c) LSV normalized ECSA and (d) schematicillustrations of the top view and side view of the Pt//CeO2 interface.The potential was referenced against an Ag/AgCl electrode and thenconverted to the values for the reversible hydrogen electrode (RHE) forbetter readability (see the ESI†).Communication Journal of Materials Chemistry AOpen Access Article. Published on 21 February 2025. Downloaded on 8/22/2025 8:38:07 AM.  This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence.View Article OnlineAnother congurational relationship, with a parallel relationbetween the Pt(111) plane and the CeO2(111) plane as a minorphase, was observed in other nanoparticles having larger grainsizes than 10 nm (ESI Fig. S4†). Note that, in contrast to thenanoparticle system, the epitaxial interface observed in the Pt//CeO2 bulk system solely showed a Pt(111)//CeO2(111) relation-ship.19 We attribute this difference in conguration to dimen-sion effects, where a larger rotational angle is necessary toaccommodate larger particle sizes, resulting in the Pt (111)//CeO2 (111) relationship.3.3 ORR catalytic activityFig. 5a shows the result of CV in Ar-saturated 0.1 M KOH. Theelectrochemical surface areas (ECSA) are evaluated as 9.0 m2 perg Pt for the Pt//CeO2 nanoparticles and 29.0 m2 per g Pt for thePt//CeO2 bulk catalyst from the area of the hydrogen desorptionvalley in CV curves (see ESI Fig. S5† for details on the ECSAevaluation). Fig. 5b shows the LSV proles for the ORR over thedifferent catalysts and Fig. 5c shows the LSV normalized ECSA.CV and LSV for the Pt5Ce nanocrystals and graphene nano-platelets are provided in ESI Fig. S6a–c.† The onset potential forthe Pt//CeO2 nanoparticles, +1.01 V vs. a reversible hydrogenelectrode (RHE), is more positive than those of the Pt//CeO2bulk catalyst, +0.91 V vs. RHE, and Pt5Ce nanocrystal, +0.93 V vs.RHE (Fig. 5c and S6c ESI†). This positive shi indicatesenhanced ORR catalytic activity of the Pt//CeO2 nanoparticlescompared to the bulk Pt//CeO2 catalyst and Pt5Ce nanocrystals.The related parameters are compared to electrochemical data ofa typically prepared CeO2-supported Pt catalyst from theThis journal is © The Royal Society of Chemistry 2025literature and provided in ESI Table. S2.† The onset potentialwas observed to be more positive for Pt(110)//CeO2(110) nano-particles compared to other CeO2-supported Pt catalysts whichis likely due to the stronger interfacial effect. We further con-ducted an electrochemistry test in 1.0 M KOH to evaluate theperformance of Pt(110)//CeO2(110) nanoparticles at differentelectrolyte concentrations (see ESI Fig. S6d and e†). LSV recor-ded in 1.0 M KOH in ESI Fig. S6e† shows that the onset potentialwas observed at +0.88 V vs. RHE. There is a shi from +1.01 V vs.RHE recorded in 0.1 M KOH. This is expected as by increasingthe molar concentration of KOH, the increased OH− concen-tration will disrupt oxygen absorption on the active surface. Thestability test performed in 0.1 M KOH (ESI Fig. S6f†) shows thatthe CV curve did not exhibit signicant changes aer repeatedcycles. This suggest that the heterointerface of Pt(110)//CeO2(110) remains stable throughout the cycle.Kinetics analysis of the ORR was performed using rotatingdisk electrode (RDE) voltammetry in O2 saturated 0.1 M KOH ata different rotating speed with a scanning rate of 1 mV s−1. Thecurrent density increases as the rotating speed increases from100 rpm to 1200 rpm due to the enhanced diffusion of reactants(see ESI Fig. S7a, c and e†). The corresponding K–L plots inFig. S7b, d and f† indicate the four-electron pathway for all thePt//CeO2 nanoparticles, Pt//CeO2 bulk catalyst and a carbon-supported Pt catalyst (Pt/C, Pt loading: 20 wt%; Fuel CellStore, Inc).The HAXPES spectrum in the Pt 4f region for the Pt//CeO2nanoparticles exhibits a 74 meV deep-level shi compared tothat of pure Pt bulk and the Pt//CeO2 bulk catalyst (see ESIFig. S8†). This shi is attributed to a strengthened interfacialeffect at the Pt(110)//CeO2(110) interface in the nanoparticles, asopposed to the Pt(111)//CeO2(111) interface in the bulk catalystas shown in the schematic image in Fig. 5d. This enhancedJ. Mater. Chem. A, 2025, 13, 9660–9664 | 9663http://creativecommons.org/licenses/by-nc/3.0/http://creativecommons.org/licenses/by-nc/3.0/https://doi.org/10.1039/d4ta07380kJournal of Materials Chemistry A CommunicationOpen Access Article. Published on 21 February 2025. Downloaded on 8/22/2025 8:38:07 AM.  This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence.View Article Onlineinterfacial effect causes a deep-level shi in the Pt core levels,along with the center of gravity of the Pt d-band in the nano-particles. Consequently, this deep-level shi in the Pt d-bandcan weaken the adsorption of intermediate species, such asOH− anions, near the Pt(110)//CeO2(110) interface.20,21 Thisweakening in the adsorption of reaction intermediates canoptimize the balance between mass transfer and electrontransfer, leading to the improved ORR activity of the Pt//CeO2nanoparticles.224 ConclusionsA nanometer-sized MON with an epitaxial interface, specicallyPt//CeO2 nanoparticles, has been successfully synthesized byutilizing the selective oxidation of precursor Pt5Ce nanocrystalssupported on graphene nanoplatelets.23 The spontaneousnanophase separation of Pt5Ce nanocrystals results in a (110)epitaxial interface between single-crystalline Pt and CeO2 pha-ses. The catalytic Pt//CeO2 nanoparticles exhibit superior ORRactivity compared to a carbon-supported Pt catalyst and bulkPt//CeO2 catalysts, due to strengthened interfacial effects at theepitaxial Pt(110)//CeO2(110) interface.Data availabilityElectrochemistry datasets for the catalytic performance test areavailable at https://doi.org/10.5281/zenodo.13888952.Author contributionsN. H. Shudin synthesized and characterized the nanoparticles.Microscopic observations were conducted by A. Hashimoto, R.Eguchi, and A. Singh. N. H. Shudin, H. Abe, and A. Hashimotowrote and edited the manuscript. All authors have read andapproved the published version of the manuscript.Conflicts of interestThe authors declare no conict of interest.AcknowledgementsThe HAXPES experiments were performed at BL09XU of SPring-8 with the approval of the Japan Synchrotron RadiationResearch Institute (JASRI) (Proposal No. 2024A1536). AHacknowledges the JST FOREST Program (Grant NumberJPMJFR213U) and JST PRESTO (Grant Number JPMJPR17S7) fornancial support. HA acknowledges the JSPS Grant-in-Aid forScientic Research (B) (KAKENHI) (Grant number 22H01799and 23K23067). This work was supported by “AdvancedResearch Infrastructure for Materials and Nanotechnology inJapan (ARIM)” of the Ministry of Education, Culture, Sports,Science and Technology (MEXT) (Grant numberJPMXP1224NM5122, JPMXP1224NM5255).9664 | J. Mater. Chem. A, 2025, 13, 9660–9664References1 T. W. Van Deelen, C. H. Mejia and K. P. Jong, Nat. Catal.,2019, 2, 955–970.2 M. A. Memon, Y. Jang, M. A. Hassan, M. Ajmal, H. Wang andY. Liu, Catalysts, 2023, 13, 1514.3 J. Zhang, J. Lian, Q. Jiang and G. Wang, Chem. Eng. J., 2022,439, 135634.4 X. Zhang, Y. Chen, X. Li, Y. Zhang, M. Li, Y. Yang, X. Sun,H. Wang and Y. Xiong, Catal. Small, 2021, 17(42), 2101573.5 Y. Wen, H. Abe, A. Hirata and A. Hashimoto, ACS Appl. NanoMater., 2021, 4, 13602–13611.6 Q. Fu, H. 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Lei, J.Hydrogen, 2018, 43, 12119–12128.This journal is © The Royal Society of Chemistry 2025https://doi.org/10.5281/zenodo.13888952http://creativecommons.org/licenses/by-nc/3.0/http://creativecommons.org/licenses/by-nc/3.0/https://doi.org/10.1039/d4ta07380k A heteroepitaxial interface of Pt//CeO2 nanoparticles for enhanced catalysis of the oxygen reduction reaction (ORR)Electronic supplementary information (ESI) available. See DOI: https://doi.org/10.1039/d4ta07380k A heteroepitaxial interface of Pt//CeO2 nanoparticles for enhanced catalysis of the oxygen reduction reaction (ORR)Electronic supplementary information (ESI) available. See DOI: https://doi.org/10.1039/d4ta07380k A heteroepitaxial interface of Pt//CeO2 nanoparticles for enhanced catalysis of the oxygen reduction reaction (ORR)Electronic supplementary information (ESI) available. See DOI: https://doi.org/10.1039/d4ta07380k A heteroepitaxial interface of Pt//CeO2 nanoparticles for enhanced catalysis of the oxygen reduction reaction (ORR)Electronic supplementary information (ESI) available. See DOI: https://doi.org/10.1039/d4ta07380k A heteroepitaxial interface of Pt//CeO2 nanoparticles for enhanced catalysis of the oxygen reduction reaction (ORR)Electronic supplementary information (ESI) available. See DOI: https://doi.org/10.1039/d4ta07380k A heteroepitaxial interface of Pt//CeO2 nanoparticles for enhanced catalysis of the oxygen reduction reaction (ORR)Electronic supplementary information (ESI) available. See DOI: https://doi.org/10.1039/d4ta07380k A heteroepitaxial interface of Pt//CeO2 nanoparticles for enhanced catalysis of the oxygen reduction reaction (ORR)Electronic supplementary information (ESI) available. See DOI: https://doi.org/10.1039/d4ta07380k A heteroepitaxial interface of Pt//CeO2 nanoparticles for enhanced catalysis of the oxygen reduction reaction (ORR)Electronic supplementary information (ESI) available. See DOI: https://doi.org/10.1039/d4ta07380k A heteroepitaxial interface of Pt//CeO2 nanoparticles for enhanced catalysis of the oxygen reduction reaction (ORR)Electronic supplementary information (ESI) available. See DOI: https://doi.org/10.1039/d4ta07380k A heteroepitaxial interface of Pt//CeO2 nanoparticles for enhanced catalysis of the oxygen reduction reaction (ORR)Electronic supplementary information (ESI) available. See DOI: https://doi.org/10.1039/d4ta07380k A heteroepitaxial interface of Pt//CeO2 nanoparticles for enhanced catalysis of the oxygen reduction reaction (ORR)Electronic supplementary information (ESI) available. See DOI: https://doi.org/10.1039/d4ta07380k A heteroepitaxial interface of Pt//CeO2 nanoparticles for enhanced catalysis of the oxygen reduction reaction (ORR)Electronic supplementary information (ESI) available. See DOI: https://doi.org/10.1039/d4ta07380k A heteroepitaxial interface of Pt//CeO2 nanoparticles for enhanced catalysis of the oxygen reduction reaction (ORR)Electronic supplementary information (ESI) available. See DOI: https://doi.org/10.1039/d4ta07380k A heteroepitaxial interface of Pt//CeO2 nanoparticles for enhanced catalysis of the oxygen reduction reaction (ORR)Electronic supplementary information (ESI) available. See DOI: https://doi.org/10.1039/d4ta07380k A heteroepitaxial interface of Pt//CeO2 nanoparticles for enhanced catalysis of the oxygen reduction reaction (ORR)Electronic supplementary information (ESI) available. See DOI: https://doi.org/10.1039/d4ta07380k A heteroepitaxial interface of Pt//CeO2 nanoparticles for enhanced catalysis of the oxygen reduction reaction (ORR)Electronic supplementary information (ESI) available. See DOI: https://doi.org/10.1039/d4ta07380k A heteroepitaxial interface of Pt//CeO2 nanoparticles for enhanced catalysis of the oxygen reduction reaction (ORR)Electronic supplementary information (ESI) available. See DOI: https://doi.org/10.1039/d4ta07380k