Ce Substitution Research Articles

Magnetocaloric effect in La1−zCez(Fe0.88−yMnySi0.12)13 with tunable, low transition temperature in high magnetic fields

Cryogenic magnetic refrigeration becomes more and more important nowadays, especially for the liquefaction of gases such as hydrogen. In this study, we have synthesized La1−zCez(Fe0.88−yMnySi0.12)13 samples and investigated their magnetic and magnetocaloric properties in order to assess their potential for cryogenic applications. By adjusting the Mn and Ce content and adding excess rare-earth elements, the first-order ferromagnetic transition was lowered from 200 to 40 K and the adiabatic temperature change of the samples was measured directly using pulsed magnetic fields. The sample with the lowest transition temperature still showed a significant adiabatic temperature change in magnetic fields up to 10 T, with an increasingly stronger first-order transition observed in samples with higher Ce substitution. In addition, we synthesized spherical powder with diameters between 20 and 120 μm using ultrasonic atomization while maintaining the magnetic transition, which is a promising starting material for future additive manufacturing of magnetocaloric materials.

Synergistic effect of isomorphism substitution of double metal Ce and Ti in Y zeolite by post-synthesis treatment for efficient removal of dye contamination

Synergistic effect of isomorphism substitution of double metal Ce and Ti in Y zeolite by post-synthesis treatment for efficient removal of dye contamination

Enhanced temperature range and stability in LaAlO3 NTC ceramics through Ce-Nb codoping

Negative temperature coefficient (NTC) thermistors have garnered increased attention due to their high sensitivity, low thermal inertia, and cost-effectiveness. However, their practical application is significantly constrained by a limited temperature range and poor stability. In this study, a series of Ce-Nb codoped LaAlO3 ceramics were synthesized using the traditional solid-state reaction method, and their unique electrical properties as NTC thermistors were examined. XRD analysis reveals that Ce-Nb codoping induces lattice distortion in the LaAlO3 ceramics. HAADF-STEM shows that Ce replaces La at A-sites, while Nb substitutes for Al at B-sites. XPS indicates that the substitution of Ce4+ for La3+ and Nb5+ for Al3+ facilitates the formation of oxygen vacancies and enhances the number of free carriers. Electrical resistance and UV measurements demonstrate that increasing the Ce and Nb doping levels improves carrier mobility and reduces the band gap of LaAlO3. These modifications significantly enhance the electrical performance and extend the temperature range to 298 K –1773 K when the Ce doping level is 0.2 and the Nb doping level is 0.1. Additionally, aging tests indicate that Ce-Nb co-doping reduces the aging drift of LaAlO3 to 0.38 % after 500 h of aging at 1273 K. This novel Ce-Nb codoped LaAlO3 ceramic, with its broad temperature range and superior stability, shows significant potential for application in NTC thermistors.

Effect of Equivalent La and Ce Substitution for Y on the Structure and Properties of A2B7-Type La–Y–Ni-Based Hydrogen Storage Alloys

Effect of Equivalent La and Ce Substitution for Y on the Structure and Properties of A₂B₇-Type La–Y–Ni-Based Hydrogen Storage Alloys

Enhancing structural strength and microwave dielectric properties of the Ba4(Sm1-xCex)9.33Ti18O54 ceramics

Herein, microwave dielectric ceramics of the Ba4Sm9.33Ti18O54 ceramics are substituted at A sites by partially replacing Sm at A1 sites with Ce, and the effects of ionic substitution at A sites on ceramic crystal structure and microwave dielectric properties are investigated. The Ba4(Sm1-xCex)9.33Ti18O54 (BSCT) ceramics prepared through the solid phase method has a typical tungsten–bronze structure, and its lattice spacing increases gradually with the increase in Ce content x. This increase is reflected in the increase in the cell volume and growth of ceramic grains. However, the excess Ce after Ce content exceeds 0.25 leads to the growth of ceramic grains and increase in porosity between grains, which in turn increases the dielectric loss of the ceramic. Under optimal sintering conditions, the ceramic crystal has a maximum atomic packing density of x = 0.25, which corresponds to its most stable structural properties, and the highest Q × f value of 9013 GHz. Raman spectroscopy results indicate that in titanium oxygen octahedrons, an increase in Ce substitution can effectively weaken the bending and tensile vibration intensities of titanium oxygen bonds, further enhancing structural strength.

Synergistic effects of liquid phase sintering and B-site substitution to enhance proton conductivity of BaZr0.1Ce0.7Y0.1Yb0.1O3-δ for protonic ceramic fuel cell

This paper is dedicated to improving the sintering and conductivity of BaZr0.1Ce0.7Y0.1Yb0.1O3-δ (BZCYYb) by adding ZnO–CuO dual-sintering aids. The synergistic effects of liquid-sintering of Zn and B-site substitution of Cu on the sinterability and proton conductivity of BZCYYb are systematically investigated. X-ray diffraction (XRD) analysis of BZCYYb after addition of ZnO–CuO (BZCYYb-Zn-Cu) confirms the complete perovskite phase formation without any secondary phase. The substitution of Ce4+ (0.87 Å) with Zn2+ (0.74 Å) or Cu2+ (0.73 Å) induces a shift in XRD diffraction peak to higher angle due to a decrease in lattice constant. Energy dispersive X-ray spectroscopy analysis indicate a distinct distribution of Zn primarily at the grain boundaries, while Cu is predominantly located within the grains of BZCYYb-Zn-Cu. The addition of ZnO–CuO into BZCYYb results in a denser microstructure with larger average grain size. Furthermore, the substitution of Ce4+ by Cu2+ increases the concentration of oxygen vacancies and reduces activation energy. For BZCYYb-Zn-Cu, the proton conductivity reaches 4.52 × 10−2 S/cm at 750 °C, approximately 3 times higher than that of BZCYYb. This enhancement can be attributed to the synergistic effects of larger average grain size resulting from liquid phase sintering of Zn, low active energy, and high concentration of oxygen vacancies arising from Cu B-site substitution. BZCYYb-Zn-Cu is used as the electrolyte for anode support SOFC, and the single cell exhibits remarkable electrochemical performance and excellent stability in H2 fuel. This research establishes a crucial theoretical foundation for the preparation and performance evaluation for large-size protonic ceramic cell.

Substitution of Ce4+ for ionic at both A/B sites greatly improves the microwave responses of (Sr0.9Ca0.1)1/2La1/2Al1/2Ti1/2O3 perovskite ceramics

In this paper, (Sr0.9Ca0.1)1/2La1/2Al1/2Ti1/2O3-x wt.% CeO2 (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5) ceramics were synthesized via solid state reaction. The effects of Ce4+ doping on microstructure and microwave dielectric properties were studied. All samples crystallized as perovskite single-phase. Ce4+ substitution for La3+ occurred at the A site for 0 < x ≤ 0.4, and for Ti4+ at the B site for 0.4 ≤ x ≤ 0.5. Oxygen vacancy concentration was linked to substitution sites, decreasing for x ≤ 0.3 and increasing for x ≥ 0.4, as shown by XPS analysis. The quality factor was influenced by oxygen vacancies, grain size, and packing fraction. Bonding valence and oxygen octahedral distortion affected the temperature coefficient of resonant frequency. At x = 0.4 and sintered at 1570 °C, the ceramics showed excellent properties: εr = 38.83, Q×f = 54058 GHz, τf = 2.137 ppm/°C, making it a promising low-loss dielectric ceramic for microwave communication applications.

DBD plasma assisted synthesis of Ce-MIL-88B(Fe) with electron-rich CUSs and mixed-valent bimetallic sites for enhanced photo-Fenton performance

Iron-based metal-organic frameworks (Fe-MOFs) are regarded as a kind of prospective catalysts for photo-Fenton process. However, high cost, rate-limiting Fe(III)/Fe(II) circulation and limited metal sites greatly restricted the application of Fe-MOFs in photo-Fenton system. Ce-MIL-88B(Fe) was synthesized with mixed-valent bimetallic sites and tunable coordinated unsaturated metal sites (CUSs) using dielectric barrier discharge (DBD) plasma with waste PET. The incorporation of Ce altered the structure and the electron aggregation, as well as induced structural defects. Ce substitution in Fe-MOFs induced the regulation of the ratio of Fe ions and formation of electron-rich CUSs, which were beneficial for the rapid adsorption and activation of H2O2, thus enhancing the photo-Fenton performance. The effect of reaction conditions on TC degradation was investigated by response surface methodology (RSM) combined with Box-Behnken design (BBD). This study demonstrates a new perspective on the construction of bimetallic MOFs for the photo-Fenton system.

Unraveling the hydrogen storage features of A5B19-type La0.67R0.05Y0.13Mg0.15Ni3.70Al0.15 (R = La, Ce, Nd, Sm, Gd) alloys

In this work, we demonstrate the substitutional effect of typical A-side elements of Ce, Nd, Sm, and Gd on the crystal structure and hydrogen storage properties of an A5B19-type La0.72Y0.13Mg0.15Ni3.70Al0.15 alloy aiming to provide further design for enhancing the commercial application of RE–Mg–Ni-based alloys for nickel-metal hydride (Ni/MH) batteries. The results reveal that Ce substitution significantly improves discharge ability at higher rates, delivering 283.3 mAh g−1 at 5C and 183.7 mAh g−1 at 10C, which present increases of 16.7% and 44.0% over the unsubstituted alloy, respectively. Additionally, Sm substitution effectively extends the alloy's cycling life, retaining 66.2% capacity after 500 cycles, representing a 14.4% increase compared to the original alloy. Moreover, the substitution of Nd increases the hydrogen storage capacity from 1.23 wt% to 1.50 wt%, while Gd reduces plateau hysteresis and slope factor during (de)hydrogenation.

Effect of Pressure on Ce-Substituted Nd-Fe-B Hot-Deformed Magnets in the Hot-Pressing Process.

With the increasing demand for Nd-Fe-B magnets across various applications, the cost-effective substitution of Ce has garnered significant interest. Many studies have been conducted to achieve the high magnetic properties of Nd-Ce-Fe-B hot deformation magnets in which Nd is replaced with Ce. We propose a method to improve magnetic properties of the Ce-substituted Nd-Ce-Fe-B hot-deformed magnets by optimizing the hot-pressing process. This study investigates the microstructure and properties following hot deformation of Ce-substituted Nd-Ce-Fe-B magnets fabricated at a constant temperature and different pressures (100-300 MPa) during the hot-pressing process. The results highlight the influence of pressure from previous hot-pressing processes on grain alignment and microstructure during hot deformation. Magnets subjected to hot pressing at 200 MPa followed by hot deformation achieved superior magnetic properties, with Hci = 8.9 kOe, Br = 12.2 kG, and (BH)max = 31 MGOe with 40% of Nd replaced with Ce. Conversely, precursors prepared at 100 MPa exhibited low density due to high porosity, resulting in poor microstructure and magnetic properties after hot deformation. In magnets using precursors prepared at 300 MPa, coarsened grains and a condensed h-RE2O3 phase were observed. Incorporating Ce into the magnets led to insufficient formation of RE-rich phases due to the emergence of REFe2 secondary phases, disrupting grain alignment and hindering the homogeneous distribution of the RE-rich phase essential for texture formation. Precursors prepared under suitable pressure exhibited uniform distribution of the RE-rich phase, enhancing grain alignment along the c-axis and improving magnetic properties, particularly remanence. In conclusion, our findings present a strategy for achieving the ideal microstructure and magnetic properties of hot-deformed magnets with high Ce contents.

Sonochemical synthesis of S-scheme CuO/CeO2 heterojunction for enhanced photocatalytic degradation of rhodamine B dye under solar radiations

CeO2 is renowned photocatalyst with 2.8 eV band gap energy and exceptional optical features. However, the slow charge transportation and the fast recombination of the electron-hole pair hindered the photocatalytic efficiency. In this pioneering research, S-scheme CuO/CeO2 heterojunctions were engineered sonochemically with rational compositions of CeO2 and CuO nanoparticles for enhanced the photocatalytic efficiency of CeO2 in destructing rhodamine B dye under full solar radiations. Diffuse reflectance spectrum [DRS], photoluminescence [PL], high resolution transmission electron microscope [HRTEM], selected area electron diffraction [SAED], N2-adsorption-desorption isotherm, X-ray photoelectron spectroscopy [XPS] and X-ray diffraction [XRD] investigated the physicochemical properties of CuO/CeO2 heterojunction. Monoclinic CuO nanoparticles of 8 nm size are facilely incorporated in cubic CeO2 crystallites of 27.3 nm through substitution of Ce4+ by Cu2+ ions which ascribed to smaller ionic radii of Cu2+ compared with Ce4+ and Ce3+ ions. Homogeneous distribution of CuO nanoparticles on CeO2 surface was further investigated by SEM and TEM analysis. HRTEM, XRD, SAED and XPS analysis recorded the co-existence of crystalline peaks of CeO2 and CuO implying the successful construction of CuO/CeO2 heterojunction. The depression in the surface area of CeO2 from 91.4 to 83.6 m2/g with incorporating 5 wt % of CuO revealed the deposition of CuO on CeO2 surface. XPS analysis implied the existence of Ce3+ and oxygen vacancies that provide more adsorption sites for oxygen, which are beneficial for enhancing the catalytic performance of catalysts. CuO nanoparticles with 1.3 eV band energy enhanced the visible light absorbability of the heterojunctions in deep visible region for broading the photocatalytic response. Significant reduction in photoluminescence signals intensity by 60 % with incorporation 5 wt % of CuO revealed the favorable reduction in the rate of electron-hole recombination. In particular, CeCu5 containing 5 wt % CuO expelled 96 % of RhB dye within 6-h under solar simulator compared with 13 % removal on pristine CeO2 and CuO surface. Hot radicals and positive holes degraded RhB dye molecules on the heterojunction surface as elucidated from scavenger experiments and PL analysis of terephthalic acid. The exceptional removal of RhB dye under solar radiation was ascribed to the alignment in the band structure of CeO2 and CuO nanoparticles and the successful production of an efficient S-scheme heterojunction with strong redox potential and better electron transportation and separation.

Comprehensive improvement of AB2 hydrogen storage alloy: Substitution of rare earth elements for different A-side alloys

Rare earth substitution enhances the activation, absorption/desorption properties of hydrogen storage alloys, a crucial research area. Despite the extensive variety of A-site elements in multicomponent alloys, there remains a scarcity of reports on how to enhance the hydrogen storage capacity of alloys by substituting different elements with rare earth elements at the A-site, which needs to be further explored. In this study, the AB2 type Ti-Mn based hydrogen storage alloy was selected as the research object, and the effect of replacing different elements in the A-position by rare earth elements with equal atomic ratios was systematically analyzed by replacing the hydrogen absorption elements Ti/Zr with the rare earth metal Ce. The result reveals that Ce substitution significantly enhances the hydrogen storage and cyclic performance of the alloys, with Ce substituting for Ti showing superior performance. Theoretical calculations indicate that Ce substitution for Ti in alloys leads to lower formation energy and easier hydrogen absorption than Ce substitution for Zr. Beyond the influence of the Lundin’s theory, this work proposes for the first time that the difference in electronegativity between substituent elements may one of the crucial factors affecting the hydrogen storage performance of alloys. The greater difference in electronegativity may lead to a higher hydrogen storage capacity of the hydrogen storage alloy. This opens a new avenue for research into doping/substitution modifications of hydrogen storage alloy elements. These findings not only enrich the knowledge on element doping modification but offer valuable insights for future research on rare earth-doped modification of hydrogen storage alloys.

Exploring Sintered Fe-(Ce, Nd)-B with High Degree of Cerium Substitution as Potential Gap Magnet.

The more effective use of readily available Ce in FeNdB sintered magnets is an important step towards more resource-efficient, sustainable, and cost-effective permanent magnets. These magnets have the potential to bridge the gap between high-performance FeNdB and hard ferrite magnets. However, for higher degrees of cerium substitution (>25%), the magnetic properties deteriorate due to the lower intrinsic magnetic properties of Fe14Ce2B and the formation of the Laves phase Fe2Ce in the grain boundaries. In this paper, sintered magnets with the composition Fe70.9-(CexNd1-x)18.8-B5.8-M4.5 (M = Co, Ti, Al, Ga, and Cu; with Ti, Al, Ga, and Cu less than 2.0 at% in total and Cobal; x = 0.5 and 0.75) were fabricated and analyzed. It was possible to obtain coercive fields for higher degrees of Ce substitution, which previous commercially available magnets have only shown for significantly lower degrees of Ce substitution. For x = 0.5, coercivity, remanence, and maximum energy product of µ0Hc = 1.29 T (Hc = 1026 kA/m), Jr = 1.02 T, and (BH)max = 176.5 kJ/m3 were achieved at room temperature for x = 0.75 µ0Hc = 0.72 T (Hc = 573 kA/m), Jr = 0.80 T, and (BH)max = 114.5 kJ/m3, respectively.

Toluene oxidation over defected Mn-based catalyst with controlled Mn-O strength derived from LaMnO3 perovskite

Mn-based heterostructure catalysts show great potential for catalytic oxidation of toluene. Here we fabricated a Mn-based catalyst with controlled Mn–O strength from a LaMnO3 perovskite parent, the surficial structure of which was optimized via defect engineering by joint modification of Ce substitution and acid etching. The findings displayed that after introduction of Ce, a Mn3O4/Ce6O11 hybrid was in situ formed inside LaMnO3 structure owing to the incompatibility of Ce atoms, and the etching of acid resulted in the exposure of Mn3O4/Ce6O11 hybrid by exfoliating the surficial structure. The reconstruction of catalyst structure and dismutation of Mn species was conductive to forming more lattice defects and Mn–O–Ce active sites, thereby harmonizing Mn–O strength. Furthermore, the fabricated catalyst exhibited a suitable Mn2+/Mn4+ ratio and more oxygen vacancies, which inferred easy-release of lattice oxygen and improved oxygen adsorption-activation capacity, therefore synergistically contributed to the highest performance (T90 = 259 °C) of toluene oxidation.

High‐Cerium‐Content Fe–Ce–Nd–B Sintered Magnets with High Coercivity

Ce substitution of Nd in FeNdB sintered magnets is very interesting for reasons of resource efficiency, sustainability and costs. However, the magnetic properties of high Ce‐content magnets are poor. This is mainly due to the lower values of intrinsic magnetic properties of Fe14Ce2B compared to Fe14Nd2B as well as the Laves phase Fe2Ce, which is formed in the grain boundaries and forms flat aggregates for higher Ce‐content. In this article, sintered magnets with 75 at% degree of substitution of the composition Fe70.9–[(Ce1−xLax)0.75Nd0.25]18.8–B5.8–M4.5 (M = Co, Ti, Al, Ga, Cu, 0 ≤ x ≤ 0.3) are produced and analyzed. It is shown that a new rare earth rich grain boundary phase is formed adding La and that the Laves phase fraction can be reduced by up to 85%. With increasing La content, the remanence and Curie temperature increase and the temperature coefficient of Hc improves. A coercivity, remanence, and maximum energy density of up to μ0Hc = 0.74 T, Jr = 0.98 T, and (BH)max = 139.9 kJ m−3 have been achieved.

First principles study of structural and electronic properties of Ce substituted Ti2O3 slabs with compositions TixCe4-xO6 where x = 0, 1, 2, 3, 4

This study employs Density-functional theory (DFT) to investigate the structural and electronic properties of Ce2O3–Ti2O3 alloys. We systematically examined the structural and electronic properties of the two dimensional (2D) alloys, thereby exploring the impact of Ce substitution in Ti2O3 in full alloy range. The study of charge transfer and bonding analysis revealed the series of materials have dominant ionic character and it decreases linearly with an increase of Ce percentage. Initially, we observed that the parent material Ti2O3 exhibited semiconducting behavior with a narrow band gap of 0.29 eV. However, upon further incorporating Ce substitution into the pristine crystal structure, all the prepared alloys showed an increase of population of states in the band structure. Notably, the band gap of Ti3CeO6 alloy decreased to 0.13 eV and eventually reduced to zero. This trend was consistent across other metallic alloy systems, including Ti2Ce2O6, TiCe3O6, Ce2O3. Moreover, our results revealed that an increased concentration of Ce atoms led to the emergence of magnetic behaviour in the alloys. The work function of all materials to check the reactivity of the studied alloys is also reported. Further, the DFT + U method is employed to include the Hubbard U correction for electronic properties of materials.

J[formula omitted] Mott-insulating to S = 0 metal transition in Ce@Y-doped Y[formula omitted]NiIrO[formula omitted]

Double perovskite oxides (DPOs) having 3d-5d electrons provide an optimal field to investigate the entanglement between spin–orbit coupling and electron correlation, displaying unusual physical phenomena. Here, we predicted a large magnetic anisotropy energy (MAE) constant of 1.7 × 108 erg/cm3 in a pristine ferrimagnetic (FiM) Y2NiIrO6 DPO with the magnetic easy axis of the monoclinic b-axis. The estimated Curie temperature (TC) of 198 K using the Heisenberg model agrees well with the experimentally observed value of 192 K. Antiferromagnetic coupling between Ni and Ir ions is confirmed, which supports the FiM as a ground state of the system. Furthermore, it is found that the motif displays a Mott-insulating nature because of the exceptional Jeff=12 state of Ir+4 with an effective magnetic moment (meff.) of ∼2.19μB/u.c. (per unit cell), where Ni/Ir ion contains 1.68/−0.49μB. Upon substitution of Ce at Y-site (Ce@Y), few states grow at the Fermi level which belongs to Ir 5d orbitals and meff. enhanced to 3.13 μB/u.c., while FiM survives as a ground state. Along with this, Ni moment remains unchanged, while it substantially reduces to −0.10μB for Ir ion which leads to be in a ＋ 3 (5d6) state with S = 0 and almost persists in the paramagnetic phase. Due to the larger atomic radii of Ce than that of Y, the Ce@Y-doped motif exhibits a large structural distortion as compared to the pristine one, which increases the MAE and TC values simultaneously. Furthermore, calculated enthalpies of formation, distinct elastic constants, and phonon dispersion spectrums ensure the thermodynamic, mechanical, and dynamical stability of the pristine as well as the Ce@Y-doped system, respectively.

Magnetic properties and microstructure of Ce and Zr synergetic stabilizing Ti-lean SmFe12-based strip-casting flakes

Recently ThMn12-type samarium iron alloys have been promising materials for permanent magnets. Due to the high abundance and low cost, Ce as a possible stabilizer can be introduced into ThMn12-type alloys. The effect of Ce doping on the magnetic moment and phase stability in Ti-lean (Ce,Sm,Zr)(Fe,Co,Ti)12 compounds were predicted by the first-principles calculations. The CexSm0.8-xZr0.2(Fe0.8Co0.2)11.5Ti0.5 (x = 0–0.8) alloys with ThMn12 structure were produced by strip-casting into flakes by a wheel speed of 1.5 m/s and annealed at 1000 °C for 24 h. The Ce0.8Zr0.2(Fe0.8Co0.2)11.5Ti0.5 annealed flake shows a high saturation magnetization value of 13.6 kGs at room temperature. With the increase of Ce substitution in the annealed flakes, the content of α-(Fe,Co,Ti) phase decreases and the saturation magnetization increases. The 1:12 phase and the 1:9 phase have an orientation relationship that can be expressed as [0 0 –1]1:12//[100]1:9 and (020)1:12//(010)1:9. Besides, annealing process promotes the formation of 1:12 phase transformed from 1:9 phase. Coercivity is expected to be improved by obtaining uniform microstructure and suppressing the formation of soft α-(Fe,Co,Ti) phase in the ThMn12-based alloys.

Tailoring tunnel-type potassium-free manganese oxide catalyst via cerium substitution for catalytic NO reduction with NH3 at ultra-low temperatures

Manganese oxide (KMn8O16, K-MO) was widely used for selective catalytic reduction (SCR) denitration due to its superior ability for activating and converting NO to N2 with NH3. However, the harmful K+ in its tunnel structure tends to consume NH3, leading to limited low-temperature activity and stability. Herein, a Ce substitution strategy was developed for the preparation of K-free Ce-MO for NH3-SCR. As-prepared Ce-MO exhibits a high NOx conversion (95%) at an ultra-low temperature of 75°C, with negligible activity decay within 60 h. Systematic characterizations elucidate the important role of Ce substitution in improvement of catalytic efficiency and stability for NO removal. The introduction of Ce not only eliminates harmful K+ and improves the stability of the catalyst, but also enhances the removal efficiency of NOx by the generation of oxygen vacancies. In addition, the formation of intermediate NH4NO3 is critical to improving the catalytic efficiency and stability over Ce-MO base on in-situ DRIFTS. This work provides a favorable strategy for the preparation of free-K tunnel-type manganese oxide catalyst for denitration with high activity and superior stability at ultra-low temperature.

Cerium Dioxide as an Electron Buffer to Stabilize Iridium for Efficient Water Electrolysis

AbstractSustaining the steady state for highly active non‐stoichiometric iridium (Ir)‐based oxide (IrOx) at low Ir loading remains challenging primarily due to the continuous oxidation and sequent dissolution of Ir active sites during the oxygen evolution reaction (OER). In this context, a new iridium–cerium (Ce) substitution solid solution oxide (SSO) has been developed, featuring uniformly dispersed Ir atoms within Ce dioxide (CeO2) matrix as electron buffer, which delivers remarkable acidic OER catalytic activity and enhanced stability. The electron‐buffering capacity of CeO2 facilitates the charge transfer toward Ir atoms, leading to abundant active low‐valence Ir sites and effectively prevent their oxidation and dissolution. As a result, Ir─Ce SSO demonstrates an overpotential of merely 238 mV@10 mA cm−2. Proton exchange membrane water electrolyzer employing Ir─Ce SSO at a low Ir loading of 396 µgIr cm−2 operates consistently for over 100 h@500 mA cm−2. Density functional theory (DFT) calculations corroborate that the electron‐buffering effect of CeO2 enriches the density of IrIII and substantially increases the dissolution energy barrier of Ir atoms. This study presents a viable approach to addressing the issues of instability and low efficiency in Ir‐based OER electrocatalysts for acidic water electrolysis.