Structure Of BaTiO3 Research Articles

Dielectric behavior of point defects on ferroelectric films for different substrate strains by phase–field simulations

AbstractRelaxor films constructed by doping point defects are widely applied in various fields, including nanoelectromechanical systems, capacitive energy storage, and pyroelectric energy conversion. Despite their broad utility, the underlying mechanisms by which point defects affect the dielectric properties of these films under varying substrate strains remain insufficiently understood. This work employs a phase–field model to explore the influence of point defects on the domain structure and dielectric properties of BaTiO3 and Pb(Zr,Ti)O3 films, with a comparative analysis of their respective responses to different substrate strains. Our results reveal that the domain sizes in both BaTiO3 and Pb(Zr,Ti)O3 films decrease with doping, leading to a transition into a relaxor state. Notably, Pb(Zr,Ti)O3 exhibits a dielectric peak at a lower doping concentration and a more pronounced reduction in dielectric constant, which can be attributed to its smaller domain size and greater susceptibility to phase transitions. As substrate strain increases from −4% to 4%, the dielectric constant initially rises, peaking at zero strain. Moreover, compared with Pb(Zr,Ti)O3, the BaTiO3 relaxor films display a higher dielectric constant, due to a larger proportion of noninitial phases and a more uniform phase structure. These findings provide valuable theoretical insights into the manipulation of substrate strain as a strategy to tailor the dielectric properties of relaxor films.

Moiré polar vortex, flat bands, and Lieb lattice in twisted bilayer BaTiO3.

Through first-principles calculations based on density functional theory, we investigate the crystal and electronic structures of twisted bilayer BaTiO3. Our findings reveal that large stacking fault energy leads to a chiral in-plane vortex pattern that was recently observed in experiments. We also found nonzero out-of-plane local dipole moments, indicating that the strong interlayer interaction might offer a promising strategy to stabilize ferroelectric order in the two-dimensional limit. The vortex pattern in the twisted BaTiO3 bilayer supports localized electronic states with quasi-flat bands, associated with the interlayer hybridization of oxygen pz orbitals. We found that the associated bandwidth reaches a minimum at ∼19∘ twisting, configuring the largest magic angle in moiré systems reported so far. Further, the moiré vortex pattern bears a notable resemblance to two interpenetrating Lieb lattices and the corresponding tight-binding model provides a comprehensive description of the evolution the moiré bands with twist angle and reveals the topological nature.

Multifunctional electrically switchable metalens

Here, we propose three all-solid-state, electrically switchable, transmissive, and multifunctional metalens arrays comprising tunable metal-oxide material BaTiO3 (BTO) nanopillars with different structural parameters. To produce the required phase profile for each metalens, the rectangular nanopillars, as the unit cell of the BTO structure, are developed to support arbitrary combinations of two independent phase shifts (0−2π) with bias voltage states of 0 V and 60 V, at first. Second, the structure parameters of different functional metalens arrays are generated efficiently and accurately based on the dual-phase modulation characteristics of a single structure. Finally, we use the finite-difference time-domain method to simulate the three kinds of switchable metalenses. The results show that the three metalenses can realize the function of adjustable focus position, switchable beam focusing and beam deflection, and switchable beam focusing and beam splitting.

Structure, Dielectric, and Ferroelectric Properties of Li/Er and Li/Bi Co-Substituted BaTiO3 Ceramics

The effects of Li/Er and Li/Bi co-substitution on the structure, dielectric, and ferroelectric properties of BaTiO3 (BT) ceramics were investigated and analyzed. X-ray diffraction measurements show that the doped samples have a single tetragonal structure without secondary phases. Rietveld refinement results show that the Li/Er and Li/Bi ions tend to replace A-sites of BT lattices at low doping content. As the doping content increases, the Curie temperature moves to the high-temperature region due to the increased tetragonality and internal stress. Compared with the undoped ceramics, the ferroelectric properties of the doped ceramics are improved. The enhanced remnant polarization is attributed to the combined effects of large grain modulation and defect dipole arrangement.

FTIR characterization analysis of BaTiO3 nanoparticles synthesized using Terminalia catappa leaf extract

Ferroelectric materials are materials that are in great demand in high-density memory applications, such as ferroelectric random access memory, ferroelectric field effect transistors, negative capacitance field effect transistors, and ferroelectric tunnel junctions. Barium titanate (BaTiO3) is a lead-free ferroelectric material with a high dielectric constant and low dielectric loss. The method used is sol gel for the synthesis of BaTiO3 solution, extract for ketapang (Terminalia catappa) leaves, and characterized by FTIR. The FTIR spectrum synthesized with ketapang leaf extract displays several characteristic peaks in the mid-infrared region (4000 – 400 cm-1). These peaks can be determined by the specific vibration mode of the structure and organic compounds contained in the ketapang leaf extract. BaTiO3 has a cubic perovskite structure with a peak wave number of 600 cm-1. Ketapang leaf extract is incorporated into the BaTiO3 structure. BaTiO3 has a Ti–O functional group. Ketapang leaf extract has C–O, C=O, C–H, and O–H functional groups.

High-precision BaTiO3 piezoelectric ceramics via vat photopolymerization 3D printing

BaTiO3 ceramics with high precision and superior performance are fabricated by vat photopolymerization 3D printing technology. The curing behaviors and photosensitive mechanisms are systematically investigated. Through the optimization of printing parameters, BaTiO3 ceramics with a high relative density of 95 % and few defects are obtained. Notably, the sintered BaTiO3 ceramics exhibit impressive properties, including a high piezoelectric coefficient d33 of 201 pC/N and strong ferroelectric characteristics with a maximum polarization Pmax of 31.4 μC/cm2 and residual polarization Pr of 18.5 μC/cm2. More importantly, a series of complex BaTiO3 structures including the body-centered cubic lattice and triply periodic minimal surface (TPMS) structures are created perfectly with the feature size as fine as 75 μm. Compared with other reported BaTiO3 structures printed by vat photopolymerization and material extrusion technologies, this work realizes a much higher printing resolution. The excellent performance and high precision of these BaTiO3 ceramics make them great potential for practical applications in piezoelectric components.

Effects of La-N Co-Doping of BaTiO3 on Its Electron-Optical Properties for Photocatalysis: A DFT Study.

In cation-anion co-doping, rare earth elements excel at regulating the electronic structure of perovskites, leading to their improved photocatalytic performance. In this regard, the impact of co-doping rare earth elements at the Ba and Ti sites in BaTiO3 on its electronic and photocatalytic properties was thoroughly investigated based on 2 × 2 × 2 supercell structures of BaTiO3 with different La concentrations of 12.5% and 25% using DFT calculations. The band structure, density of states, charge density difference, optical properties, and the redox band edge of the co-doped models mentioned above were analyzed. The results indicated that the BaTiO3 structure co-doped with 25% La at the Ti site exhibited higher absorption in the visible range and displayed a remarkable photocatalytic water-splitting performance. The introduced La dopant at the Ti site effectively reduced the energy required for electronic transitions by introducing intermediate energy levels within the bandgap. Our calculations and findings of this study provide theoretical support and reliable predictions for the exploration of BaTiO3 perovskites with superior photocatalytic performances.

Morphological, and Optical Properties of BaTiO3 Nano Particles

Barium titanate (BaTiO3) nano particles have garnered significant attention due to their unique structural, morphological and optical properties, which hold promise for various technological applications. This study presents a comprehensive investigation in to the synthesis potential of BaTiO3 nano particle. The synthesis of BaTiO3 nano particles was achived through various methods, including sol-gel, hydrothermal, and solvothermal routes, with meticulous control over parameters such as temperature, pH, and precursor concentration to tailor the nano particle size and morphology. The structural characterization using techniques such as x-ray diffraction (XRD) revealed the formation of pure –phase BaTiO3nanoparticles with crystallite sizes in the nanometer range, exhibiting a perovskite strucure. Morphological analysis using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) elucidated the morphology, size distribution, and surface chacteristics of the nano particles. The results showcased well –defined, uniform nano particles with controllable sizes and shapes, ranging from spherical to cubic, depending onthe synthesis conditions. futher more, the optical properties ofBaTiO3 nanoparticles were investigated using UV-visible spectroscopy and photoluminescence spectroscopy. The UV- visible spectra exhibited characteristic absorption peaks corresponding to the electronic transitions within the band structure of BaTio3,while photoluminescence spectra revealed emission peaks indicative of defect states with in the nanoparticle. These optical properties were found to be tunable by varying the nano particle size, morphology, and surface characteristics, offering opportunities for optoelectronic and photonic device applications. The key findings of this study underscore the importance of understanding the interplay between synthesis parameters and resulting structural, morphological, and optical properties of BaTiO3 nanoparticles.

Boosting tribo-catalytic degradation of organic pollutants by BaTiO3 nanoparticles through metallic coatings

Recently, tribo-catalysis has emerged as an appealing technology to harvest mechanical energy for environmental remediation. While most investigations have focused on catalyst optimization to enhance tribo-catalytic degradation, here we studied the effects of some metal disks placed on beaker bottoms (named coatings) on the tribo-catalytic degradation by BaTiO3 (BTO) nanoparticles under magnetic stirring. For 20 mg/L Rhodamine B (RhB) solution, Cr, Cu, and Ti coatings improved the kinetic constants of BTO nanoparticles by 3.1, 3.4, 5.2 folds, respectively. Ti coating was further found to result in 99 % degradation in just 3 h for 50 mg/L RhB solution, and elevate the kinetic constants by 19.1 and 16.6 folds for 20 mg/L methyl orange (MO) and 20 mg/L methylene blue (MB) solutions, respectively. EPR, FL and UV–vis spectroscopy verified that modifying vessel bottom with Ti coating enabled BTO nanoparticles to generate more active species. First-principles calculations of the work functions of Cr, Cu, and Ti surfaces, and the energy-band structure of BTO revealed a decreased electron-hole recombination rate due to the transfer of excited electrons to metallic coatings. These results suggest that modifying vessel bottoms with suitable metallic coatings is a simple, eco-friendly and efficient strategy to boost tribo-catalysis for environmental remediation.

Calculations of Ba(1-x)SrxTio3 structure and band gap properties by using density functional theory

TThe aim of this study is to simulate features using molecular modeling methods. The point is to show that it will accelerate research in material development studies by directing us, researchers, in terms of gaining time, material and workforce. In this study, the structural and electronic properties of undoped BaTiO3 and Sr-doped BaTiO3 were calculated by molecular modeling. In the study, energy calculations were made with the PBE and GGA (Generalized Gradient Approximation approach) developed by Perdew, Burke and Ernzerhof (PBE) using the density functional theory (DFT) calculation method, the CASTEP module of the Materials Studio program. First, the structural and electronic properties of the BaTiO3 crystal phase were calculated. Then, the lattice constants, band gap values and electron state densities of the Sr doped structure to BaTiO3 structure were calculated. The values in the literature were compared with the calculations made using the( DFT) density functional theory and it was determined that the calculations were in agreement with the values in the literature. It has been revealed that it will accelerate research in material development studies by giving direction to us researchers in terms of gaining from materials and workforce. As a result of geometric optimization of the non-stoichiometric Ba(1-x)SrXTiO3 structure and DFT calculations, it was determined that the electronic band gap shifted after %1 and %3Sr addition towards the conduction band and the band gap respectively decreased to 1,911 eV and 1.989eV.

Reduced leakage current and enhanced energy storage performance of BZNT/BTO multilayer structures: Implications in electronic devices

The extremely high recoverable energy density (Wrec) and efficiency (η) of lead-free thin films make them a promising candidate for application in miniature power devices. Here, a stable design of multilayered structures of BaTiO3 (BTO) and Bi[Zn2/3(Nb0.85Ta0.15)1/3]O3 (BZNT) have been fabricated using the pulsed laser deposition (PLD) technique on n-type Si, and Pt/Ti/SiO2/Si (Pt-Si) substrates. The effect of a number of stacking of alternate BTO and BZNT layers on the structural, microstructural, electrical, and ferroelectric properties is investigated. The films exhibited a polycrystalline nature, and the tetra-layer stacked film (BZNT/BTO3) exhibited better crystallinity, improvement in microstructure, and grain growth than that of the bi-layer stacked film (BZNT/BTO1). The improvement in ferroelectric response in the tetra-layer film is well correlated to the low leakage current density (∼10-7 A/cm2 at ±500 kV/cm) owing to reduced defects in the film. The reduced oxygen vacancies and dielectric loss tangent of order 10-3 validate the high quality of BZNT/BTO3 film exhibiting a large Wrec of 52.19 J/cm3 and high energy efficiency of 92.21 % achieved through interface engineering. These findings demonstrate the promising future for BTO-based multilayer thin film in high-power and energy-storage device applications.

Experimental and first-principles investigation of structural, electronic, optical, elastic and ferroelectric properties of BaTiO[formula omitted

Structural, electronic, optical, elastic and ferroelectric properties of lead-free BaTiO3 perovskite has been investigated experimentally and theoretically by DFT + U calculations with U = 5 eV using Quantum ESPRESSO code. The ceramic sample was synthesized through solid-state reaction method and its detailed structural investigation done by combined Rietveld (JANA 2020), Pair Distribution Function (PDF) and Raman analysis. The calculated structural properties including the frequency position of Raman lines are found to be in good agreement with experimental results and the electronic study shows that the calculated band structure of tetragonal BaTiO3 at Γ point has an direct energy gap (Eg) about 3.43 eV. Optical parameters and also the elastic constants were computed and compared with the available experimental data. Spontaneous polarization of 0.34 C/m2 for tetragonal BaTiO3 was calculated using Berry phase calculation and it is comparable with the experimental value of 0.20 C/m2.

Effects of MgO and Rare-Earth Oxides (Y2O3, Yb2O3, Dy2O3) on the Structural Characteristics and Electrical Properties of BaTiO3

This study investigated the impact of MgO and rare-earth oxides (Y2O3, Yb2O3, and Dy2O3) on the structural characteristics and electrical properties of BaTiO3. Specimens sintered at 1350 °C for durations ranging from 1 to 5 h in air exhibited a single phase of BaTiO3 with a tetragonal structure. This was observed for pure BaTiO3 and specimens co-doped with MgO-Y2O3 and/or MgO-Dy2O3. However, a pseudo-cubic structure of BaTiO3 was detected for specimens doped with MgO or co-doped with MgO-Yb2O3. The unit-cell volume of the sintered specimens was found to be dependent on the type of substitution ion for the A/B site of BaTiO3 (ABO3). The dielectric constant (εr) of the sintered specimens decreased with the substitution of MgO and rare-earth oxides due to a decrease in tetragonality (c/a). The electrical resistivities of the sintered specimens were influenced not only by their microstructural characteristics but also by the secondary phases of the sintered specimens. The BaTiO3 specimens co-doped with MgO-Yb2O3 and/or doped with MgO met the EIA X7R and X8R specifications (−55 to 125~150 °C, ΔC/C = ±15% or less), respectively.

New BaTi0.96Cu0.02X0.02O3 (X = V, Nb) Photocatalysts for Dyes Effluent Remediation: Broad Visible Light Response

The problem of industrial dyes depollution has pushed the scientific research community to identify novel photocatalysts with high performance. Herein, new photocatalysts composed of BaTiO3, BaTi0.96Cu0.04O3, BaTi0.96Cu0.02V0.02O3 and BaTi0.96Cu0.02Nb0.02O3 powders were prepared by solid-state reaction. The structural analysis of the samples confirmed the formation of the BaTiO3 structure. The splitting of (002) and (200) planes verified the formation of the tetragonal phase. The XRD peaks shifted, and the unit cell volume expansion verified the substitution of the Ti4+ site by Cu2+, V4+ and Nb5+ ions. The morphological measurements showed that the addition of (Cu, V) and (Cu, Nb) ions changes the particles’ morphology of BaTiO3, reducing its grains size. After the incorporation of (Cu, V) and (Cu, Nb) ions, the band gap of BaTiO3 was reduced from 3.2 to 2.84 and 2.72 eV, respectively. The modification of BaTiO3 by (Cu, Nb) ions induced superior photocatalytic properties for methyl green and methyl orange with degradation efficiencies of 97% and 94% during 60 and 90 min under sunlight irradiation, respectively. The total organic carbon results indicated that the BaTi0.96Cu0.02Nb0.02O3 catalyst has a high mineralization efficiency. In addition, it possesses a high stability during three cycles. The high photodegradation efficiency of Bi0.96La0.02Gd0.02FeO3 was related to the wide-ranging visible light absorption.

BaTiO3 solid solutions co-doped with Gd3+ and Eu3+: Synthesis, structural evolution and dielectric properties

In this paper, the synthesis, structural evolution, and dielectric properties of BaTiO3 solid solutions co-doped with rare earth elements (Gd3+ and Eu3+) prepared using the solid-state reaction method are presented. Chemically pure precursor powders of BaCO3, TiO2, Gd2O3, and Eu2O3 were mixed in stoichiometric proportions, ground in an agate mortar before being uniaxially pressed at 250 MPa and sintered at 1300 °C in air atmosphere for 6 h to obtain Ba1–3xGd2xTi1–3xEu4xO3 (x = 0, 0.0015, 0.01 and 0.1). X-ray diffraction (XRD) and Rietveld's refinement results reveal the crystal phase ferroelectric tetragonal BaTiO3 for the samples with x = 0, 0.0015 and 0.01, as well as a consistent increment in the lattice parameters caused by the doping. The solubility limit of Gd3+ and Eu3+ in the BaTiO3 structure is reached for the sample with x > 0.01, and the orthorhombic Eu2TiO5 and monoclinic BaTi2O5 secondary phases were identified. The Raman results show the characteristic peaks of ferroelectric tetragonal BaTiO3 around 716 cm−1 (LO of A1 symmetry), 515 cm−1 (TO of A1 symmetry), and 305 cm−1 (B1). The maximum relative permittivity measured at 1 kHz was recorded to be 6151.8 for the sample with x = 0.0015, and a decrease in the Curie temperature to 105 °C with respect to the undoped sample was observed. The punctual microanalysis for the samples with x = 0.0015, 0.01, and 0.1 reveals grains composed of Ba, Ti, O, Gd, and Eu homogeneously distributed in the BaTiO3 structure. The Ba/Ti ratios for samples with x = 0.0015, 0.01 and 0.1 are 2.86, 2.91, and 0.68, respectively, indicating substitution at the Ti site for samples with x = 0.0015 and 0.01 and a substitution at the Ba site for the sample with x = 0.1.

The Effect of Chemical Environment and Temperature on the Domain Structure of Free-Standing BaTiO3 via In Situ STEM.

Ferroelectrics, due to their polar nature and reversible switching, can be used to dynamically control surface chemistry for catalysis, chemical switching, and other applications such as water splitting. However, this is a complex phenomenon where ferroelectric domain orientation and switching are intimately linked to surface charges. In this work, the temperature-induced domain behavior of ferroelectric-ferroelastic domains in free-standing BaTiO3 films under different gas environments, including vacuum and oxygen-rich, is studied by in situ scanning transmission electron microscopy (STEM). An automated pathway to statistically disentangle and detect domain structure transformations using deep autoencoders, providing a pathway towards real-time analysis is also established. These results show a clear difference in the temperature at which phase transition occurs and the domain behavior between various environments, with a peculiar domain reconfiguration at low temperatures, from a-c to a-a at ≈60°C. The vacuum environment exhibits a rich domain structure, while under the oxidizing environment, the domain structure is largely suppressed. The direct visualization provided by in situ gas and heating STEM allows to investigate the influence of external variables such as gas, pressure, and temperature, on oxide surfaces in a dynamic manner, providing invaluable insights into the intricate surface-screening mechanisms in ferroelectrics.

Influence of the Hydride Content on the Local Structure of a Perovskite Oxyhydride BaTiO3–xHx

The local structure of BaTiO3 perovskite has been investigated for studying phase transitions by several groups. While it has been shown that H– doping into BaTiO3 changes its long-range average crystal symmetry from tetragonal to cubic, factors contributing to the structural change have not been fully understood. In this work, we investigated the dependence of the local structure of BaTiO3–xHx on the doped H– amount by means of Raman and X-ray absorption fine-structure (XAFS) spectroscopy measurements. The x value of BaTiO3–xHx could vary in the range of 0–0.5 by changing the amount of the CaH2 precursor in the topochemical synthesis of BaTiO3–xHx. Raman spectroscopy indicated that the cubic phase is induced in the initial tetragonal phase when the doped H– amount was relatively large (x ≥ 0.2). On the other hand, XAFS measurements revealed that the symmetry of the TiO6 octahedral in BaTiO3–xHx is strongly affected by the doped H– amount. The local distortion of the Ti [111] displacement is relaxed with an increase of H–, causing the tetragonal-to-cubic structural change.

Giant dielectric constant and ac electrical conductivity: Cu and Cu/W incorporated perovskite BaTiO3

Gigantic relative permittivity and ac electrical conductivity characteristics were realized in BaTiO3 through incorporation of Cu2+ and Cu2+/W4+ ions. The XRD results evidenced that pure BaTiO3 powder has a single phase with tetragonal structure. In Cu doped and (Cu, W) codoped samples, α-Ba2TiO4 phase with ratio of 17–25% was formed into BaTiO3 powder. The crystal analysis proved that the formed α-Ba2TiO4 phase naturally decay with time or heating at high temperature. The SEM micrographs illustrated the formation of elongated connected network particles in Cu doped and (Cu, 1%W) codoped BaTiO3 while cauliflower-like grains were seen for (Cu, 3% W) codoped BaTiO3 sample. Pure BaTiO3 powder reveals an ultraviolet (UV) absorption edge, corresponding to band gap energy of 3.25 eV. Owing to Cu2+ doping and (Cu2+, W4+) codoping, the absorption edge of BaTiO3 structure was powerfully red shifted and displayed oblique lines, matching to band gap energies within 3.06–2.68 eV. Pure BaTiO3 reveals a relative permittivity value of 811 (42 Hz) which transferred to gigantic values of (7.01572 × 105), (9.54016 × 105) and (3.00234 × 105) after insertion of Cu2+ and (Cu2+, W4+) ions. For Cu doped and (Cu, 1% W) codoped BaTiO3, the giant relative permittivity was considerably increased with temperature up to 125 °C and until 150 °C for (Cu, 3% W) codoped BaTiO3 sample. After decomposition of α-Ba2TiO4 phase (α-Ba2TiO4 → BaTiO3 + BaO), the dielectric constant still reveals stable colossal values equal to (7.5300 × 104), (3.66431 × 105) and (1.2277 × 104) at frequency of 42 Hz for Cu doped, (Cu, 1% W) and (Cu, 3% W) codoped BaTiO3, respectively.

BaTiO3 perovskite for optoelectronics application: A DFT study

BaTiO3 perovskite material is an attractive material for optoelectronics applications. Here, we discuss the results of our investigations using density functional theory(DFT)into the BaTiO3 structure. The computations were performed utilizing Generalized Gradient Approximation (GGA) and Local Density Approximation (LDA) through SIESTA code. In the current study, we have calculated the electronic properties such as energy band structure, density of states (DOS)/eV and optical properties of the BaTiO3 perovskite material. The band structure of this material was estimated using the Spin Orbital Coupling (SOC) effect. The band gap value for the BaTiO3 perovskite material produced by GGA is 1.54 eV and LDA is 1.67 eV, which is quite comparable with previously reported work. The calculated DOS and PDOS for this perovskite materials show that the states of Ti-3d and O-2p has a significant effect on the electronic properties. The static dielectric constant, reflectivity R(ω), absorption coefficient α(ω) and refractive index n(ω) have also been estimated in terms of optical characteristics. The results obtained on the optical properties such as the low reflectivity rate and high absorption of the incident photon energy range in GGA is 2–4 eV and LDA is 2–5 eV. This energy range suggests that BaTiO3 in perovskite solar cells has a good optical response to absorbingsolar wavelengths.

Performance of Ni-doped BaTiO3 hollow porous spheres supported reduced graphene oxide as an efficient bifunctional electrocatalyst for oxygen evolution reaction and oxygen reduction reaction

Perovskite oxides are promising and effective electrocatalysts for various energy related applications due to their low cost, versatile structures, as well as interesting catalytic activity. Herein, aerosol spray pyrolysis was used to synthesize hollow spherical structure of BaTiO3, Ni-doped BaTiO3 and Ni-doped BaTiO3 supported on reduced graphene oxide (rGO). The prepared nanocomposites were used as bifunctional electrocatalysts simultaneously for oxygen reduction and oxygen evolution reactions. Several characterization techniques were utilized for characterizing the prepared materials. The morphological analysis revealed that the produced spheres consisted of nanoparticles ranging in size from 5 to 20 nm, while the Brunauer–Emmett–Teller surface analysis assured the high mesoporous features of the prepared hollow spheres. The oxygen evolution reaction (OER) results exhibited an exceptional current density up to 80 mA cm−2 at potential 1.6 V vs. RHE, this performance was five times higher than the pure BaTiO3 (BTO). The Tafel slope was reduced by 75.5 % compared to BaTiO3. Ni-doped BaTiO3/rGO hollow porous spheres show excellent OER electrocatalytic activity compared to the commercial IrO2 electrocatalyst in basic medium. Moreover, the prepared Ni-doped BaTiO3/rGO hollow porous spheres presented excellent catalytic activity for oxygen reduction reaction (ORR), mainly favored a direct four-electron pathway, enhanced the charge transfer, led to the lowest onset potential (0.77 V vs RHE), and also achieved excellent long-term durability. The results demonstrated that the prepared perovskite/rGO composites effective bifunctional electrocatalysts.