Doping Elements Research Articles

Effects of doping of Sm, Y, Ce and La on crystal structure, phase and photocatalytic performance of TiO2 powders prepared by sol-gel method

In the present work, pure and 1 mol% samarium (Sm), yttrium(Y), lanthanum (La), cerium (Ce)-doped titanium dioxide (TiO2) powders were prepared by sol-gel method. Taking Methylene blue (MB) dye as degradation targets the photodegradation performance of the photocatalysts was studied. XRD spectra confirmed that the doping of rare earth elements (RE) could inhibit the transformation of TiO2 from anatase to rutile crystal at high temperature of 800 °C. XPS analyzed the chemical state of the elements in the powder. Characterization such as SEM and TEM found that the doping of the RE elements made the severely agglomerated particles become dispersed and refined, increased the specific surface area, and reduced the optical bandgap. Simulated visible light degradation results of MB showed that the degradation efficiency was significantly improved by doping of the RE elements, and the best efficiency is 88 % for Sm-doped TiO2 powder samples.

Synthesis, Structure, Photoluminescence, and Optical Properties of (Co/B) Co‐Doped ZnO Nanoparticles

AbstractCo/B co‐doped ZnO nanoparticles, denoted as Zn0.95‐xBxCo0.05O, are synthesized using the sol–gel method to explore the effects of the defects on optical properties. The stoichiometry is adjusted by varying the doping levels (x = 0.00, 0.01, 0.02, 0.03, 0.04, and 0.05). X‐ray diffraction is employed to analyze the structural characteristics of all Co/B co‐doped ZnO nanoparticles, confirming the presence of a hexagonal Wurtzite structure by assessing the c/a ratios. To investigate structural defects, photoluminescence properties are measured using the Fluorescence Spectrophotometer, revealing violet, blue, green, and red emissions. With the doped of boron (B), a shift from green emission to blue emission occurs, indicating a transformation of singly charged oxygen vacancies (VO+) to VZn vacancies. Fourier Transform Infrared (FTIR) spectra (4000–400 cm−1) are acquired using the Perkin Elmer Spectrum Two FTIR‐ATR spectrophotometer. The surface morphology, crystallite size, and nanoparticle shapes are characterized through Transmission Electron Microscope (TEM) analysis. Elemental compositions are determined using Electron Dispersive Spectroscopy (EDAX). The Shimadzu 2600 UV‐Spectrophotometer is used to examine optical characteristics. The samples' energy band gaps are calculated, and the impact of dopant elements on these optical characteristics is examined. Five different models are used to compute the refractive index.

Cobalt-doped graphitic carbon nitride: A multifunctional material for humidity sensing, electrochemical water splitting and environmental remediation applications

Graphitic carbon nitride (g-C3N4) has emerged as a promising eco-friendly material for catalysis and sensing applications due to their unique properties. However, limitations like low specific surface area, insufficient light absorption, and poor conductivity hinder their broader usability. Elemental doping has been established as an effective approach to modify the electronic structure and bandgap of g-C3N4 thus significantly expanding its light-responsive range for enhanced charge separation. This work reports on the fabrication of cost-effective and stable g-C3N4 and cobalt-doped g-C3N4 (Co@g-C3N4) via a simple one-step calcination process. The humidity sensing performance of both g-C3N4 and Co@g-C3N4 was evaluated across a broad humidity range (7 % - 94 % RH) at various testing frequencies. The results demonstrated good reversibility with Co@g-C3N4 exhibiting superior performance compared to pristine g-C3N4. Furthermore, the synthesized materials were assessed for their suitability as photoelectrochemical water splitting catalysts for hydrogen production, representing a step towards energy-efficient fuel cells. Notably, Co@g-C3N4 displayed enhanced performance with a lower onset potential (420 mV) and a lower Tafel slope (65.4 mV dec-1) for the hydrogen evolution reaction (HER) compared to undoped counterparts. Additionally, Co@g-C3N4 nanorods exhibited remarkable performance for the oxygen evolution reaction (OER), showcasing a lower onset potential (1.505 V) and a considerably low overpotential (270 mV), surpassing numerous reported electrocatalysts and even rivaling precious-metal-based ones. Finally, enhanced photocatalytic activities for organic dyes degradation were recorded for the mentioned materials. Therefore, g-C3N4 and related materials have great potential for their industrial electrochemcial applications.

Effects of electrical and mechanical properties of Ba0.92Ca0.08Zr0.05Ti0.95O3 ceramics with lanthanum dopants

Element doping is one of the important approaches to improve the performance of lead-free piezoelectric ceramics. In this study, Ba0·92Ca0·08Zr0·05Ti0·95O3-xLa (BCZT-xLa) piezoelectric ceramics were prepared by sol–gel method. The effects of La3+ contents on the phase structure, mechanical properties, and electrical properties of BCZT-xLa ceramics were investigated. Results showed that La3+ could affect the properties of ceramics by adjusting the concentration of oxygen vacancies and microstructure. When the La3+ contents were 0.008, the ceramics showed the best performance (the maximum permittivity was 8736.27, the remnant polarisation was 9.69 μC/cm2 and the coercive field was 3.44 kV/cm). The influences of Vickers hardness on ceramics were investigated using various La3+ contents. The lattice energy and oxygen vacancies were the main factors for the change in Vickers hardness. With an increment of x, the Vickers hardness values decreased from 6.271 GPa to 1.438 GPa. This study could provide a reference for BCZT piezoelectric ceramics doped with rare earth elements.

Effect of sites of doped Mg on the stability of lattice oxygen in lithium-rich manganese-based cathode materials

Elemental doping is considered as an effective method for altering the localized electronic structure of lattice oxygen in lithium-rich manganese-based oxides (LRMO) and enhancing their structural stability. However, the effect of doping heteroatoms at different sites on the oxygen redox is not clear. In this work, Mg is introduced into transition metals (TM) and lithium (Li) sites of LRMO at co-precipitation stage and lithiation stage to prepare LRMO-TM and LRMO-Li, respectively. The experimental results and density-functional theory calculations demonstrate that the oxygen release is reduced from 4.1653 nmol mg−1 of pristine to 3.3886 nmol mg−1 of LRMO-Li, and 2.7688 nmol mg−1 of LRMO-TM. The reduction of oxygen release of LRMO-Li is related to the formation of strong Mg-O interactions. Different from that, the lower oxygen release of LRMO-TM is mainly due to the reduction of electron holes in the O 2p state caused by the weaker Mn-O covalency, which effectively restricts the over-oxidization of oxygen. The capacity retention of LRMO-TM is 85.18 % at 0.2C after 200 cycles, which is higher than that of LRMO (78.63 %) and LRMO-Li (82.28 %). This work reveals the mechanism of enhancing lattice oxygen stability caused by Mg doping at different sites.

(Y3+/Sm3+)-doped and co-doped CoFe2O4 for heterogeneous advanced oxidation process: structural, magneto-optical, and photocatalytic investigations.

The photocatalytic properties of CoFe2O4 nanoparticles were activated by the doping and co-doping of a low level of Y3+ and Sm3+ cations. After optimizing the annealing temperature, 900°C was found to be the optimal temperature for the successful incorporation of Y3+ and Sm3+ into the spinel structure. The purity of our samples annealed at 900°C was confirmed using several characterization methods, including PXRD, SEM, XPS, VSM, FTIR, and Raman spectroscopy. Thus, we were able to increase the photocatalytic degradation of orange G dye from 9.9 to 64.63% for the Sm3+-doped sample, 76.42% for the Y3+-doped sample, and even 85.81% for the co-doped sample under 60min of UV-visible light irradiation. The beneficial effect of samarium and yttrium doping and co-doping is attributed to several factors: the first factor is doped and co-doped rare earth impurities induce distortion in the lattice, the larger the ionic radii of dopant element, the highest is the photocatalytic activity; second factor, upon doping and co-doping of rare earth impurities in the structure of CoFe2O4 leads to the creation of donor state level within the band gap, causing the Fermi energy to shift near the conduction band. Third factor, co-doping produced strong interactions, which accelerated photocarrier mobility and transport; lastly, longer electron-holes lifetime. We have provided a detailed study of the structural, vibrational, and optical properties to support our conclusions.

Increased interlayer spacing N-doping Ti3C2Tx MXene-based mezzanine heterostructure for enhanced performance lithium/sodium storage

Structure of the electrode materials play a critical role in electrochemical performance for both lithium-ion batteries and sodium ion batteries. Herein, MXene modified by element doping and compositing metal–organic frameworks (MOF)-based Fe2O3@Carbon nanofibers (CNFs) with a mezzanine heterostructure, is constructed to achieve low interfacial impedance, high specific capacity stability in lithium/sodium storage processes. The prepared mezzanine heterostructure Fe2O3@C@N-Ti3C2Tx composite is highly conductive and mesoporous. During the nitrogen-doping thermal treatment process, the interlayer spacing of Ti3C2Tx MXene was increased, providing wider ion transport channels. Additionally, inert carbon atoms were transformed into electrochemically active nitrogen atoms, leading to the construction of more active centers and surface defects. The spatial confinement of N-Ti3C2Tx MXene during the electrochemical process, effectively mitigating volume expansion and maintaining structural stability upon applied as electrode materials. Benefitting from the unique 3D conductive network, the mezzanine heterostructure Fe2O3@C@N-Ti3C2Tx composite nanofibers exhibits excellent Li/Na storage performance. In LIBs, it delivers a capacity of 226 mAh/g at 10 A/g and retains 314 mAh/g after 2800 ultra-long cycles at 5 A/g. For SIBs, it exhibits a capacity of 135 mAh/g at 5 A/g and maintains 209 mAh/g after 3000 cycles at 2 A/g.

New Piezoceramic SrBi2Nb2-2xWxSnxO9: Crystal Structure, Microstructure and Dielectric Properties.

By using the method of high-temperature solid-phase reaction, the new piezoceramic SrBi2Nb2-2xWxSnxO9 was obtained, where partial substitution of niobium (Nb) atoms with Sn4+ and W6+ atoms in the compound SrBi2Nb2O9 occurred in the octahedra of the perovskite layer (B-position). X-ray diffraction investigations showed that these compounds are single-phase SrBi2Nb2-2xWxSnxO9 (x = 0.1, 0.2) and two-phase SrBi2Nb2-2xWxSnxO9 (x = 0.3, 0.4), but all of them had the structure of Aurivillius-Smolensky phases (ASPs) with close parameters of orthorhombic unit cells. It corresponded to the space group A21am. The temperature dependences of the relative permittivity ε/ε0 and the tangent of the dielectric loss angle tan d were defined at various frequencies. It was found that doping SrBi2Nb2-2xWxSnxO9 (x = 0.1) improved the electrophysical properties of the compound: losses decreased, and the relative permittivity increased. This result was obtained for the first time. Moreover, a new result was obtained that indicated an improvement in the electrophysical properties of SrBi2Nb2O9 using the chemical element Sn (tin). This refutes the previously existing opinion about the impossibility to use Sn as a doping element.

Manipulating Orbital Hybridization of CoSe2 by S Doping for the Highly Active Catalytic Effect of Lithium-Sulfur Batteries.

In recent years, various transition metal compounds have been extensively studied to deal with the problems of slow reaction kinetics and the shuttle effect of lithium-sulfur (Li-S) batteries. Nevertheless, their catalytic performance still needs to be further improved by enhancing intrinsic catalytic activity and enriching active sites. Doping is an effective means to boost the catalytic performance through adjusting the electron structure of the catalysts. Herein, the electron structure of CoSe2 is adjusted by doping P, S with different p electron numbers and electronegativity. After S doping (S-CoSe2), the content of Co2+ increases, and charge is redistributed. Furthermore, more electrons are transferred between Li2S4/Li2S and S-CoSe2, and optimal Co-S bonds are formed between them with optimized d-p orbital hybridization, making the bonds of Li2S4/Li2S the longest and easy to break and decompose. Consequently, the Li-S batteries with the S-CoSe2-modified separator achieve improved rate performance and cycling performance, benefiting from the better bidirectional catalytic activity. This work will provide reference for the selection of the anion doping element to enhance the catalytic effect of transition metal compounds.

Modulation Strategies for Improving Electrocatalytic Performance of Transition Metal Phosphides

AbstractWith growing concerns regarding global warming and the depletion of fossil fuel resources, there is an increasingly urgent demand for electrochemical energy storage and conversion technologies, including zinc‐air batteries, fuel cells, and integrated water splitting systems. The development of cost‐effective and efficient electrocatalysts is pivotal to the commercial viability of electrocatalytic technologies related to energy. Transition metal phosphides (TMPs) have emerged as promising electrocatalysts in the energy sector owing to their adjustable electronic structure, abundant availability, and distinctive physicochemical properties. Modification of transition metal phosphides can be expected to result in enhanced catalytic performance. In this paper, several commonly employed strategies for improving performance including elemental doping, M/P stoichiometric ratios tuning, vacancy engineering, heterointerface engineering and carbon materials incorporation, which are of reference value for promoting the development of TMPs electrocatalysts and constructing highly active TMPs electrocatalysts to solve a variety of energy and environmental problems.

The synergistic effect of co-doping with Ti, Nb, and Ni on the hydrogen storage capacity of ZrCo

The effectiveness of element doping in enhancing the hydrogen storage performance of ZrCo alloys has been well established. However, the impact of single element doping is limited, and research on the synergistic effect of multi-element alloying remains relatively scarce. In this paper, the hydrogen storage properties of Zr0·75Ti0·125Nb0·125Co0·75Ni0.25 (ZTNCN) alloy were investigated using the first-principles method to explore the synergistic effect of Ti, Nb and Ni doping on ZrCo. The results indicate that the (−110) surface of ZTNCN undergoes significant reconstruction, leading to enhanced adsorption and dissociation of hydrogen on the surface. Moreover, there is no apparent dissociation barrier for H2, facilitating easier migration of H on the surface. The difference in atomic size leads to a variation in lattice interstices, resulting in a lower diffusion energy barrier for H compared to that of the ZrCoHx system. Through atomic substitution, the space within the 8e site becomes compressed, which makes the alloy exhibit improved resistance against disproportionation. Therefore, the synergistic effect of Ti, Nb, and Ni can greatly enhance hydrogen absorption and desorption kinetics in alloys and improve anti-disproportionation.

The Role of Doping in Modifying Semiconductor Properties

Doping is a fundamental process employed to modify the intrinsic properties of semiconductor materials, making them adaptable for a diverse array of technological applications. By introducing specific impurities into the semiconductor crystal lattice, parameters such as electrical conductivity, bandgap energy, and carrier concentration can be precisely engineered. This paper investigates the effects of various doping methods and elements on semiconductor performance, with a particular focus on their influence in devices like transistors, diodes, and solar cells. The analysis emphasizes how doping alters the optical and electrical properties of semiconductor materials, thereby enhancing their functionality in optoelectronic and advanced electronic applications. Through this study, the critical role of doping in driving the progress of semiconductor technology is underscored, highlighting its importance for the future advancement of electronic devices.

A Mild Synthesis of 0D Mn2+‐Doped Cs3CdBr5 Metal Halide for White Light‐Emitting Diodes and X‐Ray Imaging

AbstractAll‐inorganic Cd‐based metal halide is widely studied and applied in the field of optoelectronics due to its superior stability, diverse phase structure, and unique photoelectric properties. However, all‐inorganic 0D Cd‐based metal halide is not widely studied due to their extreme synthesis conditions. In this paper, a simple mild solution method is devised to successfully synthesize 0D Cs3CdBr5 by manipulating the crystal growth kinetics. Simultaneously, the influence of the doping element Mn on the transition matrix and the optical properties are investigated. By doping with an appropriate concentration of Mn2+, a green emission (520 nm) with photoluminescence quantum yield (PLQY) as high as 97.39% is obtained. Benefiting from near‐unity PLQY and the excellent optical properties, the white emitting light‐emitting diodes (WLEDs) with Cs3CdBr5:20%Mn as green phosphor exhibit warm white light emission with color rendering index (CRI) of 91 and correlated color temperature (CCT) of 4108 K. In addition, Cs3CdBr5:20%Mn also demonstrates excellent X‐ray scintillation properties with a low detection limit of 32.83 nGyair·s−1. The results show that Cs3CdBr5:Mn is not only a promising candidate for solid‐state lighting but also a promising candidate for low‐dose high‐resolution X‐ray imaging.

Atomic insight on the electronic structure and interfacial bonding characterization of the Cu/TiC interface

The interfacial bonding characteristics of ceramic reinforced phase and metal matrix in metal matrix composites have a significant impact on their strength. Herein, the interfacial bonding properties and alloy element doping of the Cu/TiC interface in TiC-reinforced Cu matrix composites with a stoichiometric ratio of TiC of 1:1 were investigated by atomistic DFT simulations. The analysis of twelve Cu/TiC interfacial models reveals that the TiC(111) in Cu/TiC interface with C-terminated is more stable than that of TiC(111) interface with Ti-terminated due to the stronger covalent bonds formed by Cu-C. The Cu(110)/TiC(111)-C interface with the highest work of adhesion (2.871 J/m2) is the most stable interface among these Cu/TiC interfaces. Moreover, the Cu-Co/TiC interface has the highest Wad (4.223 J/m2) compared to Cu/TiC, Cu-Ni/TiC, and Cu-Zn/TiC interfaces. And the Cu-Zn/TiC interface has the lowest Wad (2.092 J/m2), which is even lower than that of the Cu/TiC interface (2.306 J/m2). During interfacial tension, the Cu/TiC, Cu-Ni/TiC, and Cu-Zn/TiC interfaces start to fracture either at the interface layer or the sub-interface layer on the Cu side, while the Cu-Co/TiC interface begins to fracture within the Cu slab. The Cu-Co/TiC interface has the highest tensile strength of 20.12 GPa at14 % strain compared to Cu/TiC (14.76 GPa), Cu-Ni/TiC (16.35 GPa), and Cu-Zn/TiC (15.30 GPa) interfaces, which is attributed to the strengthening of both the interface and sub-interface by Co doping. Thus, Co doping in the Cu matrix significantly strengthens the Cu/Ti interfacial bonding, Ni doping has a weaker strengthening effect, and zinc doping weakens the interfacial bonding.

Microstructural and electrical properties of La0.9B0.1AlO3 (B=Pr, Nd, Sm) ceramics obtained by rare-earth ion doping

This study used the solid-phase method to prepare thermosensitive perovskite ceramics, La0.9B0.1AlO3 (B = Pr, Nd, Sm). The XRD and EDS results indicated that all components presented a single phase and all elements were uniformly distributed, formed a good solid solution. The SEM results clearly illustrated that the doped elements had enhanced the surface morphology, resulting in more uniform grain formation. The TEM results showed that linear defects were present, which led to an uneven stress distribution; consequently, this enhanced the carrier transport. The alternating current (AC) impedance showed that the grain boundary resistance determined the overall complex impedance and exhibited a different conductive mechanism with increasing temperature, from polariton to ion conduction. With the introduction of Nd3+, the conductivity of La0.9Nd0.1AlO3 increased and its temperature range increased from 600 – 1400 °C to 100–1500 °C. In La0.9Sm0.1AlO3, the presence of Sm2+ enhances the aging stability by elevating the oxygen vacancy concentration and the aging drift rate (ΔR/R0) was found to be lower than 2 %. In addition, DFT-based calculations were performed to investigate the property changes in the crystal structure and energy band structure of pure and doped LaAlO3. This study demonstrated an effective way to improve the performance of high-temperature thermistor materials using different doping strategies.

Stabilizing Interlayer Repulsion in Layered Sodium-Ion Oxide Cathodes via Hierarchical Layer Modification.

Layered sodium-ion oxides hold considerable promise in achieving high-performance sodium-ion batteries. However, the notorious phase transformation during charging, attributed to increased O2-─O2- repulsion, results in substantial performance decay. Here, a hierarchical layer modification strategy is proposed to stabilize interlayer repulsion. During desodiation, migrated Li+ from the transition metal layer and anchored Ca2+ in sodium sites maintain the cationic content within the sodium layer. Meanwhile, partial oxygen substitution by fluorine and the involvement of oxygen in redox reactions increase the average valence of the oxygen layer. This sustained cation presence and elevated anion valence collectively mitigate increasing O2-─O2- repulsion during sodium extraction, enabling the Na0.61Ca0.05[Li0.1Ni0.23Mn0.67]O1.95F0.05 (NCLNMOF) cathode to retain a pure P2-type structure across a wide voltage range. Unexpected insights reveal the interplay between different doping elements: the robust Li─F bonds and Ca2+ steric effects suppressing Li+ loss. The NCLNMOF electrode exhibits 82.5% capacity retention after 1000 cycles and a high-rate capability of 94 mAh g-1 at 1600mA g-1, demonstrating the efficacy of hierarchical layer modification for high-performance layered oxide cathodes.

Recent progress on non-metallic carbon nitride for the photosynthesis of H2O2: Mechanism, modification and in-situ applications

Photocatalytic hydrogen peroxide (H2O2) production has been considered as a promising strategy for H2O2 synthesis due to its environmentally friendly. Among various photocatalysts, carbon nitride-based materials are excellent candidates for H2O2 production because of their excellent visible-light response, low cost and high stability. In this review, we summarize in detail the research progress on the photocatalytic production of H2O2 by carbon nitride. First, we summarize the basic principles of photocatalysis and photocatalytic H2O2 production. Second, the classification and modification methods of carbon-nitride-based materials are discussed, including morphology modulation, noble metal loading, defect control, heterojunction regulation, molecular structure engineering and elemental doping. Finally, the different in-situ applications of H2O2via photosynthesis were discussed, including disinfection and antibiotic resistant genes degradation, organic pollutants degradation, medical applications and fine chemical synthesis. This review brings great promise for in-situ H2O2 photosynthesis which is expected to serve as a key component in future applications.

Controllable p- and n-type behaviours in emissive perovskite semiconductors.

Reliable control of the conductivity and its polarity in semiconductors is at the heart of modern electronics1-7,and has led to key inventions including diodes, transistors, solar cells, photodetectors, light-emitting diodes and semiconductor lasers. For archetypal semiconductors such as Si and GaN, positive (p)- and negative (n)-type conductivities are achieved through the doping of electron-accepting and electron-donating elements into the crystal lattices, respectively1-6. For halide perovskites, which are an emerging class of semiconductors, mechanisms for reliably controlling charge conduction behaviours while maintaining high optoelectronic qualities are yet to be discovered. Here we report that the p- and n-type characteristics in a wide-bandgap perovskite semiconductor can be adjusted by incorporating a phosphonic acid molecular dopant with strong electron-withdrawing abilities. The resultant carrier concentrations were more than 1013 cm-3 for the p- and n-type samples, with Hall coefficients ranging from -0.5 m3 C-1 (n-type) to 0.6 m3 C-1 (p-type). A shift of the Fermi level across the bandgapwas observed. Importantly, the transition from n- to p-type conductivity was achieved while retaining high photoluminescence quantum yields of 70-85%. The controllable doping in the emissive perovskite semiconductor enabled the demonstration of ultrahigh brightness (more than 1.1 × 106 cd m-2) and exceptional external quantum efficiency (28.4%) in perovskite light-emitting diodes with a simple architecture.

Dielectric properties of (N, B) and (N, Cl) co-doped rutile TiO2 ceramics

Extensive studies on TiO2-based colossal permittivity (CP, dielectric constant ε’ >103) materials have focused on the cation doping of metal elements; however, little attention has been paid to nonmetallic dopants. Compared to metallic elements, nonmetallic atoms with small radii and high activities, such as H, C, B, and N, can be used as anion-doping elements. Their incorporation into the TiO2 lattice includes interstitial and substitutional doping, which can influence the bandgap of TiO2 and its electron transport performance differently, thereby exhibiting considerable potential in TiO2-based applications. In this study, different N-containing compounds (BN and NH4Cl) were doped into rutile TiO2, while homogeneous ceramics of single-phase rutile TiO2 were prepared via solid-state sintering. The effects of co-doping N, Cl, and N, B on the dielectric properties of rutile TiO2 ceramics were investigated. While N and Cl doping showed no considerable effect on the dielectric properties of rutile TiO2 ceramics, the co-doping of N and B doping in rutile TiO2 considerably increased the dielectric constant to >104 with suppressed tan δ in a wide frequency range from 1 kHz to 10 MHz. These ceramics exhibited excellent frequency stability (up to 100 MHz) and temperature stability (153–513 K), which outperforms most reported transition metal co-doped TiO2 ceramics, thereby highlighting the untapped potential of the non-metallic dopants in enhancing dielectric materials.

Solid-State Oxide Fuel Cells

Solid-State Oxide Fuel Cell (SOFC) is an efficient energy conversion device that directly covers fuel's chemical energy into electricity. With a high energy conversion efficiency, it is not limited by the Carnot cycle. Fuel adaptability is wide, clean and pollution-free, all solid structure, do not use precious metal catalyst and other advantages. It is of great significance to achieve the goal of carbon peak and carbon neutrality target in China. However, there are some problems, mainly including: conductivity, relatively low conductivity of medium-temperature solid oxide fuel cells, which limits the performance of batteries, sintering, cost, and stability. To improve the conductivity, researchers are exploring different material combinations and doping strategies to optimize the crystal structure and chemical composition of the electrolyte. Finally, the importance of the electrolyte, the role of the oxygen vacancy, the influence of the doping elements, and the balance of the performance and the cost are drawn.