Cr Doping Research Articles

Impact of Cr doping on Hall resistivity and magnetic anisotropy in SrRuO3 thin films.

Hall effects, including anomalous and topological types, in correlated ferromagnetic oxides provide an intriguing framework to investigate emergent phenomena arising from the interaction between spin-orbit coupling and magnetic fields. SrRuO3 is a widely studied itinerant ferromagnetic system with intriguing electronic and magnetic characteristics. The electronic transport of SrRuO3 is highly susceptible to the defects (O/Ru vacancy, chemical doping, ion implantation), and interfacial strain. In this regard, we investigate the impact of Cr doping on the magnetic anisotropy and the Hall effect in SrRuO3 thin films. The work encompasses a comprehensive analysis of the structural, spectroscopic, magnetic, and magnetotransport properties of Cr-doped SrRuO3 films grown on SrTiO3(001) substrates. Cross-sectional transmission electron microscopy reveals a sharp and coherent interface between the layers. Notably, perpendicular magnetic anisotropy is preserved in doped films with thicknesses up to 113 nm. The resistivity exhibits a T^2 dependence below the Curie temperature, reflecting the influence of disorder and correlation-induced localization effects. Interestingly, in contrast to the undoped parent compound SrRuO3, an anomaly in the Hall signal has been observed up to a large thickness (56 nm) attributed to the random Cr doping and Ru vacancy. Based on our measurements, a field-temperature (H -T) phase diagram of anomalous Hall resistivity is constructed.

Studies of Structural, Impedance, Modulus Spectroscopy, and Magnetic Properties of Cr‐Modified SrTiO3 Perovskite Ceramic

This study investigates the effects of chromium inclusion on the structural, microstructural, frequency dependent electrical and magnetic properties of SrTiO3 perovskite. The composition of Sr1−xCrxTiO3 (SCT) ceramics with x = 0.00, 0.02, 0.04 is preapred via a high‐temperature solid‐state reaction route. Rietveld refinement of X‐ray diffraction data revealed a cubic structure with space group . All SCT samples have been analyzed for Cr incorporation at the Sr‐site using Raman and Fourier transform infrared spectroscopy. Field‐emission scanning electron microscopy studies probed a gradual increase in grain size due to the uniform distribution of dopants across sample surfaces, as confirmed by energy‐dispersive X‐ray spectroscopy analysis. Cr doping strongly influences the electrical properties of grain and grain boundary resistance. All samples undergo Arrhenius‐type transport via oxygen ion migration and mixed conduction (ionic/electron), whereas relaxation occurs through mixed‐type association () and (). The magnetic nature of Cr‐doped samples confirms room‐temperature ferromagnetism due to carrier‐associated oxygen vacancies and Ruderman‐Kittel‐Kasuya‐Yosida interaction. These findings investigate Cr doping as mixed‐ionic and electronic conductors for intermediate temperature‐solid oxide fuel cells and spintronics‐based semiconductor devices.

Molecular dynamics simulation of friction in DLC films with different Cr doping levels

This study systematically investigates the impact of varying Cr doping levels on the friction properties of DLC films using molecular dynamics simulations. The results demonstrate that under identical friction velocities and load conditions, the friction force of DLC films significantly decreases when the Cr doping content reaches 16.5 %. High Cr doping levels lead to the formation of Cr atomic clusters at the interface, hindering contact and reducing the number of interface bonds. These clusters act as lubricants, filling the interface gaps and thereby reducing the friction force. Internal stress calculations indicate that Cr doping effectively reduces the average internal stress of DLC films. For DLC films with lower Cr doping levels, the friction force exhibits similar trends under different friction velocities, while films with higher Cr doping levels show a more pronounced response, with friction force increasing at higher velocities. Increasing the load significantly raises the friction force, especially for DLC films with higher Cr doping levels. Furthermore, high Cr doping levels under high loads lead to significant structural damage and adhesive wear. This study provides theoretical and technical references for optimizing the friction performance of DLC films.

Cr-doped NiFe sulfides nanoplate array: Highly efficient and robust bifunctional electrocatalyst for the overall water splitting and seawater electrolysis

To replace precious metals and reduce production costs for large-scale hydrogen production, developing stable, high-performance transition metal electrocatalysts that can be used in a wide range of environments is desirable yet challenging. Herein, a self-supported hybrid catalyst (NiFeCrSx/NF) with high electrocatalytic activity was designed and constructed using conductive nickel foam as a substrate via manipulation of the cation doping ratio of transition metal compounds. Due to the strong coupling synergy between the metal sulfides NiS2, Fe9S11, and Cr2S3, as well as their interaction with the conductive nickel foam (NF), the energy barrier for catalytic reactions is reduced, and the charge transfer rate is enhanced. This significantly improves the hydrogen evolution reaction (HER) performance of NiFeCrSx/NF, achieving a current density of 10 mA cm−2 with an overpotential of just 66 mV. Furthermore, doping with chromium generates different valence states of Cr during the catalytic process, which can synergize with the high-valent Fe and Ni, promoting the formation of oxygen vacancies and enriching the active sites for the oxygen evolution reaction (OER). Consequently, at a current density of 10 mA cm−2 in 1.0 M KOH, the overpotential for OER is only 223 mV for NiFeCrSx/NF. Additionally, the in situ grown of self-supporting nanoflower structure on NiFe-LDH not only provides a large catalytic surface area but also facilitates electrolyte penetration during the catalytic process, endowing NiFeCrSx/NF with high long-term stability. When used as a bifunctional catalyst for overall water splitting, the NiFeCrSx/NF||NiFeCrSx/NF electrolyzer requires only 1.29 V to deliver a current density of 10 mA cm−2. Simultaneously, Cr doping protects the Fe sites by maintaining stable valence states, ensuring high performance and stability of NiFeCrSx/NF, even when it is utilized for seawater splitting. This strategy offers novel concepts for creating catalysts based on non-precious metals that can be utilized in various application scenarios.

Insights into the role of the Cr and rare element in improving the corrosion resistance of HRB400 rebars in simulated SO2-polluted marine environment

The present work aims to offer insights into the role of Cr and rare element (RE) in improving the corrosion resistance of HRB400 rebar in simulated concrete pore solution (SCPS) containing NaCl and NaHSO3. Electrochemical tests reveal that the increased SO2 concentration reduces the pitting potential and charge transfer resistance. However, the addition of Cr/RE significantly lowers the corrosion current density of HRB400, as confirmed by the corrosion morphology observed after immersion tests. Quantitative analysis of corrosion pits shows that SO2-induced corrosion tends to develop longitudinally, a tendency mitigated by the Cr/RE alloyed rebar. X-ray photoelectron spectroscopy (XPS) results confirm the presence of Cr and RE oxides in the oxide film and demonstrate that SO2 affects the Fe(II)/Fe(III) ratio. Cr and RE doping not only refines the microstructure and modifies inclusions but also enhances the protective properties of the oxide film on the rebar. Therefore, the combination of Cr and RE improves the durability of rebars in SO2-polluted marine environments.

Theoretical Investigation of Transition Metal (Cr, Fe)-Doped AlN in a rocksalt structure: A DFT Study on Physical Properties

This study presents first-principles computations to explore the structural, electronic, optical, elastic, vibrational, and thermodynamic properties of Aluminum Nitride (AlN) doped with the transition metals Chromium (Cr) and Iron (Fe) in the rocksalt structure. Using spin-polarized density functional theory (DFT) within the CASTEP code, we applied GGA-PBE, GGA+U, and HSE06 approximations for exchange-correlation functions. Our results reveal that Cr doping transforms AlN into a dilute magnetic semiconductor (DMS), while Fe doping induces a transition to a metallic state. Both Al0.₇₅Cr₀.₂₅N and Al₀.₇₅Fe₀.₂₅N exhibit strong covalent bonding, contributing to enhanced hardness. The substantial increase in static dielectric constant and refractive index suggests strong optical responses. Furthermore, our analysis confirms the mechanical and dynamic stability of these compounds. Al₀.₇₅Cr₀.₂₅N is a promising candidate for electronic and spintronic applications, whereas Al₀.₇₅Fe₀.₂₅N, with its high conductivity, is well-suited for magnetic storage devices and electrical contacts. Our findings for AlN are consistent with prior theoretical and experimental data, while the results for Al₀.₇₅Cr₀.₂₅N and Al₀.₇₅Fe₀.₂₅N offer novel insights for future research.

Utilizing armchair and zigzag nanoribbons for improved detection of SO2 Toxicity with graphene biosensor

Graphene nanoribbons (GNRs), with their distinctive structural and electronic characteristics, offer significant potential for use as biosensors in the detection of sulfur dioxide (SO₂) levels. This study employs Density Functional Theory (DFT) to evaluate the sensitivity of armchair graphene nanoribbons (AGNRs) to SO₂ gas. Specifically, we investigate the influence of SO₂ molecules on the electronic and transport characteristics of both pure and Cr-doped zigzag graphene nanoribbons (ZGNRs) and Cr-doped AGNRs. Key electronic properties, including band structure, adsorption energy, and density of states (DOS), were analyzed following SO₂ adsorption. The results indicate that Cr doping leads to significant changes in the electronic properties of AGNRs upon SO₂ exposure, including alterations in the Fermi surface that result in band separation and the formation of a forbidden band. The adsorption energy of Cr-doped AGNR increased from 0.07 eV (pristine AGNR) to 0.55 eV (Cr-doped AGNR), nearly eight times higher, indicating strong chemisorption of SO₂. These findings suggest that Cr-doped AGNRs exhibit high sensitivity to SO₂, making them promising candidates for gas detection. Furthermore, this study reveals that SO₂ adsorption in the armchair direction results in a more pronounced peak-to-valley ratio compared to the zigzag direction, highlighting distinct characteristics in SO₂ adsorption behavior. These findings could facilitate the development of advanced sensors with improved sensitivity and selectivity for environmental monitoring and safety applications.

Investigation on electronic and magnetic properties of Cr doped V2O5 thin films prepared by chemical solution deposition method

The present study examines the role of Cr doping on the electronic and magnetic behaviour of V2O5i.e. V2-xCrxO5 (x = 0, 0.05, and 0.10) thin films, prepared by chemical-solution deposition technique on Si (111) substrate. X-Ray diffraction technique shows the purity of the films and confirms no secondary phase formation. The atomic force microscopy was used to confirm the roughness of the films. A morphological investigation is done using High-resolution scanning electron microscopy associated with Energy dispersive X-Ray mapping of each element of the film. Fourier transform Infrared spectroscopy is utilised to identify functional groups that are present in obtained samples. The band-gap of these obtained samples is in the range of 0.8–0.6 eV, as examined by UV–Vis i.e., its value is decreasing with Cr doping. Using vibrating sample magnetometer, it is clear that samples shows ferromagnetic (FM) behaviour with saturation magnetization 0.3–0.6 μB/cc consistent with Langevin function fitting. It concludes the presence of FM behaviour of films and magnetization increases with carrier density, consistent with the carrier-induced origin of the ferromagnetism. X-ray photoemission spectroscopy (XPS) is utilised to understand its electronic properties. Core level spectra measurements suggest that V is in mixed state of 5+ and 4+. However Cr is in 3+ states. XPS and UV–Vis measurements imply that oxygen vacancies significantly contribute to the declination of the band gap and the promotion of FM-like behaviour. This discovery offers a promising pathway for engineering novel devices.

Regulating the Electrochemical Microenvironment of Ni(OH)2 by Cr Doping for Highly Efficient Methanol Electrooxidation

Regulating the Electrochemical Microenvironment of Ni(OH)₂ by Cr Doping for Highly Efficient Methanol Electrooxidation

Revealing Enhanced Active Oxygen Formation by Incorporating Chromium into Nickel Hydroxide Nanosheets for Improved Oxygen Evolution Reaction.

Nickel-based oxyhydroxides have emerged as promising catalysts for the oxygen evolution reaction (OER) among Earth-abundant metals. While the incorporation of foreign elements is recognized to enhance catalytic activity, the origin of this enhancement is still debated. We synthesize and examine Ni hydroxide nanosheets, both with and without Cr doping, to elucidate the underlying enhancements. Operando UV-vis and Raman spectroscopy are employed to unravel the behavior of the catalysts. The Cr doping facilitates the oxidation of Ni, resulting in the generation of active oxygen species. The enriched active oxygen species improves OER performance through a lattice oxygen-mediated pathway in Fe-free KOH, and further contribute to the creation and increased activity of FeOxHy sites in the presence of Fe impurities. This work provides a mechanistic understanding of the performance enhancement in Ni-based catalysts through Cr doping and suggests a strategy for the design of more efficient catalysts in the future.

Cr3+doped α-Fe2O3 nanoparticles for photodegradation of organic pollutants with their disinfection efficacy

Pristine and Cr-doped α-Fe2O3 nanoparticles were synthesized using a low-cost and simple one-step hydrothermal method without any precipitating agent. Cr-doped α-Fe2O3 was found to be a promising candidate for recyclable photocatalytic application for Tetracycline (TC) and Congo-red (CR) degradation under normal sunlight irradiation along with excellent antibacterial properties. Addition of Cr shows a significantly improved degradation efficiency from 20% to 91% in just 25 min for CR, while the degradation rate reached to 81% for TC, which was also monitored in real-time using internet of things (IoT). Also, a high degree of mineralization was achieved (∼87.9%), which was confirmed using total organic carbon (TOC) content. In parallel, the biochemical oxygen demand/chemical oxygen demand (BOD5/COD) ratio confirmed the fast degradation efficiency using a small amount of catalytic dosage (∼ 0.40 g/L). Also, degradation of multiple dyes provides a promising avenue for addressing complex waste water treatment challenges. Moreover, Cr-doped α-Fe2O3 displays excellent antibacterial activity towards E.coli and E.Faecium. Major factors involved in sunlight driven photocatalytic activity for example absorbance range, porosity, separation between e--h+, and charge transfer property were surprisingly improved by Cr doping and henceforth increased photocatalytic activity and antibacterial properties. This work highlights the potential utilization of Cr-doped α-Fe2O3 for the purification and disinfection of industrial waste water.

Transition metal-doped modification of lattice defects in formaldehyde catalysts − Controlling the specific surface area and mass transfer

Exploring room temperature treatment of formaldehyde (HCHO) is a crucial area of ongoing research, with transition metal catalysts showing promise for future development due to their cost-effectiveness. However, the challenge lies in the limited ability of these catalysts to activate oxygen efficiently and maintain stable catalytic oxidation of HCHO. The Mn3O4 catalyst doped with Cr, Cu, Zn, and Co was synthesized via hydrogen reduction in this study. Cr/Mn3O4 showed exceptional catalytic performance by completely converting HCHO at 30 °C and 200 ppm, while maintaining excellent stability during a 75-hour durability test. The characterization techniques revealed that the incorporation of transition metal Cr into the Mn3O4 lattice resulted in an increased number of oxygen vacancy defects on its surface, thereby significantly enhancing its ability to activate oxygen. Furthermore, Cr doping substantially augmented the specific surface area and abundance of mesoporous structures in the catalyst, which provided ample active sites and facilitated efficient mass transfer for substrate oxidation by promoting diffusion to these active sites. These enhancements ultimately led to a heightened activation of oxygen and H2O into reactive oxygen species, consequently reducing the dominance of side reaction pathways caused by intermediates occupying active sites.

Self-sacrificial hydrogen channel enhances the poisoning resistance of ZrCo-based alloy

ZrCo alloy is considered as a promising candidate for hydrogen isotope storage in nuclear fusion reactors. However, severe poisoning caused by the impurities contained in hydrogen is an inevitable issue in engineering applications. Herein, the effects of Cr-doped ZrCo with segregated the reticular ZrCr2 phase on the activation and oxidation resistance were investigated systematically. Experimental results show ZrCo0·95Cr0.05 can achieve 1.71 wt% hydriding capacity within about 37 min under 1 mol% O2 + 99 mol% H2, whereas ZrCo consumes more than 4 times (150 min) to reach the same capacity. Specifically, the improved anti-poisoning ability of the ZrCo–Cr system could be attributed to the three-step chain effect induced by Cr doping, including the hydrogenation-prone and oxygen resistance character of ZrCr2 phases, sacrificial and catalysis of in-situ formed metallic Cr clusters, and protective effects of Cr oxide layers. Hence, the active sites for rapid hydrogen absorption were obtained and inferior oxygen resistance of ZrCo substrates was alleviated through the self-sacrifice of ZrCr2 and Cr. This work not only proves the feasibility of the multi-component alloying strategy in the field of ZrCo alloy anti-poisoning modification, but also reveals that the core of the multi-component alloying strategy is to realize the modulation of the microstructure through the composition design.

Key roles of surface Cr in the NiFe layered double hydroxides for an efficient oxygen evolution reaction via adaptive reconfiguration

Cr doping is a new strategy to enhance the OER (Oxygen Evolution Reaction) performance of NiFe-LDH (NiFe-Layered Double Hydroxides) by optimizing surface states and offering a scalable production process. However, as an additive element, Cr itself has weak OER performance, so its promotion on the Ni- and Fe-active site by electron perturbation and structural stabilization in NiFeCr-LDH has been the focus. Herein, a one-step hydrothermal method is used to incorporate Cr into NiFe-LDH, systematically investigating the relationship between Cr content and the material's microstructure. The results of physical characterization show that Cr ion plays a leading role in the electron perturbation Ni/Fe-active center, which causes the increasing of Fe3+ and Ni3+ content. Furthermore, variations in Cr content resulted in the lattice stretching and morphology evolving synchronously. The optimized NiFeCr-LDH exhibited significantly enhanced OER activity and durability compared to undoped NiFe-LDH and outperformed commercial RuO2 catalysts. Additionally, a microstructure comparison was made between the initial- and long-term used-NiFeCr-LDH. The findings reveal that the material's distinctive structural evolution behavior confers it with exceptional self-adaptability to the OER reaction, which results in a consistent enhancement of activity lasting up to 12 h during long-term I-t test showing a new idea for the design of high performance NiFeCr-LDH.

Membrane‐Free Electrocatalytic Co‐Conversions of PBS Waste Plastics and Maleic Acid into High‐Purity Succinic Acid Solid

AbstractPlastic pollution, an increasingly serious global problem, can be addressed through the full lifecycle management of plastics, including plastics recycling as one of the most promising approaches. System design, catalyst development, and product separation are the keys in improving the economics of electrocatalytic plastics recycling. Here, a membrane‐free co‐production system was devised to produce succinic acid (SA) at both anode and cathode respectively by the co‐electrolysis of polybutylene succinate (PBS) waste plastics and biomass‐derived maleic acid (MA) for the first time. To this end, Cr3+‐Ni(OH)2 electrocatalyst featuring much enhanced 1,4‐butanediol (BDO) oxidation reaction (BOR) activity has been synthesized and the role of doped Cr has been revealed as an “electron puller” to accelerate the rate‐determining step (RDS) in the Ni2+/Ni3+ cycling. Impressively, an extra‐high SA production rate of 3.02 g h−1 and ultra‐high apparent Faraday efficiency towards SA (FEapparent=181.5 %) have been obtained. A carbon dioxide‐assisted sequential precipitation approach has been developed to produce high‐purity SA and byproduct NaHCO3 solids. Preliminary techno‐economic analysis demonstrates that the reported system is economically profitable and promising for future industrial applications.

Membrane-Free Electrocatalytic Co-Conversions of PBS Waste Plastics and Maleic Acid into High-PuritySuccinic Acid Solid.

Plastic pollution, an increasingly serious global problem, can be addressed through the full lifecycle management of plastics, including plastics recycling as one of the most promising approaches. System design, catalyst development, and product separation are the keys in improving the economics of electrocatalytic plastics recycling. Here, a membrane-free co-production system was devised to produce succinic acid (SA) at both anode and cathode respectively by the co-electrolysis of polybutylene succinate (PBS) waste plastics and biomass-derived maleic acid (MA) for the first time. To this end, Cr3+-Ni(OH)2 electrocatalyst featuring much enhanced 1,4-butanediol (BDO) oxidation reaction (BOR) activity has been synthesized and the role of doped Cr has been revealed as an "electron puller" to accelerate the rate-determining step (RDS) in the Ni2+/Ni3+ cycling. Impressively, an extra-high SA production rate of 3.02 g h-1 and ultra-high apparent Faraday efficiency towards SA (FEapparent=181.5%) have been obtained. A carbon dioxide-assisted sequential precipitation approach has been developed to produce high-purity SA and byproduct NaHCO3 solids. Preliminary techno-economic analysis demonstrates that the reported system is economically profitable and promising for future industrial applications.

Surface Electronic Structure of Cr Doped Bi2Se3 Single Crystals

Here, by using angle-resolved photoemission spectroscopy, we showed that Bi2−xCrxSe3 single crystals have a distinctly well-defined band structure with a large bulk band gap and undistorted topological surface states. These spectral features are unlike their thin film forms in which a large nonmagnetic gap with a distorted band structure was reported. We further provide laser-based high resolution photoemission data which reveal a Dirac point gap even in the pristine sample. The gap becomes more pronounced with Cr doping into the bulk of Bi2Se3. These observations show that the Dirac point can be modified by the magnetic impurities as well as the light source.

Insights of oxygen vacancies engineered structural, morphological, and electrochemical attributes of Cr-doped Co3O4 nanoparticles as redox active battery-type electrodes for hybrid supercapacitors

The global warming issue is spurring the development of renewable energy solutions, where supercapacitors are emerging as promising options for energy storage. Despite advancements in battery-type materials, doping is a practical approach to enhancing electrochemical performance. In this study, using the solution combustion method, we synthesized spinel Co3O4 nanoparticles doped with chromium (Cr) at 2.5 % and 5 % concentrations. The addition of Cr significantly modifies the structural, morphological, surface, and electrochemical properties of Co3O4 nanoparticles. Raman and X-ray photoelectron spectroscopy confirm that this doping method effectively regulates the oxygen vacancy defect level. Moreover, Cr dopants and oxygen vacancies modify electronic states, facilitating more accessible contact to active sites, improving electrical conductivity and more intricate redox chemistry. Notably, the 2.5 % Cr-doped Co3O4 configuration demonstrates substantially enhanced specific capacity (334.64 C g−1/92.95 mAh g−1 at 1 A g−1) and rate performance (59 %), surpassing those of 5 % Cr-doped Co3O4 and undoped Co3O4. Furthermore, the as-fabricated 2.5 % Cr-doped Co3O4//activated carbon (AC) hybrid supercapacitor (HSC) device exhibits a noteworthy energy density of 42.5 Wh kg−1 at 1295.73 W kg−1, withstanding 33.54 Wh kg−1 even at a power density of 5720.46 W kg−1. The HSC device showcases outstanding cyclic performance with 100 % capacity retention after 5000 cycles. Therefore, our work offers a viable way to improve the efficiency of hybrid supercapacitors by providing essential insights into the design of defect-engineered battery-type electrode materials.

Theoretical Study of the Multiferroic Properties of Pure and Ion-Doped Pb5M3F19, M = Fe, Cr, Al.

In a first theoretical investigation of the multiferroic properties of Pb5Fe3F19 (PFF) and Pb5Cr3F19 (PCF), we analyze their magnetic, ferroelectric, and dielectric characteristics as functions of temperature, magnetic field, and ion doping concentration using a microscopic model and Green's function theory. The temperature-dependent polarization in PFF and PCF shows a distinctive kink at the magnetic Neel temperature TN, which vanishes when an external magnetic field is applied, indicating the multiferroic behavior of these two compounds. Ion doping effectively tunes the properties of PFF and PCF. In PFF, Cr ion doping leads to a decrease in the Neel temperature TN, while Cr and Al ion doping lowers the ferroelectric Curie temperature TC. In the case of PCF, we observe the enhancement of TC by Fe ion doping and the reduction by Al ion doping. The last result coincides well quantitatively with the experimental data. Additionally, the magnetodielectric coefficient of PFF is enhanced with the increasing magnetic field.

Cr dopant mediates hydroxyl spillover on RuO2 for high-efficiency proton exchange membrane electrolysis

Simultaneously improving the activity and stability of catalysts for anodic oxygen evolution reaction (OER) in proton exchange membrane water electrolysis (PEMWE) remains a notable challenge. Here, we report a chromium-doped ruthenium dioxide with oxygen vacancies, termed Cr0.2Ru0.8O2-x, that drives OER with an overpotential of 170 mV at 10 mA cm−2 and operates stably over 2000 h in acidic media. Experimental and theoretical studies show that the synergy of Cr dopant and oxygen vacancy induces an unconventional dopant-mediated hydroxyl spillover mechanism. Such dynamic hydroxyl spillover from Cr dopant to Ru active site changes the rate-determining step from OOH* formation to O2 formation and thus greatly improves the OER performance. Moreover, the Cr dopant and oxygen vacancy also play a crucial role in stabilizing surface Ru and lattice oxygen in the Ru-O-Cr structural motif. When assembled into the anode of a practical PEMWE device, Cr0.2Ru0.8O2-x enables long-term durability of over 200 h at an ampere-level current density and 60 degrees centigrade.