Perovskite-type La0 Research Articles

Evidence of multifunctional properties of ferromanganite La0.5Ca0.5Mn0.5Fe0.5O3

Synthesis and characterization of the magnetic and electrical properties of the perovskite-type ferro-magnetite La0.5Ca0.5Mn0.5Fe0.5O3 are reported. Structural analysis reveals crystallization of the material in an orthorhombic structure, space group Pbnm (#62). The optical response suggests semiconductor-type behavior with bandgap Eg=2.3 eV. Susceptibility curves as a function of temperature and magnetization as a function of applied field suggest a soft ferromagnetic type response below room temperature, with evidence of disorder characterized by magnetic irreversibility at low temperatures and low applied fields. Resistivity measurements as a function of temperature and corroborate the semiconductor nature of the material and hysteretic I-V curves enhance its applicability in programmable logic memory devices. Band structure calculations around the Fermi level result in two different band gap values for the two spin up and spin down polarizations, as expected in ferromagnetic semiconductor materials. The hybridizations observed in the density of states curves as a function of energy suggest that the ferromagnetic character is due to double exchange mechanisms, coexisting with antiferromagnetic super-exchange, which is essentially due to the disorder of Fe3+ and Mn4+ cations in the octahedra along the three crystallographic axes.

La0·8Mn0·2FeO3 impregnated ceramic membrane for membrane fouling elimination via peroxymonosulfate activation

To endow SiC ceramic membranes a catalytic self-cleaning capability, a pore-functionalized SiC ceramic membrane with impregnated a perovskite-type catalyst La0·8Mn0·2FeO3 was fabricated by a urea-assisted one-step combustion method. Diffraction of X-ray (XRD), canning electronic microscopy (SEM) with an energy dispersion X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) were employed to investigate the effects of the impregnating of La0·8Mn0·2FeO3 on SiC membrane pore-structure (La0·8Mn0·2FeO3-CM). The catalytic self-cleaning performance of the as-prepared membranes was assessed through peroxymonosulfate (PMS) activation under a cross-flow filtration mode. Results indicate that La0·8Mn0·2FeO3 has been successfully impregnated into the macropores of SiC membranes without pore blocking, and 92.4 % of the flux recovery rate (FRR) was achieved when the PMS concentration was 70 mM and catalytic flushing time was 45 min. Therefore, the La0·8Mn0·2FeO3 impregnated SiC membrane exhibited excellent catalytic self-cleaning property, which can effectively avoid the environmental pollution and the deterioration of membrane materials caused by chemical cleaning for membrane fouling. In addition, the radical quenching experiment and electron spin resonance (EPR) tests were conducted in the catalytic self-cleaning process, and the results suggested that the hydroxyl radical (⋅OH) and sulfate radical (SO4•‾) are simultaneously captured and ⋅OH is the dominant active species. This study embarks on a novel and environmental friendly membrane cleaning approach for irreversible fouling eliminates in diverse membrane separation applications.

The effect of partial substitution of noble metal (Pd) at the B site of La0.6Sr0.4FeO3 as a supercapacitor electrode material.

Sol-gel combustion was used to produce the perovskite-type La0.6Sr0.4FeO3 (LSF) and La0.6Sr0.4Fe0.9Pd0.1O3 (LSFP) materials and assessed as supercapacitor electrodes. The synthesized materials' crystal structure, morphology, and electrochemical performance were thoroughly analyzed. The partial substitution of Pd in the B site of the LSF structure affected the electrochemical properties of this compound and improved its performance. In fact, the greatest effect of Pd substitution was on the content of oxygen vacancies, which are known as the active sites of the perovskite surface in the supercapacitor cell. The specific capacitance obtained for the sample containing Pd was about 80 F.g-1 at a current density of 1 A.g-1 in 1M KOH. In addition, this sample had a decreased intrinsic resistance to ion and electron diffusion. The remarkable structural and morphological features of LSFP contribute to its superior electrochemical performance. At a power density of 1000 W.kg-1 and a current density of 1 A.g-1, an LSFP symmetrical cell had an energy density of 44.45 W.h.kg-1.

Efficient Li2O2 oxidation kinetics of perovskite-type lanthanum chromium-based oxide by promoter interface formation for lithium-oxygen batteries

The development of oxygen evolution reaction (OER) catalysts for the decomposition of discharge products, Li2O2, is important in terms of energy efficiency because of the significant overpotentials during the charging process. In this study, the perovskite, ABO3, has been synthesized as an important functional material that exhibits various stoichiometries and crystal structures. They can accommodate metals entirely or partially at the A and/or B sites without destroying the crystal structure owing to their structural features. Therefore, perovskites provide a way to correlate solid-state chemistry with catalytic properties. Herein, we design a series of La0.8Sr0.2CrOx as practical OER catalysts by controlling the oxidation states and ionic/electron conductivities using the crystallization modulation method. In-situ Raman spectroscopy confirms that the perovskite-type La0.8Sr0.2CrO3 nanowires actively oxidize Li2O2 and increases the OER activity. The La0.8Sr0.2CrO3 nanowires exhibit OER activity by providing an electron acceptor or donor (Cr3+–Cr6+) that is modulated as an OER–active site (Li2CrO4) capable of favorable interaction with Li–deficient solid solution (Li2-xO2) during the charging process. This study provides fundamental insights into OER mechanisms and understanding of OER catalysts properties. These are essential for designing effective electrodes with high–energy efficiency, which is one of the key challenges for rechargeable Li–O2 batteries.

Catalytic recycling of medical plastic wastes over La0.6Ca0.4Co1–xFexO3−δ pre-catalysts for co-production of H2 and high-value added carbon nanomaterials

In this work, waste medical masks collected from daily life usage were pyrolyzed and catalytically decomposed with perovskite-type La0.6Ca0.4Co1–xFexO3−δ pre-catalysts for co-production of carbon nanomaterials and H2. The influences of catalysis reaction temperature and Co/Fe ratio in the investigated pre-catalysts on the yields and selectivity of the gaseous products and carbon deposition were systematically studied. The physicochemical characteristics of the produced carbon nanomaterials were comprehensively characterized by the state-of-the-art techniques. La0.6Ca0.4Co0.2Fe0.8O3–δ possessed the highest hydrogen and carbon nanomaterials yields at 850 °C among all the investigated pre-catalysts. Especially, this pre-catalyst showed an excellent performance during the 10 cycles of successive deconstruction of plastic wastes with the highest hydrogen yield of 34.33 mmol / gplastic at the 7th cycle. More importantly, carbon nanotubes generated had higher graphitic characteristics and fewer defects. The presented results demonstrated that the developed perovskite-type pre-catalyst is a promising candidate for the production of hydrogen and carbon nanotube composites for energy storge applications from medical waste plastics.

Investigation on crystal growth behavior of La0.8Sr0.2FeO3 nanopowders fabricated with different organic additions

The crystal growth behavior of the perovskite-type La0.8Sr0.2FeO3 nanopowders fabricated via sol–gel process was controlled by adjusting the addition of acetic acid (HAc) and ethanol. As a result, the La0.8Sr0.2FeO3 with a stable orthorhombic structure was fabricated with high ethanol content after heat treatment at 1200 °C. Based on the relationship between the crystal size and heat-treatment temperature, the crystal growth rate of La0.8Sr0.2FeO3 powders at the low-temperature stage was much larger than that at the high-temperature stage. Correspondingly, the activation energy for crystal growth of the La0.8Sr0.2FeO3 powders was increased firstly and then decreased with the increase of HAc or ethanol content in the raw solution, owing to different hydrolysis rates in the H2O/ethanol system. The lowest activation energy for crystal growth at the low-temperature stage ((15.25 ± 0.23)kJ/mol) and high-temperature stage ((5.74 ± 0.01)kJ/mol) were obtained by controlling the molar ratio of HAc/Metal ions with 4:1 and the volume ratio of ethanol/H2O with 3:1.

Cu-doped La0.5Sr0.5CoO3-δ perovskite as a highly efficient and durable electrocatalyst for hydrogen evolution.

The preparation of a high-efficiency and durable electrocatalyst for the alkaline hydrogen evolution reaction (HER) is essential for realizing renewable energy technologies. Herein, a series of La0.5Sr0.5CoO3-δ perovskites with different amounts of Cu cations substituting at B-sites were fabricated for the HER. Specifically, the optimized La0.5Sr0.5Co0.8Cu0.2O3-δ (LSCCu0.2) exhibits a significantly enhanced electrocatalytic activity with an ultralow overpotential of 154 mV at 10 mA cm-2 in 1.0 M KOH, which is reduced by 125 mV compared with that of pristine La0.5Sr0.5CoO3-δ (LSC, 279 mV). It also delivers a robust durability with no obvious degradation after 150 h. Impressively, the HER activity of LSCCu0.2 is superior to that of commercial Pt/C at large current densities (>270 mA cm-2). XPS analysis indicates that Co2+ ions replaced by an appropriate amount of Cu2+ ions can increase the proportion of Co3+ and generate high content of oxygen vacancies in LSC, which leads to an increased electrochemically active surface area, thereby greatly facilitating the HER. This work offers a simple way for the rational design of cost-effective and highly efficient catalysts, which may be extended to other Co-based perovskite oxides for the alkaline HER.

Mesoporous perovskite-type La0.8Sr0.2Cu0.7Mn0.3O3/SiO2 nanocomposite-decorated-graphene-oxide nanosheets: Green synthesis and application in the sensitive determination of Morin in kiwi fruit samples

Perovskite nanocrystals (PNCs) are highly tolerant to defects, unlike metal chalcogenides, and do not need surface passivation to retain high quantum yields. Remarkably, the defect structures and trap states in perovskites are often found only in their conduction and/or valence bands and not in the mid-states of the bandgap. Such intrinsic features of them essentially boost their properties and largely favor their sensing applications. In the present research work, perovskite/graphene oxide nanosheets were used to modify the surface of a glassy carbon electrode to the determination of the Morin in the kiwifruit samples. For this purpose, perovskite nanosheets were synthesized using the sol-gel method and combined with graphene oxide, which was prepared using Hummer’s method, to prepare the modifier suspension. To ensure the effective synthesis of the perovskite nanosheets, the morphological study has been applied and the modified electrode was examined by various characterization techniques. The electrochemical behavior of Morin on the surface of the modified carbon glass electrode was investigated using the cyclic voltammetry (CV) technique. The analytical figure of merits including the linear range of 10–110 μM and a detection limit of 4.49 μM were obtained. Finally, the designed sensing assay was efficiently applied for the determination of Morin in kiwifruit. The results obtained from the prepared sensor indicate suitable analytical properties including low detection limits, wide linear range, and good performance for the determination of Morin. Moreover, to check the accuracy of the proposed assay, the recovery index of 97 % indicates high performance in real samples. Stability, repeatability, and high reproducibility of the modified electrode are other prominent analytical features of the designed sensor. Consequently, it was possible to verify that the sensing assay has the potential for being desirably utilized in the determination of Morin in various real samples.

Coke-resistant ferrite anode decorated with in-situ exsolved ceria for carbonaceous fuel oxidation

In this work, the perovskite-type La0.8Ce0.2FeO3 (LCF) is employed as a host oxide for the exsolution of ceria in air and the further doping on La site using Pr3+ (La0.7Pr0.1Ce0.2FeO3, LPCF) or Gd3+ (La0.7Gd0.1Ce0.2FeO3, LGCF) is used to achieve the exsolution of PrOx- and Gd2O3- doped ceria (PDC and GDC). The exsolution of (doped) ceria is accompanied by the segregation of Fe2O3 that can promote fuel oxidation. The resulting perovskites are used as potential anode materials for solid oxide fuel cells. At 800 °C, the LPCF with 1 wt% Ni infiltration cell on a LSGM (La0.9Sr0.1Ga0.8Mg0.2O3-δ) electrolyte yields the lowest Rp (polarization resistance) value (0.11 Ω cm2) and the highest cell performance (808 mW cm−2) in H2 fuel, but the cells with LCF and LGCF anode show a stable performance under hydrocarbon fuel conditions if Ni is infiltrated into the anode to assist the deprotonation. The parameters controlling the exsolution of the doped ceria and the catalysis for the hydrocarbon reforming are analyzed, proposing an intriguing path to achieving the exsolution of complex oxide on the surface of perovskite for the construct of a hierarchical electrode/catalyst for the applications in fuel conversion.

Oxygen Reduction Activity and Interfacial Structures of La<sub>0.8</sub>Sr<sub>0.2</sub>CoO<sub>3</sub> at Initial Electrochemical Process in an Alkaline Solution

Oxygen reduction and evolution reactions (ORR and OER, respectively) of perovskite-type La0.8Sr0.2CoO3 were characterized using two-dimensional model electrodes with different reaction planes (001), (110), and (111). Synthesized by pulsed laser deposition, these thin (30 nm) and flat (roughness < 1 nm) electrodes can reveal the reaction plane dependence of the ORR activity. From steady-state polarization measurements in KOH (aq.), the ORR activity was the highest on the (001) film during the first ORR/OER cycle, and it decreased significantly during the second cycle. In-situ synchrotron X-ray diffraction clarified crystal structure changes in the bulk and surface regions of La0.8Sr0.2CoO3, and these changes are associated with forming oxygen defects during the initial electrochemical process. Furthermore, the La0.8Sr0.2CoO3 surface partially decomposed upon reacting with the aqueous solution, as clarified by hard X-ray photoemission spectroscopy. Therefore, the interfacial structures formed in the electrochemical reaction field is important for enhancing ORR and OER activities.

Oxygen Evolution Activity of LaNbN2O-Based Photocatalysts Obtained from Nitridation of a Precursor Oxide Structurally Modified by Incorporating Volatile Elements

The perovskite-type oxynitride LaNbN2O is a photocatalyst that can evolve oxygen from aqueous solutions in response to long-wavelength visible light. However, it is challenging to obtain active LaNbN2O because of the facile reduction of Nb5+ during the nitridation of the precursor materials. The present study attempted to synthesize a perovskite-type oxide La0.6Na0.4Zn0.4Nb0.6O3, containing equimolar amounts of La3+ and Nb5+ in addition to volatile Na+ and Zn2+, followed by the nitridation of this oxide to generate LaNbN2O. The obtained oxide was not the intended single-phase material but rather comprised a cuboid perovskite-type oxide similar to La0.5Na0.5Zn0.33Nb0.67O3 along with spherical LaNbO4 particles and other impurities. A brief nitridation was found to form a LaNbN2O-like shell structure having a light absorption onset of approximately 700 nm on the cuboid perovskite-type oxide particles. This LaNbN2O-based photocatalyst, when loaded with a CoOx cocatalyst, exhibited an apparent quantum yield of 1.7% at 420 nm during oxygen evolution reaction from an aqueous AgNO3 solution. This was more than double the values obtained from the nitridation products of LaNbO4 and LaKNaNbO5. The present work demonstrates a new approach to the design of precursor oxides that yield highly active LaNbN2O and suggests opportunities for developing efficient Nb-based perovskite oxynitride photocatalysts.

Perovskite-Type Oxides La0.6M0.4Ni0.6Cu0.4O3 (M = Ag, Ba, Ce) towards the Oxygen Reduction Reaction (ORR) in Alkaline Medium: Structural Aspects and Electrocatalytic Activity

In this work, La0.6M0.4Ni0.6Cu0.4O3 (M = Ag, Ba, and Ce, denoted as LANC, LBNC, and LCNC, respectively) electrocatalysts were synthesized by the Pechini method at 1023 K for two hours in air. Rietveld refinement allowed the identification of the crystallographic phases present in all oxides. The electrocatalytic performance of these oxides towards the oxygen reduction reaction (ORR) was examined in alkaline medium by rotating disk electrode (RDE) technique and scanning electrochemical microscopy (SECM) in the redox competition mode. The results indicate that the best performance was found with the LANC electrocatalyst prepared with carbon as a conducting agent (LANC/Carbon), which showed good catalytic activity towards the ORR via a pseudo fourelectron transfer pathway. The enhanced electrocatalytic activity of LANC is probably a result of the presence of a Ag phase, which improves the synergistic effect between the perovskite and carbon added to increase the conductivity, thus leading to a higher ORR performance when compared to other materials.

Performance of Perovskite-Type Oxides for Oxygen Reduction Reaction in Direct Hydrazine Fuel Cell

Perovskite-type oxide-based La0.6Sr0.4Mn(1-x)Co x O3/carbon (x = 0, 0.1, 0.2, 0.3, 1) catalysts were prepared by calcination of a mixture of metal nitrates and PVP at 600 °C, followed by milling of the calcined powder with a carbon support. The catalytic activities for the oxygen reduction reaction (ORR) were tested in alkaline electrolyte by using a rotating ring-disk electrode (RRDE) at 25 °C. With an increase in the doping amount of Co, the onset potential of the La0.6Sr0.4Mn(1-x)Co x O3/carbon catalyst was found to be shifted in a positive direction and the ring current during ORR decreased. Especially, the La0.6Sr0.4Mn0.7Co0.3O3/carbon (x = 0.3) catalyst showed the highest ORR activity among the prepared catalysts. The La0.6Sr0.4Mn0.7Co0.3O3/carbon was tested as the cathode of an alkaline membrane-type direct hydrazine fuel cell (DHFC), and a maximum power density of 133 mW cm−2, which exceeded that for the MEA using Pt/C (73.4 mW cm−2), was obtained at 50 °C. In addition, the open circuit voltage (OCV) for the DHFC (0.846 V) was greater than that of a commercial Pt/C cathode (0.788 V). Thus, the perovskite-type La0.6Sr0.4Mn0.7Co0.3O3 catalyst is expected to be a good candidate for use as a catalytic material for a DHFC cathode as an alternative to Pt.

(Invited) Incorporation of Bulk Proton Carriers in Manganese Perovskites Triggered By Charge Disproportionation between Metal and Oxygen Atoms

Protonic ceramic cells (PCCs), including fuel cells and electrolysis cells, are based on protonic conducting Ba(Zr, Ce)O3 electrolytes, and have more advantages at operating temperatures below 600 °C than solid oxide cells (SOCs) based on a oxide ion conducting Y-ZrO2 because the activation energy required for proton conduction (0.3–0.6 eV) is lower than that required for oxide ion conduction (0.8 eV), which is key to lowering fuel cell costs and extending lifetimes. One major issue of protonic cells is a lack of suitable air electrodes that promote the association of protons and oxide ions via oxygen evolution reaction (OER) / oxygen reduction reaction (ORR). Cobaltite-based cathodes, such as (Sm,Sr)CoO3, (Ba, Sr)(Co,Fe)O3, and (La,Sr)(Co,Fe)O3 are typical oxide ion conductors; there is a mismatch of main ionic carriers between the air electrodes and the electrolyte, which limits the efficient area for air electrodes’ reaction to the electrode–electrolyte–gas triple phase boundaries (TPB). Therefore, it is urgent task to develop electrode materials that exhibit H+/e-/O2- triple conduction to extend the efficient reaction zones beyond the TPB and thus reduce the air electrodes’ overpotentials and improve electrochemical performances for PCCs. The transition metal oxides which is capable of hydration at relatively high temperatures must be promising candidate. Nevertheless, robust design concepts for MPECs, namely, transition metal oxides realizing enhanced bulk hydration ability at intermediate temperatures are still missing. Therefore, it is of both fundamental and technological importance to come up with a key ‘descriptor’ to enhance the proton uptakes of electron-conducting metal oxides. Although La1-x Sr x MnO3 (LSM) is a well-known cathode material for SOFCs and recognized as a good oxide ion electron mixed conductor at elevated temperature, it has not been subject to a proton conducting material. Herein, we report pronounced hydration ability of cubic perovskite type La0.7Sr0.3MnO3- δ in air conditions attributed to the association of water and oxygen vacancies mediated by Mn oxidation, and subsequent proton attachment to oxygen neighbors in exchange for oxygen hole carriers [1,2]. Hence La0.7Sr0.3MnO3- δ is capable of up-taking bulk proton carriers in wet air with the proton contents equaling to that of well-known protonic electrolyte material Ba(Zr,Y)O3 at the intermediate temperature (IT) region.

Morphological and electrical properties of La0.8Ca0.1Pb0.1FeO3 perovskite nanopowder for NH3 and CO gas detection

Nanocrystalline gas sensitive material based on Perovskite type La0.8Ca0.1Pb0.1FeO3 (LCPFO) sample has been prepared by the sol-gel method with the citric acid route. The gas sensitivities under different temperatures of the (LCPFO) compound have been investigated toward the two NH3 and CO reducing gases. The synthesized compound has been analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS) and atomic force microscopy (AFM). It was found that the compound exhibits an orthorhombic symmetry with the Pnma space group. The effect of the experiment environment (under vacuum and air) on the conductance and activation energy Ea of the LCPFO compound has been evaluated. The Ea values have been found to be in the range of 0.43 eV < Ea < 0.53 eV and to be located between 0.42 and 0.62 eV under vacuum and air, respectively. Furthermore, the lowest detectable concentrations (10 and 40 ppm) of NH3 and CO, respectively, have been achieved.

Preparation, Sinterability, Electrical Transport and Thermal Expansion of Perovskite-Type La0.8Ca0.2CrO3 Composites

Perovskite-type was synthesized by two methods, the combustion method and conventional solid state reaction (SSR) method. The effect of synthesis methods on sinterability and physical properties of the ceramic were investigated. The results show that there are advantages of the combustion method in producing doped lanthanum chromites. Compared with the SSR method, the combustion method reduces the sintering temperature of La0.8Ca0.2CrO3, elevates the electronic conductivity and thermal expansion coefficient (TEC) of the ceramic, due to optimizing the microstructure. At the same densities level (–93%), the specimen synthesized by the combustion method reaches a superior electrical conductivity of 31.6 S·cm-1 and a compatible TEC of 10.7 × 10−6 K−1 at 800 °C.

Conversion of cerium and lanthanum from rare earth polishing powder wastes to CeO2 and La0.6Ca0.4CoO3

In the present work, a feasible approach was developed for the recovery of cerium and lanthanum from rare earth polishing powder wastes to synthesize shape-controlled CeO2 and perovskite-type La0.6Ca0.4CoO3 powders. The process proposed here includes six steps: (i) Pre-roasting treatment, (ii) H2SO4 digestion and water leaching, (iii) double salt (NaRE(SO4)2·xH2O) precipitation, (iv) conversion of NaRE(SO4)2·xH2O into RE‑carbonate, (v) oxidation and separation of cerium and lanthanum, and (vi) oxalic salt precipitation conversion and calcinations to synthesize CeO2 and glycine-nitrate combustion process to get La0.6Ca0.4CoO3.The recovery yield for the total process was 91.73% for cerium and 90.45% for lanthanum. In the preparation process of CeO2 and La0.6Ca0.4CoO3, CeO2 powders with controlled shapes were obtained by modifying the final pH value in the precipitate transformation from Ce(OH)4 to cerium oxalate and subsequent calcinations. On the other hand, based on the polarization curves, the prepared La0.6Ca0.4CoO3 exhibited a good catalytic activity for oxygen reduction reaction, showing potential applications in zinc-air batteries.

Ozone detection based on nanostructured [formula omitted] thin films

The present paper describes the synthesis of gas sensors based on thin films perovskite-type La0.8Pb0.1Ca0.1Fe0.8Co0.2O3 over a SiO2/Si substrate with interdigitated Pt-electrodes using the drop coating method. The perovskite starting nanoparticles have been prepared by the sol-gel method and they have an orthorhombic structure with Pnma space group. The prepared thin film has been tested as a sensitive film for ozone detection and shows a promising response. The detection of low concentration of ozone (equal to 50 ppb) makes the prepared thin film a potential sensor for ozone detection.

Insight into high electrochemical activity of reduced La0·3Sr0·7Fe0·7Ti0·3O3 electrode for high temperature CO2 electrolysis

Electrochemical reduction of CO2 under the high temperature electrolysis condition with favored kinetics is a promising method to utilize and convert CO2 to valuable chemicals and to reduce its environmental impact. In this work, the electrochemical performance of perovskite-type La0·3Sr0·7Fe0·7Ti0·3O3 (LSFT) oxide was thoroughly investigated as a cathode for high temperature solid oxide electrochemical reduction under practical CO2 electrolysis conditions of various current densities, partial pressures, and different CO–CO2 mixtures. The rate-limiting step of CO2 reduction on the LSFT surface was determined by the electrochemical impedance spectroscopy technique with a three-electrode configuration. The exceptional performance of LSFT cathode is confirmed as reflected by the low polarization resistance and the extremely low activation energy. Moreover, improved electrode performance is also obtained on the reduced LSFT sample under reducing atmosphere with CO, while the rate-determining step is not changed. It is also confirmed that the reduced LSFT cathode gives increased surface oxygen vacancy concentration which is believed to serve as accommodation for chemical adsorption and consequently the active sites for electrochemical activation of CO2, leading to the improved electrochemical performance.

One-Pot Facile Synthesis of La0.5Sr0.5CoO3/C by Sol-Microwave Method and Its Electrocatalytic Activity for Oxygen Evolution Reaction

The La0.5Sr0.5CoO3/C was synthesized by sol-microwave process, which has globular particle with size range of 15–25 nm and distributed evenly. The electrode prepared with this catalyst has a current density of 141 mA·cm−2 at 0.7 V (vs. Hg/HgO) in an alkaline medium (6 mol·L−1 KOH). La0.5Sr0.5CoO3/C has excellent catalytic performance for oxygen evolution, which is superior to RuO2/C catalyst and can replace noble metal catalytic materials. The polarization curves of oxygen evolution for La0.5Sr0.5CoO3/C electrode and RuO2 (20%)/C electrode are shown. At 0.7 V (vs. Hg/HgO), the oxygen evolution current density is 141 and 135 mA·cm−2, respectively. The results show that perovskite-type oxide La0.5Sr0.5CoO3/C prepared by sol-microwave method has better catalytic performance than RuO2(20%)/C.