Activity For O2 Reduction Research Articles

Endogenously doped mixed-oxide CoO/Co2O3 in ZIF-derived carbon deposited on graphite felt for electrochemical oxidation of pharmaceutics

Some of the important goals in the development of the electro-Fenton (EF) process are to increase the performance of the electrodes while reducing their size as an alternative for expensive electrodes, expanding the active pH range, and also generating reactive oxygen species (ROSs) directly without using other homo/heterogeneous catalysts. This work modified graphite felt (GF) using a rapid and in-situ synthesis with Co/Zn doped mixed-metal ZIF. After calcination, various physicochemical analyses, including XRD, SEM, and XPS, confirmed that a carbonic material doped with mixed-oxide CoO/Co2O3 is embedded on the surface of GF fibers. LSV analysis showed that the modification significantly improved the electrode activity for O2 reduction. The modified CoZnCal-GF electrode showed good performance and higher kinetics in the EF process. It removed 87% of rifampin (RIF) in a short period of 30 min without any homo/heterogeneous catalysts. The selected conditions for this process were 1.0 V, 40 mg/L, and 5.6 for applied voltage, initial RIF concentration, and pH, respectively. The non-radical species 1O2 showed the most important role in removing RIF. LC-MS analysis was performed, and while confirming the complete removal of RIF, it was used to investigate the degradation pathway and identify the produced intermediates.

Design and Optimization of Critical-Raw-Material-Free Electrodes towards the Performance Enhancement of Microbial Fuel Cells

Microbial fuel cells (MFCs) are sustainable energy recovery systems because they use organic waste as biofuel. Using critical raw materials (CRMs), like platinum-group metals, at the cathode side threatens MFC technology’s sustainability and raises costs. By developing an efficient electrode design for MFC performance enhancement, CRM-based cathodic catalysts should be replaced with CRM-free materials. This work proposes developing and optimizing iron-based air cathodes for enhancing oxygen reduction in MFCs. By subjecting iron phthalocyanine and carbon black pearls to controlled thermal treatments, we obtained Fe-based electrocatalysts combining high surface area (628 m2 g−1) and catalytic activity for O2 reduction at near-neutral pH. The electrocatalysts were integrated on carbon cloth and carbon paper to obtain gas diffusion electrodes whose architecture was optimized to maximize MFC performance. Excellent cell performance was achieved with the carbon-paper-based cathode modified with the Fe-based electrocatalysts (maximum power density-PDmax = 1028 mWm−2) compared to a traditional electrode design based on carbon cloth (619 mWm−2), indicating the optimized cathodes as promising electrodes for energy recovery in an MFC application.

Reduction of molecular oxygen in flavodiiron proteins - Catalytic mechanism and comparison to heme-copper oxidases

The family of flavodiiron proteins (FDPs) plays an important role in the scavenging and detoxification of both molecular oxygen and nitric oxide. Using electrons from a flavin mononucleotide cofactor molecular oxygen is reduced to water and nitric oxide is reduced to nitrous oxide and water. While the mechanism for NO reduction in FDPs has been studied extensively, there is very little information available about O2 reduction. Here we use hybrid density functional theory (DFT) to study the mechanism for O2 reduction in FDPs. An important finding is that a proton coupled reduction is needed after the O2 molecule has bound to the diferrous diiron active site and before the OO bond can be cleaved. This is in contrast to the mechanism for NO reduction, where both NN bond formation and NO bond cleavage occurs from the same starting structure without any further reduction, according to both experimental and computational results. This computational result for the O2 reduction mechanism should be possible to evaluate experimentally. Another difference between the two substrates is that the actual OO bond cleavage barrier is low, and not involved in rate-limiting the reduction process, while the barrier connected with bond cleavage/formation in the NO reduction process is of similar height as the rate-limiting steps. We suggest that these results may be part of the explanation for the generally higher activity for O2 reduction as compared to NO reduction in most FDPs. Comparisons are also made to the O2 reduction reaction in the family of heme‑copper oxidases.

Boosting Reactive Oxygen Species Formation Over Pd and VOδ Co-Modified TiO2 for Methane Oxidation into Valuable Oxygenates.

Direct photocatalytic methane oxidation into value-added products provides a promising strategy for methane utilization. However, the inefficient generation of reactive oxygen species (ROS) partly limits the activation of CH4. Herein, it is reported that Pd and VOδ co-modified TiO2 enables direct and selective methane oxidation into liquid oxygenates in the presence of O2 and H2. Due to the extra ROS production from the in situ formed H2O2, a highly improved yield rate of 5014µmolg-1h-1 for liquid oxygenates with a selectivity of 89.3% is achieved over the optimized Pd0.5V0.2-TiO2 catalyst at ambient temperature, which is much better than those (2682µmolg-1h-1, 77.8%) without H2. Detailed investigations also demonstrate the synergistic effect between Pd and VOδ species for enhancing the charge carrier separation and transfer, as well as improving the catalytic activity for O2 reduction and H2O2 production.

Single Zn Atoms with Acetate‐Anion‐Enabled Asymmetric Coordination for Efficient H2O2 Photosynthesis

AbstractExploring unique single‐atom sites capable of efficiently reducing O2 to H2O2 while being inert to H2O2 decomposition under light conditions is significant for H2O2 photosynthesis, but it remains challenging. Herein, we report the facile design and fabrication of polymeric carbon nitride (CN) decorated with single‐Zn sites that have tailorable local coordination environments, which is enabled by utilizing different Zn salt anions. Specifically, the O atom from acetate (OAc) anion participates in the coordination of single‐Zn sites on CN, forming asymmetric Zn−N3O moiety on CN (denoted as CN/Zn−OAc), in contrast to the obtained Zn−N4 sites when sulfate (SO4) is adopted (CN/Zn−SO4). Both experimental and theoretical investigations demonstrate that the Zn−N3O moiety exhibits higher intrinsic activity for O2 reduction to H2O2 than the Zn−N4 moiety. This is attributed to the asymmetric N/O coordination, which promotes the adsorption of O2 and the formation of the key intermediate *OOH on Zn sites due to their modulated electronic structure. Moreover, it is inactive for H2O2 decomposition under both dark and light conditions. As a result, the optimized CN/Zn−OAc catalyst exhibits significantly improved photocatalytic H2O2 production activity under visible light irradiation.

Single Zn Atoms with Acetate-Anion-Enabled Asymmetric Coordination for Efficient H2 O2 Photosynthesis.

Exploring unique single-atom sites capable of efficiently reducing O2 to H2 O2 while being inert to H2 O2 decomposition under light conditions is significant for H2 O2 photosynthesis, but it remains challenging. Herein, we report the facile design and fabrication of polymeric carbon nitride (CN) decorated with single-Zn sites that have tailorable local coordination environments, which is enabled by utilizing different Zn salt anions. Specifically, the O atom from acetate (OAc) anion participates in the coordination of single-Zn sites on CN, forming asymmetric Zn-N3 O moiety on CN (denoted as CN/Zn-OAc), in contrast to the obtained Zn-N4 sites when sulfate (SO4 ) is adopted (CN/Zn-SO4 ). Both experimental and theoretical investigations demonstrate that the Zn-N3 O moiety exhibits higher intrinsic activity for O2 reduction to H2 O2 than the Zn-N4 moiety. This is attributed to the asymmetric N/O coordination, which promotes the adsorption of O2 and the formation of the key intermediate *OOH on Zn sites due to their modulated electronic structure. Moreover, it is inactive for H2 O2 decomposition under both dark and light conditions. As a result, the optimized CN/Zn-OAc catalyst exhibits significantly improved photocatalytic H2 O2 production activity under visible light irradiation.

Operando Fe dissolution in Fe-N-C electrocatalysts during acidic oxygen reduction: impact of local pH change.

Atomic Fe in N-doped C (Fe-N-C) catalysts provide the most promising non-precious metal O2 reduction activity at the cathodes of proton exchange membrane fuel cells. However, one of the biggest remaining challenges to address towards their implementation in fuel cells is their limited durability. Fe demetallation has been suggested as the primary initial degradation mechanism. However, the fate of Fe under different operating conditions varies. Here, we monitor operando Fe dissolution of a highly porous and >50% FeN x electrochemical utilization Fe-N-C catalyst in 0.1 M HClO4, under O2 and Ar at different temperatures, in both flow cell and gas diffusion electrode (GDE) half-cell coupled to inductively coupled plasma mass spectrometry (ICP-MS). By combining these results with pre- and post-mortem analyses, we demonstrate that in the absence of oxygen, Fe cations diffuse away within the liquid phase. Conversely, at -15 mA cm-2 geo and more negative O2 reduction currents, the Fe cations reprecipitate as Fe-oxides. We support our conclusions with a microkinetic model, revealing that the local pH in the catalyst layer predominantly accounts for the observed trend. Even at a moderate O2 reduction current density of -15 mA cm-2 geo at 25 °C, a significant H+ consumption and therefore pH increase (pH = 8-9) within the bulk Fe-N-C layer facilitate precipitation of Fe cations. This work provides a unified view on the Fe dissolution degradation mechanism for a model Fe-N-C in both high-throughput flow cell and practical operating GDE conditions, underscoring the crucial role of local pH in regulating the stability of the active sites.

Electrochemical investigations of the multicopper oxidase from Aquifex aeolicus under direct electron transfer with carbon electrodes

The study of redox proteins confined over an electrode surface is a powerful approach enabling precise modulation of the driving force for interfacial electron transfer through the control of the electrode potential. In this work, we present the investigation of a protein variant of the multicopper oxidase from Aquifex aeolicus obtained by directed evolution. Motivated by the enhanced performance of the protein variant for the oxidation of organic compounds in solution, the enzyme is studied under direct electron transfer with the electrode. A marked dependence of the redox potential with the pH of the electrolyte solution is observed, which is further confirmed by studies under non-turnover conditions. Further investigations show the need for an initial reductive activation to attain maximum bioelectrocatalytic activity for O2 reduction, in agreement with similar observations made for other multicopper oxidases (MCOs). Moreover, the influence of chloride ions on the bioelectrocatalytic reaction is described. The O2-reduction activity is barely affected at KCl concentrations as high as 100 mM. However, a shift in the O2-reduction potential towards more negative values is observed at low pH, explaining the apparent loss in activity for the oxidation of organic substrates in the presence of KCl. The obtained results contribute to a more detailed understanding of the electrochemical properties of metallo-oxidases and other MCOs.

Preferred catalysis distinctly determined by metals doped with nitrogen in three-dimensionally ordered porous carbon materials.

Three-dimensionally ordered nanoporous structures were generated in carbon materials doped with metals and nitrogen as catalytically active sites for electrochemical reactions. Free-base and metal phthalocyanines with a strategically designed molecular structure were used as carbon sources to obtain an ordered porous structure via homogeneous self-assembly with Fe3O4 nanoparticles as the pore template and the prevention of melting away during carbonization. The doping of Fe and nitrogen was achieved by a reaction between the free-base phthalocyanine and Fe3O4 through carbonization at 550 °C, while Co and Ni were doped using the corresponding metal phthalocyanines. The preference of these three types of ordered porous carbon materials for catalytic reactions was distinctly determined by the doped metals. Fe-N-doped carbon showed the highest activity for O2 reduction. Additional heat treatment at 800 °C enhanced this activity. CO2 reduction and H2 evolution were preferred by the Ni- and Co-N-doped carbon materials, respectively. A change in the template particle size was capable of controlling the pore size to enhance mass transfer and improve performance. The technique presented in this study enabled systematic metal doping and pore size control in the ordered porous structures of carbonaceous catalysts.

Biocathodes reducing oxygen in BPE-ECL system for rapid screening of E. coli O157:H7

After discovery of electron transfer from bacteria, most bacteria known to be electrochemically active are utilized as a self-regenerable catalyst at the anode of microbial fuel cells (MFCs). However, the reverse phenomenon, cathodic catalysts is not so widely researched. This present study demonstrated that E. coli O157:H7 was electrochemically active, and it was able to catalyze oxygen reduction at the cathode of bipolar electrode (BPE). Applying a constant potential to the BPE, E. coli O157:H7 can catalyze electrochemical reduction of O2, decrease the overpotential of O2 reduction at the cathode, which in turn generates an electrochemiluminescence (ECL) reporting intensity change at the anode. Significantly, a majority of food matrix does not exhibit catalytic activity for electrochemical reduction of O2. Meanwhile, due to the physically separation of two poles of closed BPE, complex food matrix at the cathode does not interfere with the ECL reaction at the anode. Therefore, the effect of food matrix is negligible when measuring E. coli O157:H7 levels in food. A low detection limit of 10 CFU mL−1 E. coli O157:H7 could be identified within 1 h. Thus, biocathodes reducing oxygen in BPE-ECL system has shown excellent characteristics in the field of rapid detection of electroactive bacteria in food.

A Sandwich-Type Electrochemical Immunosensor for Insulin Detection Based on Au-Adhered Cu5 Zn8 Hollow Porous Carbon Nanocubes and AuNP Deposited Nitrogen-Doped Holey Graphene.

Rapid, accurate, and sensitive insulin detection is crucial for managing and treating diabetes. A simple sandwich-type electrochemical immunosensor is engineered using gold nanoparticle (AuNP)-adhered metal-organic framework-derived copper-zinc hollow porous carbon nanocubes (Au@Cu5 Zn8 /HPCNC) and AuNP-deposited nitrogen-doped holey graphene (NHG) are used as a dual functional label and sensing platform. The results show that identical morphology and size of Au@Cu5 Zn8 /HPCNC enhance the electrocatalytic active sites, conductivity, and surface area to immobilize the detection antibodies (Ab2 ). In addition, AuNP/NHG has the requisite biocompatibility and electrical conductivity, which facilitates electron transport and increases the surface area of the capture antibody (Ab1 ). Significantly, Cu5 Zn8 /HPCNC exhibits necessary catalytic activity and sensitivity for the electrochemical reduction of H2 O2 using (i-t) amperometry and improves the electrochemical response in differential pulse voltammetry. Under optimal conditions, the immunosensor for insulin demonstrates a wide linear range with a low detection limit and viable specificity, stability, and reproducibility. The platform's practicality is evaluated by detecting insulin in human serum samples. All these characteristics indicate that the Cu5 Zn8 /HPCNC-based biosensing strategy may be used for the point-of-care assay of diverse biomarkers.

Mass-transfer control for selective deposition of well-dispersed AuPd cocatalysts to boost photocatalytic H2O2 production of BiVO4

Owing to excellent activity and selectivity for two-electron O2 reduction to H2O2, well-dispersed AuPd nanoalloy cocatalyst is high desired for photocatalytic H2O2 production. In practice, however, it is hardly realized due to technical difficulty. Utilizing the directed transfer of photocarriers in BiVO4 single crystal with crystal-facet exposure, in this work, a mass-transfer control approach is developed for selective photodeposition of well-dispersed AuPd cocatalysts to boost photocatalytic H2O2 production. The as-obtained BiVO4 (010)-AuPd photocatalysts exhibit improved photocatalytic activity for H2O2 production compared with BiVO4 (010)-Au (1.15 mmol L−1) and BiVO4 (010)-Pd (1.37 mmol L−1). Therein, the optimum BiVO4 (010)-AuPd photocatalyst (the mass ratio of Au to Pd for 19:1) presents the highest H2O2 production (2.29 mmol L−1 in 2 h under 420 nm light irradiation) and the corresponding AQE value is 11.38 %. In the case, the synergistic effect of electronic effects and geometric effects for the well-dispersed AuPd nanoalloy cocatalysts contribute to excellent activity and selectivity for two-electron O2 reduction to H2O2 and thus boost the photocatalytic H2O2 production of BiVO4. The present work also provides an insight into the modification of well-dispersed nanoalloy cocatalysts for photocatalytic H2O2 production.

Electrochemical performance of Sr1.9La0.1Fe1.5Mo0.5O6-δ symmetric electrode for solid oxide fuel cells with carbon-based fuels

La-doped Sr2-xLaxFe1.5Mo0.5O6-δ perovskite oxides are synthesized and used as a symmetric electrode to evaluate the effect of La on the crystal structure, conductivity, and catalytic activity for O2 reduction and H2 oxidation reaction. The electronic doping effect dominates the oversize effect in Sr2-xLaxFe1.5Mo0.5O6-δ oxide, resulting in unit cell volume expansion and decreased conductivity in air. In addition, the introduction of La increases the chemical structural stability of Sr2Fe1.5Mo0.5O6-δ in reducing condition due to the higher La–O bond compared with Sr–O bond, leading to high catalytic activity for the H2 oxidation reaction. At 800 °C, the Rp values of Sr1.9La0.1Fe1.5Mo0.5O6-δ symmetric cell in air and wet H2 are as low as 0.075 and 0.21 Ω cm2, respectively. Moreover, the peak power densities of 769, 561, 439, and 653 mW cm−2 at 850 °C are obtained when wet H2, CO, CH4, and C3H8 are used as fuels on Sr1.9La0.1Fe1.5Mo0.5O6-δ/LSGM/Sr1.9La0.1Fe1.5Mo0.5O6-δ cell. The symmetric cell also shows excellent stability (>100 h) in wet H2/air, implying Sr1.9La0.1Fe1.5Mo0.5O6-δ oxide is a promising symmetric electrode material.

Identification of a cytochrome bc1-aa3 supercomplex in Rhodobacter sphaeroides

Respiration is carried out by a series of membrane-bound complexes in the inner mitochondrial membrane or in the cytoplasmic membrane of bacteria. Increasing evidence shows that these complexes organize into larger supercomplexes. In this work, we identified a supercomplex composed of cytochrome (cyt.) bc1 and aa3-type cyt. c oxidase in Rhodobacter sphaeroides. We purified the supercomplex using a His-tag on either of these complexes. The results from activity assays, native and denaturing PAGE, size exclusion chromatography, electron microscopy, optical absorption spectroscopy and kinetic studies on the purified samples support the formation and coupled quinol oxidation:O2 reduction activity of the cyt. bc1-aa3 supercomplex. The potential role of the membrane-anchored cyt. cy as a component in supercomplexes was also investigated.

High-efficiency catalytic reduction of residual oxygen for purification of carbon dioxide streams from high-pressure oxy-combustion systems

Cobalt–manganese composite catalysts in a reverse-flow fixed-bed reactor showed excellent activity and selectivity for reduction of residual O2 for CO2 purification from pressurized oxy-combustion flue gases.

High-Throughput Calculation Investigations on the Electrocatalytic Activity of Codoped Single Metal–Nitrogen Embedded in Graphene for ORR Mechanism

Two types of single metal atoms embedded in graphene were investigated as a potential electrocatalyst for oxygen reduction reaction (ORR) for the application in a fuel cell. ORR was considered in the four elementary reaction steps of oxygen hydrogenation, perhydroxyl production, atomic oxygen hydrogenation, and final water form. All calculations of catalytic activity were performed with the Vienna Ab Initio Simulation Package (VASP) on an M@Gra (M = Mn, Fe, Co, and Ir)–embedded structure, indicating that high-efficiency catalytic activity in the oxidation reaction takes place on the top of metal atom sites. Our calculations revealed that ORR is profiled via four-electron transfer pathway. Activity of these catalysts is closely related to the same scaling linear relations between the adsorption energies of the ORR intermediates on different catalytic surfaces; this can improve their catalytic activity for O2 reduction through a high-efficiency 4e reaction path. Mn- and Ir-doped of cell A graphene exhibited excellent ORR catalytic performance in case of their small overpotential (less than 0.23 V) and low-energy barrier (less than 0.64 eV) of the Ir-doped graphene rate-determining step. Mn@Gra and Fe@Gra of cell B monolayers showed poor ORR catalytic performance due to the strong interaction between various ORR-involved species. Based on the free energy change and activation energy of each intermediate reaction in ORR, Fe@Gra and Ir@Gra are promising catalysts for ORR processes in fuel cells. This provides useful guidance for different types of catalysts in applications to fuel cells.

Significantly improved electrocatalytic oxygen reduction by an asymmetrical Pacman dinuclear cobalt(ii) porphyrin–porphyrin dyad

Pacman dinuclear CoII triphenylporphyrin-tri(pentafluorophenyl)porphyrin 1 and dinuclear CoII bis-tri(pentafluorophenyl)porphyrin 2, anchored at the two meso-positions of a benzene linker, are synthesized and examined as electrocatalysts for the oxygen reduction reaction (ORR). Both dinuclear Co bisporphyrins are more efficient and selective than corresponding mononuclear CoII tetra(pentafluorophenyl)porphyrin 3 and CoII tetraphenylporphyrin 4 for the four-electron electrocatalytic reduction of O2 to water. Significantly, although the ORR selectivities of the two dinuclear Co bisporphyrins are similar to each other, 1 outperforms 2, in terms of larger catalytic ORR currents and lower overpotentials. Electrochemical studies showed different redox behaviors of the two Co sites of 1: the CoIII/CoII reduction of the Co-TPP (TPP = triphenylporphyrin) site is well-behind that of the Co-TPFP (TPFP = tri(pentafluorophenyl)porphyrin) site by 440 mV. This difference indicated their different roles in the ORR: CoII-TPFP is likely the O2 binding and reduction site, while CoIII-TPP, which is generated by the oxidation of CoII-TPP on electrodes, may function as a Lewis acid to assist the O2 binding and activation. The positively charged CoIII-TPP will have through-space charge interactions with the negatively charged O2-adduct unit, which will reduce the activation energy barrier for the ORR. This effect of Co-TPP closely resembles that of the CuB site of metalloenzyme cytochrome c oxidase (CcO), which catalyzes the biological reduction of O2. This work represents a rare example of asymmetrical dinuclear metal catalysts, which can catalyze the 4e reduction of O2 with high selectivity and significantly improved activity.

Structural changes at the surface of cytochrome c oxidase alter the proton-pumping stoichiometry

Data from earlier studies showed that minor structural changes at the surface of cytochrome c oxidase, in one of the proton-input pathways (the D pathway), result in dramatically decreased activity and a lower proton-pumping stoichiometry. To further investigate how changes around the D pathway orifice influence functionality of the enzyme, here we modified the nearby C-terminal loop of subunit I of the Rhodobacter sphaeroides cytochrome c oxidase. Removal of 16 residues from this flexible surface loop resulted in a decrease in the proton-pumping stoichiometry to <50% of that of the wild-type enzyme. Replacement of the protonatable residue Glu552, part of the same loop, by an Ala, resulted in a similar decrease in the proton-pumping stoichiometry without loss of the O2-reduction activity or changes in the proton-uptake kinetics. The data show that minor structural changes at the orifice of the D pathway, at a distance of ~40 Å from the proton gate of cytochrome c oxidase, may alter the proton-pumping stoichiometry of the enzyme.

Hydrothermal Carbonization‐Derived Carbon from Waste Biomass as Renewable Pt Support for Fuel Cell Applications: Role of Carbon Activation

Pt catalysts in proton exchange membrane fuel cells (PEMFCs) typically use carbon blacks such as Vulcan (Vulcan is a registered trademark of the company Cabot Corporation) based on fossil sources. Thus, an important research task is using sustainable supports in PEMFCs. Hydrothermal carbonization (HTC) converts biomasses into chars, which are possible substitutes for fossil‐based carbons. Herein, a Pt catalyst derived from HTC of coconut shells is developed for catalysis of O2 reduction in acidic media. Thermal activation enlarges the specific surface area by factor of 7 to 546 m2 g−1 and generates electrical conductivity making the material suitable for catalysis. Pt particles of 1.8 ± 0.5 nm are distributed well on the activated carbon. Cyclic and CO stripping voltammetry show an electrochemical surface area (ECSA) of 69 ± 21 m2 gPt−1, almost identical to that of the commercial catalyst using Vulcan (69 ± 6 m2 gPt−1). Although ECSAs are highly comparable, the activity for O2 reduction is lower compared with the commercial catalyst. HTC‐derived carbon has a lower degree of graphitization, less functional oxygen groups on its surface, and a lower electrical conductivity than Vulcan. This suggests different Pt–support interactions.

Synthesis, characterization, and electrochemical behavior of a new Nd1.9Sr0.1Ni0.9Co0.1O4 ± δ material as electrocatalyst for the oxygen reduction reaction

The oxygen reduction reaction (ORR) was studied using Nd1.9Sr0.1Ni0.9Co0.1O4 ± δ (NSNCO01) nickelates as cathode material at room temperature in aqueous phase. The citrate method was used for preparing the material. The electrochemical study of ORR was carried out in a 0.5-M NaOH solution at 25 °C with a rotating disk electrode. XRD and SEM analysis were performed to characterize the crystallinity of the material. XPS analysis is used to evaluate the surface state of the material. Electrochemical studies were followed by linear voltammetry and impedance spectroscopy measurements. The electrocatalyst composite Nd1.9Sr0.1Ni0.9Co0.1O4 ± δ/C, consisting of oxide nickelate and carbon (Vulcan XC-72), was mixed and deposited as a layer on a glassy carbon substrate. At room temperature, a significant electrocatalytic activity is observed for the studied material that shows a relatively high electrocatalytic activity for O2 reduction.