Fe-doped Co3O4 Research Articles

Gold nanoparticles on Fe-doped Co3O4 for enhanced low-temperature CO oxidation

Gold nanoparticles on Fe-doped Co3O4 for enhanced low-temperature CO oxidation

Tailoring the electrochemical performance of rods-like Co-MOF: Fe-derived Co3O4: Fe electrodes for supercapacitor applications

With the increasing global demand for energy, there is a critical need for efficient and sustainable energy storage solutions. Supercapacitors (SCs) have emerged as promising candidates due to their high-power density, long cycle life, and environmental friendliness. This study explores the development of iron-doped cobalt metal–organic frameworks (Co-MOFs: Fe) and their derived oxides supported on Ni foam as high-performance supercapacitor electrodes. The impact of conversion temperature on electrochemical properties of Co-MOFs: Fe derived Co3O4: Fe was evaluated. The results disclosed that the conversion at 500 °C significantly enhances the surface area, specific capacitance, and charge transfer efficiency of the electrodes. It exhibited the highest specific capacity of ∼ 2135.08 F g−1 at a current density of 1 A/g, along with excellent cycling stability of 87 %. Subsequently, an asymmetric supercapacitor was constructed with the MOF-derived Co3O4: Fe at 500 °C as anode and activated carbon as cathode materials. The device exhibited a specific capacitance of 233.98 F g−1 at 1 A/g with an energy density of ∼ 51.99 Wh/kg, power density of 500.14 W/kg, and a significant capacity retention of ∼ 89 % over 10,000 cycles. These findings validate the potential of Co-MOF: Fe derived Fe-doped Co3O4 as potential materials for practical energy storage applications.

Coupling effect of Fe-doped Co3O4 nanoparticles with SrTiO3 nanotubes on the high-efficiency photocatalytic activities of basic violet 16 dye degradation and H2 evolution

The photocatalytic activity of semiconductors can be enhanced by doping with metal and/or nonmetal elements and coupling them with other semiconductors. Herein, highly ordered SrTiO3 nanotubes (NTs) and Fe-doped Co3O4 nanoparticles (NPs) were fabricated via the liquid phase deposition (LPD) process and the sol–gel method, respectively. Fe-doped Co3O4 NPs were assembled on the surface of SrTiO3 NTs to form heterostructured nanocomposites (NCs). The formation mechanism of SrTiO3 NTs and SrTiO3/Fe:Co3O4 NC was proposed, and the photocatalytic activity of the products was analyzed using basic violet 16 (BV16) dye as the pollutant and H2 evolution under visible light irradiation. The results showed that the SrTiO3/Fe:Co3O4 NC has the highest photocatalytic performance, with degradation rate of BV16 and H2 production rate of 1718 μmol.g−1.h−1, which was 13.2 and 2.8 times that of SrTiO3 NTs, respectively. The enhanced photocatalytic activity could be principally attributed to the improvement of charge separation resulting from the effects of doping Co3O4 NPs with Fe ions and their coupling with SrTiO3 NTs. The outstanding results using the SrTiO3/Fe:Co3O4 heterojunction exhibited its potential for the BV16 degradation and H2 production in environmental applications.

Nanosheet floral clusters of Fe-doped Co3O4 for high-performance supercapacitors

A straightforward hydrothermal process followed by thermal treatment is developed for constructing Fe-doped Co3O4 nanosheet floral clusters, which exhibit excellent electrochemical performance as supercapacitor electrodes.

Oxygen vacancy modulated Fe-doped Co3O4 hollow nanosheet arrays for efficient oxygen evolution reaction.

Herein, Fe-doped Co3O4 hollow nanosheet arrays with rich oxygen vacancies (Vo-Fe-Co3O4) are constructed using a facile strategy. Benefiting from the compositional and structural superiorities, Vo-Fe-Co3O4 exhibits a remarkable OER overpotential of 231 mV at 10 mA cm-2 and a Tafel slope of 57.45 mV dec-1 in an alkaline medium.

MOF-derived flower-like Fe-doped Co3O4 porous hollow structures with enhanced n-butanol sensing properties at low temperature

Metal oxide-based gas sensors are widely used in the detection of toxic and harmful gases due to their advantages of high precision, convenient use and stable performance, but their application range is limited due to the high working temperature. In this work, MOF-derived flower-like Fe-doped Co3O4 porous hollow structures are obtained using a simple solvothermal method. The obtained samples are characterized in terms of their crystalline structure, morphology, chemical composition, optical properties and specific surface area. This study systematically investigates the sensing performance of pristine and Fe-doped Co3O4 samples. The results show that the 2 at% Fe-Co3O4 sample has the best n-butanol sensing properties. This sample exhibits high response and rapid response/recovery speed at a low working temperature of 110 °C, as well as good repeatability and anti-humidity features. The enhanced sensing properties can be attributed to several factors, including the adjustment of baseline resistance, increase in oxygen vacancies, decrease in bandgap, and the formation of unique hollow and porous structures. Overall, this work provides valuable insights into the potential applications of Fe-doped Co3O4 materials in sensing technologies.

Fe-doped Co3O4 nanowire strutted 3D pinewood-derived carbon: A highly selective electrocatalyst for ammonia production via nitrate reduction

Fe-doped Co3O4 nanowire strutted 3D pinewood-derived carbon: A highly selective electrocatalyst for ammonia production via nitrate reduction

Synthesized Fe-doped Co3O4 nanoparticles-based anode for high-performance lithium-ion batteries application

ABSTRACT Co3O4 has been considered a promising anode material because of its high theoretical capacity (890 mAh/g) and remarkable energy density. Unfortunately, it suffers from low initial coulombic efficiency, rapid capacity fading, poor electronic conductivity, large volume changes, and aggregation during the lithium ion intercalation/deintercalation process. In this work, a series of Fe2+-doped Co3O4 nanostructured materials Co3(1-x)Fe3xO4 (x = 0, 0.01, 0.02 and 0.03) were produced by a simple chemical co-precipitation method. The Fe doping led to a slight increase of the lattice parameter, which is beneficial to the rapid diffusion of Li+ ion during the lithiation/delithiation process. Meanwhile, the Fe-doped Co3O4 sample exhibited an excellent rate capability of 886.47 mAh/g at 500 mA/g, and outstanding cyclic stability (1156.91 mAh/g for 50 cycles, with the capacity retention rate of 83.53% at the current density of 100 mA/g), demonstrating improved electrochemical performance, compared with that of pure Co3O4. The good electrochemical performance profited from the formation of oxygen vacancies by Fe doping, which provided more space for Li+ diffusion and improved the electronic conductivity of the anode material. This work provides a simple way to improve the comprehensive electrochemical performance of the transitional metal oxide Co3O4 anode electrodes for lithium-ion batteries.

A Novel Approach of Sea Urchin-like Fe-Doped Co3O4 Microspheres for Li-S Battery Enables High Energy Density and Long-Lasting.

The poor cycle stability caused by the shuttle effect of polysulfides which have been key scientific issue in the development of high-efficiency lithium-sulfur (Li-S) batteries. In this work, the authors report a Fe-doped Co3O4 (named FCO) that was used as a sulfur-loaded host material for Li-S batteries. We demonstrate the important roles of well-designed Co3O4 particles and Fe atoms in regulating polysulfide conversion due to the strong adsorption of polysulfides by polar Co3O4, whereas Fe atoms and Co3O4 catalyze polysulfide conversion. Therefore, the LiS batteries with FCO-180 (When the hydrothermal temperature is 180 °C) sea urchinlike composites exhibited a high superior energy density (992.7 mAh g-1 at 0.2 C, after 100 cycles) and long-term cyclability (649.4 mAh g-1 at 1 C, 300 cycles) with high sulfur loading (75 wt%). This work confirms that the FCO-180 sea urchinlike increases not only the capacity of high-rate but also a generic and feasible strategy to construct practical Li-S batteries for emerging energy-storage applications.

Fe-doped Co3O4 anchored on hollow carbon nanocages for efficient electrocatalytic oxygen evolution

In this work, a Fe-doped Co3O4 OER electrocatalyst supported by an N-doped hollow nanocage carbon framework (Fe-Co3O4/NC) was successfully prepared by anion exchange and annealing in an air atmosphere strategy. XRD and HRTEM characterizations confirm that Fe the incorporation of Fe into the lattice of Co3O4. XPS characterization clarifies that the valence state of Co increases after the introduction of Fe, which originates from the electrons transfer from Co2+/Co3+ to Fe3+ and is induced by the valence electron configuration of cations. It simulates Co sites in-situ derived into CoOOH active species during the OER process, which is confirmed by the HRTEM and XPS characterization after the OER stability test. Electrochemical performance tests show that the Fe-Co3O4/NC electrocatalyst only exhibits 275 mV overpotential to achieve a current density of 10 mA/cm2 and stably maintains for 20 h at 100 mA/cm2. Together with 20% Pt/C electrocatalyst, the composed two-electrode system only needs 2.041 V applied potential to achieve 100 mA/cm2 for total water splitting in a self-made membrane electrode device, which has industrial application prospects.

Fe-doped Co3O4 nanostructures prepared via hard-template method and used for the oxygen evolution reaction in alkaline media

Low-cost and highly efficient anode catalysts are required for the oxygen evolution reaction (OER), which is integral to the commercialization of alkaline-based water electrolysis. Herein, pore size-controlled Fe-doped Co3O4 nanostructures are prepared as non-precious metal anode catalysts using a hard-template method with silica beads of different sizes, ranging from 20 to 1000 nm in diameter. The pore size distribution and specific surface area of the catalysts are measured by nitrogen adsorption/desorption analysis and mercury intrusion porosimetry. The electrochemical properties and OER performances of the catalysts are evaluated in half and unit cells, respectively. Among the catalysts studied, FCO-T-500 synthesized using 500 nm-sized silica beads exhibits the best OER activity and stability, given by a high current density of 847 mA cm−2 at 1.8 V and superior 100 h-stability during single cell test of anion exchange membrane water electrolysis. The improved OER performance of FCO-T-500 can be attributed to the optimal pore size favorable for gas diffusion and mass transport, sufficient surface OH and H2O groups produced via KOH leaching, the largest number of electrocatalytic active sites, and the fastest charge-transfer reaction.

Fe-doping-induced cation substitution and anion vacancies promoting Co3O4 hexagonal nanosheets for efficient overall water splitting

Water electrolysis is a green technology for hydrogen fuel production, but greatly hampered by the slow kinetics of the anodic oxygen evolution reaction (OER) and the cathodic hydrogen evolution reaction (HER). In this work, we report an efficient strategy to simultaneously promote OER and HER performance on Co3O4 hexagonal nanosheets via Fe-doping-induced cation substitution and anion vacancies. Benefiting from the integrated advantages of well-defined ultrathin nanosheets, abundant vacancies, and unique three-dimensional electrode configuration, the optimized Fe-doped Co3O4 hexagonal nanosheets/nickel foam (Fe0.4Co2.6O4 HNSs/NF) can achieve overpotentials of 328 mV at 100 mA cm−2 for OER and 315 mV at 500 mA cm−2 for HER, respectively, which is comparable to those of the benchmark noble electrocatalysts. More importantly, the Fe0.4Co2.6O4 HNSs/NF-assembled electrolyzer for overall water splitting can deliver a current density of 100 mA cm−2 at a cell voltage as low as 1.66 V and work steadily at 50 mA cm−2 with a negligible fading up to 140 h.

Enhancing pseudocapacitive properties of cobalt oxide hierarchical nanostructures via iron doping

Through co-precipitation and post-heat processing, nanostructured Fe-doped Co3O4 nanoparticles (NPs) were developed. Using the SEM, XRD, BET, FTIR, TGA/DTA, UV–Vis, and techniques were examined. The XRD analysis presented that Co3O4 and Co3O4 nanoparticles that had been doped with 0.25 M Fe formed single cubic phase Co3O4 NPs with average crystallite sizes of 19.37 nm and 14.09 nm, respectively. The as prepared NPs have porous architectures via SEM analyses. The BET surface areas of Co3O4 and 0.25 M Fe-doped Co3O4 NPs were 53.06 m2/g and 351.56 m2/g, respectively. Co3O4 NPs have a band gap energy of 2.96 eV and an extra sub-band gap energy of 1.95 eV. Fe-doped Co3O4 NPs were also found to have band gap energies between 2.54 and 1.46 eV. FTIR spectroscopy was used to determine whether M–O bonds (M = Co, Fe) were present. The doping impact of iron results in the doped Co3O4 samples having better thermal characteristics. The highest specific capacitance was achieved using 0.25 M Fe-doped Co3O4 NPs at 5 mV/s, which corresponding to 588.5 F/g via CV analysis. Additionally, 0.25 M Fe-doped Co3O4 NPs had energy and power densities of 9.17 W h/kg and 472.1 W/kg, correspondingly.

Accelerated redox conversion of an advanced Zn//Fe-Co3O4 battery by heteroatom doping.

Herein, Fe-doped Co3O4 (Fe-Co3O4) was prepared to solve the issues of poor electrical conductivity and the lack of active sites in Co3O4 materials. Due to having similar radius and physical/chemical properties to Co, Fe is an ideal choice for doping Co3O4, as it can improve intrinsic conductivity without causing severe lattice distortion. Oxygen vacancies are gradually formed as doping reactions occur to maintain electric neutrality. Owing to the merits of oxygen vacancies in Co3O4, the distribution of the electrons is changed, thus optimizing the material's intrinsic charge/ion states and modifying the band gap by introducing impurity levels. Moreover, the surface area of Fe-Co3O4 is 1.5 times larger than that of the original material. The synergistic effect promotes the electrochemical oxidation reduction reaction and improves the capacitance and cycling stability. Finally, such an advanced Zn//Fe-Co3O4 battery exhibits a discharge-specific capacity of 171.97 mA h g-1, nearly eight times higher than that of the previous Zn//Co3O4 battery (22.38 mA h g-1). In addition, the attenuation of the capacity was almost negligible after 9000 cycles.

Optimizing the electronic structure of Fe-doped Co3O4 supported Ru catalyst via metal-support interaction boosting oxygen evolution reaction and hydrogen evolution reaction

Metal-support interaction (MSI) is an efficient way in heterogeneous catalysis and electrocatalysis to modulate the electronic structure of metal for enhanced catalytic activity. However, there are still great challenges in promoting the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) simultaneously by this way. Herein, Fe-doped Co3O4 supported Ru (Ru/FeCo) catalysts are synthesized by MSI strategies to further improve the electrocatalytic activity and stability of the catalysts. The results show that the optimized Ru/FeCo catalyst exhibits the best catalytic performance. The HER and OER tests at 10 mA/cm2 in 1 mol/L KOH solution show excellent overpotentials of 155 mV and 283 mV, respectively. The activity and stability enhancement can be attributed to the MSI that effectively modify the electronic structure and improve interfacial electron transfer between Ru and Fe-doped Co3O4 (FeCo). This work provides an innovative direction for the design of high-efficiency bifunctional electrocatalysts by virtue of the MSI.

Enhanced photocatalytic water splitting of g-C3N4 loaded with Fe doped Co3O4 and Pt dual-cocatalysts

Dual cocatalysts play an important role in photocatalytic water splitting to hydrogen production. In this paper, Fe-doped Co3O4 (Fe-Co3O4) and Pt were loaded on the surface of g-C3N4 to enhance the water photocatalytic splitting, in which Fe-Co3O4 was used as an oxidation cocatalyst to capture the photo-generated holes of g-C3N4, and Pt was used as a reduction cocatalyst to transfer photo-generated electrons. Under the irradiation of visible light, its hydrogen production rate reaches up to 3.015 mmol g−1 h−1, which is 3.01 times higher than that of g-C3N4 loaded with Pt. Pt and Fe-Co3O4 dual cocatalysts not only promote the migration rate of photo-generated electrons and holes on the surface of g-C3N4, but also improve the light absorption capacity of visible light. The interfacial electric field built from the p-n heterojunction of Fe-Co3O4/g-C3N4 drives photo-generated electrons in Fe-Co3O4 flowing to the holes of g-C3N4, which further inhibiting the recombination of g-C3N4 photo-generated carriers. This work provides a reference for the development of high-efficiency photocatalyst and an effective support for the development of semiconductor cocatalyst.

Fe-doped porous Co3O4 nanosheets with highly efficient catalytic performance for soot oxidation

A series of CoxFe1-x-PNS materials were synthesized at room temperature through the one-pot MgO-mediated method and were then used as catalysts for soot oxidation. Of all the catalyst samples prepared, the porous Co0.8Fe0.2-PNS nanosheets exhibited the highest catalytic performance for soot oxidation under both loose and tight contact modes. The 2D nanosheets provided a larger external surface area for contact between the catalyst and soot, and the porous structure was beneficial to the adsorption and diffusion of reactant gas. It was found that Fe was successfully doped in the lattice of Co3O4, and the mechanism regarding how Fe doping enhances intrinsic activity was investigated by a series characterization and DFT calculations. The results indicated that Fe doping made it easier to form oxygen vacancies and adsorb gaseous O2, which effectively improved the catalytic activity of soot oxidation. Hence, it is believed that the synergy between the well-defined porous nanosheets morphology and the properties induced by the doping of Fe resulted in better catalytic activity. This study also provided insight into the design of 2D transition metal oxides nanosheets as catalysts for soot oxidation.

Iron-doped cobalt oxide nanoarray for efficient electrocatalytic nitrate-to-ammonia conversion

Electrochemical nitrate reduction reaction (NO3RR) is an attractive alternative to NH3 production under ambient conditions. Although noble metal-based catalysts exhibit decent NO3RR performance to NH3, the high cost and insufficient supply obstruct its large-scale application. In this work, we report that Fe-doped Co3O4 nanoarray efficiently catalyzes NO3RR for NH3 production in neutral conditions. It achieves a large NH3 yield of 0.624 mg mgcat.−1h−1 and high Faradaic efficiency of 95.5% at −0.7 V versus reversible hydrogen electrode. Besides, this catalyst exhibits good NO3RR stability. Density functional theory calculations reveal favorable adsorption of NO3− on Fe-doped Co3O4, which is conducive to NH3 production in the NO3RR process.

Electrochemical Performance of Iron-Doped Cobalt Oxide Hierarchical Nanostructure

In this study, hydrothermally produced Fe-doped Co3O4 nanostructured particles are investigated as electrocatalysts for the water-splitting process and electrode materials for supercapacitor devices. The results of the experiments demonstrated that the surface area, specific capacitance, and electrochemical performance of Co3O4 are all influenced by Fe3+ content. The FexCo3-xO4 with x = 1 sample exhibits a higher BET surface (87.45 m2/g) than that of the pristine Co3O4 (59.4 m2/g). Electrochemical measurements of the electrode carried out in 3 M KOH reveal a high specific capacitance of 153 F/g at a current density of 1 A/g for x = 0.6 and 684 F/g at a 2 mV/s scan rate for x = 1.0 samples. In terms of electrocatalytic performance, the electrode (x = 1.0) displayed a low overpotential of 266 mV (at a current density of 10 mA/cm2) along with 52 mV/dec Tafel slopes in the oxygen evolution reaction. Additionally, the overpotential of 132 mV (at a current density of 10 mA/cm2) and 109 mV with 52 mV/dec Tafel slope were obtained for x = 0.6 sample towards hydrogen evolution reaction (HER). According to electrochemical impedance spectroscopy (EIS) measurements and the density functional theory (DFT) study, the addition of Fe3+ increased the conductivity at the electrode–electrolyte interface, which substantially impacted the high activity of the iron-doped cobalt oxide. The electrochemical results revealed that the mesoporous Fe-doped Co3O4 nanostructure could be used as potential electrode material in the high-performance electrochemical capacitor and water-splitting catalysts.

Green Synthesis of Iron-Doped Cobalt Oxide Nanoparticles from Palm Kernel Oil via Co-Precipitation and Structural Characterization.

In this study, a bio-derived precipitating agent/ligand, palm kernel oil, has been used as an alternative route for the green synthesis of nanoparticles of Fe-doped Co3O4 via the co-precipitation reaction. The palm oil was extracted from dried palm kernel seeds by crushing, squeezing and filtration. The reaction of the palm kernel oil with potassium hydroxide, under reflux, yielded a solution containing a mixture of potassium carboxylate and excess hydroxide ions, irrespective of the length of saponification. The as-obtained solution reacts with an aqueous solution containing iron and cobalt ions to yield the desired metallo-organic precursor, iron cobalt carboxylate. Characterization of the precursors by IR and gas chromatography (GC) attests to the presence of carboxylate fatty acids in good agreement with the proportion contained in the oil, and ICP confirms that the metallic ratios are in the proportion used during the synthesis. Analysis of the products thermally decomposed between 400 °C and 600 °C by XRD, EDX, TEM and ToF-SIMS, established that cobalt iron oxide nanoparticles (Co(1−x)Fex)3O4 were obtained for x ≤ 0.2 and a nanocomposite material (Co(1−x)Fex)3O4/Fe3O4 for x ≥ 0.2, with sizes between 22 and 9 nm. ToF-SIMS and XRD provided direct evidence of the progressive substitution of cobalt by iron in the Co3O4 crystal structure for x ≤ 0.2.