Bifunctional oxygen electrocatalysts based on non-critical raw materials: Carbon nanostructures and iron-doped manganese oxide nanowires

Villanueva-Martínez, Nicolás I.; Alegre, Cinthia; Martínez-Visús, I.; Lázaro, M.J.

doi:10.1016/j.cattod.2023.114083

Cited by 6 publications

(7 citation statements)

References 65 publications

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“…This excellent catalytic behavior is due to the presence of nickel in the CNF, an active metal towards both ORR and OER, alongside the outstanding electrical conductivity of the carbon material. In a previous work [24], we showed that acid-leached carbon nanofibers also hold a considerable, yet slightly lower, catalytic activity towards ORR and non-negligible activity towards OER. As was discussed in Section 2.1, CNF, although still presenting a small amount of nickel (<2 wt%), has a large amount of structural defects, which have been reported as active sites [42].…”

Section: Effect Of the Carbon Nanostructure On The Catalytic Activity...mentioning

confidence: 76%

“…Poux et al synthesized La-Sr-Mn perovskites/pyrolytic carbon composites [23] and concluded that carbon not only increases the electrical conductivity of the catalyst but also increases the surface area and favors oxygen adsorption, thus enhancing ORR. In a previous work [24], we observed that combining iron-doped manganese oxide nanowires with carbon nanofibers generated a synergistic effect that was ascribed to both an increase in the conductivity of the catalyst and to enhanced oxygen adsorption, eventually favoring ORR.…”

Section: Introductionmentioning

confidence: 87%

“…Despite not having the highest number of electrons transferred, CNF is more active than the other materials in the diffusional limit, as is corroborated by the intercept on the Y-axis at a lower value (higher kinetic current at 0.2 V vs. RHE). The superior performance of nanofibers can be explained by their physical-chemical properties: the presence of nickel from the catalyst [24], their relatively high surface area and the amount of structural defects acting as active sites [42]. Two paths have been described in the literature for oxygen reduction over manganese catalysts [47].…”

Section: Effect Of the Carbon Nanostructure On The Catalytic Activity...mentioning

confidence: 99%

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On the Effect of the Nature of Carbon Nanostructures on the Activity of Bifunctional Catalysts Based on Manganese Oxide Nanowires

Villanueva-Martínez,

Alegre,

Sebastián

et al. 2023

Catalysts

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Manganese oxide nanowires (MONW) combined with carbon nanostructures were synthesized using three different carbon materials, and their effect on the activity towards Oxygen Reduction Reaction (ORR) and Oxygen Evolution Reaction (OER) was investigated in alkaline electrolytes. The carbon structures were carbon nanofibers (CNF), multiwall carbon nanotubes (CNT) and reduced graphene oxide (rGO). Both MONW and carbon nanostructures were characterized by X-ray diffraction, scanning and transmission electron microscopy, N2 physisorption and X-ray photoelectron spectroscopy. The electrochemical activity was assessed in a three-electrode cell. Composite MONW/CNF showed the best activity towards ORR, and MONW/rGO exhibited the highest activity towards OER of the series. The addition of the carbon nanostructures to MONW increased the number of electrons transferred in the ORR, indicating a synergistic effect between the carbon and manganese oxide structures due to changes in the reaction pathway. The analysis of Tafel slopes and electrochemical impedance spectroscopies showed that carbons and MONW catalyze different steps of the reactions, which explains the better activity of the composites. This led us to synthesize a MONW/rGO-CNF composite, where rGO-CNF is a hybrid carbon material. Composite MONW/rGO-CNF showed an improved activity towards ORR, close to the benchmark Pt/C catalyst, and activity towards OER, close to MONW/rGO, and better than the benchmark IrO2 catalyst. It also showed remarkable stability in challenging operation conditions.

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Section: Effect Of the Carbon Nanostructure On The Catalytic Activity...mentioning

confidence: 76%

Section: Introductionmentioning

confidence: 87%

Section: Effect Of the Carbon Nanostructure On The Catalytic Activity...mentioning

confidence: 99%

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On the Effect of the Nature of Carbon Nanostructures on the Activity of Bifunctional Catalysts Based on Manganese Oxide Nanowires

Villanueva-Martínez,

Alegre,

Sebastián

et al. 2023

Catalysts

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“…Figure c shows that NiFe@ACF has a small Tafel slope of ∼83 mV dec –1 , which is much smaller than that of Ni@ACF, Fe@ACF, ACF, and Ir/C@ACF, suggesting the favorable OER kinetics of NiFe@ACF. Considering the Tafel slope of ∼83 mV dec –1 for the NiFe@ACF, either the one electron-transfer step (M + OH – ↔ MOH + e – ) or the electron–proton-transfer step (MOOH + OH – ↔ MOO + H 2 O + e – ) is the rate-determining step. − Compared with Fe@ACF and Ni@ACF, NiFe@ACF has a much smaller Tafel slope and a much lower overpotential. It implies that the synergistic effect between Ni and Fe in NiFe@ACF could enhance OER catalytic activity. ,, In addition, a chronopotentiometric test was carried out continuously at a current density of ∼10 mA cm –2 to measure durability of the NiFe@ACF in 1 M KOH.…”

Section: Resultsmentioning

confidence: 99%

Ultrafast Thermal Synthesis of Non-Noble Metal-Based Electrocatalysts for Overall Water Splitting

Park

Jiang

Zheng

et al. 2023

ACS Appl. Energy Mater.

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Non-noble metal-based electrocatalysts have attracted extensive interest due to their low-cost, earth-abundance, and highly efficient catalytic performance as alternatives to noble metal counterparts. However, conventional approaches to synthesize electrocatalysts can endure overlong synthesis time with throughput degradation. Here, we demonstrate an ultrafast thermal method to synthesize non-noble metal-based electrocatalysts for overall water splitting. The method can be extensively used for metal-based catalysts, including metal oxides, metal carbides, alloys, and their composites. Among them, we select two outstanding electrocatalysts as examples for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The hybrid structure of nickel oxides and molybdenum carbides on activated carbon felt (Ni–Mo@ACF) for HER shows remarkable catalytic activity with a low overpotential of 87 mV and an excellent durability for 48 h at a current density of 10 mA cm–2. The NiFe alloy nanosheets on activated carbon felt (NiFe@ACF) for OER show superb catalytic activity with a low overpotential of 270 mV and great durability for 48 h at a current density of 10 mA cm–2. Consequently, an overall water splitter assembled with Ni–Mo@ACF as the cathode and NiFe@ACF as the anode only requires a low cell voltage of 1.60 V to drive a current density of 10 mA cm–2 with excellent durability for 36 h, which is the best among non-noble metal-based electrocatalysts reported so far. This work offers an approach for the ultrafast and facile synthesis of non-noble metal-based electrocatalysts for water splitting and other applications.

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“…In addition to transition metals, the transition metal oxides have recently emerged as a promising alternative to platinum for catalyzing ORR in fuel cells [27]. (Fe Y O X |Carbon) combines the advantages of both carbon and iron oxide, which can promote the ORR activity by facilitating the electron transfer and reducing the energy barrier for O 2 adsorption and reduction [27,33,34].…”

Section: Introductionmentioning

confidence: 99%

Ultra-Low Loading of Iron Oxide and Platinum on CVD-Graphene Composites as Effective Electrode Catalysts for Solid Acid Fuel Cells

et al. 2023

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We propose a new design for electrocatalysts consisting of two electrocatalysts (platinum and iron oxide) that are deposited on the surfaces of an oxidized graphene substrate. This design is based on a simple structure where the catalysts were deposited separately on both sides of oxidized graphene substrate; while the iron oxide precipitated out of the etching solution on the bottom-side, the surface of the oxidized graphene substrate was decorated with platinum using the atomic layer deposition technique. The Fe2O3-decorated CVD-graphene composite exhibited better hydrogen electrooxidation performance (area-normalized electrode resistance (ANR) of ~600 Ω·cm−2) and superior stability in comparison with bare-graphene samples (ANR of ~5800 Ω·cm−2). Electrochemical impedance measurements in humidified hydrogen at 240 °C for (Fe2O3|Graphene|Platinum) electrodes show ANR of ~0.06 Ω·cm−2 for a platinum loading of ~60 µgPt·cm−2 and Fe2O3 loading of ~2.4 µgFe·cm−2, resulting in an outstanding mass normalized activity of almost 280 S·mgPt−1, exceeding even state-of-the-art electrodes. This ANR value is ~30% lower than the charge transfer resistance of the same electrode composition in the absence of Fe2O3 nanoparticles. Detailed study of the Fe2O3 electrocatalytic properties reveals a significant improvement in the electrode’s activity and performance stability with the addition of iron ions to the platinum-decorated oxidized graphene cathodes, indicating that these hybrid (Fe2O3|Graphene|Platinum) materials may serve as highly efficient catalysts for solid acid fuel cells and beyond.

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Bifunctional oxygen electrocatalysts based on non-critical raw materials: Carbon nanostructures and iron-doped manganese oxide nanowires

Cited by 6 publications

References 65 publications

On the Effect of the Nature of Carbon Nanostructures on the Activity of Bifunctional Catalysts Based on Manganese Oxide Nanowires

On the Effect of the Nature of Carbon Nanostructures on the Activity of Bifunctional Catalysts Based on Manganese Oxide Nanowires

Ultrafast Thermal Synthesis of Non-Noble Metal-Based Electrocatalysts for Overall Water Splitting

Ultra-Low Loading of Iron Oxide and Platinum on CVD-Graphene Composites as Effective Electrode Catalysts for Solid Acid Fuel Cells

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