Enhanced Oxygen Reduction Reaction Research Articles

Enhancing oxygen reduction reaction in acidic medium: A novel electrocatalyst of Pt–Co embedded in nitrogen-rich carbon nanosheets derived from polypyrrole-g-C3N4

Enhancing oxygen reduction reaction in acidic medium: A novel electrocatalyst of Pt–Co embedded in nitrogen-rich carbon nanosheets derived from polypyrrole-g-C3N4

Greatly Enhanced Oxygen Reduction Reaction in Anion Exchange Membrane Fuel Cell and Zn-Air Battery via Hole Inner Edge Reconstruction of 2D Pd Nanomesh.

Platinum group metals (PGM) have yet to be the most active catalysts in various sustainable energy reactions. Their high cost, however, has made maximizing the activity and minimizing the dosage become an urgent priority for the practical applications of emerging technologies. Herein, a novel 2DPd nanomesh structure possessing hole inner reconstructed edges (HIER) with exposed high energy facets and overstretched lattice parameters is fabricated through a facile room-temperature reduction method at gram-scale yields. The HIER enhances the catalytic performance of Pd in electrochemical oxygen reduction reaction (ORR), achieving superior mass activity (MA) of 2.672 A mgPd -1, which is 27.8 fold and 23.6 fold higher, respectively, than those of the commercial Pt/C (0.096 A mgPt -1) and Pd/C (0.113 A mgPd -1) at 0.9 VRHE. Most significantly, in H2-air anion exchange membrane fuel cell (AEMFC) and Zn-air battery (ZAB) applications, this unique Pd catalyst delivers a much-outperformed peak power density of 0.86 and 0.22W cm-2, respectively, compared with 0.54 and 0.13W cm-2 of the commercial Pt/C catalyst, indicating a novel pathway in electrocatalyst designs through HIER engineering.

Enhancing Oxygen Reduction Reaction Electrocatalytic Performance of Nickel‐Nitrogen‐Carbon Catalysts through Coordination Environment Engineering†

Comprehensive SummarySingle‐atom catalysts (SACs) have attracted significant attention due to their high atomic utilization and tunable coordination environment. However, the catalytic mechanisms related to the active center and coordination environment remain unclear. In this study, we systematically investigated the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) catalytic activities of NiN4, NiN3, NiN3H2, NiN4X, NiN3X, and NiN3H2X (X denotes axial ligand) through density functional theory (DFT) calculations. This study unveils two distinct reaction pathways for ORR and OER, involving proton‐electron pairs adsorbed from both the solution and the catalyst surface. The overpotential is the key parameter to evaluate the catalytic performance when proton‐electron pairs are adsorbed from the solution. NiN3 and NiN3H2 show promise as pH‐universal bifunctional electrocatalysts for both ORR and OER. On the other hand, when proton‐electron pairs are adsorbed from the catalyst surface, the reaction energy barrier becomes the crucial metric for assessing catalytic activity. Our investigation reveals that NiN3H2 consistently exhibits optimal ORR activity across a wide pH range, regardless of the source of proton‐electron pair (solvent or catalyst surface).

Enhancing Oxygen Reduction Reaction of Single-Atom Catalysts by Structure Tuning.

Deciphering the fine structure has always been a crucial approach to unlocking the distinct advantages of high activity, selectivity, and stability in single-atom catalysts (SACs). However, the complex system and unclear catalytic mechanism have obscured the significance of exploring the fine structure. Therefore, we endeavored to develop a three-component strategy to enhance oxygen reduction reaction (ORR), delving deep into the profound implications of the fine structure, focusing on central atoms, coordinating atoms, and environmental atoms. Firstly, the mechanism by which the chemical state and element type of central atoms influence catalytic performance is discussed. Secondly, the significance of coordinating atoms in SACs is analyzed, considering both the number and type. Lastly, the impact of environmental atoms in SACs is reviewed, encompassing existence state and atomic structure. Thorough analysis and summarization of how the fine structure of SACs influences the ORR have the potential to offer valuable insights for the accurate design and construction of SACs.

Optimizing Metal-free Phenanthroline-assisted Nitrogen-doped Reduced Graphene Oxide for Enhanced Oxygen Reduction Reaction: An Experimental Design and Performance Study

Optimizing Metal-free Phenanthroline-assisted Nitrogen-doped Reduced Graphene Oxide for Enhanced Oxygen Reduction Reaction: An Experimental Design and Performance Study

Multilayer Porous Fe/Co-N-MWCNT Electrocatalyst For Rechargeable Zinc-Air Batteries.

The design of efficient, stable, low-cost non-precious metal-based electrocatalysts with enhanced oxygen reduction reaction (ORR) activity has garnered significant attention in the scientific community. This study introduces a novel electrocatalyst, Fe/Co-N-MWCNT, synthesized through the in-situ growth of ZIF-8 and Fe/Co-Phen on multi-walled carbon nanotubes (MWCNTs), followed by pyrolysis at varying temperatures to optimize its properties. The inclusion of Fe and Co during the pyrolysis process facilitated the creation of metal active sites and Fe-Co, enhancing electron transfer and ORR activity. Compared to Pt/C (E1/2=0.854 V, JL=4.90 mA cm-2), Fe/Co-N-MWCNT exhibited a similar half-wave potential (E1/2=0.812 V) and an improved limiting current density (JL=5.37 mA cm-2). Moreover, Fe/Co-N-MWCNT displayed remarkable stability, showing only a 7 mV negative shift in E1/2 after 2000 cycles. Ampere response testing indicated a current decay of only 7.8 % for Fe/Co-N-MWCNT after 10000 s, while Pt/C experienced a decay of about 18.4 %. The exceptional catalytic stability of Fe/Co-N-MWCNT positions it as a promising candidate for rechargeable zinc-air batteries, attributed to its high pyridinic nitrogen content, unique structure, and abundant metal active sites.

Exploring Enhanced Oxygen Reduction Reactions: A Study on Nanocellulose, Dopamine, and Cobalt Complex-Derived Non-Precious Electrocatalyst

Exploring Enhanced Oxygen Reduction Reactions: A Study on Nanocellulose, Dopamine, and Cobalt Complex-Derived Non-Precious Electrocatalyst

Enhanced oxygen reduction reaction with rare-earth metal-based Ce-N-C catalyst

An atomically dispersed single atom catalyst based on rare-earth metal, Cerium embedded into the porous N-doped carbon (Ce-N-C), has been synthesized by using metal-organic framework method. The Ce-N-C catalyst have been physiochemically and electrochemically characterized in detail. Transmission electron microscope studies revealed atomically dispersed Ce atoms on the N-doped carbon support. The electrochemical oxygen reduction reaction (ORR) kinetics of Ce-N-C-3 catalyst revealed an admirable activity with a half-wave potential of 0.89 V, nearly equal to state-of-the-art Pt/C catalyst. The K-L plots and RRDE measurements revealed a nearly direct 4 electron reduction of O2 to H2O by Ce-N-C-3 catalyst. In addition, the chronoamperometry studies with a simulated H2O2 environments clearly revealed the significance of Ce3+/Ce4+ redox couple in deactivating hydrogen peroxide and/or hydroperoxide radicals. The commendable ORR activity, stability and peroxide resistance of Ce-N-C-3 catalysts is credited to the high surface area, atomically dispersed Ce atoms, formation of Ce-N4-C active sites in the catalysts, evidenced from the XPS analysis, in addition to the significance of Ce3+/Ce4+ redox couple in the catalyst. Most importantly, chronoamperometric studies revealed clear evidence of Ce3+/Ce4+ couple significance, helping in effectively mitigating the peroxide related detrimental effects to the ORR catalyst.

Deciphering the enhanced oxygen reduction reaction activity of PrBa0.5Sr0.5Co1.5Fe0.5O5+δ via constructing negative thermal expansion offset for high-performance solid oxide fuel cell

Solid oxide fuel cells (SOFCs) are one of the most efficient energy conversion devices. However, the sluggish oxygen reduction reaction (ORR) kinetics at low temperatures significantly challenge the performance and commercialization of SOFCs. Introducing negative expansion coefficient materials has been recognized as an effective approach to enhancing the ORR catalytic properties, but a clear understanding of this enhanced electrochemical performance is still lacking. In this work, the composite cathode of PrBa0.5Sr0.5Co1.5Fe0.5O5+δ (PBSCF) with different amounts of negative-thermal-expansion material Sm0.85Zn0.15MnO3 (SZM) is prepared, and in-depth analysis the effect of SZM on the catalytic activity of cathodic ORR is systematically investigated. Simultaneously, the mechanistic studies verify that the enhanced ORR activity might be attributed to the constructed compression strain during sintering, which significantly improves the adsorption, dissociation, and oxygen ion exchange process of the PBSCF cathode.

Engineering Synergetic Fe‐Co Atomic Pairs Anchored on Porous Carbon for Enhanced Oxygen Reduction Reaction

AbstractThe rational design of heteronuclear dual‐atom catalyst (DAC) is intricate due to the random dispersion of metal atoms under thermal treatment. Herein, a novel precursor pre‐orientation strategy is reported to construct Fe‐Co diatomic sites atomically dispersed on nitrogen doped carbon (Fe‐Co‐NC) via cubic Prussian blue analogue as metal source. Due to the specific synergy between Fe and Co centers, the obtained Fe‐Co‐NC catalyst renders outstanding oxygen reduction reaction (ORR) performance with positive half‐wave potential and good durability in wide pH range. Density functional theory further clarifies the active centers and reveals that the Fe‐Co‐NC dual atomic catalyst follows the modulation mechanism, where the intermediates tended to adsorb on Fe site, while the neighboring Co atom can assist by lowering the d‐band center of Fe site. Experimentally and theoretically emphasizes the priority of heteronuclear diatomic Fe‐Co catalysts over homonuclear Fe‐Fe‐NC and Co‐Co‐NC DAC. Moreover, the Zn‐Air battery (ZAB) and microbial fuel cell (MFC) assembled with Fe‐Co‐NC cathodes both exhibit splendid power density (382 mW cm−2 for ZAB, 2034 ± 103 mW m−2 for MFC) as well as excellent stability. This work provides a new perspective for rational construction and precise regulation for heteronuclear dual‐atom catalysts.

CuFe nanoparticles coupled Cu–Nx for enhancing oxygen reduction reaction

For the large-scale development of zinc-air batteries (ZABs), designing efficient, and cost-effective oxygen reduction reaction (ORR) electrocatalysts is crucial yet challenging. Herein, CuFe nanoparticles coupled with Cu–Nx active sites co-anchored on 2D nitrogen–doped porous carbon nanosheets (CuFe@Cu–N–C) were obtained by the pyrolysis of Cu–MOF–74, nitrogen source, and ferric salt. The 2D porous carbon structure and the coupling effect between CuFe nanoparticles and Cu–Nx active sites endowed the CuFe@Cu–N–C electrocatalyst with excellent ORR electrocatalytic performance. Consequently, the CuFe@Cu–N–C electrocatalyst exhibited enhanced ORR activity with a higher half–wave potential than Cu–N–C, surpassing even that of the commercial 20 % Pt/C by 21 mV in alkaline media. Additionally, the CuFe@Cu–N–C electrocatalyst exhibited superior ORR stability to commercial 20 % Pt/C. Primary ZABs assembled with the CuFe@Cu–N–C as the cathode ORR electrocatalyst also showed excellent electrochemical properties. The work shows that the prepared CuFe@Cu–N–C electrocatalyst can serve as an ideal alternative to Pt-based catalysts for ZABs.

Enhancing oxygen reduction reaction of microbial fuel cells by core-double shell structure MnO2/NiFe-LDH@NiCo2S4 as cathode catalyst

Manganese dioxide (MnO2) and NiFe-layered double hydroxide (LDH) nanosheets were deposited on bimetallic metal sulfide (NiCo2S4) by hydrothermal reaction method, and MnO2/NiFe-LDH@NiCo2S4 was applied as cathode catalyst in microbial fuel cell (MFC). The combination of lamellar MnO2 with NiFe-LDH coated on NiCo2S4 achieved a typical core-double shell structure. The unique core-double shell structure created a rapid pathway for electron transport and reduced interfacial impedance. The MnO2/NiFe-LDH@NiCo2S4-MFC exhibited the maximum power density of 80 mW/m2, approximately 2.16 times that of the MnO2-MFC (37 mW/m2). Additionally, the maximum voltage was around 200 mV, with good stability maintained for approximately 10 d. The material exhibited excellent electrochemical properties and possessed great potential for application as cathode catalysts of MFC.

Regulating the Electronic Configuration of Single-Atom Catalysts with Fe–N5 Sites via Environmental Sulfur Atom Doping for an Enhanced Oxygen Reduction Reaction

Regulating the Electronic Configuration of Single-Atom Catalysts with Fe–N₅ Sites via Environmental Sulfur Atom Doping for an Enhanced Oxygen Reduction Reaction

Engineering PtCu Alloy Nanoparticles on ZIF-8-Derived N-Doped Carbon for Enhanced Oxygen Reduction Reaction

Engineering PtCu Alloy Nanoparticles on ZIF-8-Derived N-Doped Carbon for Enhanced Oxygen Reduction Reaction

Unveiling the potential of a g-C3N4/BiOBr/Bi2O2CO3 ternary heterojunction photocatalyst for rechargeable zinc-air battery: Visible-light-driven photo-assisted charging for bifunctional ORR and OER at the air cathode

Advancements in solar-driven energy storage technology have been achieved for rechargeable zinc-air batteries (RZABs), facilitating accelerated kinetic responses in both the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). In this study, we successfully synthesized a novel g-C3N4/BiOBr/Bi2O2CO3 ternary heterojunction through a facile hydrothermal process, demonstrating its efficacy as a bifunctional photocatalyst. Upon exposure to LED irradiation, this heterojunction triggers an effective separation of the photogenerated electron-hole pairs, resulting in enhanced oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) performance by 46.19 % and 65.69 % respectively, compared to non-LED conditions. Interestingly, the reduction in the potential gap under LED irradiation (0.06 V), correlating with a significant 2.71 % increase in round-trip efficiency (RTE), is observed. In addition, the optimized band alignment derived from g-C3N4/BiOBr/Bi2O2CO3 ternary heterojunction for photo-assisted charging rechargeable zinc-air batteries is proposed. Insightfully, photo-enhanced charging in RZABs mechanism during the charge/discharge process through in-situ X-ray absorption spectroscopy (XAS) is monitored, confirming the large interaction between O2 adsorption and Bi 6d orbitals of g-C3N4/BiOBr/Bi2O2CO3 in the presence of LED. In conclusion, our innovative g-C3N4/BiOBr/Bi2O2CO3 ternary heterojunction underscores the significant role that visible-light-driven photocatalysts can play in enhancing the efficiency of rechargeable zinc-air batteries.

Advancements in electrocatalyst architecture for enhanced oxygen reduction reaction in anion exchange membrane fuel cells: A comprehensive review

This comprehensive review explores recent advancements in electrocatalyst architecture to enhance the oxygen reduction reaction (ORR) in anion exchange membrane fuel cells (AEMFCs). It examines strategies such as nanostructuring, alloying, and heteroatom doping to improve catalytic activity, stability, and durability properties. Key findings reveal the importance of optimizing catalyst morphology, composition, and interface engineering to mitigate challenges such as sluggish kinetics and electrode degradation. Additionally, insights into mechanistic aspects and performance metrics are discussed, highlighting the crucial role of electrocatalysts in advancing AEMFC technology. Overall, this review provides valuable perspectives for researchers and engineers in designing efficient and durable electrocatalysts for next-generation AEMFCs, thereby facilitating the transition towards sustainable energy solutions.

Asymmetrical anchor way of manganese atoms on carbon domain edge for enhanced oxygen reduction reaction

Single atomic catalysts (SACs), especially the catalysts featured by well-developed M-N4 moieties, show excellent catalytic activity and spark enormous attention. However, the highly symmetric active sites may result in some degenerate electronic states for the d orbitals of the center metal atom, which suffer from the unsatisfactory adsorption-desorption behaviors during reaction. Herein, we develop an asymmetric anchor site by two types of nitrogen (sp-N and pyridinic N) created in the inherent edge-rich carbon domain of hydrogen-substituted graphdiyne (HsGDY), where atomic catalyst like manganese atoms can be asymmetrically anchored on the one side of hexagon carbon rings. The abundant elegant hexagon carbon rings on HsGDY not only facilitate the creation of edge sites, but also provide available space for the coordination of terminal ligands (OH) with Mn atoms. The as-synthesized Mn-N-HsGDY exhibits excellent ORR activity and an impressive long-term cyclability for over 3800 cycles in a rechargeable Zn-air battery.

Engineering atomically dispersed dual Pt–Ni sites on nitrogen-doped carbon with spherical core-shell structure for enhanced oxygen reduction activity towards microbial fuel cell

Inspired by the development of efficient, durable electrocatalytic functional materials to address the issues of kinetic retardation and mass transport to enhance oxygen reduction reaction (ORR), one strategy is proposed for core-shell structural nitrogen-doped carbon with atomically dispersed binary platinum-nickel (Pt–Ni) atoms (N–C@Pt–Ni/N–C) with controlled bimetallic sites and adjusted electronic coordination environment. Practical application of experimental and simulated theoretical calculation results show the coordination microenvironment optimization for active site can promote the charge rearrangement of Pt–Ni sites, thus regulating the free energy of the reaction intermediates of oxygen-containing species. The N–C@Pt–Ni/N–C reveals astounding catalytic capacity during ORR, leading to a large power density (1472.6 ± 50.6 mW m−2) and long-term reliability (OCP by the current loss with 0.1 mA) in the actual microbial fuel cells. This work not only reveals controllable preparation of functional materials with binary isolated atomic dispersion, but also presents more perspective of electronic structure optimal performance enhancement relationship at the atomic-sized active sites.

Highly Dispersed Mn-Doped Ceria Supported on N-Doped Carbon Nanotubes for Enhanced Oxygen Reduction Reaction.

The weak adsorption of oxygen on transition metal oxide catalysts limits the improvement of their electrocatalytic oxygen reduction reaction (ORR) performance. Herein, a dopamine-assisted method is developed to prepare Mn-doped ceria supported on nitrogen-doped carbon nanotubes (Mn-Ce-NCNTs). The morphology, dispersion of Mn-doped ceria, composition, and oxygen vacancies of the as-prepared catalysts were analyzed using various technologies. The results show that Mn-doped ceria was formed and highly dispersed on NCNTs, on which oxygen vacancies are abundant. The as-prepared Mn-Ce-NCNTs exhibit a high ORR performance, on which the average electron transfer number is 3.86 and the current density is 24.4% higher than that of commercial 20 wt % Pt/C. The peak power density of Mn-Ce-NCNTs is 68.1 mW cm-2 at the current density of 138.9 mA cm-2 for a Zn-air battery, which is close to that of 20 wt % Pt/C (69.4 mW cm-2 at 106.1 mA cm-2). Density functional theory (DFT) calculations show that the oxygen vacancy formation energies of Mn-doped CeO2(111) and pure CeO2(111) are -0.55 and 2.14 eV, respectively. Meanwhile, compared with undoped CeO2(111) (-0.02 eV), Mn-doped CeO2(111) easily adsorbs oxygen with the oxygen adsorption energy of only -0.68 eV. This work provides insights into the synergetic effect of Mn-doped ceria for facilitating oxygen adsorption and enhancing ORR performance.

In-situ immobilization strategy for single-atom iron sites to enhance oxygen reduction reaction in Zn–air batteries and microbial fuel cells

A straightforward and environmentally friendly approach was utilized to synthesize single-atomic Fe–N–C catalyst. In-situ immobilization of Fe3+ during the formation of polydopamine (PDA) and ZIF-8 in aqueous solution effectively prevent metal agglomeration. The mutual promotion of PDA and aqueous solution constructed the hybrid-level porous hollow structure in P–FeNC. This method extends the solution scope from organic solution system to water solution, thus providing fascinating opportunities for investigating metal-N-C catalyst by in-situ mixing various metal salt precursor and dopamine. The optimal P–FeNC catalyst demonstrates superlative oxygen reduction reaction (ORR) performance, with the half-wave potentials (E1/2) of 0.886 V, 0.79 V, and 0.72 V in 0.1 M KOH, 0.5 M H2SO4, and 0.05 M PBS solutions, which exceeded commercial 20 wt% Pt/C. The combinatorial impacts of highly dense FeN4 active sites and interconnected hierarchical mesopores/macropores are presumed to underpin the observed enhancement in ORR performance. Further evaluations show that the power densities of P–FeNC equipped zinc-air battery (ZAB) and microbial fuel cell (MFC) are 460 mW/cm2 and 3083 ± 10 mW/m2, respectively. This study confirms the feasibility to design the innovative single-atom catalyst in aqueous solution and provides constructive ideas to employ the high-performance P–FeNC electrocatalyst in ZABs and MFCs.