Oxygen Reduction Reaction Durability Research Articles

An elegant 3D-ordered hierarchically porous framework to anchor Pt nanocrystals for durable oxygen reduction reaction

While Platinum (Pt)-based electrocatalysts have been extensively studied for the oxygen reduction reaction (ORR), improving their durability remains a challenge. One promising approach is to design structure-defined carbon supports that can uniformly immobilize Pt nanocrystals (NCs). In this study, we present an innovative strategy for constructing three-dimensional ordered, hierarchically porous carbon polyhedrons (3D-OHPCs) as an efficient support for immobilizing Pt NCs. We achieved this by template-confined pyrolysis of a zinc-based zeolite imidazolate framework (ZIF-8) grown within the voids of polystyrene templates, followed by carbonizing the native oleylamine ligands on Pt NCs to produce graphitic carbon shells. This hierarchical structure enables the uniform anchorage of Pt NCs, while enhancing facile mass transfer and local accessibility of active sites. The optimal material with graphitic carbon armor shells on the surface of Pt NCs (CA-Pt), named CA-Pt@3D-OHPCs-1600, shows comparable activities to commercial Pt/C catalysts. Furthermore, it can withstand over 30,000 cycles of accelerated durability tests, owing to the protective carbon shells and hierarchically ordered porous carbon supports. Our study presents a promising approach for designing highly efficient and durable electrocatalysts for energy-based applications and beyond.

Coupling Single-Ni-Atom with Ni–Co Alloy Nanoparticle for Synergistically Enhanced Oxygen Reduction Reaction

Developing nonprecious metal-based oxygen reduction reaction (ORR) electrocatalysts with superior activity and durability is crucial for commercializing proton-exchange membrane (PEM) fuel cells. Herein, we report a metal-organic framework (MOF)-derived unique N-doped hollow carbon structure (NiCo/hNC), comprising of atomically dispersed single-Ni-atom (NiN4) and small NiCo alloy nanoparticles (NPs), for highly efficient and durable ORR catalysis in both alkaline and acidic electrolytes. Density functional theory (DFT) calculations reveal the strong coupling between NiN4 and NiCo NPs, favoring the direct 4e- transfer ORR process by lengthening the adsorbed O-O bond. Moreover, NiCo/hNC as a cathode electrode in PEM fuel cells delivered a stable performance. Our findings not only furnish the fundamental understanding of the structure-activity relationship but also shed light on designing advanced ORR catalysts.

Rapid and durable oxygen reduction reaction enabled by a perovskite oxide with self-cleaning surface

The growth of electrochemically inert segregation layers on the surface of solid oxide fuel cell cathodes has become a bottleneck restricting the development of perovskite-structured oxygen reduction catalysts. Here, we report a new discovery in which enriched Ba and Fe ions on the near-surface of Nd1/2Ba1/2Co1/3Fe1/3Mn1/3O3−δ spontaneously agglomerate into dispersed Ba5Fe2O8 nanoparticles and maintain a highly active and durable perovskite structure on the surface. This unique surface self-cleaning phenomenon is related to the low average potential energy of Ba5Fe2O8, which is grown on the near-surface layer. The electrochemically inert Ba5Fe2O8 segregation layer on the near-surface of the perovskite catalyst achieves self-cleaning by regulating the formation energy of enriched metal oxides. This self-cleaned perovskite surface exhibits an ultrafast oxygen exchange rate, high catalytic activity for the oxygen reduction reaction, and good adaptability to the actual working conditions of solid oxide fuel cell stacks. This study paves a new way for overcoming the stubborn problem of perovskite catalyst surface deactivation and enriches the scientific knowledge of surface catalysis.

Bimetallic PdY nanosponges for enhanced oxygen reduction electrocatalysis

Controlling the morphology and composition of Pd-based catalysts is the key to construct highly efficient electrocatalysts for cathodic oxygen reduction reaction (ORR). Here, rare Earth element Y-doped Pd nanosponge (PdY NSs) are prepared by one-step reduction approach using NaBH4 as reductant, which are employed for ORR under 0.1 M KOH. The PdY NSs with plentiful voids can offer a large number of active sites and improve the mass transfer for ORR. Moreover, the introduction of Y alters the electronic structure of Pd, thus promoting the dissociation and adsorption of oxygen. Therefore, the prepared PdY NSs display superior ORR activity and durability to the Pd NSs and Pd black, highlighting the introduction of rare Earth element on the enhancement of ORR performance for Pd-based catalysts.

Spherical mesoporous Fe–N–C catalyst for the air cathode of membrane-less direct formate fuel cells

Fe–N–C catalysts with excellent performance regarding the oxygen reduction reaction (ORR) have aroused enormous interest in direct-formate fuel cells (DFFCs). However, their limited mass transfer ability, insufficient ORR active sites, and complex fabrication processes remain significant obstacles to the widespread application of Fe–N–C catalysts. Herein, we propose a simple hydrothermal-annealing method with agarose powders to synthesize a uniform spherical Fe–N–C catalyst (∼3 μm) with well-developed mesopores (Fe/rG@C/H-Agar-900). The resultant Fe/rG@C/H-Agar-900 catalyst possesses rich oxygen-containing functional groups and enhanced interconnected pores, which can significantly boost the content of catalytic sites and facilitate mass transport, resulting in a high content of active sites. In the meantime, the mesopore content of Fe/rG@C/H-Agar-900, which can facilitate the formation of the three-phase gas/electrolyte/catalyst interfaces, was optimized by varying the annealing temperature. As a result, the Fe/rG@C/H-Agar-900 demonstrates a half-wave potential of 0.91 V vs. RHE, nearly four-electron pathway selectivity, excellent durability, and excellent formate tolerance for ORR. Furthermore, when used as the air cathode in membrane-less DFFCs, the Fe/rG@C/H-Agar-900-based device exhibits a remarkable peak power density of 24.5 mW cm−2, significantly outperforming the 20 wt% commercial Pt/C. This research facilitates the synthesis of an advanced Fe–N–C catalyst and promotes the practical development of membrane-less DFFCs.

Recent Advances in Nanocarbon-Based Nonprecious Metal Catalysts for Oxygen/Hydrogen Reduction/Evolution Reactions and Zn-Air Battery

Abstract In this review article, we focus on the design and creation of earth-abundant non-precious metal-coordinated eco-friendly catalysts with high oxygen reduction reaction (ORR), oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) performances. The development of a cost-effective, efficient and durable bifunctional ORR and OER electrochemical catalyst is a key for future batteries. So far, precious metals, such as Pt and Ir, have been used as efficient catalysts for the ORR and OER, respectively. However, they are expensive and their deposits on earth are limited, which are the major drawbacks of these metals. One more drawback for the practical application is the sluggish reactions of ORR and OER. Since electroconductivity of promising metal-free catalyst candidates are poor, good electronic supporting materials are needed. Owing to the high conductivity, stability and easy handling, carbon nanotubes are a most promising material. After Introduction, we summarize recent advances in i) carbon nanotube/nanocarbon-based ORR and OER catalysts, ii) metal oxide and others/nanocarbon catalysts for ORR, OER, HER and Zn-air electrodes, as well as iii) computational study for such catalyst reactions. Such studies are highly beneficial for future energy materials design and synthesis in batteries and molecular catalysts with high performances.

Lattice-strained Pt nanoparticles anchored on petroleum vacuum residue derived N-doped porous carbon as highly active and durable cathode catalysts for PEMFCs

High cost and poor durability of Pt-based cathode catalysts for oxygen reduction reaction (ORR) severely hamper the popularization of proton exchange membrane fuel cells (PEMFCs). Tailoring carbon support is one of effective strategies for improving the performance of Pt-based catalysts. Herein, petroleum vacuum residue was used as carbon source, and nitrogen-doped porous carbon (N-PPC) was synthesized using a simple template-assisted and secondary calcination method. Small Pt nanoparticles (Pt NPs) with an average particles size of 1.8 nm were in-situ prepared and spread evenly on the N-PPC. Interestingly, the lattice compression (1.08%) of Pt NPs on the N-PPC (Pt/N-PPC) was clearly observed by aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), which was also verified by the shift of (111) crystal plane of Pt on N-PPC to higher angles. The X-ray photoelectron spectroscopy (XPS) results suggest that the N-PPC support had a strong effect on anchoring Pt NPs and endowing surface Pt NPs with lowered d band center. Thus, the Pt/N-PPC as a catalyst simultaneously boosted the ORR activity and durability. The specific activity (SA) and mass activity (MA) of the Pt/N-PPC at 0.9 V reached 0.83 mA cm−2 and 0.37 A mgPt−1, respectively, much higher than those of the commercial Pt/C (0.21 mA cm−2 and 0.11 A mgPt−1) in 0.1 M HClO4. The half-wave potential (E1/2) of Pt/N-PPC exhibited only a minimal negative shift of 7 mV after 30,000 accelerated durability tests (ADT) cycles. More importantly, an H2–O2 fuel cell with a Pt/N-PPC cathode achieved a power density of 866 mW cm−2, demonstrating that the prepared catalyst has a promising application potential in working environment of PEMFCs.

Highly Active and Durable Metal‐Free Carbon Catalysts for Anion‐Exchange Membrane Fuel Cells

AbstractThe development of highly active and durable platinum‐free oxygen reduction reaction (ORR) catalysts is of vital importance for the practical application of anion‐exchange membrane fuel cells (AEMFCs). Herein, a metal‐free carbon catalyst (marked as NDPC‐1000) with a graphitic N‐regulating defect structure is specifically designed and developed for AEMFCs by integrating theoretical calculations and experiments. Density functional theory calculations first reveal that the graphitic N can tailor the charge density of pentagon and armchair defects to reach the top of the adsorption energy‐activity volcano plot, while the enhanced durability is attributed to the high dissociation energy of the CN covalent bond. Under this guidance, the synthesized NDPC‐1000 demonstrates its high ORR activity and durability in alkaline media. With H2/O2 reacting gases, the AEMFC with this catalyst as the cathode delivers a peak power density of 913 mW cm−2. Unprecedented fuel cell durability is verified via continuous operation over 100 h at 0.25 A cm−2 with only a voltage decay of ≈25%, which is the greatest among all reported metal‐free‐based AEMFCs. Here a theory‐guided experiment strategy is provided for the development of high‐performance and durable ORR catalysts for AEMFCs.

Nitrogen-doped carbon dot/activated carbon nanotube-supported copper nanoparticles as an efficient electrocatalyst for the oxygen reduction reaction

Recent decades have witnessed remarkable progress in fuel cell technology for efficient energy conversion devices in stationary, automotive, and mobile systems. However, the choice of the electrode material in the fuel cell technologies is still limited to platinum and the other platinum group metals, necessitating further research for alternatives. Herein, activated carbon nanotubes (ACNTs) treated at a high temperature (500 °C) were used as a support to induce binding with N-doped carbon dots (NCDs). Cu(II) in the copper nanoparticles spontaneously reduced to Cu(0) using the NCDs as a reducing agent; thus, a Cu/NCD/ACNT hybrid catalyst was synthesized. The oxygen reduction reaction (ORR) activity of the Cu/NCD/ACNT catalyst (Eonset = 0.921 V) was higher than those of Cu/ACNT (Eonset = 0.821 V) and NCD/ACNT (Eonset = 0.869 V) catalysts. The Cu/NCD/ACNT catalyst also exhibited excellent tolerance to methanol, in relation to Pt/C, during a methanol fuel cell tolerance test. Moreover, the current decays after 10 h in the ORR durability test were 21% and 10% for the Pt/C and Cu/NCD/ACNT catalysts, respectively, demonstrating the greater durability of the non-metal catalyst. Thus, the Cu/NCD/ACNT catalyst, formed by the synergistic action of ACNT, N doping, and spontaneous reduction of Cu(II), is a promising alternative to commercial Pt/C catalysts.

Structurally-supported PtCuCo nanoframes as efficient bifunctional catalysts for oxygen reduction and methanol oxidation reactions

Developing highly durable and active catalysts with the morphology of structurally robust nanoframes toward oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR) in acidic environment is crucial but still a great challenge to completely achieve in a single material. Herein, PtCuCo nanoframes (PtCuCo NFs) with internal support structures as enhanced bifunctional electrocatalysts were prepared by a facile one-pot approach. PtCuCo NFs exhibited remarkable activity and durability for ORR and MOR owing to the ternary compositions and the structure-fortifying frame structures. Impressively, the specific/mass activity of PtCuCo NFs were 12.8/7.5 times as large as that of commercial Pt/C for ORR in perchloric acid solution. For MOR in sulfuric acid solution, the mass/specific activity of PtCuCo NFs was 1.66 A mgPt-1/4.24 mA cm−2, which was 5.4/9.4 times as large as that of Pt/C. This work may provide a promising nanoframe material to develop dual catalysts for fuel cells.

Atomically Dispersed Ni-N4 Sites Assist Pt3 Ni Nanocages with Pt Skin to Synergistically Enhance Oxygen Reduction Activity and Stability.

Currently, the rarity and high cost of platinum (Pt)-based electrocatalysts seriously limit their commercial application in fuel cells cathode. Decorating Pt with atomically dispersed metal-nitrogen sites possibly offers an effective pathway to synergy tailor their catalytic activity and stability. Here active and stable oxygen reduction reaction (ORR) electrocatalysts (Pt3 Ni@Ni-N4 -C) by in situ loading Pt3 Ni nanocages with Pt skin on single-atom nickel-nitrogen (Ni-N4 ) embedded carbon supports are designed and constructed. The Pt3 Ni@Ni-N4 -C exhibits excellent mass activity (MA) of 1.92 A mgPt -1 and specific activity of 2.65mA cmPt -2 , together with superior durability of 10mV decay in half-wave potential and only 2.1% loss in MA after 30000 cycles. Theoretical calculations demonstrate that Ni-N4 sites significant redistribute of electrons and make them transfer from both the adjacent carbon and Pt atoms to the Ni-N4 . The resultant electron accumulation region successfully anchored Pt3 Ni, that not only improves structural stability of the Pt3 Ni, but importantly makes the surface Pt more positive to weaken the adsorption of *OH to enhance ORR activity. This strategy lays the groundwork for the development of super effective and durable Pt-based ORR catalysts.

General Synthesis of a Diatomic Catalyst Library via a Macrocyclic Precursor-Mediated Approach.

Heterogeneous catalysts containing diatomic sites are often hypothesized to have distinctive reactivity due to synergistic effects, but there are limited approaches that enable the convenient production of diatomic catalysts (DACs) with diverse metal combinations. Here, we present a general synthetic strategy for constructing a DAC library across a wide spectrum of homonuclear (Fe2, Co2, Ni2, Cu2, Mn2, and Pd2) and heteronuclear (Fe-Cu, Fe-Ni, Cu-Mn, and Cu-Co) bimetal centers. This strategy is based on an encapsulation-pyrolysis approach, wherein a porous material-encapsulated macrocyclic complex mediates the structure of DACs by preserving the main body of the molecular framework during pyrolysis. We take the oxygen reduction reaction (ORR) as an example to show that this DAC library can provide great opportunities for electrocatalyst development by unlocking an unconventional reaction pathway. Among all investigated sites, Fe-Cu diatomic sites possess exceptional high durability for ORR because the Fe-Cu pairs can steer elementary steps in the catalytic cycle and suppress the troublesome Fenton-like reactions.

N,S-Codoped Carbon Nanostructures Encapsulated with FeNi Nanoparticles as a Bifunctional Electrocatalyst for Rechargeable Zn–Air Batteries

The exploration of highly efficient, low-cost, and durable oxygen reduction reaction (ORR)/oxygen evolution reaction (OER) bifunctional electrocatalysts is extremely desirable but challenging for the practical application of Zn–air batteries. Herein, we report the fabrication of a FeNi alloy nanoparticle (NP)-decorated N,S dual-doped carbon nanocomposite (denoted FeNi/NS-C) as a bifunctional electrocatalyst for Zn–air batteries. The FeNi/NS-C electrocatalyst is produced through the complexation of a N-rich imidazolyl-phenanthroline derivative with metal salts, followed by pyrolysis in the presence of trithiocyanuric acid (TTCA). The FeNi/NS-C electrocatalyst shows comparable ORR activity to that of Pt/C (E1/2 = 0.83 V) and superior OER activity to that of IrO2 (Ej=10 = 1.585 V). The liquid- and solid-state Zn–air batteries assembled with the FeNi/NS-C exhibit high power density and specific capacity. In particular, the FeNi/NS-C-based Zn–air batteries display remarkable durability over 1000 h at 5 mA cm–2 and 70 h at 2 mA cm–2 in liquid and solid electrolytes, respectively. The high performance of the FeNi/NS-C may be related to the synergistic effect of the bimetallic alloy NPs and the N,S dual-doped carbon matrix with a high surface area, porous structure, and unique hybridized morphology.

Stabilizing Ni atoms on PtNi crystals by constructing PtNix-(CeO2)y heterostructures for improving durability of oxygen reduction reaction in acidic media

The oxygen reduction reaction (ORR) activity of PtNi alloys is easily decreased on account of the Ni leaching under the harsh acidic environment. Therefore, we prepared a PtNi1.5-(CeO2)0.8/C electrocatalyst with abundant PtNi1.5-(CeO2)0.8 interfaces by a wet-chemical synthesis strategy. Electrochemical tests revealed that PtNi1.5-(CeO2)0.8/C exhibits excellent ORR performance with mass activity (MA) of 551.1 mA mgPt−1 and specific activity (SA) of 1.3 mA cmPt−2 @ 0.9 V vs. RHE, respectively, which are better than commercial JM Pt/C (MA of 152.9 mA mgPt−1 and SA of 0.2 mA cmPt−2@ 0.9 V vs. RHE). More interestingly, it displays remarkable durability with 9.0% of its initial MA loss after 10,000 CV cycles, outperforming JM Pt/C (a 15.1% loss) and PtNi1.5/C counterparts (a 35.5% loss). The density functional theory (DFT) calculations explained that the electronic interaction at interfaces leads to a lower d-band center (εd) and weaker oxygen adsorption energy E(ads)(O) in Pt atoms of PtNi1.5-(CeO2)0.8 than that in Pt NPs, which is favorable for the desorption of O* and promotes the ORR process. Furthermore, the diffusion energy barrier E(FS-IS) of Ni atoms in PtNi1.5-(CeO2)0.8 from subsurface to surface is higher than that in PtNi1.5 counterparts, indicating the Ni leaching can be decelerated.

Multicore-shell structure CuxCoy-Fe alloy nitrogen doped mesoporous hollow carbon nanotubes composites for oxygen reduction reaction

Carbon-based materials with transition metal modifications are the dominant materials for oxygen reduction reaction (ORR), but the synthesis in a simple and efficient way is still a great challenge. Herein, multicore-shell structure CuxCoy-Fe alloy nitrogen doped mesoporous hollow carbon nanotubes (N-MHCNT/CuxCoy-Fe@C) were designed and synthesized by a facile and environment-friendly method. In the process of pyrolysis, polypyrrole serving as the substrate to form N-doped hollow carbon nanotubes and the polydopamine (PDA) acts as the carbon and nitrogen source to form a shell structure. Additionally, the cubic CuxCoy-Fe MOFs synthesized at room temperature collapses to form multiple alloy cores. Notably, the mesoporous structure of N-MHCNT/CuxCoy-Fe@C enhances the mass transfer process, while the carbon shell protects the metal active sites. Moreover, mesoporous hollow carbon, rich M-Nx (M=Cu, Co, Fe) active sites, the synergistic effects between N-MHCNTs, CuxCoy-Fe alloys and multiple core-shell structures allowed N-MHCNT/Cu2Co1-Fe@C exhibited high activity and long-term durability in ORR. Besides, the RRDE tests confirms the reaction kinetics of N-MHCNT/Cu2Co1-Fe@C as a mainly 4-electron reaction with an electron transfer number of 3.78 (Pt/C is 3.86) and a low hydrogen peroxide yield of 16%. This work provides a new strategy for the development of non-precious metal ORR catalysts by rational structural design and metal ratio adjustment.

Antipoisoning catalysts for the selective oxygen reduction reaction at the interface between metal nanoparticles and the electrolyte

AbstractOne of the primary challenges in relation to phosphoric acid fuel cells is catalyst poisoning by phosphate anions that occurs at the interface between metal nanoparticles and the electrolyte. The strong adsorption of phosphate anions on the catalyst surface limits the active sites for the oxygen reduction reaction (ORR), significantly deteriorating fuel cell performance. Here, antipoisoning catalysts consisting of Pt‐based nanoparticles encapsulated in an ultrathin carbon shell that can be used as a molecular sieve layer are rationally designed. The pore structure of the carbon shells is systematically regulated at the atomic level by high‐temperature gas treatment, allowing O2 molecules to selectively react on the active sites of the metal nanoparticles through the molecular sieves. Besides, the carbon shell, as a protective layer, effectively prevents metal dissolution from the catalyst during a long‐term operation. Consequently, the defect‐controlled carbon shell leads to outstanding ORR activity and durability of the hybrid catalyst even in phosphoric acid electrolytes.

Oxygen reduction performance measurements: Discrepancies against benchmarks

AbstractOxygen electrocatalysis is crucial for renewable energy conversion and storage technologies. Specifically for proton exchange membrane fuel cells (PEMFCs), oxygen reduction reaction (ORR) is the primary reaction that determines performance and costs. The ORR activity and durability are commonly assessed using a rotating disk electrode (RDE). However, there are numerous inconsistencies in the RDE measurements among researchers when comparing newly developed ORR catalysts to state‐of‐the‐art ones. These inconsistencies in activity and durability evaluation and deviations from standard protocols result in irreproducible screening and benchmarking of electrocatalysts. Despite the fact that the US Department of Energy has established and regularly revises the standard protocols, many reported studies do not adhere to these guidelines. This perspective aims to draw attention to the discrepancies in ORR activity and stability measurements at RDE as primary screening and emphasizes implementing the mandatory standard for a meaningful comparison of ORR activity and durability. We intend to emphasize the use of available ORR test standards ubiquitously for more accurate comparisons and accelerate the development of fuel cell catalysts.

Synthesis of Platinum Nanocrystals Dispersed on Nitrogen-Doped Hierarchically Porous Carbon with Enhanced Oxygen Reduction Reaction Activity and Durability.

Platinum-based catalysts are widely used for efficient catalysis of the acidic oxygen reduction reaction (ORR). However, the agglomeration and leaching of metallic Pt nanoparticles limit the catalytic activity and durability of the catalysts and restrict their large-scale commercialization. Therefore, this study aimed to achieve a uniform distribution and strong anchoring of Pt nanoparticles on a carbon support and improve the ORR activity and durability of proton-exchange membrane fuel cells. Herein, we report on the facile one-pot synthesis of a novel ORR catalyst using metal-nitrogen-carbon (M-N-C) bonding, which is formed in situ during the ion exchange and pyrolysis processes. An ion-exchange resin was used as the carbon source containing R-N+(CH3)3 groups, which coordinate with PtCl62- to form nanosized Pt clusters confined within the macroporous framework. After pyrolysis, strong M-N-C bonds were formed, thereby preventing the leaching and aggregation of Pt nanoparticles. The as-synthesized Pt supported on the N-doped hierarchically porous carbon catalyst (Pt/NHPC-800) showed high specific activity (0.3 mA cm-2) and mass activity (0.165 A mgPt-1), which are approximately 2.7 and 1.5 times higher than those of commercial Pt/C, respectively. The electrochemical surface area of Pt/NHPC-800 remained unchanged (~1% loss) after an accelerated durability test of 10,000 cycles. The mass activity loss after ADT of Pt/NHPC-800 was 18%, which is considerably lower than that of commercial Pt/C (43%). Thus, a novel ORR catalyst with highly accessible and homogeneously dispersed Pt-N-C sites, high activity, and durability was successfully prepared via one-pot synthesis. This facile and scalable synthesis strategy for high-efficiency catalysts guides the further synthesis of commercially available ORR catalysts.

Synthesis and electrochemical oxygen reduction reaction activities of palladium-based intermetallic nano-electrocatalysts

Changing the atomic structure of a material to alter its characteristics is a key and powerful technique in materials research. Electrocatalytic applications are a growing field for structurally long range ordered materials. Similar electrocatalysts with a disordered structure, however, are unable to perform as well as those with an ordered structure because of the specific functionalities that may be achieved by the ordered structure. There has been a lot of interest in using highly active and stable ordered intermetallics as electrocatalysts for polymer electrolyte membrane fuel cells (PEMFCs). Electrocatalysts based on palladium have lately emerged as one of the most promising classes for the oxygen reduction reaction (ORR) in alkaline media because of their superior ORR activity and durability at lower prices than platinum. As electrocatalysts for fuel cells, palladium-based intermetallic nano-electrocatalysts (Pd-INECs) have gained a lot of interest in recent years. Pd-INECs have exceptional catalytic activity and great stability due to their well-defined composition and predictable control over structural, geometric, and electronic effects. In this short article, we will briefly go through the current state of knowledge on Pd-INECs for cathodic ORR in fuel cells. The first step is a brief review of the synthetic ways in which Pd-INECs with a predetermined stoichiometry and a well-defined atomic structure will be discussed. We also emphasized the use of Pd-INECs in electrochemical ORR operations as a second part of the review. Methods are comprehensively reviewed for enhancing the electrocatalytic activity of Pd-INECs. Finally, suggestions for future research directions and current difficulties are made.

Heteroatom sulfur-doping in single-atom Fe-NC catalysts for durable oxygen reduction reaction in both alkaline and acidic media

The highly active S-modified single-atom Fe-NC catalyst exhibits excellent ORR activity and stability in both alkaline and acidic solutions.