Boosting the covalency of FeS via a built-in electric field in FeS/MnS heterojunctions for durable oxygen electrocatalysis in zinc-air batteries.

Breaking activity-stability trade-off via Pt-In dual site dissociative pathway for highly durable oxygen reduction.

Developing active and durable platinum-based catalysts is critical for advancing proton-exchange membrane fuel cells (PEMFCs). To overcome the Cu dissolution and poor stability of PtCu intermetallics, we propose a Mn-doping strategy to fabricate L10-ordered PtCuMn nanocatalysts. Mn incorporation modulates the Pt electronic structure, enhances L10 ordering, and induces compressive strain within a Pt-rich shell. Consequently, the catalyst demonstrates exceptional oxygen reduction reaction (ORR) activity with a half-wave potential of 0.921 V, a mass activity (MA) of 0.96 A mgPt-1 and a negligible half-wave potential shift after 30 000 cycles. In PEMFCs, it delivers peak power densities of 1.31 W cm-2 (H2-air) and 2.23 W cm-2 (H2-O2). Furthermore, its MA reaches 0.78 A mgPt-1, which exceeds the U.S. Department of Energy (DOE) 2025 target. Operando characterizations and theoretical calculations confirm that Mn doping downshifts the Pt d-band center, accelerates the conversion kinetics of the key *OH intermediate, and thereby optimizes the ORR performance.

By using the sol–gel method, a series of Nd1−xSrxMnO3 perovskite oxides (x = 0.1, 0.2, 0.3), designated as NSM-0.9, NSM-0.8, and NSM-0.7, were prepared and characterized using analytical techniques including XRD, FESEM, TEM, EDS, and XPS. Our investigation revealed that NSM-0.7 (Nd0.7Sr0.3MnO3) is the most effective electrocatalyst for the oxygen reduction reaction (ORR). Its superior electrocatalytic performance in a 0.1 M KOH solution, evaluated with RDE and RRDE techniques, was quantified by an onset potential (Eon) of 0.82 V vs. RHE, a half-wave potential (E1/2) of 0.58 V vs. RHE, a limiting current density (JL) of −5 mA cm−2, which is the same as the current density of Pt/C, and a kinetic current density (Jk) of 0.41 mA cm−2 at 1600 rpm. This material also favoured a highly efficient 4e− pathway with the formation of a minimal amount of H2O2. NSM-0.7's superior catalytic performance is attributed to optimal Sr-doping at the perovskite's A-site, a process that significantly enhances its Mn valence and oxygen adsorption capacity. Furthermore, chronoamperometry confirmed that NSM-0.7 exhibits superior stability compared to the benchmark Pt/C catalyst, demonstrating that strategic A-site doping is a promising approach for improving conventional perovskite oxides for electrocatalytic applications.

Phase-controlled Er2O3-Co Mott-Schottky heterostructures for efficient bifunctional oxygen electrocatalysts toward long-lifespan rechargeable zinc-air batteries.

Development of efficient and durable oxygen reduction reaction (ORR) electrocatalysts is of great interest yet remains challenging. Herein, we predicted and screened a bilayer graphite carbon-supported Ir-N4/Fe-N4 catalyst with high ORR activity using density functional theory calculations. Subsequently, various bimetallic single atom supported on 3D ordered macroporous carbon were rationally designed and experimentally synthesized via a colloidal microsphere template-confined reaction method. As anticipated, the resulting Ir-N4/Fe-N4 bimetallic single-atom catalysts (IrFe-SACs) exhibit superior ORR activity and durability, reaching a half-wave potential of 0.928V. The IrFe-SACs also demonstrate outstanding performance in Zn-air batteries, including a high discharge power density (314mW cm⁻2) and excellent cycling stability (~ 1650 cycles over 550h). Further experimental characterizations and theoretical analysis reveal that introducing interlayer-adjacent Ir-N4 sites facilitates the transition of Fe-N4 from a low-spin state to a medium-spin state, which optimizes the spin polarization of Fe 3d orbitals and enhances the non-localization of the Fe-O/OH molecular orbital, thereby significantly improving the ORR intrinsic activity and durability of atomic Fe-N4 sites.

Tailoring porosity and diameter into carbon nanofiber membrane: freestanding electrodes with mechanical flexibility and catalytic functionality in direct methanol fuel cell.

Efficient oxygen reduction reaction (ORR) requires coordination of oxygen adsorption, transport, and catalysis at active sites. Yet most studies address only one step, overlooking whole-pathway O2 regulation and thus limiting performance. Here, we report a bioinspired Co-doped Fe2P on N-doped carbon featuring a hierarchical eucalyptus-like nanoarchitecture, engineered to regulate oxygen throughout the electrochemical cycle, where Fe-P-Co hetero-coordinated bridges anchored to the carbon substrate through Fe─N bonds induce strong electronic coupling and polarization. The hierarchical structure generated local electric fields that enriched OH- and O2, while multilevel porosity accelerated oxygen transport. This enabled coordinated optimization of oxygen adsorption, transfer, and active-site electronic configuration. This nanohybrid achieved a half-wave potential of 0.938V vs. RHE, sustained discharge in Al-air batteries for 373 h, and delivered an energy density of 3487Wh/kg. Theoretical simulations revealed that Co-doping shortened Fe─P bonds and tuned the Fe electronic environment, lowering the d-band center and weakening Fe 3d-O 2p interactions, which reduced the *OH desorption barrier and accelerated ORR kinetics. In situ Raman spectroscopy revealed that Fe-P-Co bridges served as active centers facilitating *OH release during ORR. These findings indicate that integrating hierarchical architecture, hetero-coordinated Fe-P-Co bridges, and electronic-state modulation enables whole-pathway O2 management for efficient oxygen electrocatalysis.

Strong bifunctional electrocatalysts capable of sustaining both oxygen reduction (ORR) and oxygen evolution (OER) at high depths-of-discharge are crucial for practical rechargeable zinc-air batteries (ZABs). Here, we present a novel MnFeCoNiCu high-entropy alloy uniformly anchored on nitrogen-doped carbon nanotubes, derived from a high-entropy layered double hydroxide precursor. A dicyandiamide-assisted pyrolysis enabled simultaneous CNT growth, nitrogen doping, and alloy nanoparticle formation, yielding a single-phase face-centered cubic HEA at 900°C (HEA900). Structural analyses confirmed homogeneous atomic-level metal dispersion, significant lattice distortion, and strong metal-carbon coupling, providing abundant active sites and enhanced conductivity. Owing to these synergistic effects, HEA900 exhibited excellent bifunctional activity with an OER overpotential of 475mVat10mA/cm2, an ORR half-wave potential of 0.81V, and a low ΔE of0.89V. The HEA-based ZAB showed a near-theoretical specific capacity of 801 mAh/gZn, and a peak power density of 186mW/cm2. The cell's remarkable reversibility and mechanical robustness were confirmed by extended cycling under high DOD (up to 10h per cycle) and impressive energy efficiency over 3325 cycles. Flexible gel-polymer ZABs further demonstrated robust mechanical and electrochemical durability, highlighting this HELDH-derived HEA strategy as a promising paradigm for entropy-engineered catalysts in high-performance ZABs.

Efficient bifunctional oxygen electrocatalysts are crucial for overcoming the high overpotentials and sluggish kinetics of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in rechargeable zinc-air batteries (ZABs). Iron-based single-atom catalysts exhibit promising ORR activity, however, their excessive adsorption of oxygen-containing intermediates, together with the scaling relationships between these intermediates, limits their bifunctional performance. Herein, a unique Fe-Dy dual-atom catalyst (FeDy-DAC) is constructed, leveraging the strong orbital coupling between Fe-3d and Dy-4f orbitals to precisely modulate the electronic structure of the Fe sites. This modulation effectively weakens the overly strong adsorption of oxygen-containing intermediates on Fe sites, facilitating *OH desorption. Meanwhile, the unique dual-site co-adsorption configuration of *O drives efficient O─O bond coupling, ultimately leading to a significant reduction in the rate-determining energy barriers of both ORR and OER. Therefore, FeDy-DAC exhibits outstanding bifunctional catalytic performance, with a high ORR half-wave potential of 0.90V and a narrow ORR/OER potential gap of 0.68V. Moreover, FeDy-DAC maintains stable operation for over 2500 h in ZABs, showcasing excellent long-term durability. This work provides a novel strategy and insights for high-performance bifunctional electrocatalyst design.

Given their low volatility and heteroatom-rich composition, ionic liquids (ILs) are considered excellent precursors for fabricating various porous heteroatom-modified carbon materials, which exhibit good electrocatalytic activity for the oxygen reduction reaction (ORR). In the heteroatom-doped carbons, the pyridinic N-doped carbon is considered the active sites. Herein, a pyrazine IL that structurally resembles the pyridinic N-doped carbon is selected as the precursor for synthesizing a N,P-codoped carbon (Cpyr) material, which exhibits a high pyridinic N content of 19.2 at%, in contrast to the pyridinic N content of 11.2 at% of the control sample (Cmim) derived from 2-methylimidazole. The pyrazine IL-derived Cpyr has a unique 0D/2D hybridized morphology and a larger electrochemical surface area, while Cmim displays the general sheet-like appearance. The high pyridinic N content and unique 0D/2D hybridized structure synergistically enhance the ORR performance of Cpyr. The onset potential and half-wave potential of Cpyr are 0.94VRHE and 0.75VRHE and those of Cmim are 0.90VRHE and 0.58VRHE, respectively. Thus, this work provides a promising strategy to prepare highly electroactive carbon materials via the rational design of IL precursors at the molecular level.

Achieving high-performance single-atom catalysts (SACs) for rechargeable Zn-air batteries (ZABs) requires simultaneous optimization of pore structure and coordination environment. However, MOF-derived SACs typically feature micropore-dominated carbon frameworks and planar coordination symmetry, restricting oxygen diffusion and intrinsic activity. Here, we introduce a dual-engineering strategy that combines polymer encapsulation with wavy graphene oxide (GO) substrates. Bimetallic Co/Zn zeolitic imidazole framework (Co-ZIF-8) precursors were coated with polyvinylpyrrolidone (PVP) and assembled on GO, followed by pyrolysis to yield CoSA@P-NC/rGO. The PVP layer induced mesopores via controlled shrinkage of the ZIF structure, while the wavy GO substrate modulated the coordination environment of atomically dispersed Co─Nx sites, extending bond lengths and introducing symmetry distortion. Benefiting from these structural and electronic features, CoSA@P-NC/rGO exhibited outstanding bifunctional activity, with a half-wave potential of 0.90V for oxygen reduction reaction and a low overpotential of 397mV at 10mA cm-2 for oxygen evolution reaction. When employed as a ZAB cathode, it achieved a high power density of 190mW cm-2, a specific capacity of 832mA h g-1, and durable cycling over 600 cycles. This synergistic strategy of pore and coordination engineering provides a promising platform for developing efficient, long-lived SACs for energy storage applications.

The development of highly efficient and durable Pt-based oxygen reduction reaction (ORR) catalysts is paramount for the widespread adoption of proton exchange membrane fuel cells (PEMFCs). Herein, we present a novel Y-doped PtFeNi medium-entropy alloy catalyst, PtFeNiY8 (PFNY8, 8% Y doping), synthesized via a simple one-pot method, achieving preferential exposure of the highly active (111) crystal facet. Systematic experiments and density functional theory calculations demonstrate that Y doping lowers surface energy to promote the formation of the (111) crystal facet, with an optimal doping level of 8% achieving the most stable electronic structure and the most favorable d-band center. The PFNY8/C catalyst demonstrates outstanding ORR performance, with a half-wave potential (E1/2) of 0.93 V, mass activity (MA) of 3.00 A mg-1 Pt, and excellent durability (after 80,000 ADT cycles, the E1/2 decreases by only 11 mV, and the MA retention is 73.4%). Furthermore, in PEMFCs, PFNY8/C demonstrates a peak power density of 1.75 W cm-2 under H2/O2 conditions, outperforming commercial Pt/C. This study offers valuable insights into the role of Y doping in tailoring nanoparticle morphology and facet exposure, presenting a new strategy for designing high-performance Pt-based catalysts for next-generation PEMFCs.

The advancement of catalysts that are both platinum-group-metal (PGM)-free and iron-free is essential for the oxygen reduction reaction (ORR), which is kinetically slow, particularly in anion-exchange membrane fuel cells (AEMFCs). One of the primary obstacles lies in achieving adequate activity and stability within the membrane electrode assembly (MEA) under real-world hydrogen-air operating conditions. Herein, an effective MnN4 site encased within N-doped carbon nanofibers (denoted as MnN4@N-CNFs) is designed for efficient ORR electrocatalysis. Benefiting from the electronic structure modulation of MnN4 moieties through strong interfacial coupling with the carbon matrix, and structural advantages of the 3D hierarchical porosity synergizing with N-doped carbon-MnN4 coordination systems, the as-resultant MnN4@N-CNFs demonstrate a high half-wave potential of 0.89 V, outstanding durability, and impressive methanol tolerance under alkaline environments, outperforming commercial Pt/C and a diversity of reported counterparts. Notably, the engineered catalyst demonstrates remarkable fuel cell performance with a peak power density of 222.0 mW cm-2 during practical AEMFC operation, while maintaining stable operation for over 15 h, representing a 3-fold enhancement over conventional Pt/C-based counterparts. This study establishes fundamental design principles for high-efficiency AEMFCs through atomic-level engineering of precisely coordinated metal-N-C active sites, providing a robust framework for next-generation electrocatalyst development.

Atomically dispersed Fe-N-C catalysts with well-defined iron-nitrogen coordination exhibit fantastic promise for the oxygen reduction reaction (ORR). However, achieving their scalable synthesis while preventing iron aggregation and performance degradation remains a critical challenge. Here, we demonstrate a highly efficient confined flash Joule heating (CFJH) technique for the scalable and ultrafast synthesis of Fe-N-C catalysts. The coal-derived porous carbons are efficient in confining iron phthalocyanine (FePc) molecules, suppressing their migration and iron aggregation during ultrafast CFJH treatment. This process facilitates the conversion of FePc into atomically dispersed FeN4 sites embedded within a graphitization-enhanced carbon framework. Mechanistic studies reveal that, compared to an FePc precursor, these integrated FeN4 sites exhibit a shifted rate-determining step with optimized adsorption/desorption of oxygen intermediates, leading to a reduced energy barrier for efficient 4e- oxygen reduction. The resulting catalyst exhibits impressive ORR activity in alkaline media with a high half-wave potential (0.90 V vs RHE) and remarkable durability (94.5% retention over 100 h). The assembled zinc-air battery delivers a peak power density of 277.6 mW cm-2 and sustains stable operation for over 900 h, outperforming the Pt/C + IrO2 benchmark. Scalable production is achieved at a rate of 0.5 kg h-1, establishing a facile and industrially viable route for synthesizing high-performance atomically dispersed catalysts.

Single-atom Fe sites coordinated by pyrrolic nitrogen (Fe-Npyrr-C) are highly active for the oxygen reduction reaction (ORR) but suffer from rapid demetalization-induced deactivation. Here, we overcome this limitation via a Mg-assisted sacrificial templating strategy that precisely reconstructs Fe-N4 coordination, driving partial conversion of unstable pyrrolic-N to robust pyridinic-N ligands. The resulting Fe(Mg)-N-C(1) catalyst exhibits exceptional ORR performance (half-wave potential E1/2 = 0.91 V) and outstanding durability, retaining 95.2% of its initial current after 55 h, surpassing both Fe-N-C and Pt/C. In Zn-air batteries, it enables stable operation for > 530 h (peak power density: 271 mW cm- 2). This work demonstrates that enriching pyridinic-N-coordinated Fe-N4 sites simultaneously enhances activity and suppresses demetalization, offering a general coordination-engineering strategy to unify activity and stability in Fe-N-C electrocatalysts.

Covalent organic frameworks (COFs) such as iron phthalocyanine (FePc) have been considered as potential electrocatalysts. Herein, we provide important insights into modulating the intrinsic activity of FePc COFs for the oxygen reduction reaction (ORR) by adjusting their stacking configuration. The eclipsed, AA-stacked and the staggered, AB-stacked FePc COF configurations were obtained via adjusting the interlayer interaction forces. Electrochemical studies reveal that the AA-stacked FePc COF exhibits a half-wave potential of 0.856 V vs RHE, which is 0.195 V higher than that of the AB-stacked FePc COF. The assembled zinc-air battery, using AA-stacked FePc COF as the cathode, demonstrates a high cell voltage of 1.64 V vs Zn2+/Zn alongside with a superior specific capacity of 935.79 mA h-1gZn-1. The upshift in the valence band center and the high effective magnetic moment in the eclipsed, AA-stacked FePc COF suggest that the states are occupied at high energy levels, indicating a high-spin state of Fe. Density functional theory calculations suggest that the long-range spin channels aligned with iron columns in the eclipsed, AA-stacked FePc COF facilitate the spin-selective charge transport through interlayer band dispersion. The mechanism associated with the high-spin state of Fe promotes the cleavage of the *OO and *OOH intermediates, accelerating the ORR kinetics. Our study reveals that the stacking order of FePc COFs is important for modulation of the charge transfer and electron spin states, showing how to control the spin electronic characteristics of COFs through the stacking configuration-dependent interlayer interactions.

The rational design and synthesis of efficient and durable bifunctional electrocatalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is of great significance and challenging for rechargeable zinc–air batteries. While much attention has been devoted to enhancing ORR performance in recent studies, the effectiveness of OER is equally crucial for charging performance of Zn–air batteries. In this work, NH2-MIL-101(Fe) is employed as a precursor to derive Fe-NC through a straightforward pyrolysis method. Subsequently, NiFe-LDH is synthesized on the surface of Fe-NC via a wet-chemical process to obtain Fe-NC@NiFe-LDH. Capitalizing on the synergistic interplay between Fe-NC, serving as the ORR active site, and NiFe-LDH, acting as the OER active site, Fe-NC@NiFe-LDH demonstrates remarkable bifunctional electrocatalytic performance, boasting a positive half-wave potential of 0.83 V for ORR and a low potential of 1.68 V for OER at a current density of 10 mA cm−2, alongside exceptional stability in alkaline environments. Furthermore, the Fe-NC@NiFe-LDH-based Zn–air battery exhibits outstanding discharge and charge performance, maintaining excellent cycling stability over 600 h (3600 cycles).

The curvature change of the support can control the induced local stress strain and directly change the properties and performance of the layered materials. Herein, we successfully in situ grew graphdiyne (GDY) on the surface of carbon nanotubes (CNTs) to form a heterojunction material with curved structure and highly surface-active. Our results indicated that the surface-grown GDY can deform into a curved-GDY (cGDY) due to internal stress. Such structural rearrangement regulates the charge distribution on interface of graphdiyne/CNTs and increases the charge density of Csp─Csp bonds within bent diacetylene linkages (-Csp≡Csp-Csp≡Csp-). While loading iron phthalocyanine (FePc) to this bent surface, the interactions and the interfacial repulsive force in the system were greatly enhanced, resulting in the elevated energy level of Fe 3dz2, which was beneficial to the adsorption of O2, and the hybridization between Fe (3dxz, 3dyz, and 3dz2) and *OO (2px, 2py, and 2pz) orbitals, significantly enhancing activation of O2. Therefore, compared with the FeN4 moiety on pure CNTs or GDY, this heterojunction structure through axial π─bond tuning demonstrates superior performance with a half-wave potential of 0.905V and a Tafel slope of 31.7mV dec-1.

Spin-polarized co enhances interactions between PtCoCu alloys and composite carbon substrates for efficient oxygen reduction.