Oxygen Evolution Reaction Activity Research Articles

Atomically Dispersed Vanadium-Induced Ru-V Dual Active Sites Enable Exceptional Performance for Acidic Water Oxidation.

Regulating the catalytic reaction pathway to essentially break the activity/stability trade-off that limits RuO2 and thus achieves exceptional stability and activity for the acidic oxygen evolution reaction (OER) is important yet challenging. Herein, we propose a novel strategy of incorporating atomically dispersed V species, including O-bridged V dimers and V single atoms, into RuO2 lattices to trigger direct O-O radical coupling to release O2 without the generation of *OOH intermediates. Vn-RuO2 showed high activity with a low overpotential of 227 mV at 10 mA cm-2 and outstanding stability during a 1050 h test in acidic electrolyte. Operando spectroscopic studies and theoretical calculations revealed that compared with the V single atom-doping case, the introduction of the V dimer into RuO2 further decreases the Ru-V atomic distance and weakens the adsorption strength of the *O intermediate to the active V site, which supports the more energetically favorable oxygen radical coupling mechanism (OCM). Furthermore, the highly asymmetric Ru-O-V local structure stabilizes the surface Ru active center by lowering the valence state and increasing the resistance against overoxidation, which result in outstanding stability. This study provides insight into ways of increasing the intrinsic catalytic activity and stability of RuO2 by atomically dispersed species modification.

Atomically Dispersed Vanadium‐Induced Ru‐V Dual Active Sites Enable Exceptional Performance for Acidic Water Oxidation

AbstractRegulating the catalytic reaction pathway to essentially break the activity/stability trade‐off that limits RuO2 and thus achieves exceptional stability and activity for the acidic oxygen evolution reaction (OER) is important yet challenging. Herein, we propose a novel strategy of incorporating atomically dispersed V species, including O‐bridged V dimers and V single atoms, into RuO2 lattices to trigger direct O−O radical coupling to release O2 without the generation of *OOH intermediates. Vn−RuO2 showed high activity with a low overpotential of 227 mV at 10 mA cm−2 and outstanding stability during a 1050 h test in acidic electrolyte. Operando spectroscopic studies and theoretical calculations revealed that compared with the V single atom‐doping case, the introduction of the V dimer into RuO2 further decreases the Ru‐V atomic distance and weakens the adsorption strength of the *O intermediate to the active V site, which supports the more energetically favorable oxygen radical coupling mechanism (OCM). Furthermore, the highly asymmetric Ru−O−V local structure stabilizes the surface Ru active center by lowering the valence state and increasing the resistance against overoxidation, which result in outstanding stability. This study provides insight into ways of increasing the intrinsic catalytic activity and stability of RuO2 by atomically dispersed species modification.

Dissolution of nanoparticulate IrO2 in dilute acidic baths through a pre-reduction step: A method to recover Ir from electrocatalytic/catalytic bodies

We report a process for recycling Ir-based nanosized electrocatalysts through dissolution of Ir under mild conditions (in dilute acidic media at ∼100 °C) and show that otherwise corrosion-resistant Ir-Oxide nanoparticles may be activated for dissolution in dilute HCl using a pre-reduction step. Effects of the reaction parameters such as the type of reducing agent, dissolution bath composition, reaction temperature, etc. was investigated. Further, structural characterizations to investigate the effect of the prereduction step on the Ir-Oxide and on the dissolved Ir species were made. The dissolved Ir was processed further to synthesize a new Ir-Oxide electrocatalyst exhibiting electrochemical performance (mass activity for oxygen evolution reaction) similar to that of the commercial Ir-Oxide. The study provides a recycling solution for the Ir-based electrocatalysts from relevant catalytic bodies and may be used for achieving sustainable acidic electrolyzers.

Na-doped cobalt spinel electrocatalysts prepared by programmed electrostatic spraying for improving OER activity and durability in acidic media

The daunting challenge to establish a trade-off among the activity, durability, and cost of electrocatalysts for oxygen evolution reaction (OER) with sluggish reaction kinetics impedes the practical green energy conversion. Hereby, a non-noble metal-based electrocatalyst (i.e., Na-doped Co3O4) was in-situ prepared by programmed electrostatic spraying as an advanced alternative to the costly and scarce state-of-the-art IrO2 and RuO2-based electrocatalysts. The utilization of this sprayer facilitates intimate contact with the substrate electrode and provides short ion diffusion paths, facilitating efficient electron transport. Additionally, the doping of Na ions into the Co3O4 structure results in structural distortion and charge redistribution, leading to the generation of oxygen vacancies (OVs). These OVs enhance the activity of lattice oxygen atoms, thus enabling rapid and durable oxygen evolution in an acidic media (0.5 M H2SO4). The optimal Na-Co3O4 (AA) exhibits a notably low overpotential of 360 mV@10 mA·cm−2 and at least 200 h stability. In addition, density functional theory (DFT) calculations confirm that the incorporation of Na ions significantly elevates electrical conductivity by decreasing the energy band gap and reduces the free energy barrier for the conversion of *O to *OOH, thereby improving the intrinsic OER activity. Finally, by implanting the catalyst in a single-cell proton exchange membrane water electrolyzer (PEMWE), the current density of 100 mA·cm−2 is achieved at a voltage of 1.62 V. This innovative non-noble metal catalyst holds great potential for scalable PEMWE anodes.

Exploring pyrolusite β-MnO2 as a robust support for noble metal catalysts in proton exchange membrane water electrolysis

Proton exchange membrane water electrolysis (PEMWE) represents a promising avenue for producing hydrogen sustainably. Nonetheless, its widespread adoption encounters hurdles owing to the sluggishness of the oxygen evolution reaction (OER) and the expensive noble metal catalysts, particularly iridium (Ir). Our investigation addresses these challenges by examining pyrolusite β-MnO2 as a robust substrate for noble metal catalysts, including iridium (Ir) and ruthenium (Ru), within PEMWE systems. We illustrate that nanostructured β-MnO2 effectively supports Ir and Ru catalysts, resulting in significantly improved catalytic activity for acidic OER compared to conventional IrO2 catalysts. The morphology shows nanorod structures with thicknesses ranging of 30–60 nm. The catalytic activity exhibits a lower overpotential of 215 mV and a higher Ir mass activity of 2268.7 A·gIr−1. The catalyst also exhibits lower Tafel slope value (37.82 mV/dec) and higher reaction kinetics. The catalyst also shows durability for the 12h under corrosive acidic OER conditions. The enhancements in performance can be attributed to the distinctive nanostructure of the Mn1-xTixO2 (MTO) support, which facilitates the even distribution of Ir and Ru catalysts. Additionally, the incorporation of titanium in pyrolusite β-MnO2 enhances the electrochemical durability of the MTO support under challenging acidic OER conditions.

Decrypting Synergy of Alloy & Metal Nanoparticles Within Nitrogen-Doped Carbon Nanosheets for Zn-Air Batteries with Ultralong Cycling Stability.

The exploration of efficient, robust, and low-cost bifunctional electrocatalysts to drive the commercial application of Zn-air batteries (ZABs) is of great significance but still remains a challenge. Herein, a 1D coordination polymer (1D-CP) derived FeNi alloy & Co nanoparticles (NPs) co-implanted N-doped carbon nanosheets (FNC/NCS) is judiciously crafted and employed as a high-performance electrocatalyst for ultralong lifetime ZABs. The key to this strategy is the leveraging of metal-coordinated melamine to direct the pyrolysis of 1D-CP, enabling the in situ formation of well-dispersed FeNi alloy and Co NPs within the carbon matrix. The resulting FNC/NCS exhibits prominent oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) activity with a small overall oxygen potential difference (ΔE = 0.68V). Density functional theory (DFT) simulation demonstrates that the synergistic effect between FeNi alloy and Co NPs can reduce energy barriers, promote electron transfer, and optimize the formation of crucial intermediates, thereby largely boost ORR/OER activity of FNC/NCS. The FNC/NCS-assembled ZABs possess high specific capacity, large power density, and ultralong cycling life in both aqueous (> 3300h) and solid-state (150h) electrolytes. This work provides a viable strategy for 1D-CP-derived bifunctional electrocatalysts and dissects the synergistic effect between different metal species, affording significant guidance for the development of renewable energy materials.

Chirality Engineering of Nanostructured Copper Oxide for Enhancing Oxygen Evolution from Water Electrolysis.

The exploration of a new conceptual strategy for improving the oxygen evolution reaction (OER) of earth-abundant electrocatalysts is critical. In this study, chiral copper oxide nanoflower is explored by a self-assembly method. The characterization suggests the chiral structure originates from the crystal plane-level helical stack of the secondary nanosheets. Of note, the assembly illustrates a record-high degree of spin polarization of 96%, indicating the ideal alignment of electron spin. Moreover, density function theory calculations show the chiral structure reducing the reaction energy barrier (REB) while switching the potential-determining step from *O→*OOH to *OH→*O. Together with the enhanced electrochemical active surface area and accelerated charge transfer, the production of ground-state triplet O2 is improved via a spin-forbidden route that involves the singlet H2O/OH•. Consequently, the chiral nanoflower shows a overpotential of 308mV at 10mA cm-2 and a Tafel slope of 93.5mV dec-1, which is even superior to the commercial RuO2 (310mV, 101mV dec-1). This study presents a new strategy for improving the OER activity by simultaneously enhancing electronic properties and lowering the REB of an non-noble electrocatalyst via chirality engineering.

ZnS-zeolitic imidazolate framework nanostructure anchored on Ni nanowires as a bifunctional electrocatalyst for high-efficiency overall water splitting

The design and construction of stable and inexpensive bifunctional catalysts for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) present a challenge in electrocatalytic water splitting. In this study, we utilized zeolitic imidazolate frameworks-8 (ZIF-8) as the precursor to fabricate ZnS-ZIF-8 via facile sulfidation processes. The ZnS-ZIF-8 nanostructures were anchored on the surface of the nickel nanowire (denoted as Ni NWs@ ZnS-ZIF-8 nanocomposite) and their catalytic activity for HER, OER, and overall water splitting were studied. The prepared Ni NWs@ ZnS-ZIF-8 revealed a low overpotentials value of 90 and 260 mV at 10 mA cm−2 for HER and OER in 1.0 M KOH solution, respectively. The alkaline electrolyzer assembled by Ni NWs@ ZnS-ZIF-8 provides a low cell voltage of 1.61 V at 10 mA cm−2 current density to boost the overall water splitting and robust stability for 15 h. The superior electrocatalytic activity of Ni NWs@ ZnS-ZIF-8 is owing to the facile and effective electron transport of Ni NWs, accessible active sites of ZnS-ZIF-8, and as well as the synergistic effect of the nanocomposite structures. This finding presents a viable methodology for synthesizing a proficient noble-metal-free catalyst for energy conversion and storage.

Carbon fiber with superhydrophilic interface as metal-free air electrode for all-solid-state Zn-air batteries

The burgeoning interest in all-solid-state Zn-air batteries as next-generation power sources for portable electronics is conspicuous. A pivotal aspect of their advancement lies in developing cost-effective, metal-free air electrodes with high-activity bifunctional oxygen electrocatalysts. This study introduces a superhydrophilic carbon fiber modified with oxygen functional groups (CF-O), achieved through a straightforward one-step activation treatment. Comparative analyses reveal that the CF-O electrode surpasses pristine CF in oxygen reduction and evolution reaction (OER and ORR) activity due to enhanced active sites and expedited ion transport. Notably, the OER/ORR performance depends on the type and quantity of oxygen functional groups. The optimal CF-O electrode displays an OER overpotential of 365.6 mV at 10 mA cm-2 and an ORR peak potential of 0.683 V. Utilizing the CF-O sample as the air electrode in all-solid-state Zn-air batteries yields an open-circuit voltage of 1.28 V and a peak volume power density of 82.8 mW cm-3. Furthermore, endurance testing reveals a charge/discharge voltage gap of 1.07 V at a current density of 1.0 mA cm-2 after 30 cycles. This facile and economical fabrication approach for metal-free air electrodes holds promise for advancing high-performance metal-air batteries compared to various existing techniques.

Facet Engineering of Cobalt Manganese Oxide for Highly Stable Acidic Oxygen Evolution Reaction

AbstractDeveloping cost‐effective, robust, and durable catalysts for water oxidation in acidic conditions remains a significant challenge for the practical application of proton exchange membrane electrolyzers. Cobalt‐based spinel catalysts, known for their effective oxygen evolution reaction (OER) activity in acidic environments, are promising alternatives to the costly iridium‐based catalysts. However, their application is often limited by poor stability under corrosive acidic conditions and oxidative potential. Here it is demonstrated that doping Co2MnO4 with Ni effectively regulates the structural and electronic properties of the catalysts, enabling stable operation for over 285 h at 100 mA cm−2 in 0.5 m H2SO4. This stability enhancement is primarily due to the increased exposure of the (400) facet, a result supported by theoretical studies. The proton exchange membrane water electrolysis (PEMWE) performance of Ni(5%)Co2MnO4 further demonstrates its potential, achieving 1 A cm−2 at a cell voltage of 2.3 V, with minimal degradation over 100 h at 500 mA cm−2. This study not only provides insights into the design of advanced OER catalysts through the doping of heteroatoms but also offers a pathway to enhance the sustainability and economic viability of acidic OER applications.

Electrospun Co-MoC Nanoparticles Embedded in Carbon Nanofibers for Highly Efficient pH-Universal Hydrogen Evolution Reaction and Alkaline Overall Water Splitting.

The construction of highly efficient and self-supported electrocatalysts with abundant active sites for pH-universal hydrogen evolution reaction (HER) and alkaline water splitting is significantly challenging. Herein, Co and MoC nanoparticles embedded in nitrogen-doped carbon nanofibers (Co-MoC/NCNFs) which display a bamboo-like morphology are prepared by electrospinning followed by the carbonization method. The electrospun MoC possesses an ultrasmall size (≈5nm) which can provide more active sites during electrocatalysis, while the introduction of Co greatly optimizes the electronic structure of MoC. Both endow the Co-MoC/NCNFs with superior HER performances over a wide pH range, with low overpotentials of 86, 116, and 145mV to achieve a current density of 10mAcm-2 in alkaline, acidic, and neutral media, respectively. Additionally, the catalyst exhibits remarkable alkaline oxygen evolution reaction (OER) activity with an overpotential of 254mV to reach 10mAcm-2. Density functional theory calculations confirm that electron transfer from Co to MoC regulates the adsorption free energy for hydrogen, thereby promoting HER. Moreover, an electrolyzer assembled with Co-MoC/NCNFs requires only a cell voltage of 1.59V at 10mAcm-2 in 1m KOH. This work opens new pathways for the design of high-efficiency electrocatalysts for energy conversion applications.

Ir Doping Modulates the Electronic Structure of Flower-Shaped Phosphides for Water Oxidation.

Electrolysis of water to produce hydrogen is an efficient, clean, and environmentally friendly hydrogen production method with unlimited development prospects. However, its overall efficiency is hampered by the slow oxygen evolution reaction (OER) with complex electron transfer processes. Therefore, designing efficient and low-cost OER catalysts is the key to solving this problem. In this paper, Ir-doped Co2P/Fe2P (abbreviated as Ir-CoFeP/NF) was grown on nickel foam through the strategies of low amount noble-metal doping and mild phosphating. Phosphide derived from a floral metal-organic framework (MOF) exhibits regular three-dimensional (3D) morphology and large active area, avoiding the stacking of active sites. The addition of Ir can effectively adjust the electronic structure, change the position of the d-band center, and increase active sites, thus enhancing the catalytic activity. Hence, the optimized catalyst exhibits unexpected electrocatalytic OER activity with an ideal overpotential of 213 mV at 10 mA cm-2, as well as a low Tafel slope of 40.63 mV dec-1. Coupling with Pt/C for overall water splitting (OWS), the entire device only needs an ultralow cell voltage of 1.50 V to achieve a current density of 10 mA cm-2. Besides, the OWS can be maintained for more than 70 h. This study demonstrates the superiority of Ir-doped phosphide in accelerating water oxidation.

Atomic Manipulation to Create High-Valent Fe4+ for Efficient and Ultrastable Oxygen Evolution at Industrial-Level Current Density.

Manipulating the electronic structure of a catalyst at the atomic level is an effective but challenging way to improve the catalytic performance. Here, by stretching the Fe-O bond in FeOOH with an inserted Mo atom, a Fe-O-Mo unit can be created, which will induce the formation of high-valent Fe4+ during the alkaline oxygen evolution reaction (OER). The highly active Fe4+ state has been clearly revealed by in situ X-ray absorption spectroscopy, which can both enhance the oxidation capability and lead to an efficient and stable adsorbate evolution mechanism (AEM) pathway for the OER. As a result, the obtained Fe-Mo-Ni3S2 catalyst exhibits both superior OER activity and outstanding stability, which can achieve an industrial-level current density of 1 A cm-2 at a low overpotential of 259 mV (at 60 °C) and can stably work at the large current for more than 2000 h. Moreover, by coupling with commercial Pt/C, the Fe-Mo-Ni3S2∥Pt/C system can be used in the anion exchange membrane cell to acquire 1 A cm-2 for overall water splitting at 1.68 V (2.03 V for 4 A cm-2), outperforming the benchmark RuO2∥Pt/C system. The efficient, low-cost, and ultrastable OER catalyst enabled by manipulating the atomic structure may provide potential opportunities for future practical water splitting.

Dual Cocatalytic Sites Synergize NiFe Layered Double Hydroxide to Boost Oxygen Evolution Reaction in Anion Exchange Membrane Water Electrolyzer

AbstractNickel‐iron layered double hydroxide (LDH) is a promising cost‐efficient catalyst to replace noble metals for alkaline oxygen evolution reaction (OER), yet its intrinsic activity under high current density conditions is not satisfactory, which greatly constrains the industrial application of NiFe LDH catalysts. Herein, a new class of integrated Co and W co‐doped NiFe LDH catalysts is reported with dual cocatalytic sites for alkaline OER catalysis. The optimized Co2.8, W3.8‐NiFe LDH integrated catalyst has superior alkaline OER activity (255 mV@1000 mA cm−2) and excellent catalytic stability (200 h@500 mA cm−2). The turnover frequency value of Co2.8, W3.8‐NiFe LDH can reach 4.02 s−1 at 1.49 V versus RHE, which is 9.6 times higher than that of NiFe LDH and superior to the noble metal catalysts. Moreover, it can achieve 1.0 A cm−2 at 1.86 V and maintain 300‐h stable operation in anion exchange membrane water electrolyzer. Theoretical and experimental studies indicate that W sites promote the *OH adsorption and Co sites favor protons desorption of OH*. These dual cocatalytic sites jointly promote *O coverage, effectively accelerating alkaline OER kinetic.

Computational screening of Group VⅢ@C5N4 single-atom electrocatalysts for overall water splitting

Single-atom catalysts (SACs) have great potential for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) since their high atomic utilization and strong metal–support interactions. Herein, we develop TM@C5N4 (TM = Fe, Co, Ni, Ru, Rh, Pd, Os, Ir and Pt) catalysts via embedding Group VⅢ TM in holey C5N4 substrate and further evaluate their electrocatalytic activity using density functional theory (DFT) calculations. Systematical studies indicate that Fe@C5N4, Pd@C5N4 and Ir@C5N4 catalysts all exhibit excellent HER performance, which mainly because of their small ΔGH* values of 0.101 eV, -0.114 eV and 0.070 eV, respectively. In parallel, Rh@C5N4 and Ir@C5N4 possess high OER activity along with low overpotential of 0.50 V, which is superior to the commercial IrO2 catalyst (0.56 V). Obviously, Ir@C5N4 could be utilized as bifunctional electrocatalysts both HER and OER in water splitting. Furthermore, we analyze their correlative catalytic mechanisms using the molecular orbitals. Besides, biaxial strain modulation could effectively regulate the catalytic activity of HER and OER. Particularly, 2 % biaxial tensile strain could bring Ir@C5N4 superb HER/OER catalytic performance. Finally, we anticipate that this strain engineering would provide a new perspective for developing high-performance SACs for water splitting.

Toward Finding the Role of Surface Iron Ions in Enhancing Oxygen-Evolution Reaction.

The oxygen evolution reaction (OER) in alkaline media is crucial for energy conversion technologies, and Fe-based catalysts have garnered significant attention for their efficacy. In this study, we provide an investigation of Fe-based catalysts under OER conditions using some techniques. Our findings reveal minimal structural alterations in the bulk FeHxOy framework during OER, indicating that the bulk structure remains largely intact. Instead, the catalytic activity is primarily localized on the material's surface. This conclusion is corroborated by the measured low electrochemical surface area (ECSA) of FeHxOy, suggesting that its limited OER performance stems from a paucity of active sites rather than low intrinsic activity. The superior efficiency of Fe ions in conductive oxides or on conductive metal substrates (e.g., copper and gold) in OER is attributed to the increased availability of surface-active sites in these systems. To further elucidate this phenomenon, we investigated two additional systems: NiFe and VFe (hydr)oxides. For NiFe (hydr)oxides, we demonstrate that only surface Fe ions contribute actively to OER. In contrast, in VFe (hydr)oxides, the removal of vanadium resulted in a marked increase in ECSA and the generation of defect sites, significantly enhancing OER activity. These findings provide critical insights into the surface-specific role of Fe ions in catalytic activity and could inform future design strategies for more efficient OER catalysts by optimizing the availability and reactivity of surface-active Fe sites.

Oxyanions Enhancing Crystallinity of Reconstructed Phase for Oxygen Evolution Reaction.

The catalysts were always undergoing continuous amorphization and dissolution of active structure in operating condition, hindering the compatibility between stability and activity for oxygen evolution reaction (OER). Herein, we propose the selective adsorption of leached NO3- to strengthen the crystallinity and activity of surface reconstructed layer with amorphous and crystalline (a-c) heterojunction. Taking a-c Ni doped Fe2O(OH)3NO3·H2O (Ni-FeNH) as a model precatalyst, we uncover that the leached NO3- are readily adsorbs on the crystalline phase in the formed a-c Fe(Ni)OOH during OER, lowering the disorder degree and further activating Ni and Fe ion of the crystalline Fe(Ni)OOH on a-c heterojunctions. Accordingly, Ni-FeNH deliver a low overpotential of 303 mV and high durability of 500 hours at 500 mA cm-2 for OER. Particularly, constructing industrial water electrolysis equipment exhibits high stability of 100 hours under a high operating current of 8000 mA.

Oxyanions Enhancing Crystallinity of Reconstructed Phase for Oxygen Evolution Reaction

The catalysts were always undergoing continuous amorphization and dissolution of active structure in operating condition, hindering the compatibility between stability and activity for oxygen evolution reaction (OER). Herein, we propose the selective adsorption of leached NO3‐ to strengthen the crystallinity and activity of surface reconstructed layer with amorphous and crystalline (a‐c) heterojunction. Taking a‐c Ni doped Fe2O(OH)3NO3·H2O (Ni‐FeNH) as a model precatalyst, we uncover that the leached NO3‐ are readily adsorbs on the crystalline phase in the formed a‐c Fe(Ni)OOH during OER, lowering the disorder degree and further activating Ni and Fe ion of the crystalline Fe(Ni)OOH on a‐c heterojunctions. Accordingly, Ni‐FeNH deliver a low overpotential of 303 mV and high durability of 500 hours at 500 mA cm‐2 for OER. Particularly, constructing industrial water electrolysis equipment exhibits high stability of 100 hours under a high operating current of 8000 mA.

Structural Regulation of a Multi-Component Co2P2O7-MoN/NC Electrocatalyst for Efficient Oxygen Evolution Reaction.

Realizing efficient and durable non-precious metal-based electrocatalysts for oxygen evolution reaction (OER) still remains a great challenge. Here, a multi-component composite of Co2P2O7-MoN/NC containing pyrophosphate, nitride, and nitrogen-doped carbon is successfully prepared via a facile two-step synthesis method. Combining the structural regulation between the active metal- and non-metal-based species, Co2P2O7-MoN/NC demonstrates superior activity and durability for OER, requiring an overpotential of 278 mV at a current density of 10 mA cm-2, a Tafel slope of 83.3 mV dec-1, and long-term stability over 100 h in an alkaline solution. Post-characterizations reveal that synergistic effect among stable Co2P2O7, partially dissolved MoN, N-doped carbon, and new-formed CoOOH nanosheets enable structural reconstruction, fast charge transfer, and formation of oxygen-containing intermediates, promoting the OER performance significantly. This work provides a promising pathway to tune multi-components to fabricate efficient transition-metal-based electrocatalysts in energy conversion applications.

Fleeting-Active-Site-Thrust Oxygen Evolution Reaction by Iron Cations from the Electrolyte.

Oxygen evolution reaction (OER) is key to sustainable energy and environmental engineering, thus necessitating rational design of high-performing electrocatalysts that requires understanding the structure-performance relationship with a possible dynamic nature under working conditions. Herein, we uncover a novel type of OER mechanisms thrust by the fleeting active sites (FASs) dynamically formed on Ni-based layered double hydroxides (Ni-LDHs) by Fe cations from the electrolyte under OER potentials. We employ grand-canonical ensemble methods and microkinetic modeling to elucidate the potential-dependent structures of FASs on Ni-LDHs and demonstrate that the fleeting-active-site-thrust (FAST) mechanism delivers superior OER activity via the FAST intramolecular oxygen coupling pathway, which also suppresses the lattice oxygen mechanism, leading to improved operando stability of Ni-LDHs. We further reveal that introducing only trace-level loadings (10-100 ppm) of FASs on Ni-LDHs can significantly boost and govern the catalytic performance for OER. This underscores the crucial importance of considering the novel FAST mechanism in OER and also suggests the electrolyte as a key part of the structure-performance relationship as well as an effective design strategy via engineering the electrolyte.