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The engineering of the electronic structure in transition metal oxide (TMO) catalysts has emerged as a promising approach to enhance the oxygen evolution reaction (OER) in water-splitting, achieved through precise modulation of the absorption and desorption energies of water intermediates. Among various strategies, strain-induced tunability in electronic structures has shown great potential to significantly improve the performance of the OER performance. In this study, we utilized artificial superlattices (LaNiO₃)_n/(SrRuO₃)_m (LNO_n/SRO_m) to optimize the surface orbital occupancy of LNO and maximize the strain effect’s effectiveness. Our findings indicate that, compared to single-layer LNO films, the LNO₁/SRO₂ superlattice exhibits an impressive 28% reduction in Tafel slope, along with an approximately 315% enhancement in catalytic current density at 1.65 V for the OER process. The approach of the 3dx2‐y2 orbital of e_g toward the 2p orbital by strain in superlattice is responsible for this OER enhancement, where the centering of e_g and 2p orbitals is improved. Our results not only provide a promising strategy for the enhanced OER by engineering the TMO’s surface electronic structure, but also showcase the exceptional design of OER catalysts using artificial TMO superlattices.

Efficient oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) bifunctional electrocatalysts have been pursued for decades. Meanwhile, single metal atoms embedded in a two-dimensional material substrate (2D-substrate) have emerged as an outstanding catalyst. Herein, we report on computational ORR/OER efficiencies of a series of single atom catalyst systems, with a nitrogen-doped boron phosphide monolayer (N₃-BP) as the 2D-substrate, and with Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Rh, Pd, Ir, and Pt as the single-atom subject (M). In brief, our density functional theory results show that the overpotentials for ORR/OER are low for CoN₃-BP, NiN₃-BP, and PtN₃-BP, with {η^ORR; η^OER} of {0.36; 0.42 V}, {0.29; 0.44 V}, and {0.32; 0.25 V}, respectively. The relevant attributes such as the chemical stability of the 2D-substrate in the ORR/OER environments, immobilization of the single-atom subject on the 2D-substrate, and mechanisms of the ORR/OER activity and the catalyst recovery on the MN₃-BP catalysts were carefully examined. The key to the comparative study is how the electronic states of the reaction center near the Fermi level of the catalytic system match the frontier orbitals of ORR/OER reaction intermediates. In short, our method predicts the ORR/OER catalytic efficiencies of novel catalysts via a single-atom/2D-substrate design strategy.

Transition metal oxides are widely pursued as potent electrocatalysts for the oxygen evolution reaction (OER). However, single-metal chromium catalysts remain underexplored due to their intrinsic activity limitations. Herein, we successfully synthesize mixed-valence, nitrogen-doped Cr₂O₃/CrO₃/CrN@NC nanoelectrocatalysts via one-step targeted pyrolysis techniques from a binuclear Cr-based complex (Cr₂(Salophen)₂(CH₃OH)₂), which is strategically designed as a precursor. Comprehensive pyrolysis mechanisms were thoroughly delineated by using coupled thermogravimetric analysis and mass spectrometry (TG–MS) alongside X-ray diffraction. Below 800 °C, the generation of a reducing atmosphere was noted, while continuous pyrolysis at temperatures exceeding 800 °C promoted highly oxidized CrO₃ species with an elevated +6 oxidation state. The optimized catalyst pyrolyzed at 1000 °C (Cr₂O₃/CrO₃/CrN@NCs-1000) demonstrated remarkable OER activity with a low overpotential of 290 mV in 1 M KOH and excellent stability. Further density functional theory (DFT) calculations revealed a much smaller reaction energy barrier of CrO₃ than the low oxidation state species for OER reactivity. This work reveals fresh strategies for rationally engineering chromium-based electrocatalysts and overcoming intrinsic roadblocks to enable efficient OER catalysis through a deliberate oxidation state and compositional tuning.

Designing highly active and more durable oxygen electrocatalysts for regenerative metal-air batteries and water splitting is of practical significance. Herein, an advanced Co/N–C-800 catalyst composed of abundant Co–N_x structures and carbon defects derived from cobalt phthalocyanine is synthesized. Remarkably, this catalyst exhibits favorable catalytic performance toward the oxygen evolution reaction (OER) with a receivable overpotential of 274 mV in an alkaline medium achieving a current density of 10 mA cm^–2 and a Tafel slope of 43.6 mV decade^–1, outperforming the commercial RuO₂ catalyst. It further displays a high half-wave potential (0.82 V) for the oxygen reduction reaction in 0.1 M KOH. Theoretical calculations reveal that the Co–N_x active sites along with the carbon defects can decrease the adsorption energy of intermediates (OH*, O*, and OOH*) and enhance the electron-transfer ability, thus boosting the OER process.

Using lignite as the raw material to prepare a new OER catalyst, and thus to make high-value use of lignite and to meet the research and development needs for new energy materials at the same time, a novel Fe/Fe₃C active species has been reported as a promising catalyst to replace precious metals. In this study, we developed a facile method for the preparation of Fe₃C@C/CNT hybrid materials by catalytic pyrolysis of lignite using KOH and FeCO₃. The structural characteristic of Fe₃C@C/CNT hybrid materials is that Fe₃C nanoparticles are encapsulated in carbon layers and carbon nanotubes, forming a special core–shell structure. The prepared materials have good graphitization and a large specific surface area (957 m² g^–1). We discussed the effects of KOH, FeCO₃, and melamine in the catalytic pyrolysis of lignite to produce Fe₃C@C/CNT materials: (1) Lignite can be catalyzed by KOH to generate carbon nanotubes and porous structures. (2) The transformation of carbon matrix to graphitic carbon is catalyzed and the Fe source for Fe₃C is provided by FeCO₃. (3) The aggregation of Fe into large and irregular Fe nanoparticles is inhibited by melamine, which facilitates the generation of Fe₃C. When the Fe₃C@C/CNT hybrid is used as an OER catalyst, the OER overpotential is only 407 mV at a current density of 10 mA cm^–2 in an alkaline electrolyte, which has great application potential. This work is conducive to improving the economic benefits of lignite and provides a new idea for the high value-added utilization of lignite.

Developing a cost-effective and highly efficient electrocatalyst with superior catalytic activity is crucial for clean and green water splitting, including the hydrogen evolution reaction (HER), the oxygen evolution reaction (OER), and the oxygen reduction reaction (ORR). The single-atom catalyst (SAC) is a breakthrough in industrial catalysis because of the advantages of maximum metal atom utilization, single active sites, strong metal–support interactions, and great potential to accomplish high catalytic performance and selectivity. Herein, we investigate the electrocatalytic performance of a series of SACs supported on a phosphomolybdic acid (PMA) cluster for the HER, OER, and ORR by using first-principles-based calculations. It has been found that the most plausible binding site for the single-metal adatoms is the 4-fold hollow (4H) site over the PMA cluster. Due to the higher stability and catalytic activity of single-metal adatoms, fast electron transfer kinetics is permissible through catalysis. Mainly, Pt₁/PMA, Ru₁/PMA, V₁/PMA, and Ti₁/PMA realized decent catalytic performance toward the HER due to nearly ideal (ΔG_H* = 0) ΔG_H* values via the Volmer–Heyrovsky pathway. The Co₁/PMA (0.45 V) and Pt₁/PMA (0.49 V) can be active and selective catalysts for the OER with their overpotentials comparable those of to MoC₂, IrO₂, and RuO₂. Among the considered candidates, a non-noble metal Fe₁/PMA SAC is a promising electrocatalyst for the ORR with an overpotential of 0.42 V, which is lower than that for the most favorable Pt (0.45 V) catalyst. Furthermore, Pt₁/PMA is an auspicious multifunctional electrocatalyst for overall water splitting (−0.02 V for the HER and 0.49 V for the OER) and a metal-air battery (0.79 V for the ORR) catalyst. The current study is further extended to calculate the kinetic potential energy barrier for the excellent catalytic performance of Co₁ for the OER and Fe₁ for the ORR. The results suggest that the kinetic activation barrier values in all proton-coupled electron transfer steps are in good agreement with the thermodynamic results. It was revealed that the PMA cluster is a promising single-atom support for the HER, OER, and ORR and provides low-cost and highly efficient electrocatalytic activity under normal reaction conditions.

Research has been focused on regulating the amorphous surface of Ir-based materials to achieve a higher oxygen evolution reaction (OER) activity. The IrO_x amorphous layer is generally considered to be substantial enough to break the limitation created by the conventional adsorbate evolution mechanism (AEM) in acidic media. In this work, we used lanthanides to regulate IrO_x amorphization–crystallization through inhibiting the crystallization of iridium atoms in the calcination process. The chosen route created abundant crystalline–amorphous (c-a) interfaces, which greatly enhanced the charge transfer kinetics and the stability of the materials. The mass activity of iridium in the synthesized IrO₂@LuIr_1–nO_x(OH)_y structure reached 128.3 A/g_Ir, which is 14.6-fold that of the benchmark IrO₂. All the IrO₂@LnIr_1–nO_x(OH)_y (Ln = La–Lu) structures reflected 290–300 mV of overpotential at 10 mA/cm_geo². We demonstrate that a highly active c-a interface possesses an efficient charge transfer capability and is conducive to the stability of the activated oxygen species. The surface-activated oxygen species and the tensile strain [IrO₆] octahedron regulated by lanthanides are synergistically beneficial for increasing the intrinsic OER activity. Our research findings introduce c-a interface generation by the regulation of lanthanides as a new method for the rational design of robust OER catalysts.

AlOOH has long been used as excellent adsorbent for removal of heavy metal cations from wastewater. Herein we report one-pot synthesis of carboxylic-functionalized Ni-doped AlOOH nanoflowers (AlOOH NFs) with high adsorptive capability toward various transition metal cations, and more importantly, the AlOOH NFs adsorbed with various transition metal cations were for the first time directly used as electrocatalyst for oxygen evolution reaction (OER). By simply manipulating the initial metal cation concentration and their molar ratio, the OER catalytic performance of the resulting catalysts could be modulated. The lowest overpotential at a current density of 10 mA cm^–2 prepared from AlOOH NFs adsorbed with Fe^III and Ni^II is 0.32 V in 0.1 M KOH and 0.275 V in 1.0 M KOH. Such AlOOH-supported electrocatalyst demonstrates remarkable stability, which shows no evident increase of the overpotential at 10 mA cm^–2 after 2 h of steady electrolysis at an overpotential of 0.42 V. The excellent OER electrocatalytic activity originates from the on-site formation of ultrafine FeOOH and NiOOH nanoclusters with average sizes below 3 nm during the electrocatalytic process. As such, we demonstrate the workability of using functionalized AlOOH NFs as a bifunctional platform for adsorption of transition metal cations and easy preparation of efficient and cost-effective OER catalysts.

The construction of an efficient oxygen reduction reaction and oxygen evolution reaction (ORR/OER) bifunctional electrocatalyst is of great significance but still remains a giant challenge for high-performance metal–air batteries. In this study, uniform FeS/Fe₃C nanoparticles embedded in a porous N,S-dual doped carbon honeycomb-like composite (abbr. FeS/Fe₃C@NS-C-900) have been conveniently fabricated by pyrolysis of a single-crystal Fe-MOF, which has a low potential gap ΔE of ca. 0.72 V, a competitive power density of 90.9 mW/cm², a specific capacity as high as 750 mAh/g_Zn, and excellent cycling stabilities over 865 h (1730 cycles) at 2 mA/cm² when applied as a cathode material for rechargeable zinc–air batteries. In addition, the two series-linked Zn–air batteries successfully powered a 2.4 V LED light as a real power source. The efficient ORR/OER bifunctional electrocatalytic activity and long-term durability of the obtained composite might be attributed to the characteristic honeycomb-like porous structure with sufficient accessible active sites, the synergistic effect of FeS and Fe₃C, and the N,S codoped porous carbon, which provides a promising application potential for portable electronic Zn–air battery related devices.

Designing low-cost and high-activity electrocatalysts is significant to enhance the slow kinetic process of oxygen evolution reaction (OER). Inspired by the Lego game, hierarchical CdP₂–CDs–CoP nanoarrays were fabricated by combining negatively charged carbon quantum dots (CDs) with positively charged Co and Cd ions. Because of the low evaporation temperature of Cd and relatively high solubility product (K_sp) of Cd(OH)₂, trace CdP₂ is trapped on the surface of CdP₂–CDs–CoP nanoarrays. When coupled with CDs, CdP₂ enriches the defects and active sites of catalysts. The CdP₂–CDs–CoP nanoarray, as a robust OER electrocatalyst, delivers an overpotential of 285 mV to drive a current density of 10 mA cm^–2, demonstrating its superiority over commercial RuO₂.

SrTiO₃ (STO) is a widely used photocatalyst for water splitting, which has no photoactivity without a cocatalyst. The reason for this unclear. Here, we performed an oxygen evolution reaction (OER) on clean and oxygen deficient (100), (110), and (111) surfaces on STO by density functional theory. Combining our results with experimental results in the literature, we demonstrated that the overpotential is small enough for OER to occur on (100) surfaces. There is no photoactivity due to the photogenerated holes that cannot migrate to the (100) surfaces. On the (110) and (111) surfaces, the overpotential is very high, which prevents the OER from taking place on these two surfaces. Our work gives a guidance principle to understand the water splitting from the overpotential of OER and migrating photogenerated carriers. It may be helpful to design high efficiency photocatalysts based on STO.

Nanoclusters are ideal electrocatalysts due to their high surface activity. However, their high activities also lead to serious agglomeration and performance attenuation during the catalytic process. Here, highly dispersed Ni nanoclusters (∼3 nm) confined in an amorphous carbon matrix are successfully fabricated by pulsed laser deposition, followed by rapid temperature annealing treatment. Then, the Ni nanoclusters are further doped with nitrogen element through a clean N₂ radio frequency plasma technology. It is found that the nitrogen-doped Ni nanoclusters obtained under optimized conditions showed superior OER performance with a very low overpotential of 240 mV at a current density of 10 mA/cm², together with good stability. The excellent OER performance of the nanoclusters can be attributed to the unique confined structure and nitrogen doping, which not only provide more active sites but also improve the conductivity. Our work provides a controllable method for the construction of a novel confined structure with controllable nitrogen doping, which can be used as a high-efficiency OER electrocatalyst.

Only a few materials can remain undissolved under working conditions for the oxygen evolution reaction (OER) in acidic media, which limits the choice of catalysts and supports. One of the practical catalyst/support candidates is IrO_x/Sb:SnO₂ (Ir/ATO) because both components are thermodynamically stable under low-pH anodic conditions. Moreover, between Ir and ATO, a strong metal–support interaction is present, thereby allowing for long-lasting OER activity unless the support degrades. However, we demonstrate that the strong interaction can paradoxically deactivate Ir/ATO structures when synthesizing them using the polyol process. We reveal that the strong interaction in the presence of polyol at elevated temperatures can cause the reduction of the Sb dopant to zero-valency. Findings show that the varied oxidation state of the dopant decreases the electrical conductivity of the Ir/ATO, impeding the electron transfer through the support, hence deteriorating electrocatalytic activity toward the OER.

Composition optimization, structural design, and introduction of external magnetic fields into the catalytic process can remarkably improve the oxygen evolution reaction (OER) performance of a catalyst. NiFe₂O₄@(Ni, Fe)S/P materials with a heterogeneous core–shell structure were prepared by the sulfide/phosphorus method based on spinel-structured NiFe₂O₄ nanomicrospheres. After the sulfide/phosphorus treatment, not only the intrinsic activity of the material and the active surface area were increased but also the charge transfer resistance was reduced due to the internal electric field. The overpotential of NiFe₂O₄@(Ni, Fe)P at 10 mA cm^–2 (iR correction), Tafel slope, and charge transfer resistance were 261 mV, 42 mV dec^–1, and 3.163 Ω, respectively. With an alternating magnetic field, the overpotential of NiFe₂O₄@(Ni, Fe)P at 10 mA cm^–2 (without iR correction) declined by 45.5% from 323 mV (0 mT) to 176 mV (4.320 mT). Such enhancement of performance is primarily accounted for the enrichment of the reactive ion OH^– on the electrode surface induced by the inductive electric potential derived from the Faraday induction effect of the AMF. This condition increased the electrode potential and thus the charge transfer rate on the one hand and weakened the diffusion of the active substance from the electrolyte to the electrode surface on the other hand. The OER process was dominantly controlled by the charge transfer process under low current conditions. A fast charge transfer rate boosted the OER performance of the catalyst. At high currents, diffusion exerted a significant effect on the OER process and low OH^– diffusion rates would lead to a decrease in the OER performance of the catalyst.

Harnessing the potential of oxygen vacancies (O_v) in metal oxides presents a promising avenue for expediting reaction kinetics in water oxidation. In this context, layered double hydroxides (LDH) offer a versatile platform for developing cost-effective electrocatalysts with exceptional performance, thanks to their distinctive lamellar morphology. In this study, we unveil the augmented electrochemical efficiency of CoFeLDH by deliberately inducing an optimal oxygen vacancy (O_v) under ambient conditions for the oxygen evolution reaction (OER). The transformation of CoFeLDH nanorods (CoFeLDH) into O_v-rich CoFeLDH (CoFeLDH-O_v) takes place through a chemical reduction process at room temperature. The effect of O_v within the catalyst is substantiated through qualitative analyses, such as X-ray photoelectron spectroscopy (XPS), photoluminescence (PL), and electron paramagnetic resonance (EPR). The resulting catalyst, CoFeLDH-O_v, exhibits an overpotential of 220 mV at a current density of 30 mA/cm² in a 1 M KOH electrolyte, indicating an enhanced electroactivity when compared to CoFeLDH (without O_v defects). The catalyst also reveals excellent stability for more than 500 h at a higher current density of 50 mA/cm². To validate the catalyst’s conducive nature, density functional theory (DFT) calculations are performed, revealing iron (Fe) as the prominent active site within the catalyst. By means of comprehensive experimental and theoretical analyses, the substantial influence of O_v on the electronic structure of the LDH system is demonstrated, which, in turn, facilitates facile charge transfer and strengthens the efficiency of the oxygen evolution reaction (OER).

Water electrolysis is considered as one of the alternative potential approaches for producing renewable energy. Due to the sluggish kinetic nature of oxygen evolution reaction (OER), it encounters a significant overpotential to achieve water electrolysis. Hence, the advancement of cost-effective transition metal-based catalysts toward water splitting has gained global attention in recent years. In this work, the doping of Fe over amorphous NiWO₄ increased the OER activity effectively and achieved stable oxygen evolution in the alkaline medium, which show better electrocatalytic activity as compared to crystalline tungstate. As NiWO₄ has poor activity toward OER in the alkaline medium, the doping of Fe³⁺ will tune the electronic structure of Ni in NiWO₄ and boost the OER activity. The as-synthesized Fe-doped amorphous NiWO₄ exhibits a low overpotential of 230 mV to achieve a current density of 10 mA cm^–2 and a lower Tafel slope value of 48 mV dec^–1 toward OER in 1.0 M KOH solution. The catalyst also exhibits long-term static stability of 30 h during chronoamperometric study. The doping of Fe improves the electronic conductivity of Ni-3d states in NiWO₄ which play a dominant role for better catalytic activity via synergistic interaction between Fe and active Ni sites. In future, these results offer an alternative route for precious metal-free catalysts in alkaline medium and can be explicitly used in various tungstate-based materials to increase the synergism between the doped atom and metal ions in tungstate-based materials for further improvement in the electrocatalytic performance.

The (100) crystallographic plane is the most active facet of iridium dioxide (IrO₂) for the oxygen evolution reaction (OER). Pulsed laser deposition was used to grow (100) IrO₂ on a (100) SrTiO₃ substrate at deposition temperature ranging from room temperature to 600 °C. Detailed structural and morphological characterization was performed using AFM, XRD, and X-ray reciprocal space mapping (RSM) to unravel the geometrical arrangement of [IrO₆] octahedra in the (100) IrO₂ thin films. It is shown that the symmetry mismatch between the substrate and the epitaxial thin film imposed an orthorhombic distortion of the tetragonal structure of IrO₂ and, as a consequence, the [IrO₆] geometry is distorted. These data were correlated to the OER characteristics established from electrochemical measurements. DFT modeling was employed to relate differences in surface relaxation of IrO₂ films prepared at different temperatures with changes in OER activity. Vacancy formation leads to higher surface stability at temperatures around 500 °C, which corresponds to the deposition temperature at which the electrocatalytic activity of (100) epitaxial IrO₂ film is maximal.

The Fe-embedded N-doped graphene (Fe–N–C) is the most representative single atom catalyst (SAC) that has shown great potentiality in electrocatalysis, such as oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). However, the active moiety of Fe–N–C is still elusive due to contradictory experimental results. Moreover, early simulations mainly focus on the thermodynamic potential of adsorbates, while the effect of spin multiplicity receives little attention. To explore the role of spin multiplicity in electrocatalysis, we employ the constant-potential density functional theory (DFT) to systematically study the structural evolution of the high-spin (HS) and intermediate-spin (IS) FeN₄ site (marked by FeN₄^HS/IS) in OER and ORR processes. With the consideration of spin multiplicity, our simulation shows spontaneous oxidation from Fe(II)N₄^IS to Fe(III)N₄^HS at potential U = 0.4 V versus SHE. Further simulation indicates that the FeN₄^IS site undergoes a sequential adsorption of *OH and *OOH along with U increase, which leads to the spin state transition from IS to HS. According to the constant-potential free energy analysis, the FeN₄^HS*OOH is confirmed to be the practical active centers of OER, while the FeN₄^HS*OH and FeN₄^IS are assigned to the active center of ORR in low and high overpotentials. The predicted ORR activity of FeN₄^HS*OH agrees with the in situ X-ray absorption near-edge spectroscopy (XANES) and ⁵⁷Fe Mössbauer spectroscopy measurement by Xiao et al. [Microporous Framework Induced Synthesis of Single-Atom Dispersed Fe-NC Acidic ORR Catalyst and its In Situ Reduced Fe-N₄ Active Site Identification Revealed by X-Ray Absorption Spectroscopy. ACS Catal. 2018, 8, 2824–2832]. Based on the geometry and orbital analysis, the bond length of Fe–N and coordination number of Fe center are found to have a significant impact on the d orbital splitting energy and thus induce the turnover of HS/IS stability in the OER/ORR intermediates. Our study brings comprehensive insights into the evolution of coordination and spin state in Fe–N–C, which reveals the significance of spin multiplicity in electrocatalysis and benefits further theoretical design of SACs from the perspective of spin effects.

In the present study, three mass-produced commercial IrO_x samples from different suppliers were studied to establish correlations between various properties and their OER activities. The structures of the electrocatalysts at different scales were explored through laboratory instrumentation, powder X-ray diffraction, and synchrotron-based X-ray total scattering experiments combined with pair distribution function analysis. X-ray photoelectron spectroscopy and energy-dispersive X-ray spectroscopy using a transmission electron microscope were used to determine respectively the surface and the bulk elemental compositions of the samples. The coherent domain size (CDS) values of IrO_x phases within the catalyst particles were estimated to be ∼10, ∼ 19, and ∼ 54 Å for the three IrO_x samples. Surprisingly, the sample with a CDS of ∼19 Å turned out as the best OER electrocatalyst among the three in terms of mass-specific activity, I_OER(m), followed by the 10 and 54 Å species. The amount of surface native compound oxygen was found to be a key parameter for the interface electrochemical accessibility. The intrinsic OER activity, evaluated using area-specific activity, I_OER(a), suggests that the oxide with lattice disorder presenting a mixture of tetragonal and orthorhombic phases (70:20 w/w) is of superior intrinsic OER activity; however, the oxide with the presence of a monoclinic-like phase is of inferior intrinsic OER activity, which may also be due to the surface presence of Ir³⁺ along with Ir⁴⁺. The classic belief that the pure tetragonal phase is the best crystalline structure as the OER catalyst is challenged. Iridium oxides with disordered crystallinities may offer a class of highly active oxygen evolution electrocatalysts. The knowledge thus obtained should have a significant impact on the understanding, selection, and processing of IrO_x-based OER electrocatalysts.

Due to ample low-coordinated surface atoms, a distorted lattice endows thin-layered transition metal oxides with a flexible electronic structure, making them the ideal candidates for overall ammonia synthesis. This work proposes a novel and facile method for the controllable synthesis of thin-layered Co₃O₄ catalysts with graphene as a conductive matrix to further enhance the overall N₂ fixation performance. X-ray photoelectron spectroscopy (XPS) and synchrotron radiation X-ray absorption spectroscopy (XAS) demonstrate that the sandwiched Co₃O_4–x/GO catalysts enable exposure of more coordination unsaturated active sites, resulting in numerous oxygen vacancies. With a higher conductivity and distorted crystalline structure, excellent electrochemical NRR activity is realized with a NH₃ production rate of 5.19 mmol g^–1 h^–1 and a Faradaic efficiency of 10.68% at −0.4 V vs reversible hydrogen electrode (RHE). The density functional theory (DFT) calculation demonstrates that introducing oxygen vacancies in thin-layered cobalt oxides could result in an increased density of states (DOS) near the Fermi level, which would accelerate the NRR rate-determining step. Charge transfer could be accelerated through a weak Co 3d–N 2p σ hybrid bond with a lower energy level. No obvious performance decay could be found after six cycles. Furthermore, the sandwiched Co₃O_4–x/GO catalyst exhibits a low overpotential of 280 mV@10 mA cm^–2 and an outstanding durability for the anode OER, even better than those of the benchmark RuO₂. Such an inexpensive sandwiched transition metal oxide catalyst shows great potential in the field of overall N₂ fixation.