Oxygen Evolution Reaction Process Research Articles

Extraordinary Structural Reconstruction of Nanolaminated Ta2FeC MAX Phase for Enhanced Oxygen Evolution Performance.

Renewable energy technologies, such as water splitting, heavily depend on the oxygen evolution reaction (OER). Nanolaminated ternary compounds, referred to as MAX phases, show great promise for creating efficient electrocatalysts for OER. However, their limited intrinsic oxidative resistance hinders the utilization of conductivity in Mn+1Xn layers, leading to reduced activity. In this study, a method is proposed to improve the poor inoxidizability of MAX phases by carefully adjusting the elemental composition between Mn+1Xn layers and single-atom-thick A layers. The resulting Ta2FeC catalyst demonstrates superior performance compared to conventional Fe/C-based catalysts with a remarkable record-low overpotential of 247mV (@10mA cm-2) and sustained activity for over 240h. Notably, during OER processing, the single-atom-thick Fe layer undergoes self-reconstruction and enrichment from the interior of the Ta2FeC MAX phase toward its surface, forming a Ta2FeC@Ta2C@FeOOH heterostructure. Through density functional theory (DFT) calculations, this study has found that the incorporation of Ta2FeC@Ta2C not only enhances the conductivity of FeOOH but also reduces the covalency of Fe─O bonds, thus alleviating the oxidation of Fe3+ and O2-. This implies that the Ta2FeC@Ta2C@FeOOH heterostructure experiences less lattice oxygen loss during the OER process compared to pure FeOOH, leading to significantly improved stability. These results highlight promising avenues for further exploration of MAX phases by strategically engineering M- and A-site engineering through multi-metal substitution, to develop M2AX@M2X@AOOH-based catalysts for oxygen evolution.

Vertically aligned ReS2 on MOF deorived CoS2–C hybrid as core-shell catalyst for promoting overall water splitting

The rational design of a core-shell structured electrocatalyst is important to improve the efficiency of electrocatalytic hydrogen production through water splitting. Herein, the catalyst is composed of rhenium disulfides (ReS2) vertically grown on cobalt sulfides/carbon hybrid by hydrothermal and activation treatment (CoS2–C@ReS2/CFP). The core-shell structure is constructed by sulfurizing the cobalt-based metal-organic framework, preventing the restacking of the ReS2 nanosheet, exposing more active sites, and facilitate electrolyte ion diffusion. Moreover, the CoS2–C@ReS2/CFP catalyst shows exceptional performance during the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) process in an alkaline electrolyte. At ·10 mA cm−2, the overpotentials of the CoS2–C@ReS2/CFP catalyst are 85 and 257 mV during the HER and OER processes with the small Tafel slope, low charge transfer resistance and exceptional catalytic stability. The combination of the CoS2 core and ReS2 shell is designed to adjust the adsorption energy of water molecules, promoting water dissociation, and enhancing the catalytic activity of CoS2–C@ReS2/CFP catalyst. This work provides an efficient strategy for developing the core-shell structured catalysts, potentially advancing the practical application into water splitting for hydrogen production.

In-situ activation of three-dimensional porous NiFe alloy: Synergistic NiFe hydroxide/alloy as composite active sites for efficiently catalyzing alkaline water splitting

The strategic engineering of bifunctional catalysts for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline media is critical for water-splitting technologies. This study presented a catalyst consisting of in situ grown nickel iron (NiFe) hydroxide/porous alloy composite catalytic sites on a nickel foam (NF) substrate. Initially, a porous NiFe alloy was electrodeposited onto NF, employing hydrogen (H2) bubbles as dynamic templates to induce a three-dimensional (3D) architecture. Subsequently, ultrathin layers of NiFe hydroxide nanosheets were synthesized in situ via electrochemical activation. The distinctive porous structure, coupled with the in-situ activated nanosheets, augmented the exposure of active sites, optimized electrolyte interaction, and expedited the expulsion of gaseous byproducts, collectively enhancing the kinetics of water electrolysis. The resultant a-Ni2Fe/NF demonstrated superior OER/HER activities, achieving overpotentials of merely 240mV for OER and 183mV for HER at a current density of 100mAcm-2 in alkaline solution. Moreover, a voltage of just 1.53V was requisite to attain a current density of 10mAcm-2 for overall water splitting. Operando Raman spectroscopy revealed the formation of NiOOH and FeOOH active phases during HER, indicating the hydroxide’s role in adsorbing hydroxyl groups and shielding NiFe alloy’s H⁎ adsorption sites from oxidation. The presence of the more reactive β-NiOOH phase was discerned during OER process, acting as an intermediate. This straightforward yet efficacious strategy heralded a new paradigm in the design of NiFe-based bifunctional catalysts, significantly bolstering the efficiency of water electrolysis catalysis.

Interface Engineering of Mo‐doped Ni2P/FexP‐V Multiheterostructure for Efficient Dual‐pH Hydrogen Evolution and Overall Water Splitting

AbstractDeveloping highly effective transition metal‐based bifunctional electrocatalysts remains a tremendously challenging task for large‐scale overall water splitting. Herein, a multiheterostructured Mo‐doped Ni2P/FexP electrocatalyst on NiFe foam with P vacancy (denoted as Mo─Ni2P/FexP‐V/NFF) is developed to serve as an efficient dual‐pH electrocatalyst. Due to the synergistic effect of multiple strategies (heteroatom doping, heterointerface, and P vacancy), the Mo─Ni2P/FexP‐V/NFF possesses remarkable hydrogen evolution reaction (HER) catalytic activity in alkaline/acidic and excellent oxygen evolution reaction (OER) in alkaline media, along with encouraging durability. The mechanisms of improved electrocatalytic activity combining multicharacterizations and density functional theory (DFT) calculations are elucidated. Specifically, X‐ray absorption fine structure experimental analysis confirms that the Mo doping can optimize the electronic structure of electrocatalyst. In situ Raman spectroscopy demonstrates that the evolved oxyhydroxides are the real active substances for the OER. DFT calculations reveal that the conductivity of as‐prepared samples can be enhanced through multiple strategy synergy. Moreover, in the HER process, multiple strategies can not only reduce the hydrogen binding energy to near zero but also enhance the H2O dissociation and *OH desorption. In the OER process, DFT calculations also verify that Mo doping and interface engineering can optimize the adsorption of the rate‐determining step, achieving the lowest theoretical overpotential.

Phosphorus Defect Mediated Electron Redistribution to Boost Anion Exchange Membrane‐Based Alkaline Seawater Electrolysis

AbstractIt is of essential importance to design bifunctional electrocatalysts with excellent performance for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in seawater splitting. Herein, an approach for manipulating electron redistribution in NiCoP treated by P defect (Pv) engineering (NiCoPv@NF) is presented, exhibiting excellent catalytic activities and stability toward HER/OER in alkaline seawater solution. The Pv reduces the surface electrooxidation reconfiguration energy barrier, making it easier to drive the local conversion of crystals to active oxy(hydroxide) in OER. In addition, the Ni site of NiCoPv and the Co site of NiCoOOH are the active sites for HER and OER processes, respectively. In situ generated PO43− adsorbed on the catalyst surface causes spatial repulsion, preventing Cl− corrosion in seawater electrolysis. The seawater AEM electrolyzer using NiCoPv@NF couple achieves excellent performance of high activity (2.43 V at 500 mA cm−2) and long‐term durability (500 mA cm−2 over 110 h). The working efficiency of AEM in 1.0 M KOH is as high as 77.0% at 100 mA cm−2 with the price of per GGE H2 as low as $ 0.87.

Bridging OER Electrocatalysis and Tumor Therapy: Utilizing Piezoelectric‐Hole‐Induced OER Electrocatalysis for Direct Oxygen Generation to Address Hypoxia

AbstractIn addressing the challenge of hypoxia within the tumor microenvironment (TME), a significant obstacle to effective cancer therapy, this research introduces a pioneering nanozyme engineered to utilize water and oxygen as reactants. Utilizing ultrasonic piezoelectricity, this nanozyme converts these substrates into oxygen (O2) and reactive oxygen species, thereby amplifying oxidative stress without relying on endogenous H2O2. This approach involves the strategic engineering of porous ZnSnOv:Mn nanosheets (named MZSO NSs), which are distinguished by oxygen‐rich vacancies and enhanced piezoelectric properties. This breakthrough represents the initial attempt to merge catalytic activities akin to catalase (CAT) with the electrocatalytic oxygen evolution reaction (OER), confirmed through both enzymatic reactions and electrochemical voltammetric analysis. The predominant mechanism of ultrasound‐augmented oxygen generation in MZSO is identified as piezoelectric hole‐induced OER. Supporting theoretical analyses clarify the synergistic impact of oxygen vacancies and Mn doping on the dynamics of carriers and the OER process, leading to a notable increase in catalytic efficiency. These findings highlight the potential of piezoelectric‐enhanced OER electrocatalysts to alleviate hypoxia in the TME, providing novel insights into the development of piezoelectric acoustic sensitizers for the treatment of cancer.

Convenient construction of electrocatalysts via combustion-assisted corrosion engineering for efficient water oxidation

Developing an efficient strategy for the universal synthesis of electrocatalysts is crucial for advancing the industrialization of water splitting, yet it remains a significant challenge. In this study, we propose combustion-assisted corrosion engineering as a rapid method to fabricate electrocatalysts for the oxygen evolution reaction (OER) within seconds. By utilizing a three-dimensional framework composed of nickel foam and the unique structure of the active species, we enable swift electrolyte diffusion and gas release. Consequently, the optimized S–NiO/NF exhibits remarkable OER catalytic activity, requiring a low overpotential of 236 mV to achieve a current density of 50 mA cm−2 in 1.0 M KOH solution. Notably, the reconfiguration during the OER process leads to the formation of actual catalytic active species, enhancing the number of active centers and thereby improving the catalyst's performance. This research presents a versatile method for industrially fabricating non-noble metal self-supporting electrodes with high efficiency, offering a practical solution for energy conversion and storage.

Metal Doping Regulates Electrocatalysts Restructuring during Oxygen Evolution Reaction.

High-efficiency and low-cost catalysts for oxygen evolution reaction (OER) are critical for electrochemical water splitting to generate hydrogen, which is a clean fuel for sustainable energy conversion and storage. Among the emerging OER catalysts, transition metal dichalcogenides have exhibited superior activity compared to commercial standards such as RuO2, but inferior stability due to uncontrolled restructuring with OER. In this study, we create bimetallic sulfide catalysts by adapting the atomic ratio of Ni and Co in CoxNi1-xSy electrocatalysts to investigate the intricate restructuring processes. Surface-sensitive X-ray photoelectron spectroscopy and bulk-sensitive X-ray absorption spectroscopy confirmed the favorable restructuring of transition metal sulfide material following OER processes. Our results indicate that a small amount of Ni substitution can reshape the Co local electronic structure, which regulates the restructuring process to optimize the balance between OER activity and stability. This work represents a significant advancement in the development of efficient and noble metal-free OER electrocatalysts through a doping-regulated restructuring approach.

Substantial Electrocatalytic Oxygen Evolution Performances of Activated Carbon-Decorated Vanadium Pentoxide Nanocomposites

Developing the ecofriendly and high-fidelity electrocatalysts for the oxygen evolution reaction (OER) is essential to foster effective production of environmentally friendly hydrogen. Herein, we fabricated the highly efficient OER electrocatalysts of the activated carbon-decorated vanadium pentoxide (AC-V2O5) nanocomposites using a facile hydrothermal technique. The AC-V2O5 nanocomposites displayed an aggregated structure of the AC nano-sheet-anchored orthorhombic V2O5 nanorods. When performing the OER process in an alkaline electrolyte at 10 mA/cm2, AC-V2O5 exhibited the low overpotential (~230 mV), small Tafel slope (~54 mV/dec), and excellent stability. These substantial OER performances of AC-V2O5 could be ascribed to the synergistic effects from both the electrochemically active V2O5 nanorods and the highly conductive AC nanosheets. The results infer that the AC-V2O5 nanocomposites possess a substantial aptitude as a high-performance OER electrocatalyst for production of the future green energy source—hydrogen.

Efficient and stable neutral seawater splitting achieved via strong-proton-adsorption in Pd-O-Co collaborative coordination

Direct electrolysis of pH-neutral seawater for hydrogen generation is a promising method for storing renewable energy. However, the oxygen evolution reaction (OER) faces a selectivity challenge, competing with chlorine evolution and confronting severe corrosion issues of the electrode. Here, we have synthesized ultrathin, polycrystalline, porous Co3O4 nanosheets with Pd single atoms (PdSA-Co3O4) for efficient and stable pH-neutral seawater decomposition. The octahedral Pd-O-Co active unit, generated by the synergistic coordination of the Pd single atom strong proton adsorption (SPA) material with Co3O4 nanosheets, resulted in PdSA-Co3O4 have activities 3, 5, and 31 times higher than Co3O4, IrO2, and commercial Co3O4, respectively. It also remained stable in pH-neutral seawater for 80 h. Operando in situ Raman spectroscopy combined with density functional theory calculations showed that synergistic interactions between the strong proton adsorption of Pd single atoms and the active site Co enhanced the adsorption of intermediates and significantly reduced the free energy of adsorption at the rate-determining step (O*→OOH*). The Pd-O-Co active units inhibited the transformation of the dynamic structure of the Co3O4 substrate and reduced the corrosive effect of Cl ions during the OER process.

Development of BaMnO3 nanoparticles embedded on rGO nanosheets via facile hydrothermal route to improve water oxidation

In light of environmental problems such as the depletion of hydrocarbon resources and global warming, the use of environment-friendly power production has become crucial nowadays. Hydrogen can serve as a globally friendly energy source because the byproduct of hydrogen combustion is only water. By a hydrothermal approach, we synthesized barium manganese oxide (BaMnO3) embedded on reduced graphene oxide (rGO) as a competent electrocatalyst for OER. We utilized X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive x-rays (EDX), Brunauer Emmette Teller (BET) and Raman to determine the crystal structure, morphology, elemental composition, surface area and lattice phenomena of the fabricated rGO/BaMnO3 nanocomposite. The BaMnO3 agglomerated nanoparticles were incorporated into the mesoporous hollow carbon nanosheets to form amorphous textured embedded rGO/BaMnO3. This enhanced the intrinsic reactivity of rGO/BaMnO3 nanocomposite for the oxygen evolution reaction (OER) in addition to increasing the effective surface area of the electrolyte. The electrochemical outcomes demonstrate that synthesized nanocomposite exhibited an impressive Tafel slope (36 mV dec−1), lowest overpotential (202 mV) and remarkable stability over 35 h. Therefore, the fabricated nanocomposite displayed exceptional efficiency in OER process as well as for numerous other future applications.

Fine-tuning nanoflower-like Fe/Co hybrids with high content oxyhydroxide accelerating oxygen evolution kinetics

Iron hydroxide (FeOOH) is a potential active component in iron-based electrocatalysts for water electrolysis. However, its catalytic performance is constrained by its slow oxygen evolution reaction (OER) kinetics. Herein, we synthesized a nanoflower-like FeCo-hydro(oxy)oxides composite with tunable Fe/Co ratios (Fex-Coy) on nickel foam (NF) via a one-step electrodeposition technique. This method allows for precise control over the morphology and composition of the hybrid nanoflowers. The optimized Fe9-Co1 discloses favorable OER performance with a low overpotential of 222 mV at 50 mA cm−2 and demonstrates good stability exceeding 60 h at 10 mA cm−2. Further, an assembled Fe9-Co1(+) || Pt/C(−) dual-electrode configuration achieves a low cell voltage of 1.73 V at the current density of 100 mA cm−2 for water splitting, with long-term stability for 70 h and minimal degradation. Studies indicate that the distinctive nanoflower morphology of Fe9-Co1 enhances active site exposure, while both FeOOH and reconstructed CoOOH serve as catalytic centers, contributing to the observed OER performance. This work introduces a facile approach for synthesizing OER electrocatalysts, underscoring the role of the high-valence state of Fe/Co as active sites in the OER process.

Ce-4f as an electron-modulation reservoir weakening Fe-O bond to induce iron vacancies in CeFevNi hydroxide for enhancing oxygen evolution reaction

Designing novel rare-earth-transition metal composites is at the forefront of electrocatalyst research. However, the modulation of transition metal electronic structures by rare earths to induce vacancy defects and enhance electrochemical performance has rarely been reported. In this study, we systematically investigate the mechanism by which Ce-4f electron modulation weakens the Fe-O bond, thereby altering the electronic structure in CeFevNi hydroxide to improve oxygen evolution reaction (OER) performance. Theoretical calculations and experimental characterizations reveal that Ce-4f orbitals function as electron-modulation reservoirs, capable not only of retaining or donating electrons but also of influencing the material's electronic structure. Moreover, Ce-4f bands optimize the Fe lower Hubbard bands (LHB) and O-2p bands, leading to weakened Fe-O bonds and the formation of cationic vacancies. This change results in the upshift of the d-band center at the active sites, favoring the reaction energy barrier for oxygen intermediates in the OER process. The synthesized catalyst demonstrated an overpotential of 201 mV at 10 mA cm−2 and a lifetime exceeding 200 h at 100 mA cm−2 under alkaline conditions. This work offers a proof-of-concept for the application of the mechanism of rare earth-induced transition metal vacancy defects, providing a general guideline for the design and development of novel highly efficient catalysts.

Boron modification promoting electrochemical surface reconstruction of NiFe-LDH for efficient and stable freshwater/seawater oxidation catalysis

Transition metal-based electrocatalysts generally take place surface reconstruction in alkaline conditions, but little is known about how to improve the reconstruction to a highly active oxyhydroxide surface for an efficient and stable oxygen evolution reaction (OER). Herein, we develop a strategy to accelerate surface reconstruction by combining boron modification and cyclic voltammetry (CV) activation. Density functional theory calculations and in-situ/ex-situ characterizations indicate that both B-doping and electrochemical activation can reduce the energy barrier and contribute to the surface evolution into highly active oxyhydroxides. The formed oxyhydroxide active phase can tune the electronic configuration and boost the OER process. The reconstructed catalyst of CV-B-NiFe-LDH displays excellent alkaline OER performance in freshwater, simulated seawater, and natural seawater with low overpotentials at 100 mA cm−2 (η100: 219, 236, and 255 mV, respectively) and good durability. This catalyst also presents outstanding Cl− corrosion resistance in alkalized seawater electrolytes. The CV-B-NiFe-LDH||Pt/C electrolyzer reveals prominent performance for alkalized freshwater/seawater splitting. This study provides a guideline for developing advanced OER electrocatalysts by promoting surface reconstruction.

Synergy of Cu doping and SO42− adsorption in the self-optimized SO42−@Cu doped Co(OH)2 reconstructed from CuCo2S4 towards enhanced oxygen evolution reaction

Catalysts in-situ reconstructed from transition metal sulfides for oxygen evolution reaction (OER) have been regarded as potential alternatives for the noble metal catalysts. Intriguingly, it was found that the self-optimized SO42−@Cu doped Co(OH)2 catalyst was reconstructed from bimetallic sulfide of CuCo2S4. During the OER process, the copper was partially leached and meantime doped into the in-situ generated Co(OH)2 with SO42− adsorption, while only oxides were discovered in counterparts of mono-metal sulfides. As a result, the SO42−@Cu doped Co(OH)2 catalyst exhibited superior OER performances, with low overpotentials of 211/272 mV to achieve the current densities of 10/100 mA cm−2, exceeding the counterparts reconstructed from mono-metal sulfides. Experimental and theoretical results suggested that the in situ generated Cu doped Co(OH)2 possessed thin and loosely layered structure with expanded lattice spacing (lattice spacing expanded from 0.28 nm to 0.46 nm) due to the SO42− adsorption, making the intermediates more accessible to the active centers. In addition, the catalyst surface changed from hydrophobicity to super hydrophilicity, which greatly accelerated the mass transfer. This work indicated that the in-situ reconstruction process was greatly influenced by the interactions between metal sites and sulfide species, directly influencing the OER performances of the reconstructed catalysts.

Grain‐Boundary‐Rich RuO2 Porous Nanosheet for Efficient and Stable Acidic Water Oxidation

RuO2 has been considered as the most likely acidic oxygen evolution reaction (OER) catalyst to replace IrO2, but its performance, especially long‐term stability under harsh acidic conditions, is still unacceptable. Here, we propose a grain boundary (GB) engineering strategy by fabricating the ultrathin porous RuO2 nanosheet with abundant of grain boundaries (GB‐RuO2) as an efficient acid OER catalyst. The involvement of GB induces significant tensile stress and creates an unsaturated coordination environment, effectively optimizing the adsorption of intermediates and stabilizing active site structure during OER process. Notably, the GB‐RuO2 not only exhibits a low overpotential (η10= 187 mV) with an ultra‐low Tafel slope (34.5 mV dec‐1), but also steadily operates for over 550 h in 0.1 M HClO4. Quasi in situ/operando methods confirm that the improved stability is attributed to GB preventing Ru dissolution and greatly inhibiting the lattice oxygen oxidation mechanism (LOM). A proton exchange membrane water electrolysis (PEMWE) using the GB‐RuO2 catalyst operates a low voltage of 1.669 V at 2 A cm‐2 and operates stably for 100 h at 100 mA cm‐2.

Co-doped NiFe carbonate hydroxide hydrate nanosheets with edge effect constructed from spent lithium-ion battery ternary cathodes for oxygen evolution reaction

The recycling of spent lithium-ion batteries (LIBs) has received increasing attention for environment and resource reclamation. Converting LIBs wastes into high-efficiency catalysts is a win-win strategy for realizing resource reclamation and addressing sustainable energy challenges. Herein, we developed a simple method to upcycle spent-LIBs cathode powder into Co-doped NiFe carbonate hydroxide hydrate (Co/NFCH-FF) as a low-cost and efficient oxygen evolution reaction (OER) electrocatalyst. The optimized Co/NFCH-FF electrode appears very competitive OER performances with low overpotentials of 201 and 249 mV at 10 and 100 mA cm−2, respectively, a small Tafel slope of 48.4 mV dec−1, and a high long-term stability. Moreover, we reveal that the existence of Co atoms leads to the formation of a crystalline/amorphous (c/a) interface at the Co/NFCH nanosheet edge, inducing the nanosheets possess a unique edge effect to enhance electric fields and accumulate hydroxide ions (OH–) at the edge during the OER process. Benefiting from edge effect, Co/NFCH-FF shows outstanding intrinsic activity. Furthermore, Co atoms as dopants stabilize the electronic structure of Co/NFCH-FF, enabling Co/NFCH-FF to exhibit excellent catalytic stability. This work provides an effective strategy for converting the end-life LIBs to high-performance multicomponent OER electrocatalysts and proposes new insights into the mechanism of enhanced catalytic activity of Co/NFCH.

Grain-Boundary-Rich RuO2 Porous Nanosheet for Efficient and Stable Acidic Water Oxidation.

RuO2 has been considered as the most likely acidic oxygen evolution reaction (OER) catalyst to replace IrO2, but its performance, especially long-term stability under harsh acidic conditions, is still unacceptable. Here, we propose a grain boundary (GB) engineering strategy by fabricating the ultrathin porous RuO2 nanosheet with abundant of grain boundaries (GB-RuO2) as an efficient acid OER catalyst. The involvement of GB induces significant tensile stress and creates an unsaturated coordination environment, effectively optimizing the adsorption of intermediates and stabilizing active site structure during OER process. Notably, the GB-RuO2 not only exhibits a low overpotential (η10= 187 mV) with an ultra-low Tafel slope (34.5 mV dec-1), but also steadily operates for over 550 h in 0.1 M HClO4. Quasi in situ/operando methods confirm that the improved stability is attributed to GB preventing Ru dissolution and greatly inhibiting the lattice oxygen oxidation mechanism (LOM). A proton exchange membrane water electrolysis (PEMWE) using the GB-RuO2 catalyst operates a low voltage of 1.669 V at 2 A cm-2 and operates stably for 100 h at 100 mA cm-2.

Tracking the role of compressive strain in bowl-Like Co-MOFs structural evolution in water oxidation reaction

Dynamic structural evolution of catalyst active sites is crucial to for transition metal-catalyzed oxygen evolution reaction (OER). Yet, the elucidation of their mechanism behind the compressive-strain-induced reconstruction during OER process remains enigmatic. Here, we construct a bowl-like cobalt-based metal-organic frameworks (BL-Co-MOFs) catalyst with compressive strain to investigate the effect of strain on the structural evolution process and the OER mechanism. In situ techniques directly observe that compressive strain exists in the reconstruction of the potential-driven CoOOH-like active phase with contractile interatomic CoCo distance, promoting a direct OO radical coupling over the Co sites (Co−O−O−Co) during the OER process. This disrupts the constrains of the inherent linear scaling relationship and achieves the kinetic-faster oxide path mechanism (OPM) during OER process. Consequently, the BL-Co-MOFs exhibit a huge mass activity of 12516 A gmetal−1 and a large turnover frequency of 6888 h−1 at a low overpotential of 275 mV (300 mA cm−2).

Molybdenum sulfide/Ni:FeOOH heterostructures as efficient water oxidation electrocatalysts in alkaline media

Sluggish oxygen evolution reaction (OER) is considered to be the bottleneck that restricts the usage of electrocatalytic water splitting to generate hydrogen. With this in mind, we demonstrate the design and preparation of a series of Mo15S19/Ni:FeOOH heterostructures toward water oxidation. As expected, the considerable acceleration of OER process is achieved by the combination of Mo15S19 with Ni:FeOOH, due to the formation of heterojunction. Under the optimized conditions, the as-prepared Mo15S19/Ni:FeOOH-21 exhibits a lower overpotential (214 mV vs RHE at 10 mA cm−2) than other control samples. The OER activity of Mo15S19/Ni:FeOOH-21 is found to be comparable to and/or better than the state-of-the-art OER electrocatalysts reported in the literature recently, making it a promising OER electrocatalyst in the industrial water electrolysis. This work opens up an efficient avenue to rational design of other high-performance composite OER electrocatalysts.