Enhanced Oxygen Evolution Reaction Performance Research Articles

A Bifunctional Electrocatalyst of Flower-Like Cr-Doped CoP/Fe2P Microsphere for Efficient Overall Water Splitting

Abstract Developing efficient, low-price non-noble metal-based electrocatalysts for overall water splitting in alkaline medium remains a formidable challenge. In our work, Cr-doped CoP/Fe2P (Cr-CoP/Fe2P) flower-like microsphere was synthesized through a simple hydrothermal and phosphating process. The resulting Cr-CoP/Fe2P electrocatalyst shows significantly enhanced oxygen evolution reaction performance (262 mV @ 10 mA cm-2) and has a satisfactory hydrogen evolution reaction performance (114 mV @ 10 mA cm-2), coupled with favorable stability in an alkaline medium. Furthermore, when assembling Cr-CoP/Fe2P into an electrolytic cell, the two-electrode system can provide a current density of 10 mA cm-2 at a voltage of 1.61 V. At high current density, the performance of the electrolytic cell composed of Cr-CoP/Fe2P is superior to that of noble metal catalyst electrode pair. Electronic structure analysis and various characterizations confirm that Cr doping and the formation of CoP/Fe2P heterogeneous interfaces redistribute the electron densities of the active sites, enlarge the specific surface area, and enhance the aerophobicity of the catalysts, thereby improving the electrocatalytic property. This work provides a referable method for engineering highly efficient and stable non-noble polymetallic phosphides, which serve as bifunctional electrocatalyst for overall water splitting.

Novel amorphous FeOOH-modified Co9S8 nanosheets with enhanced catalytic activity in oxygen evolution reaction

Efficient oxygen evolution reaction (OER) is vital for water electrolysis and advanced hydrogen energy production. However, the sluggish kinetics of this reaction require significant overpotentials, leading to high energy consumption. Therefore, developing OER electrocatalysts with exceptional performance and long-term durability is crucial for enhancing the energy efficiency and cost-effectiveness of the hydrogen production process. In this research, novel FeOOH/Co9S8 catalysts were prepared through a two-step hydrothermal reaction followed by one-step electrodeposition on nickel foam for an alkaline OER. The as-obtained catalysts possessed abundant non-homogeneous interfaces between FeOOH and Co9S8 nanosheets, conducive to optimized coordination environments of Fe and Co sites by redistributing interfacial charges. This synergy strengthened the chemisorption of oxygenated intermediates, leading to accelerated reaction kinetics, abundant active sites, and enhanced OER performance. The optimized electrocatalyst FeOOH/Co9S8-15 achieved a current density of 10 mA cm−2 at an overpotential of 248 mV and good stability for over 140 h. This study presents a novel approach for producing compelling and durable alkaline dielectric OER electrocatalysts, which will be helpful in the future manufacturing of advanced energy devices.

Iron-Nickel synergistic catalysis growth of (Fe,Ni)9S8/Ni3S2@N,S codoped carbon bridged nanowires enhanced oxygen evolution reaction performance

Iron-Nickel synergistic catalysis growth of (Fe,Ni)9S8/Ni3S2@N,S codoped carbon bridged nanowires enhanced oxygen evolution reaction performance

Tailoring hypervalent Nickel induced by oxygen vacancy toward enhanced oxygen evolution reaction performance in self-supporting NiFe-(oxy)hydroxides electrodes

NiFe-(oxy)hydroxides are the most active transition metal oxide electrocatalysts for oxygen evolution reaction (OER) under the alkaline media. Herein, we controllably manipulated oxygen vacancy (VO)-tunable NiFe-(oxy) hydroxides that their OER performances possessed a volcano-type relationship with VO concentration, positively-correlated with Ni3+/Ni2+ ratio. Theoretical simulations further unearthed the enhanced activation and dissociation of H2O by the inserting of VO. As a result, the optimal sample featuring the Ni3+/Ni2+ ratio of 30.3 % and VO of 23.8 % exhibited the overpotential of 243 mV at the current density of 100 mA cm–2, simultaneously lasting 120 h durability without any attenuation, exceding the most reported NiFe-(oxy)hydroxides. This work offers an innovative view to understand the OER performance using hypervalent Ni ratio induced by VO defects.

Rapid Construction of Double Crystalline Prussian Blue Analogue Hetero-Superstructure.

The controllable construction of complex metal-organic coordination polymers (CPs) merits untold scientific and technological potential, yet remains a grand challenge of one-step construction and modulating simultaneously valence states of metals and topological morphology. Here, a thiocyanuric acid (TCA)-triggered strategy is presented to one-step rapid synthesis a double-crystalline Prussian blue analogue hetero-superstructure (PBA-hs) that comprises a Co3[Fe(CN)6]2 cube overcoated with a KCo[Fe(CN)6] shell, followed by eight self-assembled small cubes on vertices. Unlike common directing surfactants, TCA not only acts as a trigger for the fast growth of KCo[Fe(CN)6] on the Co3[Fe(CN)6]2 phase resulting in a PBA-on-PBA hetero-superstructure, but also serves as a flange-like bridge between them. By combining experiments with simulations, a deprotonation-induced electron transfer (DIET) mechanism is proposed for formation of second phase in PBA-hs, differing from thermally and photo-induced electron transfer processes. To prove utility, the calcined PBA-hs exhibits enhanced oxygen evolution reaction performance. This work provides a new method to design of novel CPs for enriching chemistry and material science. This work offers a practical approach to design novel CPs for enriching chemistry and material science.

Unlocking the potential of Heusler alloy Ni2CuSn as an electro(pre)catalyst for enhanced oxygen evolution reaction performance

Unlocking the potential of Heusler alloy Ni2CuSn as an electro(pre)catalyst for enhanced oxygen evolution reaction performance

Customized structure engineering of MIL-53(Fe)/MoS2/NF for enhanced OER performance: Experiments and practical applications

Developing cost-effective and highly efficient catalysts to replace the expensive noble metal-based counterparts in the oxygen evolution reaction (OER) holds paramount importance for the advancement of hydrogen production. Herein, we synthesized a novel hybrid composite of MIL-53(Fe) and MoS2 using a hydrothermal method, subsequently depositing it onto commercially available nickel foam (NF), namely MIL-53(Fe)/MoS2/NF. The MIL-53(Fe)/MoS2/NF composite capitalizes on the synergies among these three components, facilitating efficient water electrolysis while remarkably curbing the OER overpotential (η10 = 238 mV, 1 M KOH), thereby enhancing electron transport efficiency. Remarkably, the OER overpotential remains consistently low even in the prepared 1 M KOH solution using seawater (η10 = 289 mV) and sewage (η10 = 301 mV). Moreover, MIL-53(Fe)/MoS2/NF exhibits enduring stability, maintaining its efficacy even after 50 h at around 50 mA/cm2 in simulated solutions, sewage, and seawater. In an electrolytic cell utilizing MIL-53(Fe)/MoS2/NF as the anode, stable gas production is achieved under 1 M KOH conditions and solar cell voltages of 1.62 V and 1.85 V. This investigation marks a pivotal advancement in forging highly efficient and economically viable OER catalysts, holding substantial implications for advancing energy conversion methodologies, thereby ushering in escalated efficiency and diminished costs.

Supramolecular Macrocycle Regulated Single‐Atom MoS2@Co Catalysts for Enhanced Oxygen Evolution Reaction

The development of active water oxidation catalysts for water splitting has stimulated considerable interest. Herein, the design and building of single atom Co sites using a supramolecular tailoring strategy are reported, that is, the introduction of pillar[4]arene[1]quinone (P4A1Q) permits mononuclear Co species stereoelectronically assembled on MoS2 matrix to construct an atomically dispersed MoS2@Co catalyst with modulated local electronic structure, definite chemical environment and enhanced oxygen evolution reaction performance. Theoretical calculations indicate that immsobilized single‐Co sites exhibit an optimized adsorption capability of oxygen‐containing intermediates, endowing the catalyst an excellent electrocatalytic oxygen evolution reaction activity, with a low overpotential of 370 mV at 10 mA cm−2 and a small Tafel slope of 90 mV dec−1. The extendable potential of this strategy to other electrocatalysts such as MoS2@Ni and MoS2@Zn, and other applications such as the hydrogen evolution reaction was also demonstrated. This study affords new insights into the rational design of single metal atom systems with enhanced electrocatalytic performance.

Pre-implanting metal oxides to endow the N-doped carbon with boosted bifunctional catalytic activities towards oxygen reduction and oxygen evolution reactions

Nitrogen-doped carbon-based materials exhibit promising prospect as the catalysts to oxygen reduction reaction (ORR). Incorporating transition metal oxides with the catalysts can endow them with oxygen evolution reaction (OER) activity to construct bifunctional catalysts for rechargeable zinc-air batteries. In this work, a catalyst (named as 300NiFe-Mi-C) was prepared by a metal oxide-implanting strategy. The mixed metal salts of Ni and Fe were first heated to produce metal oxides, and then blended with 2-methylimidazole and carbon black, and subsequently pyrolyzed at a high temperature. In the pyrolysis, a part of metal oxides was reduced to metallic state to facilitate the doping of nitrogen atoms into carbon to form the ORR active sites while a part of metal oxides was retained to afford OER activity. Benefiting from the pre-implanting strategy of metal oxides, the resultant 300NiFe-Mi-C presents enhanced OER performance with 1.56 V of OER potential at 10 mA cm−2, outperforming the 1.68 V of the controlled sample NiFe-Mi-C (without pre-implanting) and 1.70 V of RuO2. The 0.83 V of ORR half-wave potential of 300NiFe-Mi-C is also comparable to the 0.82 V of NiFe-Mi-C and 0.86 V of Pt/C, revealing satisfactory bifunctional catalytic activities. The rechargeable zinc-air battery equipped with 300NiFe-Mi-C can stably operate at ∼1.25 V with 10 mA cm−2, being higher than ∼1.21 V of Pt/C+RuO2. The battery also presents outstanding durability and rechargeability, demonstrating the bifunctional activities of 300NiFe-Mi-C can be realized in practical applications.

Engineered oxidation states in NiCo2O4@CeO2 nanourchin architectures with abundant oxygen vacancies for enhanced oxygen evolution reaction performance

Sluggish oxygen evolution reaction (OER) as the half reaction of water electrolysis hindered the production of clean hydrogen, necessitates a cost-effective electrocatalyst. Spinel nickel cobaltite (NiCo2O4), characterized by its lower cost, flexibility in oxidation states of cations, and stable spinel structure, holds promise as an OER electrocatalyst. However, there is still room for improvement in terms of its intrinsic electrochemical activity, conductivity, and active surface area. Inspired by the flexible valence states of Ni and Co, in this study, CeO2 was introduced into NiCo2O4 for further electronic structure adjustment. The result was the synthesis of an urchin-like NiCo2O4@CeO2 (NCOC), and the elucidation of its formation mechanisms, expressed conclusively through reaction formulas. NCOC, characterized by an open architecture and a rough surface, ensures rapid mass transportation and charge diffusion. Within NCOC, numerous oxophilic Ce3+ sites with oxygen vacancies construct electron transport pathways, accelerating charge-transfer. This simultaneously induces an increase in the oxidation states and proportions of Ni3+ and Co3+ in NCOC, reinforcing the covalence of Ni–O and Co–O bonds, expediting the ad/desorption of intermediates during OER. The electronic structure variations of NCOC were further verified through density functional theory (DFT) analyses, revealing alterations in adsorption configurations of intermediates and a decrease in adsorption free energies for intermediates on NCOC during OER. In practical terms, NCOC demonstrated a low overpotential of 228 mV at a current density of 10 mA cm−2 under 1 M KOH, maintaining long-term electrochemical stability for 100 h. Overall, this study provides a universal approach for designing highly cost-efficient electrocatalysts for OER.

Ce Single-Atom Incorporation Enhances the Oxygen Evolution Reaction of Co3O4 in Acid.

Oxygen evolution reaction (OER) plays an important role in energy conversion processes such as water electrolysis and metal-air batteries. At present, finding a high-performance and low-cost catalyst for the OER in acidic media remains a great challenge. It is therefore important to develop efficient, robust, and inexpensive electrocatalysts by replacing noble metal-based catalysts with transition-metal electrocatalysts. Herein, we propose a facile method for incorporating Ce-metal single atoms into Co3O4 nanosheets to boost their OER activity and stability. Owing to the enhanced charge transfer and improved electronic structure resulting from Ce incorporation, the obtained Ce single-atom-doped Co3O4 nanosheet exhibits greatly enhanced OER performance. It achieves a 10 mA cm-2 current density under a low overpotential of 348 mV in a 0.5 M H2SO4 solution with excellent stability, outperforming the state-of-the-art non-noble electrocatalysts recently reported in acid.

(General Student Poster Award Winner, 2nd Place) Enhanced Oxygen Evolution Reaction Performance through Alkaline-Earth Metal Doped Fe-Rich Nano Dry-Petals: A Cost-Effective and Eco-Friendly Electrocatalyst Approach

The progress towards hydrogen production via electrolysis technologies rely on the advancement of economical, abundant, non-toxic, stable, and efficient non-precious metal catalysts for oxygen evolution reactions (OER). As the second most abundant metal on Earth, iron (Fe) offers a cost-effective alternative to more expensive OER catalysts derived from ruthenium (Ru), iridium (Ir), cobalt (Co) and nickel (Ni). However, Fe-based catalysts typically display limited OER activity. Here we present a unique strategy of introducing an alkaline-earth metal into Fe-rich crystal for the enhanced OER activity in alkaline condition. To achieve this, a facile method was developed to obtain a nano dry-petals structured M-FeOOH electrocatalyst. The optimized M-FeOOH electrocatalyst exhibits an impressively low overpotential of +259 mV at a current density of 10 mA cm-2 in 1.0 M KOH which was found to be superior to the pristine FeOOH electrode. Through a series of experiments and density functional theory (DFT) calculations, we reveal that the addition of an alkaline-earth metal to FeOOH as a dopant optimizes the electronic structure and free energy for adsorbed intermediates synergistically. As a result, the OER activity of the M-FeOOH electrocatalyst is significantly improved. Our results highlight the possibility of doping FeOOH OER catalysts using an affordable and eco-friendly approach, setting the stage for the development of advanced OER electrocatalysts.

Oxygen Evolution Reaction Performance Changes with Varying Crystallinity and Thickness of Atomic Layer Deposited RuO2 Film

As the world's population grows and the energy consumption has increased, the use of fossil fuels is gradually increasing. The carbon dioxide emitted from burning fossil fuels is a major cause of greenhouse effect. Therefore, hydrogen is widely recommended as an energy source to alternate fossil fuels due to its high energy per mass, no production of pollutant. Among several ways to obtain hydrogen, electrolysis of water is considered the most promising method. However, the slow-rate determining step of the oxygen evolution reaction (OER) compared to hydrogen evolution reaction (HER) is a main reason for interrupting wide use of electrolysis of water in the industry. So, there have been various research for enhancing the effectiveness of water electrolysis.The development of OER electrocatalysts is needed for promote the efficiency of OER process, noble metals-based materials has been researched due to its superior activity. Among noble metals, RuO2 has been researched as promising catalyst for oxygen evolution, and the efficiency of the catalyst varies on the preparation technique (e.g., sputtering, hydrothermal methods and sol-gel). Therefore, there have been diverse studies to enhance the RuO2 electrocatalytic effectiveness of oxygen evolution via crystallinity control, increase of electrochemically active surface area by adjusting synthesizing method of RuO2 film.Atomic Layer Deposition (ALD) has strengths of large-area uniformity, excellent conformality, and being able to control the thickness of the film at the atomic scale. ALD is suitable technique to deposit catalysts materials conformably on 3D nano-structured complex materials, so the catalytic activity in the OER can be improved by increasing the surface-to-volume ratio. Therefore, ALD is assumed as a suitable synthesizing method for electrocatalyst. Besides, ALD allows low mass loading of catalyst material which is most needed factor in the industrial area. However, there have no enough research of ALD RuO2 for OER analyzing condition (crystallinity, thickness) for obtaining enhanced OER performance.In this report, RuO2 film was prepared based on ALD on Carbon Fiber Paper (CFP) at different deposition temperature and it showed different crystallinity, one was amorphous, the other one was crystalline. The crystalline one showed better OER performance due to its enlarged active sites of OER. We analyzed their growth characteristics and material properties by using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), XRD spectrometer (XRD). And dependence of film thickness of ALD RuO2 films was also studied. Electrocatalytic properties of ALD RuO2 on CFP was measured in three-electrode. It showed low overpotential and Tafel slope, which shows electrocatalytic performances. Figure 1

Enhanced Oxygen Evolution Reaction Activity and Structural Stability of Sulfur and Manganese Substituted Co(OH)2

The search for efficient, cost-effective, and sustainable energy sources is a crucial challenge for the modern world.1, 2 In this regard, the development of effective electrocatalysts for water splitting, specifically the oxygen evolution reaction (OER), is a critical aspect of renewable energy technology.3, 4 In recent years, layered double hydroxides (LDHs) have emerged as promising materials for electrocatalysis due to their unique structural and electronic properties.5, 6 This study presents the synthesis and characterization of sulfur and manganese substituted Co(OH)2 as electrocatalysts for the oxygen evolution reaction (OER). The research employed a range of structural and physical characterization techniques, including XRD, EDX, SEM, TEM, and XPS to investigate the synthesized materials.The OER activity was measured via LSV curves in 1 M KOH solution which showed that the S-Mn-Co(OH)2 has significantly low over-potential of 250 and 275 mV for current densities of 10 and 50 mA cm-2 when compared with the Co(OH)2. Additionally, the S–Mn–Co(OH)2 catalyst demonstrated after a 15 hours treatment at 50 mA cm−2 and in 1 M KOH only an overpotential increase of 34 mV and thus excellent stability. High-resolution transmission electron microscopy (HRTEM) analysis confirmed sheet like structure, while the XPS analysis revealed an increase in electron density around the Co owing to the presence of Co2+ and Co3+ in the sample. PXRD and HRTEM analysis also showed a slight reduction in the interlayer gap, indicating further stabilization of the layered structure. Both, stabilized the layered structure and increased electron density around Co could be reason for the enhanced OER performance and be important insights into the role of cation and anion substitution for enhancing LDH OER catalysts. References S. Chu and A. Majumdar, nature, 2012, 488, 294-303.M. M. Rahman, I. Khan, D. L. Field, K. Techato and K. Alameh, Renewable Energy, 2022, 188, 731-749.Y. Feng, H. Yang, X. Wang, C. Hu, H. Jing and J. Cheng, International Journal of Hydrogen Energy, 2022.X. Liu, Y. Han, Y. Guo, X. Zhao, D. Pan, K. Li and Z. Wen, Advanced Energy and Sustainability Research, 2022, 3, 2200005.P. Shandilya, R. Sharma, R. K. Arya, A. Kumar, D.-V. N. Vo and G. Sharma, International Journal of Hydrogen Energy, 2022, 47, 37438-37475.A. Hameed, M. Batool, Z. Liu, M. A. Nadeem and R. Jin, ACS Energy Letters, 2022, 7, 3311-3328.

Identification of in situ Generated Iron‐Vacancy Induced Oxygen Evolution Reaction Kinetics on Cobalt Iron Oxyhydroxide†

Comprehensive SummaryDeveloping highly efficient and low‐cost electrocatalysts towards oxygen evolution reaction (OER) is essential for practical application in water electrolyzers and rechargeable metal‐air batteries. Although Fe‐based oxyhydroxides are regarded as state‐of‐the‐art non‐noble OER electrocatalysts, the origin of performance enhancement derived from Fe doping remains a hot topic of considerable discussion. Herein, we demonstrate that in situ generated Fe vacancies in the pristine CoFeOOH catalyst through a pre‐conversion process during alkaline OER result from dynamic Fe dissolution, identifying the origin of Fe‐vacancy‐induced enhanced OER kinetics. Density functional theory (DFT) calculations and experimental results including X‐ray absorption fine‐structure spectroscopy, in situ UV‐Vis spectroscopy, and in situ Raman spectroscopy reveal that the Fe vacancies could significantly promote the d‐band center and valence states of adjacent Co sites, alter the active site from Fe atom to Co atom, accelerate the formation of high‐valent active Co4+ species, and reduce the energy barrier of the potential‐determining step, thereby contribute to the significantly enhanced OER performance.

Crystalline–amorphous Ni4.5Fe4.5S8/NiFeS heterostructure for alkaline water oxidation electrocatalysis

Electrochemical water splitting, hailed for its cost-effectiveness and eco-friendliness in hydrogen energy production, faces a significant impediment in the form of the oxygen evolution reaction (OER), characterized by inherently slow kinetics. Addressing this challenge, the utilization of crystalline-amorphous (c-a) heterostructures, offering precise interface modulation, emerges as a promising solution. In this study, we report the synthesis of a robust electrode comprising of crystalline Ni4.5Fe4.5S8 nanospheres integrated with amorphous NiFeS nanosheets (denoted as NiFeS-TH) using a hydrothermal approach. Remarkably, this electrode exhibits exceptional performance in alkaline electrolytes, requiring a mere overpotential of 420 mV to attain a current density of 2 A/cm2. This enhanced OER performance is attributed to the substantial electrochemically active surface area and the presence of compressive strain at the interfaces. These profound insights into heterostructure design hold the potential to revolutionize the tailoring and optimization of OER efficiency.

Nickel‐Based Single‐Molecule Catalysts with Synergistic Geometric Transition and Magnetic Field‐Assisted Spin Selection Outperform RuO2 for Oxygen Evolution

AbstractOvercoming slow kinetics and high overpotential in electrocatalytic oxygen evolution reaction (OER) requires innovative catalysts and approaches that transcend the scaling relationship between binding energies for intermediates and catalyst surfaces. Inorganic complexes provide unique, customizable geometries, which can help enhance their efficiencies. However, they are unstable and susceptible to chemical reaction under extreme pH conditions. Immobilizing complexes on substrates creates single‐molecule catalysts (SMCs) with functional similarities to single‐atom catalysts (SACs). Here, an efficient SMC, composed of dichloro(1,3‐bis(diphenylphosphino)propane) nickel [NiCl2dppp] anchored to a graphene acid (GA), is presented. This SMC surpasses ruthenium‐based OER benchmarks, exhibiting an ultra‐low onset and overpotential at 10 mAcm−2 when exposed to a static magnetic field. Comprehensive experimental and theoretical analyses imply that an interfacial charge transfer from the Ni center in NiCl2dppp to GA enhances the OER activity. Spectroscopic investigations reveal an in situ geometrical transformation of the complex and the formation of a paramagnetic Ni center, which under a magnetic field, enables spin‐selective electron transfer, resulting in enhanced OER performance. The results highlight the significance of in situ geometric transformations in SMCs and underline the potential of an external magnetic field to enhance OER performance at a single‐molecule level.

Highly mixed high-energy d-orbital states enhance oxygen evolution reactions in spinel catalysts

Design, synthesis, and engineering of electrocatalysts for the oxygen evolution reaction (OER) are essential for attaining desirable electrocatalytic performance towards practical implementation. Emerging spinel-type OER catalysts have not reached the desirable activity and durability, thus demanding critical research to advance the field. To achieve enhanced OER performance for spinel-type OER catalysts, we present an efficient strategy of electronic structure modulation of central metal atoms. Modulation of the electronic properties of the Zn and Co atoms through the counter anionic components (O, S, and Se) regulates the adsorption of oxygen intermediates and thus enhances OER activity, which is systematically demonstrated using Density Functional Theory (DFT) calculation. Although the zinc cobalt selenide catalyst showed the less pronounced trigonal distortion, the mixing of eg orbitals with selenium accounts for the experimentally observed enhancement in OER activity. The result is, in contrast to the benchmark catalyst made of RuO2, ZnCo2Se4@rGO demonstrated lower OER overpotential (η10 = 302 mV) and Tafel slope (58 mV dec−1) as well as greater durability at 10 mA cm−2 for 50 h. The implementation of this strategy in several spinel-type catalysts could improve their electrocatalytic performance.

Exsolution of Iron Nanoparticles from LCTFeO3 for Oxygen Evolution Reaction

Perovskite oxides (ABO3) with stable structures and flexible compositions are considered to be alternative catalysts for the oxygen evolution reaction (OER). With A-site deficiency in a perovskite, the doping metals in the B-site may be exsolved by calcination in a reduction atmosphere, which is a promising approach to increasing the activity of the catalyst. Here, an iron doped La(0.2+x)Ca(0.7-x)Ti(1-x)FexO3 (x = 0.05, 0.3, LCTFex) perovskite is successfully synthesized by a mild sol-gel method, and the iron nanoparticles anchored perovskite (R-LCTFex) can be fabricated after reduction under 5% H2/N2 atmosphere in a tubular furnace, which can be seen clearly in SEM and STEM images. Notably, the onset overpotential of R-LCTFe0.3 is reduced by 130 mV compared with LCTFe0.3 and the current density of R-LCTFe0.3 is 12-fold higher than LCTFe0.3 at the overpotential of 530 mV. The enhanced OER performance is triggered by the exsolution of Fe nanoparticles. This study establishes that exsolution of metal nanoparticles from a perovskite is a useful tactic for enhancing OER performance.

ZIF-8@ZIF-67 derived Fe–CoS2/CNT carbon polyhedron for enhanced electrocatalytic oxygen evolution reaction

In the pursuit of highly active electrocatalysts is crucial to overcome the sluggish kinetics of oxygen evolution reaction (OER). Herein, Fe–CoS2/carbon nanotubes anchored on carbon polyhedron (Fe–CoS2/CNT CPs) is prepared by using zeolitic imidazolate framework-8@zeolitic imidazolate framework-67 (ZIF-8@ZIF-67) as template. A series of analysis demonstrates the incorporation of Fe via wrapped Fe-EDTA can exert charge transfer between Co and Fe and optimize the adsorption of targeted intermediates, which favors for enhanced OER performance. Moreover, the catalytic effect of Co and Fe not only promotes the growth of carbon nanotubes but also enhances the degree of graphitization. The carbon skeletons embedded with carbon nanotubes derived from ZIF-8@ZIF-67 offer high specific surface area and strengthen the electrical conductivity of Fe–CoS2/CNT CPs. Therefore, compared with its counterpart and commercial RuO2, the designed Fe–CoS2/CNT CPs with regulated electronic structure displays the lowest overpotential of 293 mV at the current density of 10 mA cm−2 in 1.0 M KOH solution for OER. This work explores a facile strategy for manipulate electronic structure and electrical conductivity of metal-organic frameworks derived catalysts simultaneously for robust OER electrocatalysts.