High-performance Oxygen Evolution Reaction Electrocatalysts Research Articles

Iron (III)-Facilitated reconstruction in NiMn layered double hydroxides for initiating rapid oxygen evolution reaction

Layered double hydroxides (LDHs) are emerging as efficient oxygen evolution reaction (OER) electrocatalysts due to their structural advantages and compositional flexibility. Despite their promise, Mn-based LDHs are hampered by poor conductivity, limiting their OER efficacy. This research introduces a hydrothermal and chemical etching technique to fabricate NF/NiMn LDH@NiMnFe(OH)x structures, significantly improving OER performance. The study reveals that integrating Fe3+ into the NiMn LDH fosters a synergistic Ni–Fe interaction, markedly boosting electrocatalytic efficiency. The NF/NiMn LDH@NiMnFe(OH)x-90 shows a low overpotential of 250 mV at 10 mA cm−2 and a Tafel slope of 49.9 mV dec−1 in 1 M KOH, surpassing both its NM precursor and other Ni-based LDH catalysts, including commercial RuO2. In situ, Raman spectroscopy indicates a pivotal phase transition in NF/NiMn LDH@NiMnFe(OH)x to NiOOH at elevated potentials, essential for OER activity. Raman peaks at 463 and 585 cm−1 confirm this structural evolution. The OER activity boost is attributed to increased oxygen vacancies and enhanced conductivity. Moreover, NF/NiMn LDH@NiMnFe(OH)x-90 maintains stability with negligible degradation after 24 h, underscoring its durability. These findings offer a strategic approach to designing high-performance OER electrocatalysts, leveraging nickel-based layered double-metal oxides for potential water-splitting applications, and emphasize the significance of surface engineering and compositional tuning.

Unlocking the Electrocatalytic Behavior of Cu2MnS2 Nanoflake-Anchored rGO for the Oxygen Evolution Reaction in an Alkaline Medium.

A catalyst of the oxygen evolution reaction (OER) that is viable, affordable, and active for effective water-splitting applications is critical. A variety of electrocatalysts have been discovered to replace noble metal-based catalysts. Of these, transition metal-based sulfides are essential for incorporating carbonaceous materials to improve electrical conductivity, resulting in better electrocatalytic performance. Our study illustrates the synthesis of Cu2MnS2 (CMS) nanoflakes and their different rGO composites (10 to 40 wt %) via a hydrothermal technique for an effective water oxidation reaction. The X-ray diffraction pattern reveals that the prepared Cu2MnS2 nanoflakes exhibit a cubic crystal structure. The high-resolution scanning electron microscopy and the high resolution transmission electron microscopy images corroborate the formation of the nanoflake-like morphology of Cu2MnS2 with the strong interaction of rGO. The selected area electron diffraction analysis pattern reveals a polycrystalline nature. The Fourier transform infrared spectrum shows the existence of a metal sulfur vibrational band at 590 cm-1, and Raman analysis infers the presence of rGO. The X-ray photoelectron spectroscopy spectra reveal the oxidation states of the elements present in the samples. Using Brunauer-Emmett-Teller analysis, the surface area of CMS-20 is found to be 117.04 m2/g. The measured OER overpotentials using linear sweep volammetry and the values are 380, 370, 340, 376, and 400 mV at 10 mA/cm2 for CMS, CMS-10, CMS-20, CMS-30, and CMS-40, respectively, and the corresponding Tafel slope values are 179, 158, 149, 206, and 240 mV/decade, respectively. The electrochemical active surface area is estimated using cyclic voltammetry for all of the catalysts, where CMS-20 showed a larger surface area. Also, the same catalyst exhibits good stability for ∼24 h at a constant potential, which is confirmed via chronoamperometry. Thus, combining transition metal-based sulfides with carbonaceous materials indicates improved catalytic behavior for the preparation of high-performance OER electrocatalysts. Overall, the prepared CMS-20 performed as an efficient OER electrocatalyst and can be utilized for practical applications in energy conversion.

Probing the structural evolution of cobalt hydroxide in electrochemical water splitting.

Transition-metal hydroxides are a category of earth-abundant and stable electrocatalysts for energy storage and conversion devices involving sluggish oxygen evolution reaction (OER). Understanding dynamic evolution at the solid/liquid interface of transition-metal hydroxides is crucial for the rational design of high-performance OER electrocatalysts. This study implemented in situ electrochemical atomic force microscopy (EC-AFM) to directly image the dynamic structural evolution of α-Co(OH)2 platelets during the electrochemical OER. Reconstruction of α-Co(OH)2, accompanied by ion insertion from the electrolyte, results in a volume expansion, which can be well confirmed from the X-ray diffraction patterns. Our findings are important for the fundamental understanding of transition-metal hydroxide oxygen-evolution catalysts, illustrating the dynamic nature of Co-based nanostructures under electrochemical conditions.

Iron-promoted rapid self-reconstruction of nickel-based catalysts for efficient oxygen evolution

High-performance oxygen evolution reaction (OER) catalyst is critical for improving the water splitting efficiency. In this work, an efficient self-supported OER catalyst was prepared by electrodeposition of nickel–iron layered double hydroxide nanosheets on titanium mesh substrate (NiFe-LDH/Ti-mesh). This self-supporting design exposes abundant active sites. At 100 mA cm−2, the NiFe-LDH/Ti-mesh shows a low overpotential of 310 mV in 1.0 M KOH. When assembled into an anion exchange membrane water electrolyzer, it can run stably over 200 h. In-situ Raman reveals that the NiFe-LDH/Ti-mesh surface was reconstructed into NiFeOOH active species. In-situ infrared shows that the introduction of Fe promotes the evolution of oxygen intermediates. Theoretical calculations reveal a weakened binding strength of *OH and accelerated formation of *O in OER by the introduction of Fe. This study provides a facile approach for developing self-supported high-performance OER electrocatalyst, and advances the understanding on the origin of NiFe-based catalysts as well.

Highly Efficient CoFeP Nanoparticle Catalysts for Superior Oxygen Evolution Reaction Performance.

Developing effective and long-lasting electrocatalysts for oxygen evolution reaction (OER) is critical for increasing sustainable hydrogen production. This paper describes the production and characterization of CoFeP nanoparticles (CFP NPs) as high-performance electrocatalysts for OER. The CFP NPs were produced using a simple hydrothermal technique followed by phosphorization, yielding an amorphous/crystalline composite structure with improved electrochemical characteristics. Our results reveal that CFP NPs have a surprisingly low overpotential of 284 mV at a current density of 100 mA cm-2, greatly exceeding the precursor CoFe oxide/hydroxide (CFO NPs) and the commercial RuO2 catalyst. Furthermore, CFP NPs demonstrate exceptional stability, retaining a constant performance after 70 h of continuous operation. Post-OER characterization analysis revealed transformations in the catalyst, including the formation of cobalt-iron oxides/oxyhydroxides. Despite these changes, CFP NPs showed superior long-term stability compared to native metal oxides/oxyhydroxides, likely due to enhanced surface roughness and increased active sites. This study proposes a viable strategy for designing low-cost, non-precious metal-based OER catalysts, which will help advance sustainable energy technology.

Engineering Water-Lotus-like Iridium-Cobalt Carbonate Hydroxides on Plasma-Treated Carbon Fibers for Enhanced Electrocatalytic Oxygen Evolution.

The sluggish kinetics of the oxygen evolution reaction (OER) in alkaline water electrolysis remains a significant challenge for developing high-efficiency electrocatalytic systems. In this study, we present a three-dimensional, micrometer-sized iridium oxide (IrO2)-decorated cobalt carbonate hydroxide (IrO2-P-CoCH) electrocatalyst, which is engineered in situ on a carbon cloth (CC) substrate pretreated with atmospheric-pressure dielectric barrier discharge (DBD) plasma (PCC). The electrocatalyst features petal-like structures composed of nanosized rods, providing abundant reactive areas and sites, including the oxygen vacancy caused by the air-DBD plasma. As a result, the IrO2-P-CoCH/PCC electrocatalyst demonstrates an outstanding OER performance, with overpotentials of only 190 and 300 mV required to achieve current densities of 10 mA cm-2 (j10) and 300 mA cm-2 (j300), respectively, along with a low Tafel slope of 48.1 mV dec-1 in 1.0 M KOH. Remarkably, benefiting from rich active sites exposed on the IrO2-P-CoCH (Ir) heterostructure, the synergistic effect between IrO2 and CoCH enhances the charge delivery rates, and the IrO2-P-CoCH/PCC exhibits a superior electrocatalytic activity at a high current density (300 mV/j300) compared to the commercial benchmarked RuO2/PCC (470 mV/j300). Furthermore, the IrO2-P-CoCH/PCC electrocatalyst shows exceptional OER stability, with a mere 1.3% decrease with a current density of j10 for 100 h testing, surpassing most OER catalysts based on CC substrates. This work introduces a novel approach for designing high-performance OER electrocatalysts on flexible electrode substrates.

A Cu doped RuO2 catalyst for efficient and durable acidic water oxidation

AbstractProducing hydrogen by water electrolysis in acidic system is essential for advancing the proton‐exchange membrane water electrolyzer (PEMWE) and maintaining the global sustainability. However, excavating highly active and durable catalysts for anodic oxygen evolution reaction (OER) in acid medium remains a great challenge due to the sluggish kinetics of OER and the severe catalyst dissolution. In this work, we developed a Cu doped RuO2 catalyst (Cu‐RuO2@CP) through simple drop casting and low temperature pyrolysis procedures. The incorporation of Cu into RuO2 executes complicated responsibilities: improving OER activity by raising more oxygen vacancies and accelerating the charge transfer between solid‐liquid interface; strengthening the long‐term durability via suppressing the over‐oxidation of RuO2 into soluble RuO4; lowering the catalyst cost by replacing with less expensive Cu. Hence, the Cu‐RuO2@CP exhibits excellent activity and stability in 0.5 M H2SO4 electrolyte, requiring a low overpotential of 200 mV to achieve 10 mA cm−2 and preserving stability for almost 500 h. Moreover, the overpotential is as low as 397 mV even when operating under an industrial‐level current density of 1000 mA cm−2, paving a new way to develop high performance OER electrocatalyst in acidic environment to promote the large‐scale utilization of PEMWE.

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.

Superhydrophilic NiFe-LDH@Co9S8-Ni3S2/NF heterostructures for high-current-density freshwater/seawater oxidation electrocatalysts

Designing oxygen evolution reaction (OER) electrocatalysts with high efficiency and stability at large current densities is paramount for achieving hydrogen production through water splitting. In this study, a heterostructured NiFe-LDH coating Co9S8-Ni3S2 grown on nickel foam (NiFe-LDH@Co9S8-Ni3S2/NF) was successfully synthesized. The distinctive hierarchical structures featuring abundant heterointerfaces can effectively expose abundant active sites. The synergistic effect and strong electronic interaction between Co9S8-Ni3S2 and NiFe-LDH can enhance the intrinsic OER activity. Furthermore, the superhydrophilic characteristic of NiFe-LDH@Co9S8-Ni3S2/NF favors close contact between the electrode and electrolyte. Due to these advantages, NiFe-LDH@Co9S8-Ni3S2/NF can provide distinguished OER activity with low overpotentials of 274 mV in alkaline freshwater and 298 mV in alkaline seawater at 1000 mA cm−2, along with outstanding stability at high current density of 500 mA cm−2 over 200 h in both solutions. This study offers a valuable insight into fabricating high-performance OER electrocatalysts for seawater electrolysis in industrial applications.

Preparing iron oxide clusters surface modified Co3O4 nanoboxes by chemical vapor deposition as an efficient electrocatalyst for oxygen evolution reaction

Interface engineering is an effective way for optimizing the electronic configuration of Co3O4 to enhance the intrinsic activity of oxygen evolution reaction (OER). However, how to enrich accessible activity sites at the interface is still a challenge. Herein, Co3O4 hollow nanoboxes modified by iron oxide nanoclusters (FeOx NCs) (Fe-Co3O4 NBs) as OER electrocatalysts are prepared by a chemical vapor deposition process. Benefiting from high exposed surface area and utilization of atoms, FeOx NCs incorporation can not only regulates the spin state of Co sites, but also exposes more accessible sites for OER. Therefore, Fe-Co3O4 NBs shows excellent OER performance, manifested by the lower overpotential (η) of 265 mV at 10 mA cm−2 and smaller Tafel slope of 54.2 mV dec−1 compared to Co3O4 NBs, and many reported Co based OER electrocatalyst. Further density functional theory analysis reveals that FeOx NCs can downshift the d center of Co sites, which decreases the energy barrier of potential-determining step (PDS) for OER (*OH → *O + H+ + e−) to enhance the electroactivity. This work provides guidance for further designing high-performance OER electrocatalysts.

Biomineralization of Sulfate-Reducing Bacteria In Situ-Induced Preparation of Nano Fe2O3-Fe(Ni)S/C as High-Efficiency Oxygen Evolution Electrocatalyst.

Transition metal-based catalysts possess high catalytic activity for oxygen evolution reaction (OER). However, the preparation of high-performance OER electrocatalysts using simple strategies with a low cost still faces a major challenge. Herein, this work presents an innovative, in situ-induced preparation of the Fe2O3, FeS, and NiS nanoparticles, supported on carbon blacks (CBs) (denoted as Fe2O3-Fe(Ni)S/C) as a high-efficiency oxygen evolution electrocatalyst by employing biomineralization. Biomineralization, a simple synthesis strategy, demonstrates a huge advantage in controlling the size of the Fe2O3 and Fe(Ni)S nanoparticles, as well as achieving uniform nanoparticle distribution on carbon blacks. It is found that the electrocatalyst Fe2O3-Fe(Ni)S/C-200 shows a good OER electrocatalytic activity with a small loading capacity, and it has a small overpotential and Tafel slope in 1 m KOH solution with values of 264mV and 42mVdec-1, respectively, at a current density of 10mAcm-2. Additionally, it presents good electrochemical stability for over 24h. The remarkable and robust electrocatalytic performance of Fe2O3-Fe(Ni)S/C-200 is attributed to the synergistic effect of Fe2O3, FeS, and doped-Ni species as well as its distinct 3D spherical structure. This approach indicates the promising applications of biomineralization for the bio-preparation of functional materials and energy conversion.

A novel bimetallic organic framework catalyst induced by dual-ligand for highly efficient oxygen evolution

With the continuous advancement of non-noble electrocatalysts, metal-organic frameworks (MOFs) are emerging as a promising substitute for noble metal nanomaterials in oxygen evolution reaction (OER) due to their larger pre-development and higher cost-effectiveness. However, there are still challenges in modifying the electronic structure of MOFs at the molecular level to enhance their activity of OER. Herein, bimetallic CoNi MOFs were utilized and modified with terephthalic acid (A) and 2, 5-dihydroxyterephthalic acid (B) (A2.5B-CoNi MOFs) through a straightforward hydrothermal method. By adjusting the ratio of A and B dual-ligand, the A2.5B-CoNi MOFs with the best ligand ratio exhibit significantly enhanced OER activity with an overpotential of only 300 mV at a current density of 10 mA cm−2, a low Tafel slope of 45.27 mV dec−1. In addition, A2.5B-CoNi MOFs also have better long-term stability than commercial RuO2. This study provides a research direction for the development of high-performance OER electrocatalysts based on dual-ligand MOFs.

Iron doped cobalt nickel layered double hydroxide supported on nickel foam as a robust electrocatalyst for highly efficient water oxidation in alkaline sea water

The seawater electrolysis is an economically favorable approach for water splitting application because seawater is one of the plentiful abundant natural resources on our earth. In water splitting pathway, the anodic half-cell reaction from seawater stills a challenging task due to anodic corrosion and the competitive chloride oxidation process. In the current study, we prepared flower-shaped porous nanorods of iron doped cobalt nickel layered double hydroxide supported on nickel foam (Fe0.05 CoNi LDH/NF), which require very less oxygen evolution reaction (OER) overpotential in 1M KOH (212mV) and alkaline seawater (287mV) to deliver 10 mAcm−2 current density and exhibited remarkable 14h durability. At the same time, post treated sample reveals the better OER activity after chronopotentiometry analysis, because of superior conductivity and corrosion-resistance of the electrocatalyst. The doping of Fe cation in catalysis improves the OER selectivity and kinetics. Meanwhile, CoNi LDH serves as an active OER centers and NF increase the conductivity of the catalyst. Our findings suggests that Fe-doped CoNi LDH on NF provides an effective pathway towards durable and high performance OER electrocatalysts for seawater electrolysis.

Misoriented high-entropy iridium ruthenium oxide for acidic water splitting.

Designing an efficient catalyst for acidic oxygen evolution reaction (OER) is of critical importance in manipulating proton exchange membrane water electrolyzer (PEMWE) for hydrogen production. Here, we report a fast, nonequilibrium strategy to synthesize quinary high-entropy ruthenium iridium-based oxide (M-RuIrFeCoNiO2) with abundant grain boundaries (GB), which exhibits a low overpotential of 189 millivolts at 10 milliamperes per square centimeter for OER in 0.5 M H2SO4. Microstructural analyses, density functional calculations, and isotope-labeled differential electrochemical mass spectroscopy measurements collectively reveal that the integration of foreign metal elements and GB is responsible for the enhancement of activity and stability of RuO2 toward OER. A PEMWE using M-RuIrFeCoNiO2 catalyst can steadily operate at a large current density of 1 ampere per square centimeter for over 500 hours. This work demonstrates a pathway to design high-performance OER electrocatalysts by integrating the advantages of various components and GB, which breaks the limits of thermodynamic solubility for different metal elements.

NiCo-layered double hydroxides /Co9S8 with heterogeneous structure as ultra-high performance electrocatalyst for oxygen evolution reaction

Heterogeneous interface engineering is an ideal method for designing low-cost and efficient electrocatalysts for oxygen evolution reaction (OER). NiCo-layered double hydroxide (LDH)/Co9S8 with heterogeneous structure was prepared by a two-step hydrothermal method and employed for OER. The layered structure with a spherical base exhibited the lower overpotential (151 mV) and Tafel slope (100 mV dec−1) at a current density of 10 mA cm−2, which surpass commercially available IrO2 and most reported non-precious metal electrocatalysts. The synergistic effect at the interface can increase the conductivity of the material, induce electron migration between NiCo-LDH and Co9S8, and decrease the energy barrier of the OER intermediate, thereby increasing the electrocatalytic activity. At the same time, heterostructures with rough surfaces and ultra-hydrophilic properties can provide the desired stability, promote ion penetration and the release of bubbles, improve the accessibility of the active site, and thus enhance the catalytic performance of OER. This work provides a feasible way to develop high performance OER electrocatalysts.

Melamine intercalation approach for the synthesis of C, N codoped net-like NiCo oxides composites and Its Application towards oxygen evolution reaction in alkaline solution

Electrolysis of water is a leading hydrogen production pathway with the advantages of simple technology, mature development and small environmental impact. However, the energy conversion efficiency seriously decreased due to the high overpotential produced by oxygen evolution reaction (OER). To decrease the overpotential of OER, NiCoOx particles with small sizes embedded in layered structure constituted with carbon and nitrogen composites (NiCoOx-CN) were prepared through melamine intercalation method with acetylacetonate as cobalt and nickel source. Finally, NiCoOx-CN showed excellent OER performance with an overpotential of only 326 mV to obtain current density of 10 mA cm−2 and Tafel slope of 70.8 mV·dec−1. Besides, NiCoOx-CN possessed excellent long-term durability in alkaline environments. Scanning electron microscopy (SEM), electron paramagnetic resonance (EPR) and other techniques were implemented to study the mechanism for the increased OER performance of NiCoOx-CN. The microstructure of NiCoOx-CN that the nanoparticles embedded into the interlinked layered nanosheets was helpful to expose more active sites. Meanwhile, the doping of C and N heteroatom and abundant oxygen vacancies also led to the enhanced conductivity of NiCoOx-CN and the optimized the electron transfer. Thus, the OER performance of NiCoOx-CN significantly boosted. As a result, this strategy holds great promise in preparing other high performance OER electrocatalysts with melamine.

High-Efficiency Oxygen Evolution Reaction: Controllable Reconstruction of Surface Interface.

The precatalyst undergoes surface reconstruction during the oxygen evolution reaction (OER) process, and the reconstituted material is the one that really plays a catalytic role. However, the degree of surface reconstruction seriously affects the catalytic performance. For this reason, it is important to establish the link between the degree of reconstruction and catalytic activity based on a deep understanding of the OER mechanism for the rational design of high-performance OER electrocatalysts. Here, the reaction mechanism of OER is briefly introduced, the competition between adsorbate evolution mechanism (AEM) mechanism and lattice oxygen-mediated mechanism (LOM) mechanism is discussed, and several activity descriptors of OER reaction are summarized. The strategies to realize OER controllable surface reconstruction are emphatically introduced, including ion leaching, element doping, regulating catalyst size, heterogeneous structure engineering, and self-reconstruction. A mechanistic perspective is emphasized to understand the relationship between dynamic surface reconstruction and electronic structure. Controlled reconfiguration of OER surface can break the limitation of proportional relationship brought by traditional AEM mechanism, also can realize the switching between AEM mechanism and LOM mechanism, thus realizing ultra-low overpotential. This review will provide some reference for surface controllable reconstruction of OER transition metal-based catalysts and reasonable development of ideal catalytic performance.

A Porous Perovskite Nanofiber with Reinforced Aerophobicity for High-Performance Anion Exchange Membrane Water Splitting.

Perovskite oxides stand out as emerging oxygen evolution reaction (OER) catalysts on account of their effective electrocatalytic performance and low costs. Nevertheless, perovskite oxides suffer from severe bubble overpotential and inhibited electrochemical performance in large current densities due to their small specific surface areas and structural compactness. Herein, the study highlights the electrospun nickel-substituted La0.5 Sr0.5 FeO3-δ (LSF) porous perovskite nanofibers, that is, La0.5 Sr0.5 Fe1-x Nix O3-δ (denoted as ES-LSFN-x, x=0, 0.1, 0.3, and 0.5), as high-performance OER electrocatalysts. The most effective La0.5 Sr0.5 Fe0.5 Ni0.5 O3-δ (ES-LSFN-0.5) nanofibers suggest a larger specific surface area, higher porosity, and faster mass transfer than the counterpart sample prepared by conventional sol-gel method (SG-LSFN-0.5), showing notably increased geometric and intrinsic activities. The bubble visualization results demonstrate that the enriched and nano-sized porosity of ES-LSFN-0.5 enables reinforced aerophobicity and rapid detachment of oxygen bubbles, thereby reducing the bubble overpotential and enhancing the electrochemical performance. As a result, the ES-LSFN-0.5-based anion exchange membrane water electrolysis delivers a superior stability of 100h while the SG-LSFN-0.5 counterpart degrades rapidly within 20h under a current density of 100mAcm-2 . The results highlight the advantage of porous electrocatalysts in optimizing the performance of large current density water electrolysis devices by reducing the bubble overpotential.

Effect of phosphorus vacancies on activity of Fe-doped Nickel phosphide by NaBH4 reduction for efficient oxygen evolution under alkaline conditions

The development of effective, stable, and inexpensive electrocatalysts through oxygen evolution reaction (OER) is important but also very difficult. Anion defects are used to control the active sites of electrocatalysts. In this study, we persent an easy NaBH4 reduction strategy for engineering a novel Fe-doped nickel phosphide material with phosphorus vacancies, (i.e., Fe-Ni2P (PV)) for OER. Interestingly, this easy NaBH4 reduction tactic can fulfill defects engineering (i.e., P vacancies). The P vacancies can adjust the electronic structures of electrocatalyst for OER. Fe-Ni2P (PV) has outstanding OER performance, e.g., a lower overpotential (290 mV at 10 mA cm−2), smaller Tafel slope (41.15 mV dec-1), and excellent durability (93.5% for 12 h) under alkaline condition. This work indicates the detailed structural changes of NaBH4 reduction treated-engineered materials and improves understanding of the structure-effect relationship of high performance OER electrocatalyst.

In Situ Fabrication of Mn-Doped NiMoO4 Rod-like Arrays as High Performance OER Electrocatalyst

The slow kinetics of the oxygen evolution reaction (OER) is one of the significant reasons limiting the development of electrochemical hydrolysis. Doping metallic elements and building layered structures have been considered effective strategies for improving the electrocatalytic performance of the materials. Herein, we report flower-like nanosheet arrays of Mn-doped-NiMoO4/NF (where NF is nickel foam) on nickel foam by a two-step hydrothermal method and a one-step calcination method. The doping manganese metal ion not only modulated the morphologies of the nickel nanosheet but also altered the electronic structure of the nickel center, which could be the result of superior electrocatalytic performance. The Mn-doped-NiMoO4/NF electrocatalysts obtained at the optimum reaction time and the optimum Mn doping showed excellent OER activity, requiring overpotentials of 236 mV and 309 mV to drive 10 mA cm-2 (62 mV lower than the pure NiMoO4/NF) and 50 mA cm-2 current densities, respectively. Furthermore, the high catalytic activity was maintained after continuous operation at a current density of 10 mA cm-2 of 76 h in 1 M KOH. This work provides a new method to construct a high-efficiency, low-cost, stable transition metal electrocatalyst for OER electrocatalysts by using a heteroatom doping strategy.