Durable Oxygen Evolution Reaction Research Articles

Phase engineering and surface reconstruction of CrxMnFeNi high entropy alloys for electrocatalytic water splitting

The quest for cost-effective and efficient catalysts for oxygen and hydrogen evolution reactions is vital for a carbon-neutral future. High entropy alloys (HEAs), known for their exceptional thermodynamic stability and performance, have recently emerged as promising candidates in this field. Yet, the relationship between the phase and catalytic performance in HEAs remains understudied. Commonly, metallic catalysts undergo surface reconstruction under high oxidizing potentials under the oxygen evolution reaction (OER), making the identification of the truly active species essential for designing efficient catalysts. Nonetheless, characterization of surface reconstruction of nanoscale HEAs is challenging due to low content of each metal, exacerbated by the use of nonmetal support during synthesis. In this study, we unveil the phase-performance relationship in HEAs and identify that the body-centered cubic (BCC) phase CrMnFeNi outperforms its face-center cubic (FCC) phase counterparts in catalyzing both OER and the hydrogen evolution reaction (HER) due to its superior electrical conductivity and optimized electronic structures. Particularly, Cr1.5MnFeNi with the most prominent BCC phase demonstrates superior OER activity (η10 of 255 mV and Tafel slope of 28.7 mV dec−1), surpassing other Cr, Mn, Fe, Ni-based catalysts, and even state-of-the-art RuO2. X-ray photoelectron spectroscopy (XPS) analysis a transition of Mn, Fe, and Ni elements from metallic states to oxidation states, with surface dissolution of Cr after OER durability tests. This research elucidates the phase-dependent electrocatalytic performance and surface reconstruction in HEAs, providing valuable insights for designing and optimizing HEA materials for electrocatalytic applications.

Carbon cloth supporting spinel CuMn0.5Co2O4 nanoneedles with the regulated electronic structure by multiple metal elements as catalysts for efficient oxygen evolution reaction

Developing transition metal oxide catalysts to replace the noble metal oxide catalysts for efficient oxygen evolution reaction (OER) is essential to promote the practical application of water splitting. Herein, we designed and constructed the carbon cloth (CC) supporting spinel CuMn0.5Co2O4 nanoneedles with regulated electronic structure by multiple metal elements with variable chemical valences in the spinel CuMn0.5Co2O4. The carbon cloth not only provided good conductivity for the catalytic reaction but also supported the well-standing spinel CuMn0.5Co2O4 nanoneedles arrays with a large special surface area. Meanwhile, the well-standing nanoneedles arrays and mesoporous structure of CuMn0.5Co2O4 nanoneedles enhanced their wettability and facilitated access for electrolyte to electrochemical catalysis. Besides, the regulated electronic structure and generated oxygen vacancies of CuMn0.5Co2O4/CC by multiple metal elements improved the intrinsic catalytic activity and the durability of OER activity. Profiting from these merits, the CuMn0.5Co2O4/CC electrode exhibited superior OER activity with an ultralow overpotential of 189 mV at the current density of 10 mA⋅cm−2 and a smaller Tafel slope of 64.1 mV⋅dec−1, which was competitive with the noble metal oxides electrode. And the CuMn0.5Co2O4/CC electrode also exhibited long-term durability for OER with 95.3% of current retention after 1000 cycles. Therefore, the competitive OER activity and excellent cycling durability suggested that the CuMn0.5Co2O4/CC electrode is a potential candidate catalyst for efficient OER.

Tailoring Cr doped NiFeP nanoparticles embedded in 3D cellulose nanofibrils carbon architecture for efficient oxygen evolution reaction

Oxygen evolution reaction (OER) is considered the bottleneck that restricting the pace of electrocatalytic hydrogen production. Modulating structure and heterogeneous doping are essential approaches to effectively promote the electrocatalytic efficiency and stability. Herein, three-dimensional (3D) porous Cr doped NiFeP nanoparticles encapsulated in cellulose nanofibrils (CNF) carbon architecture (Cr–NiFeP/NC) with high-efficiency and durable OER performance was constructed. CNF played crucial role on the construction of 3D porous framework and promoting the OER performance significantly. Benefiting from the 3D porous structure, high specific surface area and exposed abundant active sites, the Cr–NiFeP/NC electrocatalyst displayed excellent OER performance, which the overpotential to deliver the current density of 10 mA cm−2 was only 249 mV with a Tafel slope of 51.2 mV dec−1 in 1.0 M KOH, outperforming the RuO2 and other reported electrocatalysts remarkably. In addition, the Cr–NiFeP/NC electrocatalyst exhibited outstanding stability, which the overpotential was only increased by 2.5% after 48 h chronopotential measurement to deliver a current density of 10 mA cm−2 with stable morphology and structure. This work demonstrated an integrated strategy of Cr doping and 3D porous structure modulating employed CNF as skeleton for the efficient and durable OER performance, providing a spark for hydrogen production by water splitting.

A highly efficient and durable self-standing iron-cobalt-nickel trimetallic phosphide electrode for oxygen evolution reaction

The development of cost-effective, highly efficient, and durable oxygen evolution reaction (OER) electrocatalysts is both a necessity and challenge for large-scale water electrolyzers, which is crucial for future sustainable and clean energy systems. Here we report a self-standing trimetallic phosphide (FeCoNi-P/NF) electrode prepared by the electroreduction of Fe2O3 and Co3O4 on the Ni foam in molten salts and the subsequent phosphorization process. In the electroreduction process, the Ni source provided by Ni foam participates in the alloying process as a solvent phase, which leads to the strong bonding between the substrate and the active material. In addition, the alloys grown by co-reduction and alloying on the three-dimensional skeleton of the Ni foam can expose more active sites by increasing the surface areas through the phosphorization process. Benefiting from the synergistic effects and strong electronic coupling from the Fe, Co, and Ni trinary phosphides, the FeCoNi-P/NF shows excellent OER activity and stability with an overpotential of only 239.5 mV at 10 mA cm−2 and a long-term stability of more than 200 h at 50–300 mA cm−2 in 1.0 M KOH. Overall, this paper offers a straightforward method to prepare low-cost and durable muti-component transition metal-based self-standing OER electrodes.

Fe-based amorphous alloy wire as highly efficient and stable electrocatalyst for oxygen evolution reaction of water splitting

The slow kinetics of the oxygen evolution reaction (OER) leads to low energy conversion efficiency during water electrolysis, thus it is very important to develop efficient and economical electrocatalysts. With high surface energy and rich active centers, amorphous alloys show excellent potential as self-supporting oxygen evolution catalysts for water splitting. In this work, (Fe0.8Ni0.2)71Mo5P12C10B2 amorphous alloy wire was successfully prepared, and after 5 h immersed in 0.5 mol/L HNO3, the wire surface was covered by the block metallic oxide. At a current density of 10 mA/cm2 in an alkaline electrolyte, the electrochemical results show that the overpotential is only 254 mV and the Tafel slope is 49 mV/dec. After the 194 h stability test, its oxygen evolution performance is even comparable to the commercial RuO2, which has been proven to have excellent electrochemical stability and low preparation cost. The highly efficient catalytic performance mainly originated from the synergistic effect of multi-metal elements and the unique crack surface characteristics which expose more active sites. This work provides new insight into low-metal-cost materials for efficient and durable OER electrocatalysts and their industrial applications in the future.

V-Integration Modulates t2g -Electrons of a Single Crystal Ir1- x (Ir0.8 V0.2 O2 )x -BHC for Boosted and Durable OER in Acidic Electrolyte.

Realizing efficacious π-donation from the O 2p orbital to electron-deficient metal (t2g ) d-orbitals along with separately tuned adsorption of *O and *OOH, is an imperious pre-requisite for an electrocatalyst design to demonstrate boosted oxygen evolution reaction (OER) performance. To regulate the π-donation and the adsorption ability for *O and *OOH, herein, a facile strategy to modulate the electron transfer from electron-rich t2g -orbitals to electron-deficient t2g -orbitals, via strong π-donation from the π-symmetry lone pairs of the bridging O2- , and the d-band center of a biomimetic honeycomb (BHC)-like nanoarchitecture (Ir1- x (Ir0.8 V0.2 O2 )x -BHC) is introduced. The suitable integration of V heteroatoms in the single crystal system of IrO2 decreases the electron density on the neighboring Ir sites, and causes an upshift in the d-band center of Ir1- x (Ir0.8 V0.2 O2 )x -BHC, weakening the adsorption of *O while strengthening that of *OOH, lowers the energy barrier for OER. Therefore, BHC design demonstrates excellent OER performance (shows a small overpotential of 238mV at 10mAcm-2 and a Tafel slope of 39.87mVdec-1 ) with remarkable stability (130h) in corrosive acidic electrolyte. This work opens a new corridor to design robust biomimetic nanoarchitectures of modulated π-symmetry (t2g ) d-orbitals and the band structure, to achieve excellent activity and durability in acidic environment.

Recent Advances in Nanocarbon-Based Nonprecious Metal Catalysts for Oxygen/Hydrogen Reduction/Evolution Reactions and Zn-Air Battery

Abstract In this review article, we focus on the design and creation of earth-abundant non-precious metal-coordinated eco-friendly catalysts with high oxygen reduction reaction (ORR), oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) performances. The development of a cost-effective, efficient and durable bifunctional ORR and OER electrochemical catalyst is a key for future batteries. So far, precious metals, such as Pt and Ir, have been used as efficient catalysts for the ORR and OER, respectively. However, they are expensive and their deposits on earth are limited, which are the major drawbacks of these metals. One more drawback for the practical application is the sluggish reactions of ORR and OER. Since electroconductivity of promising metal-free catalyst candidates are poor, good electronic supporting materials are needed. Owing to the high conductivity, stability and easy handling, carbon nanotubes are a most promising material. After Introduction, we summarize recent advances in i) carbon nanotube/nanocarbon-based ORR and OER catalysts, ii) metal oxide and others/nanocarbon catalysts for ORR, OER, HER and Zn-air electrodes, as well as iii) computational study for such catalyst reactions. Such studies are highly beneficial for future energy materials design and synthesis in batteries and molecular catalysts with high performances.

Nanorod-like NiFe metal-organic frameworks for oxygen evolution in alkaline seawater media

Searching for highly active and durable oxygen evolution reaction (OER) electrocatalysts is the key to break through the bottleneck of overall water splitting. Here, we prepare NixFe-BDC (H2BDC = terephthalic acid) nanorods with different Ni/Fe ratios by a facile solvothermal method for the OER. The optimal Ni3Fe-BDC exhibits a low overpotential (η10) of 265 mV and a Tafel slope of 90 mV·dec−1 in 1 M KOH. Moreover, it shows a low η10 of 280 mV and excellent stability in the mixture of 1 M NaCl and 1 M KOH, which has strong corrosion resistance to Cl− anions. The role of Fe3+ not only increases the charge transfer rate of Ni3Fe-BDC, but also affects the specific surface area of the catalyst with high electrochemical activity. Kinetic studies show that both Fe and Ni sites act as active centers, which catalyze synergistically to reduce the reaction kinetic energy barrier. Characterization results of the used Ni3Fe-BDC reveal that the in situ formed rod-like Ni3FeOOH is the active site for the OER.

Copper doping-induced high-valence nickel-iron-based electrocatalyst toward enhanced and durable oxygen evolution reaction

Copper doping-induced high-valence nickel-iron-based electrocatalyst toward enhanced and durable oxygen evolution reaction

Ultralow Fe instigated defect engineering of hierarchical N–Porous carbon for highly efficient electrocatalysis

Multifunctional electrocatalysts with excellent performance are highly desirable for new energy technologies. An electrocatalyst is synthesized using a straightforward two-step approach, whereby ultralow doping (0.06 wt%, Fe) and a heteroatom (N) generate defects. A defect-induced active sites accompanied by porous channels enables high catalytic activity and durability for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). Experiments show that such defects enhance reaction kinetics and promote electrochemical activity with an OER overpotential of 248 mV at 10 mA cm−2 and a Tafel value of 85 mV dec−1. Through density functional theory, carbon matrix defects are observed to be beneficial for OER intermediates adsorption–desorption process. Thus, an avenue for engineering defects has opened for highly efficient multifunctional electrocatalysts by incorporating non-noble metal atoms into a carbon matrix at ultralow loading levels.

Prussian blue analog-derived nickel iron phosphide-reduced graphene oxide hybrid as an efficient catalyst for overall water electrolysis

Efficient and bifunctional nonprecious catalysts for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) are essential for the production of green hydrogen via water electrolysis. Transition metal (Ni, Co, Fe, etc.) phosphides are frequently documented HER catalysts, whereas their bimetallic oxides are efficient OER catalysts, thus enabling bifunctional catalysis for water electrolysis via proper operation. Herein, phosphide-reduced graphene oxide (rGO) hybrids were prepared from graphene oxide (GO)-incorporated bimetal Prussian blue analog (PBA) precursors. The hybrids could experience partial surface oxidation to create oxide layers with OER activities, and the hybrids also possessed considerable HER properties, therefore enabling bifunctional catalytic features for water electrolysis. The typical NiFeP-rGO hybrid demonstrated an overpotential of 250 mV at 10 mA cm−2 and good durability for OER, as well as moderate HER catalytic features (overpotential of 165 mV at −10 mA cm−2 and acceptable catalytic stability). Due to the bifunctional catalytic features, the NiFeP-rGO-based symmetric water electrolyzer demonstrated a moderate input voltage and high faradaic efficiency (FE) for O2 and H2 production. The current work provides a feasible way to prepare OER and HER bifunctional catalysts by facile phosphorization of PBA-associated precursors and spontaneous surface oxidation. Given the oxidation/reduction bifunctional catalytic behaviors, phosphide-rGO hybrid catalysts have great potential for widespread application in fields beyond water electrolysis, such as electrochemical pollution abatement, sensors, energy devices and organic syntheses.

Oxidization-induced structural optimization of Ni3Fe-N-C derived from 3D covalent organic framework for high-efficiency and durable oxygen evolution reaction

Oxidization-induced structural optimization of Ni3Fe-N-C derived from 3D covalent organic framework for high-efficiency and durable oxygen evolution reaction

Surface reconstruction of Fe(III)/NiS nanotubes for generating high-performance oxygen-evolution catalyst

Designing high-performance and cost-effective oxygen-evolution electrocatalysts is highly required toward sustainable water electrolysis. Surface reconstruction is a promising strategy to realize the improvement of the oxygen-evolution reaction (OER) performance of transition metal-based electrocatalysts. Herein, we present a simple electrospinning-post treatment route to construct a novel Fe(III)/NiS electrocatalyst and investigate the key role of the surface reconstruction to significantly promote the OER performance. Owing to the unique tubular morphology and the formation of the highly efficient electrochemical active species of Ni(Fe)OOH during OER process, the prepared Fe(III)/NiS nanotubular catalyst exhibits a low overpotential of 264 mV at 10 mA cm−2, superior to the benchmark RuO2 and many other metal sulfide electrocatalysts. Furthermore, the catalyst also presents an excellent durability with no distinct activity reduction for over 70 h. This study offers a reliable surface reconstruction way to fabricate high-efficiency and outstanding durable OER electrocatalyst, enabling it promising prospect for water electrolysis with a reduced energy consumption.

Optimizing the Electronic Structure of Ruthenium Oxide by Neodymium Doping for Enhanced Acidic Oxygen Evolution Catalysis

AbstractIt is a great challenge to design active and durable oxygen evolution reaction (OER) electrocatalysts for proton exchange membrane (PEM) electrolyzer due to the high dissolution of electrocatalysts in acidic solution. Herein, the Nd‐doped RuO2 (Nd0.1RuOx) is developed for enhanced oxygen evolution in 0.5 m H2SO4 solution with an overpotential of 211 mV to achieve 10 mA cm−2. The theoretical calculation reveals that the improved activity of Nd0.1RuOx is due to the moderate decrease of d‐band center energy, which balances the adsorption and desorption of oxygen intermediates. Moreover, the formation of more high valence state Ru4+ in Nd0.1RuOx is beneficial to the chemical stability of Ru species during the OER process, indicating that the introduction of Nd can effectively suppress the dissolution of Ru in acidic electrolytes. In addition, the PEM electrolyzer using Nd0.1RuOx/CC as the anode can be operated at 10 mA cm−2 stably for 50 h. This study sheds new light on the design of the OER catalysts in acid by engineering the electronic structure of RuO2.

Noble‐Metal‐Free Oxygen Evolution Reaction Electrocatalysts Working at High Current Densities over 1000 mA cm−2: From Fundamental Understanding to Design Principles

Alkaline water electrolysis provides a promising route for “green hydrogen” generation, where anodic oxygen evolution reaction (OER) plays a crucial role in coupling with cathodic hydrogen evolution reaction. To date, the development of highly active and durable OER catalysts based on earth‐abundant elements has drawn wide attention; nevertheless, their performance under high current densities (HCDs ≥1000 mA cm−2) has been less emphasized. This situation has seriously impeded large‐scale electrolysis industrialization. In this review, in order to provide a guideline for designing high‐performance OER electrocatalysts, the effects of HCD on catalytic performance involving electron transfer, mass transfer, and physical/chemical stability are summarized. Furthermore, the design principles were pointed out for obtaining efficient and robust OER electrocatalysts in light of recent progress of OER electrocatalysts working above 1000 mA cm−2. These include the aspects of developing self‐supported catalytic electrodes, enhancing intrinsic activity, enhancing the catalyst–support interaction, engineering surface wettability, and introducing protective layer. Finally, summaries and outlooks in achieving OER at industrially relevant HCDs are proposed.

High-performance flower-like and biocompatible nickel-coated Fe3O4@SiO2 magnetic nanoparticles decorated on a graphene electrocatalyst for the oxygen evolution reaction.

The electrocatalytic oxygen evolution reaction (OER) plays a crucial role in renewable clean energy conversion technologies and has developed into an important direction in the field of advanced energy, becoming the focus of basic research and industrial development. Herein, we report the synthesis and application of flower-like nickel-coated Fe3O4@SiO2 magnetic nanoparticles decorated on a graphene electrocatalyst for the OER that exhibit high efficiency and robust durability. The catalysts were optimized using a rotating ring-disk electrode to test their oxygen evolution properties in 1.0 M KOH solution. Importantly, owing to the high specific surface area and conductivity of C3N4 and graphene, the as-synthesized Fe3O4@SiO2@NiO/graphene/C3N4 exhibits a small Tafel slope of 40.46 mV dec-1, low overpotential of 288 mV at 10 mA cm-2, and robust OER durability within a prolonged test period of 100 h. The cytotoxicity of Fe3O4@SiO2, Fe3O4@SiO2@NiO, and Fe3O4@SiO2@NiO/graphene/C3N4 was evaluated in HeLa and MC3T3-E1 cells, demonstrating that they are efficient and biocompatible catalysts for the OER. Owing to its excellent electrocatalytic efficiency and eco-friendliness, Fe3O4@SiO2@NiO/graphene/C3N4 has considerable potential as a new multifunctional composite for large-scale applications in catalysis, biology, medicine, and high-efficiency hydrogen production.

Ultralow-iridium content NiIr alloy derivative nanochain arrays as bifunctional electrocatalysts for overall water splitting.

The development of low-cost and high-durability bifunctional electrocatalysts is of considerable importance for overall water splitting (OWS). This work reports the controlled synthesis of nickel-iridium alloy derivative nanochain array electrodes (NiIrx NCs) with fully exposed active sites that facilitated mass transfer for efficient OWS. The nanochains have a self-supported three-dimensional core-shell structure, composed of a metallic NiIrx core and a thin (5-10 nm) amorphous (hydr)oxide film as the shell (e.g., IrO2/NiIrx and Ni(OH)2/NiIrx). Interestingly, NiIrx NCs have bifunctional properties. Particularly, the oxygen evolution reaction (OER) current density (electrode geometrical area) of NiIr1 NCs is four times higher than that of IrO2 at 1.6 V vs. RHE. Meanwhile, its hydrogen evolution reaction (HER) overpotential at 10 mA cm-2 (η10 = 63 mV) is comparable to that of 10 wt% Pt/C. These performances may originate from the interfacial effect between the surface (hydr)oxide shell and metallic NiIrx core, which facilitates the charge transfer, along with the synergistic effect between Ni2+ and Ir4+ in the (hydr)oxide shell. Furthermore, NiIr1 NCs exhibits excellent OER durability (100 h @ 200 mA cm-2) and OWS durability (100 h @ 500 mA cm-2) with the nanochain array structure well preserved. This work provides a promising route for developing effective bifunctional electrocatalysts for OWS applications.

Self-supported molybdenum nickel oxide catalytic electrode designed via molecular cluster-mediated electroplating and electrochemical activation for an efficient and durable oxygen evolution reaction.

Efficient and durable nonprecious catalysts for the oxygen evolution reaction (OER) are crucial for practical water electrolysis for hydrogen production. A self-supported OER catalytic electrode with sufficient exposure of the catalyst and tight anchoring onto the current collector is vital for the catalytic activity and stability, and is therefore deemed to be a preferable tactic to enhance water electrolysis performance. Herein, a polyoxometalate (POM) molecular cluster-mediated electroplating and activation tactics are proposed to design a self-supported molybdenum nickel oxide (MoNiOx) catalytic electrode for the OER. The MoNiOx active layer can anchor tightly onto the Ni foam current collector with sufficient surface exposure and high structural stability, therefore enabling high alkali OER catalytic efficiency (222mV at 10mAcm-2) and robust durability (only slight decay in catalytic efficiency upon 12days of chronopotentiometry (V-t) test). Moreover, the easily processable electroplating and active protocol can serve as a general approach to prepare other OER catalytic electrodes by altering the reactants and current collectors. The current work paves a facile and universal way to design a highly active and durable molybdenum (Mo) based hybrid catalytic electrode for OER via molecular cluster-assisted electroplating and activation treatment.

A Template Editing Strategy to Create Interlayer-Confined Active Species for Efficient and Durable Oxygen Evolution Reaction.

Substantial overpotentials and insufficient and unstable active sites of oxygen evolution reaction (OER) electrocatalysts limit their efficiency and stability in OER-related energy conversion and storage technologies. Here, a template editing strategy is proposed to graft highly active catalytic species onto highly conductive rigid frameworks to tackle this challenge. As a successful attempt, two types of NiO6 units of layered Ni BDC (BDC stands for 1,4-benzenedicarboxylic acid) metal organic frameworks are selectively edited by chemical etching-assisted electroxidation to create layered γ-NiOOH with intercalated Ni-O species. In such an interlayer-confined intercalated architecture, the large interlayer space with high ion permeability offers an ideal reaction region to sufficiently expose the OER active sites comprising high-density intercalated Ni-O species, which also suppresses the undesirable γ to β phase transformation, thus exhibiting efficient and durable OER activity. As a result, water oxidation can occur at an extremely low overpotential of 130mV and affords 1000h stability at 100mAcm-2 . The strategy conceptually shows the possibility of achieving stable homogeneous-like catalysis in heterogeneous catalysis.

Boosting large-current–density water oxidation activity and stability by phytic acid-assisted rapid electrochemical corrosion

Corrosion engineering is an efficient strategy to achieve durable oxygen evolution reaction (OER) catalysts at high current densities beyond 500 mA cm−2. However, the spontaneous electrochemical corrosion has a slow reaction rate, and most of them need to add large amounts of salts (such as NaCl) to accelerate the corrosion process. In this report, a novel and effective phytic acid (PA)-assisted in situ electrochemical corrosion strategy is demonstrated to accelerate the the corrosion process and form bimetallic active catalysts to show excellent OER performance at large current densities. In situ rapid electrochemical corrosion of nickel foam substrate and PA ligands etching realize localized high concentrations of Ni and Fe ions. High concentrations of metal ions will combine with hydroxyl to effectively form defects-enriched NiFe layered double hydroxides porous nanosheets tightly anchoring on the underneath substrate. Remarkably, the activated electrode exhibits excellent OER catalytic activities with ultralow overpotentials of 289 and 315 mV to reach high current densities of 500 and 1000 mA cm−2, respectively. When coupled with Ni-Mo-N hydrogen evolution reaction catalysts, the two-electrode cell merely requires 1.87 V to deliver 1000 mA cm−2. The ligands-assisted rapid electrochemical corrosion strategy provides a fresh perspective for facile, cost-effective, and scale-up production of superior OER catalysts at large current densities.