Electrocatalytic Oxygen Evolution Reaction Research Articles

Assembled RhRuFe Trimetallene for Water Electrolysis.

Industrializing water electrolyzers demands better electrocatalysts, especially for the anodic oxygen evolution reaction (OER). The prevailing OER catalysts are Ir or Ru-based nanomaterials, however, they still suffer from insufficient stability. An alternative yet considerably less explored approach is to upgrade Rh, a known stable but moderately active element for OER electrocatalysis, via rational structural engineering. Herein, a precise synthesis of assembled RhRuFe trimetallenes (RhRuFe TMs) with an average thickness of 1nm for boosting overall water splitting catalysis is reported. Favorable mass transport and optimized electronic structure collectively render RhRuFe TMs with an improved OER activity of an overpotential of 330mV to deliver 10mAcm-2, which is significantly lower than the Rh/C control (by 601mV) and reported Rh-based OER electrocatalysts. In particular, the RhRuFe TMs-based water splitting devices can achieve the current density of 10mAcm-2 at a low voltage of 1.63V, which is among the best in the Rh-based bifunctional catalysts for electrolyzers. The addition of Fe in RhRuFe TMs can modulate the strain/electron distribution of the multi-alloy, which regulates the binding energies of H* and OH* in hydrogen and oxygen evolution reactions for achieving the enhanced bifunctional OER and HER catalysis is further demonstrated.

Synergistic RB5 dye degradation and oxygen evolution reaction (OER) catalysis by WO3 nano-pellets: mechanistic insights and water remediation applications

Transition metal oxides (TMO), a non-noble element based oxides, establish remarkable potential in the realm of textile wastewater remediation and water splitting due to their sustainable catalytic performance. Highly functional TMO materials, in form of nanostrcutures, are of great interest owing to their robust photo and electro-catalytic activities for instituting sustainable development for the water and energy resource management framework. In the present article, we have reported catalytically active WO3 nano-pellets (NP) synthesized using microwave-assisted for photocatalytic wastewater remediation and electrocatalytic oxygen evolution reaction (OER). Promisingly, WO3 NP abetted degradation of the reactive black 5 (RB5) dye by almost 95 % in short time interval of 60 min in exposer of sun light. Present work includes the strategies to remove and observe the progression of reaction kinetics of dye degradation in neutral and alkaline media. By varying concentration of the catalyst (ranging from 250 mg/L to 1000 mg/L, in the step of 250 mg/L), we have prolifically verified that 750 mg/L turn out optimal dosage for 100% degradation in time interval of 120 min. Besides, WO3 NP has shown highest photocatalytic behaviour at 9 pH. The WO3 NP shows the electrocatalytic OER performance in an alkaline condition (1M KOH) with an overpotential of 418 mV to generate the geometric current density of 10 mA/cm² and Tafel slope of 178 mV dec⁻¹. Owing to robust nature, WO3 NP shows the almost similar photocatalytic response for ten cycles dye degradation and demonstrates the stable electrochemical charge transport for OER at 10 mA/cm2 for 50 hours.

In Situ X-ray Absorption Spectroscopy of LaFeO3 and LaFeO3/LaNiO3 Thin Films in the Electrocatalytic Oxygen Evolution Reaction.

We study the electrocatalytic oxygen evolution reaction using in situ X-ray absorption spectroscopy (XAS) to track the dynamics of the valence state and the covalence of the metal ions of LaFeO3 and LaFeO3/LaNiO3 thin films. The active materials are 8 unit cells grown epitaxially on 100 nm conductive La0.67Sr0.33MnO3 layers using pulsed laser deposition (PLD). The perovskite layers are supported on monolayer Ca2Nb3O10 nanosheet-buffered 100 nm SiNx membranes. The in situ Fe and Ni K-edges XAS spectra were measured from the backside of the SiNx membrane using fluorescence yield detection under electrocatalytic reaction conditions. The XAS spectra show significant spectral changes, which indicate that (1) the metal (co)valencies increase, and (2) the number of 3d electrons remains constant with applied potential. We find that the whole 8 unit cells react to the potential changes, including the buried LaNiO3 film.

Molten salt electrosynthesis of self-supporting FeCoNi medium entropy alloy electrocatalysts for efficient oxygen evolution reactions

High/medium entropy alloys (HEAs/MEAs) with high electrocatalytic activity have attracted great attention in water electrolysis applications. However, facile synthesis of self-supporting high/medium entropy alloys electrocatalysts with rich active sites through classical metallurgical methods is still a challenge. Here, a self-supporting porous FeCoNi MEA electrocatalyst with nanosheets-shaped surface for oxygen evolution reaction (OER) was prepared by a one-step electrochemical process from the metal oxides in molten CaCl2. The formation of the FeCoNi MEA is attributed to the oxides electro-reduction, high-temperature diffusion and solid solution. Additionally, the morphology and structure of the FeCoNi MEA can be precisely controlled by adjusting the electrolysis time and temperature. The electronic structure regulation and the reduced energy barrier of OER from the “cocktail effect”, the abundant exposed active sites brought by surface ultrathin nanosheets, the good electronic conductivity and electrochemical stability from the self-supporting structure enable the FeCoNi MEA electrode shows high-performance OER electrocatalysis, exhibiting a low overpotential of 233 mV at a current density of 10 mA cm–2, a low Tafel slope of 29.8 mV dec–1, and an excellent stability for over 500 h without any obvious structural destruction. This work demonstrates a facile one-step electrochemical metallurgical approach for fabricating self-supporting HEAs/MEAs electrocatalysts with nanosized surface for the application in water electrolysis.

A Single-step Synthesis of Aluminum-Doped WS2 for Oxygen Evolution Reaction with Loading Influence on Catalytic Performance

Recently, tungsten disulfide (WS2) has received considerable attention in aspects of electrocatalytic oxygen evolution reactions (OER). However, due to the restricted number of active sites, WS2 nanoflower has a high overpotential in OER. Thus, we provide herein a doping approach for doping WS2 nanoflower with non-noble aluminum (Al) metal to increase active sites in an effort to enhance the OER activity of WS2. The positive electrocatalytic effect of Al-doping on WS2 material results in a lower OER operating overpotential. In comparison to undoped WS2, the skeleton-like structure (0.04 %) Al-doped WS2 nanoflowers significantly enhanced OER catalytic activity with an overpotential of 650 mV at the current density of 6 mA cm−2. Furthermore, the impact of different mass loadings of (0.04 %) Al-WS2 on the OER performance has been examined using electrochemical analysis. The success of using aluminum dopants to improve OER performance would have a significant impact on the development and production of non-noble metal sulfide-based electrocatalysts for OER.

Covalent Tethering of Cobalt Porphyrins on Phenolic Resins for Electrocatalytic Oxygen Reduction and Evolution Reactions.

The front cover artwork is provided by Rui Cao's group at Shaanxi Normal University. The image shows the design of Co-porphyrin-engineered phenolic resins with intramolecular phenolic hydroxyl groups to facilitate proton and electron transfers for efficient oxygen electrocatalysis, which is bioinspired by cytochrome c oxidases, and shows the excellent performance of Zn-air batteries assembled with the hybrid material. Read the full text of the Research Article at 10.1002/cphc.202400017.

Designing Different Heterometallic Organic Frameworks by Heteroatom and Second Metal Doping Strategies for the Electrocatalytic Oxygen Evolution Reaction.

Metal-organic frameworks (MOFs) are considered one of the most significant electrocatalysts for the sluggish oxygen evolution reaction (OER). Hence, a series of novel N,S-codoped Ni-based heterometallic organic framework (HMOF) (NiM-bptz-HMOF, M = Co, Zn, and Mn; bptz = 2,5-bis((3-pyridyl)methylthio)thiadiazole) precatalysts are constructed by the heteroatom and second metal doping strategies. The effective combination of the two strategies promotes electronic conductivity and optimizes the electronic structure of the metal. By regulation of the type and proportion of metal ions, the electrochemical performance of the OER can be improved. Among them, the optimized Ni6Zn1-bptz-HMOF precatalyst exhibits the best performance with an overpotential of 268 mV at 10 mA cm-2 and a small Tafel slope of 72.5 mV dec-1. This work presents a novel strategy for the design of modest heteroatom-doped OER catalysts.

Exfoliation of Metal-Organic Frameworks to Give 2D MOF Nanosheets for the Electrocatalytic Oxygen Evolution Reaction.

The structure and properties of materials are determined by a diverse range of chemical bond formation and breaking mechanisms, which greatly motivates the development of selectively controlling the chemical bonds in order to achieve materials with specific characteristics. Here, an orientational intervening bond-breaking strategy is demonstrated for synthesizing ultrathin metal-organic framework (MOF) nanosheets through balancing the process of thermal decomposition and liquid nitrogen exfoliation. In such approach, proper thermal treatment can weaken the interlayer bond while maintaining the stability of the intralayer bond in the layered MOFs. And the following liquid nitrogen treatment results in significant deformation and stress in the layered MOFs' structure due to the instant temperature drop and drastic expansion of liquid N2, leading to the curling, detachment, and separation of the MOF layers. The produced MOF nanosheets with five cycles of treatment are primarily composed of nanosheets that are less than 10 nm in thickness. The MOF nanosheets exhibit enhanced catalytic performance in oxygen evolution reactions owing to the ultrathin thickness without capping agents which provide improved charge transfer efficiency and dense exposed active sites. This strategy underscores the significance of orientational intervention in chemical bonds to engineer innovative materials.

Exfoliation of Metal–Organic Frameworks to Give 2D MOF Nanosheets for the Electrocatalytic Oxygen Evolution Reaction

AbstractThe structure and properties of materials are determined by a diverse range of chemical bond formation and breaking mechanisms, which greatly motivates the development of selectively controlling the chemical bonds in order to achieve materials with specific characteristics. Here, an orientational intervening bond‐breaking strategy is demonstrated for synthesizing ultrathin metal–organic framework (MOF) nanosheets through balancing the process of thermal decomposition and liquid nitrogen exfoliation. In such approach, proper thermal treatment can weaken the interlayer bond while maintaining the stability of the intralayer bond in the layered MOFs. And the following liquid nitrogen treatment results in significant deformation and stress in the layered MOFs’ structure due to the instant temperature drop and drastic expansion of liquid N2, leading to the curling, detachment, and separation of the MOF layers. The produced MOF nanosheets with five cycles of treatment are primarily composed of nanosheets that are less than 10 nm in thickness. The MOF nanosheets exhibit enhanced catalytic performance in oxygen evolution reactions owing to the ultrathin thickness without capping agents which provide improved charge transfer efficiency and dense exposed active sites. This strategy underscores the significance of orientational intervention in chemical bonds to engineer innovative materials.

Bi-functional CoCr2O4 hollow-sphere for enhanced oxygen evolution reaction and photocatalyst for harmful environmental pollutants removal

The development of a high-performance, cost-effective, and durable multifunctional semiconductor is crucial for clean energy and environmental remediation applications such as oxygen evolution reaction (OER) and photocatalysts. In this research, we have developed a hollow sphere-based spinel-structured CoCr2O4 (HS.CCO) for bi-functional applications. These hollow spheres exhibit excellent electrocatalytic OER performance under an alkaline (1 M potassium hydroxide (KOH)) medium, which displays a higher electrocatalytic ability. The spinel hollow spheres demonstrate favorable overpotentials and Tafel potentials of 180 mV and 162 mV/dec, respectively towards OER activity. On the other hand, as a photocatalysis, they portrayed outstanding degradation efficiency under visible light irradiation towards Congo red (CR) dye degradation. Within the short treatment time higher CR degradation efficiency is achieved. These photo-electroactive spinel hollow spheres accelerate efficient OER and visible-light-driven photocatalysis with remarkable stability. They serve as an excellent example of a multifunctional heterogeneous catalyst. Finally, the obtained results indicate the current needs and future demands for enhancing the prospects of multifunctional semiconductor catalysts.

Ir Single Atoms Boost Metal-Oxygen Covalency on Selenide-Derived NiOOH for Direct Intramolecular Oxygen Coupling.

This investigation probes the intricate interplay of catalyst dynamics and reaction pathways during the oxygen evolution reaction (OER), highlighting the significance of atomic-level and local ligand structure insights in crafting highly active electrocatalysts. Leveraging a tailored ion exchange reaction followed by electrochemical dynamic reconstruction, we engineered a novel catalytic structure featuring single Ir atoms anchored to NiOOH (Ir1@NiOOH). This novel approach involved the strategic replacement of Fe with Ir, facilitating the transition of selenide precatalysts into active (oxy)hydroxides. This elemental substitution promoted an upward shift in the O 2p band and intensified the metal-oxygen covalency, thereby altering the OER mechanism toward enhanced activity. The shift from a single-metal site mechanism (SMSM) in NiOOH to a dual-metal-site mechanism (DMSM) in Ir1@NiOOH was substantiated by in situ differential electrochemical mass spectrometry (DEMS) and supported by theoretical insights. Remarkably, the Ir1@NiOOH electrode exhibited exceptional electrocatalytic performance, achieving overpotentials as low as 142 and 308 mV at current densities of 10 and 1000 mA cm-2, respectively, setting a new benchmark for the electrocatalysis of OER.

Carbon Nanotube Composites with Bimetallic Transition Metal Selenides as Efficient Electrocatalysts for Oxygen Evolution Reaction

Hydrogen fuel is a clean and versatile energy carrier that can be used for various applications, including transportation, power generation, and industrial processes. Electrocatalytic water splitting could be the most beneficial and facile approach for producing hydrogen. In this work, transition metal selenide composites with carbon nanotubes (CNTs) have been investigated for electrocatalytic water splitting. The synthesis process involved the facile one-step hydrothermal growth of transition metal nanoparticles over the CNTs and acted as an efficient electrode toward electrochemical water splitting. Scanning electron microscopy and XRD patterns reveal that nanoparticles were firmly anchored on the CNTs, resulting in the formation of composites. The electrochemical measurements reveal that CNT composite with nickel–cobalt selenides (NiCo-Se/CNTs@NF) display remarkable oxygen evolution reaction (OER) activity in basic media, which is an important part of hydrogen production. It demonstrates the lowest overpotential (η10mAcm−2) of 0.560 V vs. RHE, a reduced Tafel slope of 163 mV/dec, and lower charge transfer impedance for the OER process. The multi-metallic selenide composite with CNTs demonstrating unique nanostructure and synergistic effects offers a promising platform for enhancing electrocatalytic OER performance and opens up new avenues for efficient energy conversion and storage applications.

Self-etching assembly of designed NiFeMOF nanosheet arrays as high-efficient oxygen evolution electrocatalyst for water splitting.

2D metal-organic frameworks (MOFs) have emerged as potential candidates for electrocatalytic oxygen evolution reactions (OER) due to their inherent properties like abundant coordination unsaturated active sites and efficient charge transfer. Herein, a versatile and massively synthesizable self-etching assembly strategy wherein nickel-iron foam (NFF) acts as a substrate and a metal ion source. Specifically, by etching the nickel-iron foam (NFF) surface using ligands and solvents, Ni/Fe metal ions are activated and subsequently reacted under hydrothermal conditions, resulting in the formation of self-supporting nanosheet arrays, eliminating the need for external metal salts. The obtained 33 % NiFeMOF/NFF exhibits remarkable OER performance with ultra-low overpotentials of 188/231 mV at 10/100 mA cm-2 , respectively, outperforming most recently reported catalysts. Besides, the built 33 % NiFeMOF/NFF(+) ||Pt/C(-) electrolyzer presents low cell voltages of 1.55/1.83 V at 10/100 mA cm-2 , superior to the benchmark RuO2 (+) ||Pt/C(-) , implying good industrialization prospects. The excellent catalytic activity stems from the modulation of the electronic spin state of the Ni active site by the introduction of Fe, which facilitates the adsorption process of oxygen-containing intermediates and thus enhances the OER activity. This innovative approach offers a promising pathway for commercial-scale sustainable energy solutions.

Covalent Tethering of Cobalt Porphyrins on Phenolic Resins for Electrocatalytic Oxygen Reduction and Evolution Reactions.

Using functionalized supporting materials for the immobilization of molecular catalysts is an appealing strategy to improve the efficiency of molecular electrocatalysis. Herein, we report the covalent tethering of cobalt porphyrins on phenolic resins (PR) for improved electrocatalytic oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). A cobalt porphyrin bearing an alkyl bromide substituent was covalently tethered on phenolic resins, through the substitution reaction of alkyl bromides with phenolic hydroxyl groups, to afford molecule-engineered phenolic resins (Co-PR). The resulted Co-PR was efficient for electrocatalytic ORR and OER by displaying an ORR half-wave potential of E1/2=0.78 V versus RHE and an OER overpotential of 420 mV to get 10 mA/cm2 current density. We propose that the many residual phenolic hydroxyl groups on PR will surround the tethered Co porphyrin and play critical roles in facilitating proton and electron transfers. Importantly, Co-PR outperformed unmodified PR and PR loaded with Co porphyrins through simple physical adsorption (termed Co@PR). The zinc-air battery assembled using Co-PR displayed a performance comparable to that using Pt/C+Ir/C. This work is significant to present phenolic resins as a functionalized material to support molecular electrocatalysts and demonstrate the strategy to improve molecular electrocatalysis with the use of phenolic resin residues.

Crystalline to Amorphous: Unveiling the Potential of Transition Metal Oxide‐based Electrocatalysts for Facile Oxygen Evolution Reaction in Alkaline Media

AbstractTransition metal oxides/hydroxides exhibit reasonable oxygen activity in alkaline electrolytes and have been identified as potential electrocatalysts. Some highly active transition metal oxides or hydroxides can alter their surface chemistry in response to the electrolyte environment. This review presents the performance of some of the recently developed transition metal‐based oxides in electrocatalytic oxygen evolution reaction (OER). Despite the promising catalytic activity of many transition metals and their alloys due to their incompletely filled d orbitals, their low corrosion resistance in alkaline media barriers their use as electrocatalysts. Metallic glasses (MGs), with their disordered atomic structure, have many unique and exciting properties that cannot be found in crystalline metals. Metallic glasses′ unique chemical activity and corrosion resistance stem from their metastable and defective nature, as well as their structural and chemical homogeneity. In the case of Zr‐based MGs, the presence of MG−OHads and MG−Ox species on the surface for oxygen evolution enables rapid electron transfer to chemisorbed OH− with an “activated” MG surface leading to the generation of an amorphous Zr‐rich layer. Zr‐rich oxide layer formation favors the OER understood by decreased Tafel slope and highly stable nature during open circuit potential measurements in the alkaline solution. Unlike the as‐spun counterpart, the relatively small impedance magnitude and characteristic frequency for the post‐OER electrode corroborate the enhancement of oxygen evolution kinetics after electrochemistry. Compared with the early discovered electrodes, the MG‐oxide assembly outperforms many transition and precision metal‐based oxides and their composite forms regarding oxygen electroactivity and stability.

Intermetallic Cobalt Indium Nanoparticles as Oxygen Evolution Reaction Precatalyst: A Non-Leaching p-Block Element.

Merely all transition-metal-based materials reconstruct into similar oxyhydroxides during the electrocatalytic oxygen evolution reaction (OER), severely limiting the options for a tailored OER catalyst design. In such reconstructions, initial constituent p-block elements take a sacrificial role and leach into the electrolyte as oxyanions, thereby losing the ability to tune the catalyst's properties systematically. From a thermodynamic point of view, indium is expected to behave differently and should remain in the solid phase under alkaline OER conditions. However, the structural behavior of transition metal indium phases during the OER remains unexplored. Herein, are synthesized intermetallic cobalt indium (CoIn3 ) nanoparticles and revealed by in situ X-ray absorption spectroscopy and scanning transmission microscopy that they undergo phase segregation to cobalt oxyhydroxide and indium hydroxide. The obtained cobalt oxyhydroxide outperforms a metallic-cobalt-derived one due to more accessible active sites. The observed phase segregation shows that indium behaves distinctively differently from most p-block elements and remains at the electrode surface, where it can form lasting interfaces with the active metal oxo phases.

Transition Metals Based Dual Single‐atom Catalysts for Oxygen Electrocatalysis: Stunning Advances and Future Prospects

AbstractDuring the past few years, single‐atom catalysts (SACs) have attracted considerable attention in electrolysis due to their outstanding catalytic performance and efficient atomic utilization. SACs exhibit a simple structure, high catalytic activity, consistent scaling relationships for single sites, and low metal content but their practical applications are still limited. Dual single‐atom catalysts (DACs), which feature excellent selectivity, high atomic utilization efficiency, and remarkable stability, are emerging as new frontiers in heterogeneous electrocatalysis. They increase catalytic activity by promoting synergistic effects between metal‐active sites. In this paper, we present a comprehensive overview of the latest developments in dual‐atom catalysts for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). In addition, we explore the differences between homonuclear and heteronuclear configurations, the emergence of single/dual‐site metal catalysts, and the methods currently used for their synthesis. Lastly, this review discusses several perspectives for advancing the development of dual‐atom catalysts for OER and ORR electrocatalysis.

FeCoNi molybdenum-based oxides for efficient electrocatalytic oxygen evolution reaction

The search for highly efficient and inexpensive electrocatalysts is crucial to the advancement of environmentally friendly and sustainable energy sources. Here, adopting a one-step hydrothermal method, we have effectively fabricated a self-supported multi-metal molybdenum-based oxide (FeCoNi-MoO4) on nickel foam (NF). In addition to changing the catalyst's microstructure, the introducing of Fe and Co, enhanced its active center count, improved its electronic structure, and in turn reduced the difficulty for high-valence Ni and Fe species to form, which accelerates the oxygen evolution reaction (OER) kinetics by promoting the development of the actual active materials, NiOOH and FeOOH. FeCoNi-MoO4 has outstanding OER performance, requiring just 204 mV overpotentials at 10 mA cm−2 and 271 mV at 100 mA cm−2. Its exceptional OER kinetics at both low and high currents are indicated by a Tafel slope of 50.6 mV dec−1, which is attributed to the combined effect of its multi-metal composition and a higher number of active sites. Moreover, the FeCoNi-MoO4 electrode was operated continuously for over 48 h. Furthermore, the density functional theory (DFT) results demonstrated that the introducing of Fe and Co, which quickens the rate of electron transfer during the electrocatalytic process, improves the ability of oxygen intermediate species to adsorb, and ultimately lowers the overpotential, is responsible for the increased electrocatalytic activity of FeCoNi-MoO4. This work offers hope for further developments in the sector by proposing an efficient approach for creating multi-active electrocatalysts that are stable, economical, and efficient.

Operando Tracking the Interactions between CoOx and CeO2 during Oxygen Evolution Reaction

AbstractCeO2 greatly enhances the electrocatalytic oxygen evolution reaction (OER) activity of CoOx, though the enhancement mechanism beyond this synergy is yet to be understood. Here, operando hard X‐ray absorption spectroscopy (hXAS) is applied to monitor the Co K edge and Ce L3 edge in CoOx/CeO2 to shed light on the evolution of the Co and Ce oxidation states during OER. In addition, ex situ soft XAS (sXAS) characterizations provide information on the irreversible surface‐specific transformations of the Co L3 edge as well as of the O K edge. Combining the operando and ex situ spectroscopic characterizations with comprehensive electrochemical analyses, it is confirmed that CeO2 is not the active center for the OER. However, coupling CeO2 with CoOx introduces significant modifications in the Co and O species at the CoOx surface and alters the flat band potential (Efb), leading to more favorable Co oxidation state transformations during OER and possibly modifying the preferential reaction pathway. This work establishes the connections between electronic structures, Co oxidation state and the OER reaction mechanism for CoOx/CeO2 composites electrodes.

Experimental evidences of the direct influence of external magnetic fields on the mechanism of the electrocatalytic oxygen evolution reaction

The use of magnetic fields as external stimuli to improve the kinetics of electrochemical reactions is attracting substantial attention, given their potential to reduce energy losses. Despite recent reports showing a positive effect on catalytic performance upon applying a magnetic field to a working electrode, there are still many uncertainties and a lack of experimental evidence correlating the presence of the magnetic field to the electrocatalytic performance. Here, we present a combination of electrochemical and spectroscopic tools that demonstrate how the presence of an external magnetic field alters the reaction mechanism of the electrocatalytic oxygen evolution reaction (OER), accelerating the overall performance of a Ni4FeOx electrode. Complementary experimental evidence has been gathered supporting the participation of this microscopic magnetic field effect. Electrochemical impedance spectroscopy (EIS) points to a speed-up of the intrinsic reaction kinetics, independent of other indirect effects. In the same direction, the spectro-electrochemical fingerprint of the intermediate species that appear during the electrocatalytic cycle, as detected under operando conditions, indicates a change in the order of the reaction as a function of hole accumulation. All these experimental data confirm the direct influence of an external magnetic field on the reaction mechanism at the origin of the magnetically enhanced electrocatalytic OER.