Efficient OER Electrocatalysts Research Articles

Vanadium-doped FeO/NiS nanosheet arrays: Synergistic heterometal doping and heterostructure design for enhanced oxygen evolution catalysis

The quest for high-performance OER electrocatalysts has been a focal point in the field of energy conversion and storage. Despite the promise shown by nickel sulfide-based materials, the enhancement of their catalytic activity through singular strategies has been found to be inadequate for achieving the desired comprehensive performance improvements. In this context, we introduce a novel V-doped FeO/NiS nanosheet array (V-FeO/NiS/NF) synthesized through a synergistic approach involving heteroatom doping and heterostructure engineering. This advanced material exhibits structural integrity, a three-dimensional nanosheet morphology, and superior electrical conductivity, which collectively contribute to its exceptional electrochemical performance. The V-FeO/NiS/NF electrode can reach a current density of 10 mA cm−2 with an impressively low overpotential of 213 mV and sustains its activity for an extended period of 196 hours, surpassing the stability and efficiency of many electrodes. Theoretical insights reveal that vanadium doping significantly lowers the adsorption free energy of key reaction intermediates, thereby facilitating the OER process. This study not only presents a robust and efficient OER electrocatalyst but also paves the way for the design of advanced, cost-effective nickel-based sulfide catalysts through strategic heteroatom incorporation and structural optimization.

NiFeCo alloy nanoparticles composited with phosphorus-doped vacancies-abundant carbon substrates as electrocatalyst for oxygen evolution reaction

Transition metal alloy nanoparticles are cost-effective electrocatalysts for oxygen evolution reactions. Preparing alloy catalysts with flexible controllability, high activity, and long-term stability is a challenge. By adjusting the proportion of metal atoms and engineering vacancies through their composite with a carbon substrate, we can enhance electron transfer and modulate the adsorption capacity of reaction intermediates. Herein, we synthesized a hybrid catalyst using Prussian blue analogs (PBAs) as the precursor, doped with Fe and Ni atoms, and subjected them to a defective engineering and phosphatization process. As an efficient alkaline OER electrocatalyst, the formation of the alloy increases the number of active sites, while the defect-rich phosphorus-doped carbon substrate improves internal electron transfer and mass transfer channels. The synthesized NiFeCoPC-1.5 electrocatalyst exhibits excellent catalytic activity with an overpotential of 211 mV at 10 mA cm−2 and a Tafel slope of 59 mV dec−1, and demonstrates good stability up to 1000 CV cycles. This work will expand the application of alloy nanoparticles in oxygen evolution electrodes.

2D Ferromagnetic M3GeTe2 (M = Ni/Fe) for Boosting Intermediates Adsorption toward Faster Water Oxidation.

In this work, 2D ferromagnetic M3GeTe2 (MGT, M = Ni/Fe) nanosheets with rich atomic Te vacancies (2D-MGTv) are demonstrated as efficient OER electrocatalyst via a general mechanical exfoliation strategy. X-ray absorption spectra (XAS) and scanning transmission electron microscope (STEM) results validate the dominant presence of metal-O moieties and rich Te vacancies, respectively. The formed Te vacancies are active for the adsorption of OH* and O* species while the metal-O moieties promote the O* and OOH* adsorption, contributing synergistically to the faster oxygen evolution kinetics. Consequently, 2D-Ni3GeTe2v exhibits superior OER activity with only 370mV overpotential to reach the current density of 100mA cm-2 and turnover frequency (TOF) value of 101.6 s-1 at the overpotential of 200mV in alkaline media. Furthermore, a 2D-Ni3GeTe2v-based anion-exchange membrane (AEM) water electrolysis cell (1 cm2) delivers a current density of 1.02 and 1.32 A cm-2 at the voltage of 3V feeding with 0.1 and 1m KOH solution, respectively. The demonstrated metal-O coordination with abundant atomic vacancies for ferromagnetic M3GeTe2 and the easily extended preparation strategy would enlighten the rational design and fabrication of other ferromagnetic materials for wider electrocatalytic applications.

Universal synthesis of coral-like ternary MOF-derived sulfides as efficient OER electrocatalysts

Synthesize and tune a series of trimetallic sulfides to achieve efficient catalysis for the OER.

Preparation of Ni-doped ferrous oxalate nanorods electrocatalysts for oxygen evolution reaction

The development of new, efficient, and low-cost OER electrocatalysts with advanced structures is of great significance for hydrogen production by electrolysis of water. A Ni-doped ferrous oxalate nanorod electrocatalyst (Ni-FeC2O4) was synthesized using a one-step solvothermal method, which showed an outstanding OER activity with a low overpotential of 296 mV at 10 mA cm−2. The Ni-FeC2O4 electrocatalyst exhibited excellent OER stability in the 300 mV constant potential test, which was mainly attributed to the fact that Ni doping can increase the electrochemical active surface areas and the interfacial charge transfer abilities of the FeC2O4 electrocatalyst, optimize the electronic structure of the real active species ferric hydroxide, promote the formation of the decisive step *OOH of ferric hydroxide, and improve its intrinsic activity.

Accelerated deprotonation with a hydroxy-silicon alkali solid for rechargeable zinc-air batteries

Transition metal oxides are promising electrocatalysts for zinc-air batteries, yet surface reconstruction caused by the adsorbate evolution mechanism, which induces zinc-ion battery behavior in the oxygen evolution reaction, leads to poor cycling performance. In this study, we propose a lattice oxygen mechanism involving proton acceptors to overcome the poor performance of the battery in the OER process. We introduce a stable solid base, hydroxy BaCaSiO4, onto the surfaces of PrBa0.5Ca0.5Co2O5+δ perovskite nanofibers with a one-step exsolution strategy. The HO-Si sites on the hydroxy BaCaSiO4 significantly accelerate proton transfer from the OH* adsorbed on PrBa0.5Ca0.5Co2O5+δ during the OER process. As a proof of concept, a rechargeable zinc-air battery assembled with this composite electrocatalyst is stable in an alkaline environment for over 150 hours at 5 mA cm–2 during galvanostatic charge/discharge tests. Our findings open new avenues for designing efficient OER electrocatalysts for rechargeable zinc-air batteries.

The synergistic effect of Co3O4 and KNbO3 in Co3O4@KNbO3 composite for enhanced performance of water oxidation

A novel Co3O4@KNbO3 composite composed by Co3O4 and KNbO3 was synthesized via a two-step process combining the sol–gel method with calcination. Impressively, the obtained Co3O4@KNbO3 can be used as an efficient OER electrocatalyst with an overpotential of 330 mV at 10 mA·cm−2, a low Tafel slope of 61 mV·dec-1, and a negligible increase of the overpotential after the 3,000 cycle stability test. The excellent performance for OER was ascribed to the abundant electrochemical active sites and synergistic effect between Co3O4 and KNbO3.

Carbon Quantum Dots-Doped Ni3Se4/Co9Se8/Fe3O4 Multilayer Nanosheets Prepared Using the One-Step Solvothermal Method to Boost Electrocatalytic Oxygen Evolution.

Oxygen evolution reaction is a momentous part of electrochemical energy storage and conversion devices such as rechargeable metal-air batteries. It is particularly urgent to develop low-cost and efficient electrocatalysts for oxygen evolution reactions. As a potential substitute for noble metal electrocatalysts, transition metal selenides still prove challenging in improving the activity of oxygen evolution reaction and research into reaction intermediates. In this study, a simple one-step solvothermal method was used to prepare a polymetallic compound carbon matrix composite (Co9Se8/Ni3Se4/Fe3O4@C) with a multilayered nanosheets structure. It exhibited good OER activity in an alkaline electrolyte solution, with an overpotential of 268 mV at 10 mA/cm2. In addition, this catalyst also showed excellent performance in the 24 h stability test. The composite presents a multi-layer sheet structure, which effectively improves the contact between the active site and the electrolyte. The selenide formed by Ni and Co has a synergistic effect, and Fe3O4 and Co9Se8 form a heterojunction structure which can effectively improve the reaction activity by initiating the electronic coupling effect through the interface modification. In addition, carbon quantum dots have rich heteroatoms and electron transferability, which improves the electrochemical properties of the composites. This work provides a new strategy for the preparation of highly efficient OER electrocatalysts utilizing the multi-metal synergistic effect.

Integrating Cr doped FeOOH into FeSe2 nanoparticles for efficient water oxidation at large current densities

Developing a non-noble metal-based oxygen evolution electrocatalyst that works under high current densities is a challenging task in hydrogen production by water splitting. Herein, an efficient OER electrocatalyst was formed by combining Cr-doped FeOOH with high OER activity and FeSe2 with high conductivity. Through the addition of FeSe2 and the incorporation of Cr ion, the conductivity and intrinsic activity of the obtained Cr-FeOOH/FeSe2/NF towards OER are dramatically enhanced. To specific, the required overpotential is only 242 mV to realize the current density of 100 mA/cm2. In addition, the Cr-FeOOH/FeSe2/NF can output large current densities at industrial level, which only needs the overpotential of 293 and 336 mV to deliver the current density of 500 and 1000 mA/cm2, respectively. In addition, the overpotential is as low as 291 mV to attain 1000 mA/cm2 in 30 wt% KOH solution. More importantly, the obtained Cr-FeOOH/FeSe2/NF electrode can stable work for 80 h at such a high current density of industrial level, and the overpotential does not increase significantly. This result suggests that the obtained electrocatalyst has latent capacity for industrial application. This work points out the direction for building high-performance oxygen evolution electrocatalysts at large current densities.

Loose spherical FeOOH/MnO nanoarrays from a simple in situ hydrothermal method for enhanced oxygen evolution electrocatalysis

The development of abundant, low-cost, stable and efficient non-precious metal OER electrocatalysts is of great significance in large-scale water splitting for hydrogen production. Herein, loose spherical (Spherical-like composed of loose nanoarrays) MnFe bimetal oxide nanoarrays based on nickel foam were successfully synthesized by a simple in situ hydrothermal method. The loose nanoarrays facilitate water adsorption and exposure of active sites, enabling the catalyst to exhibit excellent electrocatalytic OER activity in alkaline media with an overpotential of 209 mV and a Tafel slope of 70 mV·dec−1. The addition of Fe greatly improves the electrical conductivity of the composites and the Fe site as the main active site, which together to the enhanced catalytic performance of FeOOH/MnO@NF (FeOOH/MnO In situ growth on Nickel Foam). In addition, the low crystallinity characteristic of the material is favorable for lattice distortion shrinkage, and the formation of Fe/Mn-O sites can accelerate the charge transfer rate, thereby accelerating the OER process. Meanwhile, the results of density functional theory calculations show that due to the strong interaction of electrons between the heterostructure, the displacement of the d-band center of the metal atom and the enhanced density of states near the Fermi level can adjust the binding energy intensity, which can affect the OER process, thereby improving the electrocatalytic performance. The findings broaden the exploration avenues of bimetallic oxyhydroxides as materials for water electrolysis and provides a new strategy for energy conversion and storage of sustainable energy.

Efficient OER electrocatalyst based on Co0.85Se/rGO nanocomposite

Efficient OER electrocatalyst based on Co0.85Se/rGO nanocomposite

Construction of Bimetallic Co/Fe-Incorporated PTA/FDA Nanoclusters for Boosting Electrocatalytic Oxygen Evolution

Summary. Electrochemical water decomposition as a crucial approach for the gradual growth of renewable energy has attracted extensive attention. Metal-organic frameworks (MOFs) which benefit from ultra-high specific surface area, controllable nanostructures, and excellent porosity have been widely used as high activity catalyst for the decomposition of water by electrochemical means. Herein, the composition and morphology of metal–organic framework nanoclusters with bimetallic Co/Fe-incorporated PTA/FDA nanoclusters is designed for efficient and durable OER electrocatalysts, including CoFe-BTC/PTA, CoFe-BTC/FDA, and CoFe-PTA/FDA. The crystal structure of MOF materials is composed of alternating organic hydrocarbon BTC, PTA, or FDA and inorganic metal oxide layer. Co and Fe interact as central atoms, joining BTC, PTA, or FDA ligands to form a highly symmetric MOF structure. The electronic structures and active sites of various metals are different, and the insertion of iron atoms plays a certain role in the regulation of their electronic structures. CoFe-PTA/FDA shows significant OER overpotential η 10 = 295 mV (1.525 V vs. RHE) reached 10 mA cm-2, with 62.85 mV dec-1 for Tafel slope and pretty conspicuous stability (72 hours of continuous testing). The DFT calculation results show coordination unsaturated metal atom is the primary active center of these electrocatalytic reaction, and the coupling effect caused by adding Fe is the key to adjust the electrocatalytic activity.

Sulfonated polybenzimidazole engineering defect-induced N, S-codoped carbon-supported Co3C hybrid composite as high-efficiency electrocatalyst for oxygen evolution reaction

The exploitation of efficient OER electrocatalysts has become the key to realize the commercial-application of H2 production from electrocatalytic water splitting. In this research, the novel defect-induced N, S co-doped carbon-supported Co3C nanoparticles were successfully fabricated as OER electrocatalyst by combination of wet-impregnation treatment of Co/sulfonated polybenzimidazole (sPBI) and subsequent thermal annealing treatment, which was denoted as Co3C/CNS-X (X=700, 800, 900) electrocatalyst. Among them, Co3C/CNS-800 delivered the more favorable architecture due to its large specific surface area, high dispersion of Co3C nanoparticles and especially the generation of abundant defects sites, which not only improved its conductivity and the amounts of electrocatalytically active sites but also imparted the extremely important functionality in accelerating the interfacial electron-transfer and facilitated the adsorption ability of intermediates, thus exerting the extraordinary activities for catalyzing OER. What's more, there were some evidences demonstrating the generation of the strong interfacial interactions through the Co-N coordination bonds and the formation of more pyridinic-N species though annealing treatment, which allowed the structural stability to be further strengthened and simultaneously gave impetus to the O2 release for the reduction of OER overpotential. In recognition of these approvable structural characteristics, the Co3C/CNS-800 exhibited the lowest overpotential of 300 mV at an anodic current density of 10 mA cm−2, and a small Tafel slope of 70 mV dec−1 in 1 M KOH electrolyte as well as a long durability.

Surface Reconstruction of Iron–Cobalt–Nickel Phosphides to Achieve High-Current-Density Water Oxidation Performance

The development of efficient and low-cost OER electrocatalysts that can achieve high current density and durable stability for the practical application of energy conversion devices remains a challenge. Herein, a Fe–Co–Ni-based phosphide heterojunction integrated electrocatalyst (FeCoNiP/NF) had been obtained by a facile hydrothermal-phosphating strategy. The results indicate that superior OER performance at a high current density in 1 M KOH has been achieved for the FeCoNiP/NF catalyst, which exhibits low overpotentials of 281 and 318 mV at 500 and 1000 mA cm–2, respectively. Furthermore, this catalyst also shows excellent activity and stability at industrial-grade KOH concentrations (30 wt %). The overpotentials are as low as 217 and 233 mV at 500 and 1000 mA cm–2, respectively, and they can be maintained for 48 h at 500 mA cm–2 with just 4% attenuation, which is one of the most efficient non-noble-metal-based OER catalysts at high current densities. The strong binding of P to metals and the self-supported architecture are beneficial to improve the conductivity and stability of the catalyst. Moreover, the multiple heterointerfaces will accelerate surface charge transport, and the formed oxyhydroxide active species by in situ phase reconstruction can significantly enhance the OER performance of the FeCoNiP/NF catalyst. This study not only synthesizes an efficient OER catalyst with a low overpotential at a high current density but also discusses the surface reconstruction of the catalysts in detail, which provides a distinct perspective for the design of high-performance electrocatalysts.

Cobalt modification of nickel–iron hydroxide electrocatalysts: a pathway to enhanced oxygen evolution reaction

Synthesis of ternary NiFeCo hydroxide as an efficient OER electrocatalyst using a versatile, two-step solution corrosion approach.

Experimentally revealed and theoretically certified synergistic electronic interaction of V-doped CoS for facilitating the oxygen evolution reaction.

Since electrocatalytic oxygen evolution (OER) is a four-electron transfer reaction with very slow kinetics, there is great competition to develop cheap, durable and efficient catalysts for oxygen evolution. A molecular model is designed for density functional theory (DFT) simulation calculations to guide the experiment, and this hypothesis is fully supported by the experimental data. Herein, regulating the composition and morphology of the bimetallic VCo and MoCo sulfide and monometallic sulfide nanoparticles (NPs) at the oil-water interface was achieved via a one-step hydrothermal method for efficient and durable OER electrocatalysts. Compared to CoS and MoCoS, the VCoS NPs show superior OER performance. By adjusting the atomic composition ratio of the VCoS nanoparticles, the VCoS NPs (1 : 2 : 1.5 mole ratio) showed a significant OER overpotential η = 255 mV (10 mA cm-2), and their outstanding stability was demonstrated after 48 h of continuous testing. The CoS and MoCoS NPs were also tested for comparison. Density functional theory (DFT) calculations showed that appropriate V doping (VCoS) can heighten the density of states (DOS) of the Fermi level, which generates more charge density and reduces the intermediate adsorption energy. This study not only provides efficient and powerful integrated catalysts, but also details a DFT calculation model guided by experiments to regulate the oxygen insertion technology, thus leading to the design of ideal materials and enabling more far-reaching applications in electrocatalysis.

Fe-modulated NH2–CoFe MOF nanosheet arrays on nickel foam by cation exchange reaction for an efficient OER electrocatalyst at high current density in alkaline water/seawater

Preparation of NH2–CoFe MOF for the OER in alkaline water/seawater.

Modification of micro/nanoscaled manganese dioxide-based materials and their electrocatalytic applications toward oxygen evolution reaction

The MnO2 OER electrocatalysts is modified by morphology control, structure construction, facet engineering, doping and heterojunctions, whose mechanisms and practical applications are summarized to develope efficient OER electrocatalysts.

The influence of increased content of Ni(III) in NiFe LDH via Zn doping on electrochemical catalytic oxygen evolution reaction

Developing efficient oxygen evolution electrocatalysts always shows great importance in the field of electrolysis of water. In this work, Zn-doped NiFe LDH is synthesized via a facile hydrothermal reaction. A series of structural characterizations revealed that the doping of Zn into NiFe LDH lattice can cause lattice distortion, which facilitates the formation of active NiOOH layers. The Zn–NiFe LDH electrocatalyst shows excellent performance in electrocatalytic oxygen evolution reaction, even overbeat the state-of-art RuO2. In addition, the doping of Zn into NiFe LDH significantly enhances the electrocatalytic stability of NiFe LDH, with only a 32.7 mV increase in potential after 100 h continuous OER electrolysis in 1.0 M KOH. The Zn–NiFe LDH provides an ideal strategy for designing highly efficient OER electrocatalysts for real applications.

Mn-induced strengthening hybridization effect of Co–O bond for stable oxygen evolution in acidic media

The development of transition metal-based acidic OER electrocatalyst is an important step to realize large-scale hydrogen production in low-cost proton exchange membrane (PEM) electrolytic cell. However, the current challenge is how to overcome the tendency of transition metal oxides dissolving in acidic environment to improve the long-term stability. Here, we prepared a trace amount of Mn-doped cobalt spinel oxide by simple room temperature ion exchange using a special Co-MOF precursor (CoBDC). Detailed physical characterizations combined with electrochemical tests showed that the introduction of infinitesimal Mn caused more particle cavities but did not destroy the crystal structure and intrinsic activity of cobalt spinel oxide. Due to the strengthening hybridization effect of Mn-induced Co-O bond, the stability of Mn0.08-Co3O4-400 is 4–5 times higher than that of Co3O4-400 in strong acidic environment. In addition, the confinement effect of specific metal–organic coordination structure of CoBDC also ensured the dispersity and stability of the highly active cobalt sites. In brief, this work provides an effective strategy for the preparation of stable and efficient non-noble metal-base acidic OER electrocatalysts.