Enhanced Oxygen Evolution Reaction Research Articles

Multiphase interface coupling of Ni-based sulfide composites for high-current-density oxygen evolution electrocatalysis in alkaline freshwater/simulated seawater/seawater.

Constructing highly efficient electrocatalysts is vital to enhance oxygen evolution reaction (OER) performance at industrially relevant current densities. Herein, three-phase coupled Ni3S2/r-NiS/h-NiS composites are grown in situ on Ni foam (NNSN/NF) via a one-step solvothermal approach. The as-prepared composites need overpotentials of only 377 mV, 451 mV and 476 mV at 1000 mA cm-2 for the OER in alkaline freshwater, simulated seawater and seawater, respectively. In addition, the optimized catalyst exhibited long-term durability at 300 mA cm-2. Our work clarifies designing and preparing cost-effective Ni-based sulfide electrocatalysts for the OER in alkaline freshwater/simulated seawater/seawater under industrially relevant current densities.

Co9S8 core-shell hollow spheres for enhanced oxygen evolution and methanol oxidation reactions by sulfur vacancy engineering.

Cobalt sulfides, especially Co9S8, have been widely studied as a potential earth-abundant electrocatalyst for many electrochemical reactions, such as oxygen evolution reaction (OER) and methanol oxidation reaction (MOR). However, the electrocatalytic performance of Co9S8 is not satisfactory because of its comparatively sluggish charge transport and reaction kinetics. Defect engineering and constructing hollow nanostructures are effective methods to improve their electrocatalytic performance, therefore, exploring an efficient route to obtain Co9S8 catalysts, simultaneously possessing sulfur vacancies and hollow nanostructure, is necessary. In this study, Co9S8-x core-shell hollow spheres with sulfur vacancies were prepared via a two-step solvothermal strategy, followed by thermal treatment under an H2/Ar atmosphere. The content of sulfur vacancies can be regulated by varying the temperature during the thermal treatment. The obtained Co9S8-x core-shell hollow spheres exhibited interesting sulfur vacancy defect-dependent activity, one of which showed outstanding electrocatalysis performance for OER with an overpotential (η) of 294 m V (at 10 mA cm-2) and MOR catalysis efficiency (164.9 mA cm-2 at 1.8 V vs. RHE) in an alkaline medium. This study provides a promising and feasible pathway for developing efficient trifunctional electrocatalysts for renewable energy technologies.

Moss-like CoB/CeO2 heterojunction as an efficient electrocatalyst for oxygen evolution reaction under alkaline conditions

Heterostructure construction has become increasingly recognized as an effective strategy to enhance oxygen evolution reaction (OER) performance due to the exposed active surfaces and improved mass/charge transfer. Inspired by natural...

Enhanced oxygen evolution reaction activity on two-dimensional vdW ferromagnetic Cr2Ge2Te6 through synergism between two active sites.

To design an efficient, low-cost, and easily recoverable oxygen evolution reaction (OER) electrocatalyst, this work focuses on two-dimensional vdW ferromagnetic Cr2Ge2Te6. Based on the density functional theory (DFT) calculations, the adsorption of oxygen-containing intermediates during the OER process will gradually decrease the bandgap of Cr2Ge2Te6, thus increasing its electrical conductivity. More importantly, we propose a two active sites synergistic mechanism through a hydroxyl-boosted pathway. With the combined action of the two active sites, the binding between the oxygen-containing intermediates and the surfaces is enhanced. The enhancement comes from dramatic charge-transfer-induced Te-3p and O-2p orbital enhancement. As a result, the overpotential of the OER reduces from 1.25 to 0.59 V. We hope these findings will pave the way for more experimental and theoretical research to explore the potential applications of two-dimensional vdW ferromagnetic materials in energy storage and conversion.

High ratios of Ni3+ and Co3+ facilitated by Mn-addition for enhanced oxygen evolution reaction and ethanol oxidation reaction

The design of dual-functional catalyst for oxygen evolution reaction and ethanol oxidation reaction is essential for improving H2 production efficiency, and one strategy to improve catalytic performance is the incorporation of high-valence metal.

Ultrasmall RuO2/CoFe2O4 nanoparticles with robust interfacial interactions for the enhanced acidic oxygen evolution reaction

Ultrasmall RuO2/CoFe2O4 nanoparticles with strong interfacial interactions exhibit enhanced oxygen evolution reaction (OER) performance, driven by efficient charge transfer between RuO2 and CoFe2O4.

Enhanced stability of boron modified NiFe hydroxide for oxygen evolution reaction.

The introduction of non-metal elements including boron has been identified as a significant means to enhance oxygen evolution reaction (OER) performance in NiFe-based catalysts. To understand the catalytic activity and stability, recent attention has widened toward the Fe species as a potential contributor, prompting exploration from various perspectives. Here, boron incorporation in NiFe hydroxide achieves significantly enhanced activity and stability compared to the boron-free NiFe hydroxide. The boron inclusion in NiFe hydroxide is found to show exceptionally improved stability from 12 to 100 hours at a high current density (200 mA cm-2). It facilitates the production and redeposition of OER-active, high-valent Fe species in NiFe hydroxide based on the operando Raman, UV-vis, and X-ray absorption spectroscopy analysis. It is proposed that preserving a homogenous distribution of Fe across the boron-containing catalyst surface enhances OER stability, unlike the bare NiFe hydroxide electrocatalyst, which exhibits uneven Fe dissolution, confirmed through elementary mapping analysis. These findings shed light on the potential of anionic regulation to augment the activity of iron, an aspect not previously explored in depth, and thus are expected to aid in designing practical OER electrocatalysts.

Facile synthesis of nanostructured Ni/NiO/N-doped graphene electrocatalysts for enhanced oxygen evolution reaction.

Electrocatalysts containing a Ni/NiO/N-doped graphene interface have been synthesised using the ligand-assisted chemical vapor deposition technique. NiO nanoparticles were used as the substrate to grow N-doped graphene by decomposing vapours of benzene and N-containing ligands. The method was demonstrated with two nitrogen-containing ligands, namely dipyrazino[2,3-f:2',3'-h]quinoxaline-2,3,6,7,10,11-hexacarbonitrile (L) and melamine (M). The structure and composition of the as-synthesized composites were characterized by XRD, Raman spectroscopy, SEM, TEM and XPS. The composite prepared using the ligand L had NiO sandwiched between Ni and N-doped graphene and showed an overpotential of 292 mV at 10 mA cm-2 and a Tafel slope of 45.41 mV dec-1 for the OER, which is comparable to the existing noble metal catalysts. The composite prepared using the ligand M had Ni encapsulated by N-doped graphene without NiO. It showed an overpotential of 390 mV at 10 mA cm-2 and a Tafel slope of 78.9 mV dec-1. The ligand-assisted CVD route demonstrates a facile route to control the microstructure of the electrocatalysts.

Facile synthesis of AuIr alloy nanoparticles and their enhanced oxygen evolution reaction performance under acidic and alkaline conditions.

The development of electrocatalysts that can maintain high reactivity and stability over a wide pH range during electrolysis reactions is essential for the realization of a clean hydrogen energy society. Herein, we report the synthesis of AuIr alloy nanoparticles (NPs) with an excellent oxygen evolution reaction (OER) performance over a wide pH range. The NPs were synthesized via an antisolvent crystallization-based method and maintained their small sizes regardless of adjustments in the ratio of the Au/Ir precursor. AuIr/C exhibited low overpotential and good long-term stability under acidic and alkaline conditions compared with the Ir/C and commercial RuO2. The enhanced OER performance of AuIr/C was attributed to efficient charge transfer, resulting in an optimal synergistic effect of electrons.

Electronic redistribution through the interface of MnCo2O4-Ni3N nano-urchins prompts rapid In situ phase transformation for enhanced oxygen evolution reaction.

One of the most coveted objectives in the realm of energy conversion technologies is the development of highly efficient and economically viable electrocatalysts for the oxygen evolution reaction. The commercialization of such techniques has thus far been impeded by their slow response kinetics. One of the many ways to develop highly effective electrocatalysts is to judiciously choose a coupling interface that maximizes catalyst performance. In this study, the in situ electrochemical phase transformation of MnCo2O4-Ni3N into MnCo2O4-NiOOH is described. The catalyst has an exceptional overpotential of 224 mV to drive a current density of 10 mA cm-2. Strong interfacial contact is seen in the MnCo2O4-Ni3N catalyst, leading to a considerable electronic redistribution between the MnCo2O4 and Ni3N phases. This causes an increase in the valence state of Ni, which makes it an active site for the adsorption of *OH, O*, and *OOH (intermediates). This charge transfer facilitates the rapid phase transformation to form NiOOH from Ni3N. At a higher current density of 300 mA cm-2, the catalyst remained stable for a period of 140 h. DFT studies also revealed that the in situ-formed NiOOH on the MnCo2O4 surface results in superior OER kinetics compared to that of NiOOH alone.

Atomically dispersed Ru doped on IrOx sub-nanoclusters for enhanced oxygen evolution reaction in acidic media

Atomically dispersed Ru doped on IrOx sub-nanocluster is fabricated for acidic oxygen evolution reaction, showing a low overpotential of 237 mV at 10 mA cm−2 and high durability by sustaining a current of 100 mA cm−2 for 150 hours.

Strategic cation exchange induced 2D nickel sulphide nanoplates with enhanced oxygen evolution reaction performance

A cation exchange method enables the synthesis of highly crystalline 2D NixS nanoplates with fine-tuned morphology. These nanoplates exhibit excellent OER performance, achieving a 329 mV overpotential at 10 mA cm−2 and a 52 mV dec−1 Tafel slope.

Harnessing lattice oxygens in a high-entropy perovskite oxide for enhanced oxygen evolution reaction

Development of highly active and stable electrocatalysts for oxygen evolution reaction (OER) is the main challenge in water electrolysis for green hydrogen production. Although Ru-based electrocatalysts have been in use...

Unraveling the mechanism of enhanced oxygen evolution reaction using NiOx@Fe3O4 decorated on surface-modified carbon nanotubes

Laser-driven synthesis of NiOx@Fe3O4 on surface-modified carbon nanotubes is developed for enhanced oxygen evolution reaction.

Zn-facilitated surface reconstruction of Ni-MOF for an enhanced oxygen evolution reaction.

Facilitating the surface reconstruction of pre-catalysts has been considered an effective strategy for constructing low-cost and highly efficient OER electrocatalysts. Metal doping is a feasible way to activate the surface reconstruction, thus enhancing the OER performance. Herein, we report a facile hydrothermal method to synthesize a series of Zn-doped Ni-MOF on nickel foam (NiZn-MOF/NF) as promising pre-catalysts toward the oxygen evolution reaction (OER). The Zn leaching of NiZn-MOF/NF can promote the surface self-reconstruction of NiZn-MOF/NF into oxygen-vacancy-rich NiOOH after electrochemical activation. Benefiting from the optimized electronic structure, abundant defects, more accessible active sites, and enhanced electrical conductivity, the reconstructed metal oxyhydroxide hybrids exhibit better electrocatalytic activity than the catalysts transformed from Ni-MOF/NF without Zn doping. The optimized NiZn-MOF/NF-OH as an OER catalyst has an overpotential of 336 mV at 100 mA cm-2, and a Tafel slope of 65.9 mV dec-1, as well as stability over 12 h. This work reveals that Zn cation-doping/leaching induces the surface reconstruction of pre-catalysts for enhanced oxygen catalytic activity, which provides a new approach for the development of advanced electrocatalysts.

Exquisite regulated CeO2/Co (OH)2 electrocatalysts for enhanced oxygen evolution reaction

The development of advanced transition metals catalysts for the efficient electrocatalytic oxygen evolution have been widely studied, which have the potential to replace precious metal and achieve widespread commercial application....

Unveiling the impact of oxygen vacancies in engineered bimetallic oxides for enhanced oxygen evolution reaction: insights from experimental and theoretical approaches

In this study, we presented hollow bimetallic mixed oxides of molybdenum and nickel, prepared through a facile polymer-assisted solution process.

A Co and Fe bimetallic MOF with enhanced electrocatalytic oxygen evolution performance: exploring the electronic environment modifications upon Fe incorporation

The incorporation of iron into the cobalt-based metal–organic framework modifies the electronic environment and the resulting bimetallic MOF exhibits enhanced oxygen evolution reaction performance.

Polyoxometalate-incorporated NiFe-based oxyhydroxides for enhanced oxygen evolution reaction in alkaline media.

NiFe-based oxyhydroxides are promising electrocatalysts for the oxygen evolution reaction (OER) in alkaline media, but further enhancing their OER performance remains a significant challenge. Herein, we in situ incorporated polyoxometalates into NiFe oxyhydroxides to form a homogeneous/heterogeneous hybrid material, which induces the electronic interaction between Ni, Fe and Mo sites, as revealed by a variety of characterization experiments and theoretical calculations. The resulting hybrid electrocatalyst delivers a low overpotential of 203 mV at 10 mA cm-2 and a TOF of 2.34 s-1 at 1.53 V in alkaline media. This work presents a critical step towards developing high-performance OER catalysts by constructing metal-POM hybrids.

A Hierarchical Polyoxometalate/Pd/Mos2 Hybrid: Developing an Efficient Novel Bifunctional Catalyst for Water Splitting

AbstractCatalytic water splitting is a promising approach to produce clean hydrogen fuel from renewable energy sources. However, developing hybrid heterostructures capable of efficiently breaking down water into its constituent elements, hydrogen, and oxygen, presents a considerable challenge. In this study, a novel hierarchical POM/Pd/MoS2 hybrid heterostructure, composed of sheets of MoS2 modified with Pd nanoparticles and combined with a cobalt‐based polyoxometalate (POM), serving as bifunctional catalyst for water splitting is reported. Through a synergistic synthetic approach, MoS2, acting as a reducing agent, triggers the nucleation and growth of Pd nanoparticles, which, in turn, serve as anchoring sites for the polymerization of the cobalt‐based POM into fibers. POM/Pd/MoS2 hybrid exhibits an enhanced oxygen evolution reaction (OER) activity, comparable to the benchmark catalysts Ir/C and IrO2/C in alkaline media, being its hydrogen evolution reaction (HER) activity similar to the activated Pd/MoS2 hybrid. The intriguing electrocatalytic capability of the resulting material for producing hydrogen and oxygen through electrochemical means arises from the enhanced charge storage capacity and conductivity of MoS2, the multi‐electron transfer facilitated by the POM, and the high electrocatalytic activity of the metals.