Iridium–nickel composite oxide catalysts for oxygen evolution reaction in acidic water electrolysis

Xu, Shuai; Liu, Yuan; Tong, Jinlin; Hu, Wei; Xia, Qinghua

doi:10.1134/s1023193516110124

Cited by 12 publications

(8 citation statements)

References 50 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Doping of Co within RuO 2 and IrO 2 was shown from DFT calculations to alter the electron density and influence changes in the binding energies of intermediates resulting in structures with lower activation energies . In addition to computational studies, a number of experimental studies have investigated interacting Ni within IrO x to increase the OER activity. ,− In model thin films, interaction of Ni within IrO x was shown to yield a 20-fold improvement in Ir OER mass activity over pure IrO x . The effect of Ni on the activity was explained by the leaching of unstable Ni that promoted the formation of structurally flexible and reactive OH groups that act as reactive surface intermediates …”

Section: Introductionmentioning

confidence: 99%

“…Building from our study of Ni−Pt 2D nanoframe ORR catalysts, in this work we investigated the synthesis, structure, OER activities, and stabilities of nickel−iridium (Ni−Ir) 2D nanoframes derived from Ir-decorated NiO nanosheets. Compared with prior work that investigated forming unsupported Ir−Ni structures from deposition of Ir onto metallic Ni nanowires 5 and from pyrolysis of IrCl 3 and NiCl 2 precursors, 14 we explored Ir−Ni nanoarchitectures obtained from thermal and chemical treatment of Ir-decorated NiO nanosheets which result in a unique 3D morphology, surface structure, and high OER activity. We evaluated the effects of thermal treatment temperature, acid leaching, and electrochemical oxidation on the material structure and OER activity and stability.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Self-Supported Hydrous Iridium–Nickel Oxide Two-Dimensional Nanoframes for High Activity Oxygen Evolution Electrocatalysts

et al. 2018

View full text Add to dashboard Cite

Oxygen evolution reaction (OER) electrocatalysts with high activity, high stability, and low costs are needed for proton-exchange membrane (PEM) electrolyzers. Based on the high cost and limited supply of iridium, approaches that result in iridium-based OER catalysts with increased catalytic activity are of significant interest. We report a carbon-free, self-supported hydrous iridium−nickel oxide two-dimensional nanoframe structure synthesized by thermal treatment of iridium-decorated nickel oxide nanosheets under reducing conditions and subsequent chemical leaching in acid. The catalyst nanoarchitecture contains an interconnected network of metallic iridium−nickel alloy domains with hydrous iridium oxide and nickel oxide located in the surface region. The electrochemical oxidation step maintains the three-dimensional nanoarchitecture and results in a thin (∼5 Å) oxide/hydroxide surface layer. The temperature used for thermal reduction was found to strongly affect the catalyst surface structure and OER activity. Using a lower thermal reduction temperature of 200 °C was determined to provide a higher relative surface concentration of hydroxides and nickel oxide and result in higher OER activities compared with materials treated at 300 °C. The 200 °C-treated hydrous iridium−nickel oxide electrocatalyst showed 15 times higher initial OER mass activity than commercial IrO 2 , and the activity remained 10 times higher than IrO 2 after accelerated durability testing. Density functional theory (DFT) calculations and analysis of the experimental Tafel slopes support that the second electron transfer step is the rate-limiting step for the reaction. The DFT calculations demonstrate that Ni substitution on the IrO 2 surface lowers the activation energy for adsorbed intermediates of the second electron transfer step of the OER reaction. This work establishes that noble metal-decorated metal oxide nanosheets can be transformed into high surface area, carbon-free electrocatalyst nanostructures with high catalytic activities and molecular accessibility and reveals the importance of using controlled thermal reduction temperatures to alter the surface structure and OER activity.

show abstract

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Self-Supported Hydrous Iridium–Nickel Oxide Two-Dimensional Nanoframes for High Activity Oxygen Evolution Electrocatalysts

et al. 2018

View full text Add to dashboard Cite

show abstract

“…These values were close to the ones for Ir-base materials reported in the literature. 5,8,14,17,23,24 The measured low Tafel slopes of Ir x Co 1−x O y nanocomposites with 0.46 ≤ x ≤ 0.71 suggest the favorable OER kinetics in the materials having Ir, in contrast to Co 3 O 4 nanotubes having a relatively large Tafel slope, 66.2 mV dec −1 . Table 1 also presents the potentials achieving 10 mA cm −2 for the catalysts tested in the current study.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Nanotubular Iridium–Cobalt Mixed Oxide Crystalline Architectures Inherited from Cobalt Oxide for Highly Efficient Oxygen Evolution Reaction Catalysis

Lee

Kim

et al. 2017

ACS Appl. Mater. Interfaces

View full text Add to dashboard Cite

Here, we report the unique transformation of one-dimensional tubular mixed oxide nanocomposites of iridium (Ir) and cobalt (Co) denoted as IrCoO, where x is the relative Ir atomic content to the overall metal content. The formation of a variety of IrCoO (0 ≤ x ≤ 1) crystalline tubular nanocomposites was readily achieved by electrospinning and subsequent calcination process. Structural characterization clearly confirmed that IrCoO polycrystalline nanocomposites had a tubular morphology consisting of Ir/IrO and CoO, where Ir, Co, and O were homogeneously distributed throughout the entire nanostructures. The facile formation of IrCoO nanotubes was mainly ascribed to the inclination of CoO to form the nanotubes during the calcination process, which could play a critical role in providing a template of tubular structure and facilitating the formation of IrO by being incorporated with Ir precursors. Furthermore, the electroactivity of obtained IrCoO nanotubes was characterized for oxygen evolution reaction (OER) with rotating disk electrode voltammetry in 1 M NaOH aqueous solution. Among diverse IrCoO, IrCoO nanotubes showed the best OER activity (the least-positive onset potential, greatest current density, and low Tafel slope), which was even better than that of commercial Ir/C. The IrCoO nanotubes also exhibited a high stability in alkaline electrolyte. Expensive Ir mixed with cheap Co at an optimum ratio showed a greater OER catalytic activity than pure Ir oxide, one of the most efficient OER catalysts.

show abstract

“…Prior reports on Ir‐based electrocatalysts for OER have utilized IrO 2 and/or Ir alloys supported on carbon or transition metal supports, with only one example of the pyrolysis of iridium chloride with nickel oxide . Moreover, pyrolyzing organometallics onto high surface area carbon has shown to improve OER performance .…”

Section: Figurementioning

confidence: 99%

“…[33] Prior reports on Ir-based electrocatalysts for OER have utilized IrO 2 and/or Ir alloys supported on carbon or transition metal supports, [33,34,35,36] with only one example of the pyrolysis of iridium chloride with nickel oxide. [37] Moreover, pyrolyzing organometallics onto high surface area carbon has shown to improve OER performance. [38,39,40] It has also been demonstrated that doping heteroatoms such as nitrogen, phosphorus, and boron within carbon supports can contribute to the overall improved electrocatalytic activity by modulating the electronic structure of the Ir center.…”

mentioning

confidence: 99%

Decoupling Oxygen and Chlorine Evolution Reactions in Seawater using Iridium‐based Electrocatalysts

Johnson

et al. 2020

ChemCatChem

View full text Add to dashboard Cite

A series of iridium (Ir) organometallic-based electrocatalysts fused onto high surface-area activated carbon using pyrolysis were prepared for the oxygen evolution reaction (OER) in seawater electrolysis. These catalysts had a low loading of Ir (< 6 wt%), while also inducing atom coordination to the Ir center. The morphology and chemical composition of these electrocatalysts were analyzed by scanning electron microscopy, energy dispersive spectroscopy, and X-ray photoelectron spectroscopy, which all showed a uniform dispersion of Ir and heteroatom-doped moieties. To assess electrocatalytic activity, we used an artificial electrolyte comprising 0.1 M HClO 4 + 3.5 wt % NaCl, and found that these catalysts delivered a low overpotential of 243 mV, a low Tafel slope (92 mV dec À 1), and a high exchange current density (1.4 mA cm À 2). By using a headspace chlorine gas (Cl 2) detector in situ, we discovered that a Cl 2 content of 27 ppm was present. When tested in synthetic seawater, the overpotential exhibited a twofold increase, yet Cl 2 was undetected, thus indicating favorable OER kinetics. This significant finding exemplifies the need for in situ Cl 2 detection for seawater splitting research, since further insight can be derived to help guide the design of novel electrocatalysts.

show abstract

Iridium–nickel composite oxide catalysts for oxygen evolution reaction in acidic water electrolysis

Cited by 12 publications

References 50 publications

Self-Supported Hydrous Iridium–Nickel Oxide Two-Dimensional Nanoframes for High Activity Oxygen Evolution Electrocatalysts

Self-Supported Hydrous Iridium–Nickel Oxide Two-Dimensional Nanoframes for High Activity Oxygen Evolution Electrocatalysts

Nanotubular Iridium–Cobalt Mixed Oxide Crystalline Architectures Inherited from Cobalt Oxide for Highly Efficient Oxygen Evolution Reaction Catalysis

Decoupling Oxygen and Chlorine Evolution Reactions in Seawater using Iridium‐based Electrocatalysts

Contact Info

Product

Resources

About