Ir- and Ru-doped layered double hydroxides as affordable heterogeneous catalysts for electrochemical water oxidation

Fagiolari, Lucia; Zaccaria, Francesco; Costantino, Ferdinando; Vivani, Riccardo; Mavrokefalos, Christos K.; Patzke, Greta R.; Macchioni, Alceo

doi:10.1039/c9dt04306c

Cited by 30 publications

(36 citation statements)

References 101 publications

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“…[84] Since Ir is a scarce noble metal with high price, efforts should be devoted to increasing the atom utilization efficiency of Ir. [128][129][130] For this purpose, Ir-Ag nanotubes were fabricated by acid etching of Ir-Ag nanowires. [85] Benefiting from the hollow structure and enriched oxidized Ir on the surface of Ir-Ag nanotubes, the Ir 6 Ag 9 sample requires a low overpotential of 285 mV to achieve 10 mA cm −2 in 0.5 m H 2 SO 4 .…”

Section: Mono-metallic Ir Nanostructuresmentioning

confidence: 99%

“…[36] Driven by the limited availability and unsatisfied property of Ir, much efforts have been devoted to improving the OER performance through various strategies. [128][129][130] One straightforward and commonly used approach is to design and synthesize multi-metallic Ir-based nanostructures by alloying Ir with nonprecious transition metals such as Ni, Co, and Fe. [91,131,132] By alloying and composition optimization, the activity and stability of Ir-based nanostructures can be significantly enhanced compared to pure Ir or commercial IrO 2 .…”

Section: Multi-metallic Ir Nanostructuresmentioning

confidence: 99%

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Recent Progress in Advanced Electrocatalyst Design for Acidic Oxygen Evolution Reaction

et al. 2021

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more promising approach to generating H 2 with high purity. Electrochemical water splitting, driven by renewable electricity, proceeds through hydrogen evolution reaction (HER) at the cathode side and oxygen evolution reaction (OER) at the anode side of an electrochemical cell. [7,10] The HER, a two-electron transfer process, is the simplest electrochemical reaction and relatively easy to occur. On the contrary, OER involving four-electron transfer is a much more complicated multistep reaction. A considerably large overpotential is thus added to the actual water splitting process because of the complexity of OER, leading to sluggish reaction kinetics and distinctly reducing the energy efficiency. [11] Therefore, efficient electrocatalysts with high activity and durable stability are needed to overcome the high energy barrier.OER is an electrochemical process of producing molecular O 2 through a series of proton-electron coupled steps. [12][13][14] Depending on the pH of the electrolytes, the reaction pathways of producing O 2 are totally different. In alkaline electrolytes, hydroxyl groups (OH − ) are oxidized and converted to H 2 O and O 2 . In acidic media, two water molecules (H 2 O) are oxidized generating four protons (H + ) and O 2 . Compared to acidic OER, alkaline OER possesses more favorable reaction kinetics because of the abundant hydroxyl groups in the electrolyte. For acidic OER, however, the break of the strong covalent OH bond of H 2 O requires high energy thus leading to more sluggish kinetics. Another advantage for alkaline OER lies in the wide range of catalysts such as transition metal (e.g., Ni, Co, and Fe) based oxides and hydroxides as well as carbon materials. [15][16][17][18][19][20][21][22] The electrocatalysts for acidic OER are mostly related to iridium (Ir) and ruthenium (Ru) based materials currently. [19,[23][24][25][26][27][28][29][30][31] In spite of the more favorable kinetics and wide range of catalysts for alkaline OER, however, acidic OER is more preferable than alkaline OER because of the diversified advantages of proton exchange membrane water electrolyzers over alkaline water electrolyzers. [19,23] Proton exchange membrane (PEM) is an acidic solid polymer electrolyte membrane with much smaller gas crossover than that of the alkaline solid polymer, which can ensure a larger load range and much safer operation of an acidic electrolyzer by largely avoiding forming H 2 /O 2 mixture. [32] Furthermore, the fully developed PEMs can provide high proton conductivity, resulting in low Ohmic loss and high current density. [32] Proton exchange membrane (PEM) water electrolyzers hold great significance for renewable energy storage and conversion. The acidic oxygen evolution reaction (OER) is one of the main roadblocks that hinder the practical application of PEM water electrolyzers. Highly active, cost-effective, and durable electrocatalysts are indispensable for lowering the high kinetic barrier of OER to achieve boosted reaction kinetics. To date, a wide spectrum of advanced electroca...

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Section: Mono-metallic Ir Nanostructuresmentioning

confidence: 99%

Section: Multi-metallic Ir Nanostructuresmentioning

confidence: 99%

Recent Progress in Advanced Electrocatalyst Design for Acidic Oxygen Evolution Reaction

et al. 2021

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“…The high overpotential of the OER reaction is the most important factor affecting the efficiency of water electrolysis. [11][12][13][14][15][16][17][18][19][20] Up to now, despite a lot of research, RuO 2 is still considered to be the most active electrocatalyst for OER. However, its overpotential is still not low enough, and it has disadvantages such as poor stability and high price, which still needs to be further improved.…”

Section: Introductionmentioning

confidence: 99%

Nanostructured RuO₂–Co₃O₄@RuCo-EO with low Ru loading as a high-efficiency electrochemical oxygen evolution catalyst

et al. 2021

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“…In the vast realm of known WO catalysts (WOCs), significant progress has been recently made in the exploitation of base metals (e.g., Fe, Co, and Ni); − yet, the performance of noble metal systems (e.g., Ru and Ir) − still appears more promising, especially in terms of durability. This is why many research groups have engaged in the development of molecular, − heterogenized, ,− and heterogeneous − WOCs following a “noble-metal atom economy” approach . Despite the noticeable progress over the last decade, however, catalytic performance is still far from that desirable for commercial application.…”

Section: Introductionmentioning

confidence: 99%

Substituent Effects on the Activity of Cp*Ir(pyridine-carboxylate) Water Oxidation Catalysts: Which Ligand Fragments Remain Coordinated to the Active Ir Centers?

et al. 2021

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Identifying structure–property correlations for molecular water oxidation catalysts (WOCs) is strongly hampered by the complexity of the water oxidation (WO) reaction mechanism and catalyst in situ modifications. Here, the substitution effects for [Cp*Ir(X-pic)NO3] WOCs (pic = κ2-pyridine-2-carboxylate complexes) have been systematically explored by synthesizing several complexes differing for the nature of the X substituent on the pyridine-carboxylate ligand and testing them in WO driven by NaIO4. The activity data were correlated with the σ-Hammett parameter of the various substituents, which was proven to effectively reproduce the trends in electron donor properties of the ligands. The measured TOFmax values were found to roughly increase with the σ-Hammett parameter (i.e., with decreasing electron density at the metal center), reaching plateaux at activity values comparable to that of the simpler [Cp*Ir(H2O)3](NO3)2 catalyst. This trend has been typically observed for WOCs following a water nucleophilic attack mechanism. However, nuclear magnetic resonance studies on the reaction between [Cp*Ir(X-pic)NO3] and NaIO4 suggest that the activity is actually determined by the ease of pyridine-carboxylate ligand loss, likely being a necessary step toward precatalyst activation. This indicates that the same active species is generated from all [Cp*Ir(X-pic)NO3] starting complexes, albeit at different rates and/or in different amounts. A somewhat clear picture therefore appears to emerge, partially in contradiction with some of the hypotheses previously proposed: the active species should contain some degradation fragments of the Cp* (based on previous literature studies) and no X-pic derived ligands (based on the results reported in this work).

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Ir- and Ru-doped layered double hydroxides as affordable heterogeneous catalysts for electrochemical water oxidation

Abstract: Doping low-cost LDHs with noble metal atoms represents a promising approach to develop effective heterogeneous Water Oxidation Catalysts.

Cited by 30 publications

References 101 publications

Recent Progress in Advanced Electrocatalyst Design for Acidic Oxygen Evolution Reaction

Recent Progress in Advanced Electrocatalyst Design for Acidic Oxygen Evolution Reaction

Nanostructured RuO₂–Co₃O₄@RuCo-EO with low Ru loading as a high-efficiency electrochemical oxygen evolution catalyst

Substituent Effects on the Activity of Cp*Ir(pyridine-carboxylate) Water Oxidation Catalysts: Which Ligand Fragments Remain Coordinated to the Active Ir Centers?

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Ir- and Ru-doped layered double hydroxides as affordable heterogeneous catalysts for electrochemical water oxidation

Abstract: Doping low-cost LDHs with noble metal atoms represents a promising approach to develop effective heterogeneous Water Oxidation Catalysts.

Cited by 30 publications

References 101 publications

Recent Progress in Advanced Electrocatalyst Design for Acidic Oxygen Evolution Reaction

Recent Progress in Advanced Electrocatalyst Design for Acidic Oxygen Evolution Reaction

Nanostructured RuO2–Co3O4@RuCo-EO with low Ru loading as a high-efficiency electrochemical oxygen evolution catalyst

Substituent Effects on the Activity of Cp*Ir(pyridine-carboxylate) Water Oxidation Catalysts: Which Ligand Fragments Remain Coordinated to the Active Ir Centers?

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Nanostructured RuO₂–Co₃O₄@RuCo-EO with low Ru loading as a high-efficiency electrochemical oxygen evolution catalyst