Breaking Long-Range Order in Iridium Oxide by Alkali Ion for Efficient Water Oxidation

Gao, Jiajian; Xu, Chao; Hung, Sung‐Fu; Liu, Wei; Cai, Weizheng; Zeng, Zhiping; Jia, Chunmiao; Chen, Hao Ming; Xiao, Hai; Li, Jun; Huang, Yanqiang; Liu, Bin

doi:10.1021/jacs.8b11456

Cited by 404 publications

(389 citation statements)

References 60 publications

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“…In literatures, the Tafel slopes of crystalline IrO 2 and metallic Ir were recorded in the range from 40 to 70 and over 70 mV dec −1 , respectively, while the Tafel slopes for amorphous and hydrous IrO x were below 45 mV dec −1 in acidic media. [ 5,19 ] The Tafel slope of a ‐PN/IN frame/C was measured to be 47.49 mV dec −1 , indicating that the surface of a ‐PN‐IN frame/C consists of hydrous IrO x and crystalline IrO 2 as also revealed by XANES and XPS. Meanwhile, the Tafel slopes of a ‐PN‐IPN frame/C, a ‐IPN cage/C, and a ‐Ir/C catalysts were around 55 mV dec −1 , which are similar to the reported crystalline IrO 2 phases, indicating that these catalysts are less oxidized, leaving metallic Ir on the surface (Figure 4c,e).…”

Section: Resultsmentioning

confidence: 82%

“…[ 3 ] An amorphous form of electrochemically oxidized Ir (Ir III ) with the hydrated or hydroxylated structure has exhibited the highest catalytic activity among various material phases, owing to the flexible structure of catalytic sites. [ 4–6 ] Unfortunately, such Ir III oxides eventually worsen the OER performance because high potentials promote the oxidation and dissolution of active Ir during long‐term operation. [ 7–9 ] Meanwhile, Geiger et al showed that the rutile structure in IrO 2 (Ir IV ) exhibits much higher stability than amorphous Ir III oxides.…”

Section: Introductionmentioning

confidence: 99%

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Pt Dopant: Controlling the Ir Oxidation States toward Efficient and Durable Oxygen Evolution Reaction in Acidic Media

Choi

Park

Kabiraz

et al. 2020

Adv Funct Materials

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Dissolution of Ir oxides in Ir‐based catalysts, which is closely linked to the catalyst activity and stability toward the oxygen evolution reaction (OER) in acidic media, is a critical unresolved problem in the commercialization of water electrolysis. Doping foreign elements into the Ir oxides can accomplish an optimal combination of Ir oxidation states that is conducive to the leaching‐resistance of active catalytic sites. Here, it is reported that Pt doping into IrOx‐based nanoframe is beneficial in both terms of activity and stability. The Pt‐doped IrOx‐based nanoframe achieves the mass activity of 0.644 A mg−1Ir+Pt at 1.53 VRHE, which is 15‐fold higher than that of the commercial IrO2. During the accelerated durability test, the IrIV‐to‐IrIII ratio of 5 is maintained in the presence of Pt dopant to effectively mitigate the degradation of Ir catalyst, leading to the superb catalyst durability in acidic media.

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Section: Resultsmentioning

confidence: 82%

Section: Introductionmentioning

confidence: 99%

Pt Dopant: Controlling the Ir Oxidation States toward Efficient and Durable Oxygen Evolution Reaction in Acidic Media

Choi

Park

Kabiraz

et al. 2020

Adv Funct Materials

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“…Independently, the different researchers have found that under OER condition the surface of Ir-based catalysts finally forms short-range ordered octahedral IrO x H y phase ( Fig. 1) no matter what structure or composition of the catalysts started with [3][4][5]. This surface transfor-mation process is often called as surface reconstruction.…”

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confidence: 99%

Transition metal oxides for water oxidation: All about oxyhydroxides?

2019

Sci. China Mater.

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To realize a sustainable hydrogen energy infrastructure, techniques to produce hydrogen gas without involving fossil fuels are critical. It has been proposed in last century that producing hydrogen gas by splitting water could be a sustainable way because of plenty of water in this planet. Given electricity from clean energy resources, like solar and wind energy, water electrolysis ideally will be a fossil fuel free process. Water electrolysis is not a new technique. It was firstly observed in the 18 th century by

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“…Recently, many high‐performance and low‐cost catalysts, such as Co‐ and Ni‐based materials, have been developed for electrochemical and photoelectrocatalytic water oxidation in alkaline media. Nevertheless, OER in acidic environments is more imperative because of the high ionic (proton) conductivity and fewer side reactions of proton exchange membrane (PEM) electrolyzers . As reported, iridium oxide‐based nanocrystals are most widely used active and stable OER electrocatalysts in acidic electrolyte .…”

mentioning

confidence: 99%

Strain Regulation to Optimize the Acidic Water Oxidation Performance of Atomic‐Layer IrO_x

et al. 2019

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Strain regulation has become an important strategy to tune the surface chemistry and optimize the catalytic performance of nanocatalysts. Herein, the construction of atomic‐layer IrOx on IrCo nanodendrites with tunable IrO bond length by compressive strain effect for oxygen evolution reaction (OER) in acidic environment is demonstrated. Evidenced from in situ extended X‐ray absorption fine structure, it is shown that the compressive strain of the IrOx layer on the IrCo nanodendrites decreases gradually from 2.51% to the unstrained state with atomic layer growth (from ≈2 to ≈9 atomic layers of IrOx), resulting in the variation of the IrO bond length from shortened 1.94 Å to normal 1.99 Å. The ≈3 atomic‐layer IrOx on IrCo nanodendrites with an IrO bond length of 1.96 Å (1.51% strain) exhibits the optimal OER activity compared to the higher‐strained (2.51%, ≈2 atomic‐layer IrOx) and unstrained (>6 atomic‐layer IrOx) counterparts, with an overpotential of only 247 mV to achieve a current density of 10 mA cm−2. Density functional theory calculations reveal that the precisely tuned compressive strain effect balances the adsorbate–substrate interaction and facilitates the rate‐determining step to form HOO*, thus assuring the best performance of the three atomic‐layer IrOx for OER.

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Breaking Long-Range Order in Iridium Oxide by Alkali Ion for Efficient Water Oxidation

Abstract: Breaking long-range order in iridium oxide by alkali ion for efficient water oxidation

Cited by 404 publications

References 60 publications

Pt Dopant: Controlling the Ir Oxidation States toward Efficient and Durable Oxygen Evolution Reaction in Acidic Media

Pt Dopant: Controlling the Ir Oxidation States toward Efficient and Durable Oxygen Evolution Reaction in Acidic Media

Transition metal oxides for water oxidation: All about oxyhydroxides?

Strain Regulation to Optimize the Acidic Water Oxidation Performance of Atomic‐Layer IrO_x

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Breaking Long-Range Order in Iridium Oxide by Alkali Ion for Efficient Water Oxidation

Abstract: Breaking long-range order in iridium oxide by alkali ion for efficient water oxidation

Cited by 404 publications

References 60 publications

Pt Dopant: Controlling the Ir Oxidation States toward Efficient and Durable Oxygen Evolution Reaction in Acidic Media

Pt Dopant: Controlling the Ir Oxidation States toward Efficient and Durable Oxygen Evolution Reaction in Acidic Media

Transition metal oxides for water oxidation: All about oxyhydroxides?

Strain Regulation to Optimize the Acidic Water Oxidation Performance of Atomic‐Layer IrOx

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Product

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Strain Regulation to Optimize the Acidic Water Oxidation Performance of Atomic‐Layer IrO_x