Mixed metal–antimony oxide nanocomposites: low pH water oxidation electrocatalysts with outstanding durability at ambient and elevated temperatures

Sibimol, Luke; Chatti, Manjunath; Yadav, Ajay Kumar; Kerr, Brittany; Kangsabanik, Jiban; Williams, Tim; Cherepanov, Pavel V.; Johannessen, Bernt; Tanksale, Akshat; MacFarlane, Douglas R.; Hocking, Rosalie K.; Alam, Aftab; Yella, Aswani; Simonov, Alexandr N.

doi:10.1039/d1ta07293e

Cited by 31 publications

(52 citation statements)

References 89 publications

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“…An almost invariable ECSA over the temperature region validates that the α-FeO(OH) active overlayer structure merely changes with the temperature. This is in line with the previous finding for IrO 2 , NiO(OH), and FeNiO(OH). ,, Consequently, the improved OER activity at higher temperatures is due to the improved electro-kinetics. ,,,,, …”

Section: Resultssupporting

confidence: 91%

“…Enhancement of electrocatalytic with cell temperature due to the notable drop in the OER overpotential was recently reported with different transition-metal-based anodes such as intermetallic FeSi, NiFeO x , NiCo 2 O 4 , IrO 2 , Co 3 O 4 , and MSbO y (M = Ru and Mn). 28,29,32,38,71,72 The significant decrease in the overpotential could partially be due to a linear drop of the thermodynamic water oxidation potential (E H2O/O2 = 1.23 V at RT) with the increase in cell temperature. 28 Besides the thermodynamics, at higher temperatures, enhanced mass transport and faster gas (O 2 ) molecule desorption from the electrode surface could also be the responsible factor for a better OER at high temperatures.…”

Section: Log Logmentioning

confidence: 99%

“…13,29,31 Consequently, the improved OER activity at higher temperatures is due to the improved electro-kinetics. 28,29,32,38,71,72 The correlation of the Tafel slope with temperature directly implicates the electron-transfer pathway. In this context, the transfer coefficient (α) can be determined from the temperature-dependent LSV.…”

Section: Log Logmentioning

confidence: 99%

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Greigite Fe₃S₄-Derived α-FeO(OH) Promotes Slow O–O Bond Formation in the Second-Order Oxygen Evolution Reaction Kinetics

2022

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The mechanistic pathway of oxygen evolution reaction (OER) invariably changes with the surface structure of the catalyst and difficult to envisage. Concerning the mechanistic interpretation of the rate-limiting step, the order of the reaction, and other intrinsic parameters, electrokinetic study is thereby of particular interest. Greigite Fe 3 S 4 nanosheets prepared herein via a solvothermal route while deposited on the nickel foam (NF) electrode surface act as an acceptable OER catalyst with a recorded overpotential of 251 (±6) mV at a j value of 10 mA cm −2 comparable to some benchmark iron/nickel oxy-hydroxide catalysts. Ex situ post-OER analysis of a Fe 3 S 4 /NF anode has affirmed the formation of α-FeO(OH) as the active species for the alkaline OER. The OER performance however can be improved upon elevating the cell temperature from 303 to 338 K. Electrokinetic data obtained at variable temperatures provide several important intrinsic parameters. The experimentally determined transfer coefficient α (1.90), exchange current density j s ′ (3.06 × 10 −6 mA cm −2 ), and a Tafel slope of 45.9 mV dec −1 implicate the O−O bond formation as the rate-limiting step following a Rossmeisl's peroxide path (RPP) where a nucleophilic attack of OH − to the Fe(IV)�O results in the formation of iron(III) hydroperoxo (Fe(III)-OOH) in the slowest step. From the variable temperature OER kinetics, the calculated activation energy (E a ) 53 (±2.1) kJ mol −1 is comparable to the noble metal oxide (IrO 2 ) but lower than other active transition metal (Co, Ni) oxide/-oxyhydroxide. Calculated E a and other kinetic data further evidence that the fair OER performance is due to a low activation barrier for the O−O bond formation step on the electro-generated FeO(OH) materials. The bimolecular RPP mechanism, nucleophilic attack of OH − to the Fe(IV)�O, has further been validated by the experimentally derived second-order rate of reaction with respect to [OH − ]. Moreover, the observed linear drop of the Tafel slope with increasing size of the electrolyte's cation (Li + , Na + , K + ), inferred a change in the mechanism, albeit it provides evidence on the weak non-covalent interaction of the surface adsorbed −OH with the cation of the electrolyte. The detailed electrokinetic study presented herein with the electrogenerated α-FeO(OH) can provide some useful guidelines to establish further the accurate OER mechanism on iron oxide/oxy-hydroxide materials.

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Section: Resultssupporting

confidence: 91%

Section: Log Logmentioning

confidence: 99%

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Greigite Fe₃S₄-Derived α-FeO(OH) Promotes Slow O–O Bond Formation in the Second-Order Oxygen Evolution Reaction Kinetics

2022

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“…Importantly, online analysis of O 2 evolved during experiments with the Co−Bi‐based electrodes (Supplementary Video) confirmed 100 % faradaic efficiency for the oxygen evolution reaction (OER) (Figure S4). Higher performance of the cobalt‐bismuth system as compared to combinations based on other transition metals examined here agrees well with observations for the conceptually similar OER catalysts based on PbO 2 [28,16,29] and SbO x [18b,c] . Interestingly, electrodes modified with BiO x only did not produce intense gas evolution, indicating that other processes, possibility H 2 O oxidation to H 2 O 2 , substantially contribute to the measured currents (Supplementary Video).…”

Section: Resultssupporting

confidence: 87%

Durable Electrooxidation of Acidic Water Catalysed by a Cobalt‐Bismuth‐based Oxide Composite: An Unexpected Role of the F‐doped SnO₂ Substrate

Chatti

Kerr

et al. 2022

ChemCatChem

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Aiming to design a catalyst for stable electrooxidation of water at low pH, the present work explores the properties and structural features of electrodeposited composite oxides based on Bi and Co, which were anticipated to provide stability and catalytical activity, respectively. Materials deposited as very thin (ca 50 nm) films on F-doped SnO 2 (FTO) substrate do not initially exhibit high activity in 0.1 M H 2 SO 4 , but are activated during operation through the electrooxidatively-induced enrichment of the catalytic surface with Co and Sn oxides. The latter originate from the FTO support and are identified as an important component of the catalyst through control experiments with a Sn-free substrate and with Sn 2 + intentionally added at the electrodeposition stage. A distinctive feature of the CoÀ BiÀ Sn-based electrocatalyst is the slow but persistent improvement in the activity during operation in 0.1 M H 2 SO 4 at both ambient and elevated (60 °C) temperatures, which contrasts with the continuously degrading behaviour of state-ofthe-art oxygen evolution catalysts at low pH. This is demonstrated by 9-day-long galvanostatic tests at 10 mA cm À 2 , during which the CoÀ BiÀ Sn-based thin film catalyst shows no degradation and sustains stable water oxidation at ca 1.9 V vs. reversible hydrogen electrode. The effects of tin leaching from the support detected herein might have implications to other acidic water oxidation catalysts supported on high-surface area doped SnO 2 materials.

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“…It is very common for functional materials to have two or more components, and resolving the structural components of complex materials is a strength of XAS characterization. Some key examples of multicomponent samples include (i) the well-known alkaline water oxidation electrocatalyst NiFeOOH, (ii) recent reports of acid-stable antimony- − and lead-based water oxidation catalysts, ,, and (iii) photocatalyst materials, like CoO x /TiO 2 systems reported by Barenek and co-workers . In a functional material with two or more metal-based components, it is not always obvious if one component is doped into the substrate of another (Figure a), a composite (Figure b), or a surface-sorbed species (Figure c) .…”

Section: Xas On Energy Materialsmentioning

confidence: 99%

Characterization of Energy Materials with X-ray Absorption Spectroscopy─Advantages, Challenges, and Opportunities

et al. 2022

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X-ray absorption spectroscopy (XAS) plays a critical role in the characterization of energy materials, including thinfilm electrocatalysts and battery materials. XAS is well-suited for this purpose because it is element-specific and can target distinct chemical environments within a material, even in a mixed or complicated matrix. Even so, some key energy materials are far from "ideal" XAS samples. This means that both sample preparation and experimental conditions need to be considered when collecting and interpreting data to ensure that conclusions are correct. This review outlines some of the key questions that an XAS experiment is well-suited to answering, including speciation of amorphous materials, understanding how multi-metal systems interact, and the different ways that we may observe single atoms. In addition, we show how XAS can be highly complementary to other analytical techniques in developing a full picture of a material over different scale bars. Importantly, we also examine instances where the sample matrix can distort XAS data, show an example where bond-length disorder can be confused with a change in the coordination number, and discuss some of the advantages and challenges of in situ electrocatalysis. Finally, we examine the future role that XAS will play in innovations in energy materials.

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Mixed metal–antimony oxide nanocomposites: low pH water oxidation electrocatalysts with outstanding durability at ambient and elevated temperatures

Abstract: Stability of the anode catalysts for PEM water electrolysers can be substantially improved by combining the catalytic component with antimony oxides. However, the mechanisms of the catalyst stabilisation differ depending on the active element used.

Cited by 31 publications

References 89 publications

Greigite Fe₃S₄-Derived α-FeO(OH) Promotes Slow O–O Bond Formation in the Second-Order Oxygen Evolution Reaction Kinetics

Greigite Fe₃S₄-Derived α-FeO(OH) Promotes Slow O–O Bond Formation in the Second-Order Oxygen Evolution Reaction Kinetics

Durable Electrooxidation of Acidic Water Catalysed by a Cobalt‐Bismuth‐based Oxide Composite: An Unexpected Role of the F‐doped SnO₂ Substrate

Characterization of Energy Materials with X-ray Absorption Spectroscopy─Advantages, Challenges, and Opportunities

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Mixed metal–antimony oxide nanocomposites: low pH water oxidation electrocatalysts with outstanding durability at ambient and elevated temperatures

Abstract: Stability of the anode catalysts for PEM water electrolysers can be substantially improved by combining the catalytic component with antimony oxides. However, the mechanisms of the catalyst stabilisation differ depending on the active element used.

Cited by 31 publications

References 89 publications

Greigite Fe3S4-Derived α-FeO(OH) Promotes Slow O–O Bond Formation in the Second-Order Oxygen Evolution Reaction Kinetics

Greigite Fe3S4-Derived α-FeO(OH) Promotes Slow O–O Bond Formation in the Second-Order Oxygen Evolution Reaction Kinetics

Durable Electrooxidation of Acidic Water Catalysed by a Cobalt‐Bismuth‐based Oxide Composite: An Unexpected Role of the F‐doped SnO2 Substrate

Characterization of Energy Materials with X-ray Absorption Spectroscopy─Advantages, Challenges, and Opportunities

Contact Info

Product

Resources

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Greigite Fe₃S₄-Derived α-FeO(OH) Promotes Slow O–O Bond Formation in the Second-Order Oxygen Evolution Reaction Kinetics

Greigite Fe₃S₄-Derived α-FeO(OH) Promotes Slow O–O Bond Formation in the Second-Order Oxygen Evolution Reaction Kinetics

Durable Electrooxidation of Acidic Water Catalysed by a Cobalt‐Bismuth‐based Oxide Composite: An Unexpected Role of the F‐doped SnO₂ Substrate