Applications of ALD MnO to electrochemical water splitting

Pickrahn, Katie L.; Gorlin, Yelena; Seitz, Linsey C.; Garg, Aaron; Nordlund, Dennis; Jaramillo, Thomas F.; Bent, Stacey F.

doi:10.1039/c5cp00843c

Cited by 47 publications

(45 citation statements)

References 52 publications

(75 reference statements)

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“…The resulting film thickness as a function of the number of cycles is shown in Figure a for growth at 160 °C. Manganicone MLD exhibits a constant growth rate of 0.9 Å per cycle up to at least 350 cycles, close to the growth rates observed for ALD of pure manganese oxide (≈1 Å per cycle) . Saturation curves (Figure b,c) verify the characteristic self‐limiting nature of the MLD process with increasing exposure time, though some variance in the growth rate is observed, as has been seen previously for ALD/MLD processes .…”

Section: Resultssupporting

confidence: 82%

“…One of the main limitations in the creation of new electrochemically active materials using MLD is the lack of studies on elements relevant for electrochemical applications. While most hybrid MLD studies focus on Al, Zn, and Ti, manganese oxide, for instance, can be used in both Li ion batteries as a cathode material and in the electrochemical conversion of water into oxygen via the oxygen evolution reaction (OER) . Despite its potential, only two studies have explored the use of MLD to synthesize manganese hybrid materials.…”

Section: Introductionmentioning

confidence: 99%

“…Nanostructured manganese oxide has also been of interest for catalysis, particularly for the OER . For instance, previous work has shown that manganese oxide grown using ALD can be annealed to induce restructuring and to create high surface area, active catalysts …”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Structurally Stable Manganese Alkoxide Films Grown by Hybrid Molecular Layer Deposition for Electrochemical Applications

Bergsman

Baker

Closser

et al. 2019

Adv Funct Materials

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Hybrid molecular layer deposition (MLD) has significant potential for the creation of ultrathin electrochemically active materials, due to its ability to combine organic and inorganic species to modulate film properties. However, only a limited number of hybrid MLD processes are demonstrated with electrochemically relevant elements, such as manganese. Here, a "manganicone" manganese hybrid MLD chemistry is developed using the precursors bis(ethylcyclopentadienyl)manganese and ethylene glycol. The resulting manganese alkoxide coordination networks are shown to have many interesting properties, including the ability to seamlessly fill high aspect ratio vias and the chemical conversion into manganese carboxylate in air over several hours at room temperature. Linear, self-saturating growth is reported. Importantly, hybrid manganicone films annealed to 480 °C in air demonstrate a greater stability to restructuring during electrochemical testing than their inorganic counterparts grown by atomic layer deposition, without reducing the activity of the reactive sites on the manganese surface. Thus, hybrid manganese films grown by MLD have significant promise for use as catalysts for the oxygen evolution reaction and as electrodes in thin film batteries.

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Section: Resultssupporting

confidence: 82%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Structurally Stable Manganese Alkoxide Films Grown by Hybrid Molecular Layer Deposition for Electrochemical Applications

Bergsman

Baker

Closser

et al. 2019

Adv Funct Materials

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“…19 Work continues in developing it as an OER catalyst, but the best illuminated results reported imply negative potentials (power losing cells) of several hundred millivolts after accounting for the photovoltage. Protection layers including graphene or other carbon films have also been explored [20][21][22] as has Ta 2 O 5 as a protection layer for nZnO absorbers, 23 but, in general produce worse results than those listed.…”

Section: Discussionmentioning

confidence: 99%

Understanding Photovoltage in Insulator-Protected Water Oxidation Half-Cells

Scheuermann

Chidsey

McIntyre

2015

J. Electrochem. Soc.

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In the pursuit of a photosynthetic and efficient water splitting device, detailed investigations of individual aspects of the whole device are necessary: catalysis, electronic conductivity, cathode and anode stability, and kinetics among other aspects. Improvement in one aspect can, however, often require fundamental tradeoffs affecting others. High solar-to-hydrogen efficiency of the overall system is the ultimate goal of water splitting research. When optimizing half-cells, either the anode or cathode, the photovoltage required to achieve a current density of interest is an especially important metric. This report investigates the photovoltage in insulator-protected water oxidation anodes using ALD-TiO 2 protected silicon devices as a case study and looks in depth at how photovoltage is correctly determined from typical electrochemical analysis and how this relates to the underlying solid-state carrier transport. Finally, the photovoltage at 10 mA/cm 2 referenced to the thermodynamic potentials is reviewed from several leading research reports for various photoanodes and photocathodes, providing a direct comparison of cell performance. Half-cell efficiency and photovoltage metrics.-The solar-tohydrogen (STH) efficiency is the most important metric for characterizing water splitting cells, and can be calculated in a variety of ways. When optimizing an anodic or cathodic half-cell, the impliedefficiencies are often reported as the product of the photovoltage and current, divided by the input solar power. The power point of an actual water splitting device, however, will be determined by current matching among the components, and also necessitates a minimum voltage to drive the reactions of interest. As such, implied half-cell efficiency plots as a function of voltage can include values that are not meaningful for full cell operation. As will be shown at the end of this report, most reported anodes and cathodes do not yet provide sufficient photovoltage for photosynthetic operation of full water-splitting cells, meaning the current stand-alone full cell efficiency is still zero.The closest metric to efficiency that can be easily compared from report to report and used to best imply final device operation is the photovoltage at a relevant current, namely the voltage given to or required from the rest of the device, including the other half cell, at a certain operating current. When the photovoltage is measured close to zero current, an approximation of the open-circuit photovoltage is obtained. When it is measured at a reasonable operating current like 10 mA/cm 2 , an approximation of the power given or needed at the max power point is obtained. The tables at the end of this report show the voltage provided from a given half-cell and needed from the other at 10 mA/cm 2 to illustrate these comparisons. Comparing experimental results to theory helps illustrate the difference between half-cell and full-device efficiency calculations and how to transform values between the two. Pinaud et al. have attempted to calculat...

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“…The low cost, stable, and adequately active transition metal oxides [6,7], hydroxides [8], sulfides [9], nitrides [10], layered double hydroxides [11,12] and perovskites [13,14] have been developed as alternative electrocatalysts. Among them, metal oxides such as MnO 2 [15,16], NiO [17,18], Co 3 O 4 [7,19], and Fe 2 O 3 [20,21] are widely studied due to their wide range of properties such as diverse crystal structures, variable morphologies, and rich redox chemistry governed by coordination environments.…”

Section: Introductionmentioning

confidence: 99%

NiCo2O4/rGO hybrid nanostructures for efficient electrocatalytic oxygen evolution

Umeshbabu

Rajeshkhanna

Justin

et al. 2016

J Solid State Electrochem

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We report the synthesis of NiCo 2 O 4 /reduced graphene oxide (NiCo 2 O 4 /rGO) hybrid hierarchical structures with unique nanonet and microsphere morphologies by organic polar solvent-assisted solvothermal method. The electrocatalytic oxygen evolution reaction (OER) activity of these materials is studied by cyclic voltammetry, linear sweep voltammetry and chronoamperometry methods in O 2 -saturated 0.1 M KOH solution. The NiCo 2 O 4 /rGO hybrid nanocomposite materials are found to be highly active electrocatalysts for OER at lower overpotentials. The nanonet and microspherelike NiCo 2 O 4 /rGO catalysts require overpotentials of 0.450 and 0.530 V at a current density of 10 mA cm −2 , and their corresponding Tafel slopes are 53 and 62 mV dec −1 , which are much lower than values reported for non-precious electrocatalysts. Further, both NiCo 2 O 4 /rGO catalysts show good catalytic stability with current retention more than 92 % over long period of 15,000 s determined by chronoampirometry and at the end of 1000th cycle determined by linear sweep voltammetry. The enhanced OER activity of nanostructured NiCo 2 O 4 /rGO hybrid catalysts is attributed to synergistic interaction between rGO and NiCo 2 O 4 , which seems to be essential for maintaining the large contact area at the electrode-electrolyte interface, better mass, and charge transport and to minimize the aggregation of NiCo 2 O 4 nanoparticles.

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Applications of ALD MnO to electrochemical water splitting

Cited by 47 publications

References 52 publications

Structurally Stable Manganese Alkoxide Films Grown by Hybrid Molecular Layer Deposition for Electrochemical Applications

Structurally Stable Manganese Alkoxide Films Grown by Hybrid Molecular Layer Deposition for Electrochemical Applications

Understanding Photovoltage in Insulator-Protected Water Oxidation Half-Cells

NiCo2O4/rGO hybrid nanostructures for efficient electrocatalytic oxygen evolution

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