Enhanced water electrolysis: Electrocatalytic generation of oxygen gas at manganese oxide nanorods modified electrodes

El‐Deab, Mohamed S.; Awad, Mohamed I.; Mohammad, Ahmad M.; Ohsaka, Takeo

doi:10.1016/j.elecom.2007.06.011

Cited by 148 publications

(123 citation statements)

References 37 publications

Supporting

Mentioning

117

Contrasting

Unclassified

Order By: Relevance

“…El-Deab et al 29 compared the OER electrocatalytic activity of g-MnOOH nanorods deposited on Au, Pt and glassy carbon (GC) substrates. They found that the lowest OER onset potential was obtained for a manganese oxide modified Au substrate.…”

Section: Bulk Oxide/hydroxide Electrodesmentioning

confidence: 99%

“…[13][14][15][16][17][18] Consequently, a significant body of research exists on the application of non-noble transition metal oxides as OER anodes. Among the most promising materials are various intermetallic alloys, [19][20][21] electrodeposited nickel, [22][23][24][25] cobalt [26][27][28] and manganese oxides, 29 spinels including nickelites, [30][31][32][33] cobaltites [34][35][36] and ferrites, 37,38 perovskites, [39][40][41][42] and hematite photoanodes. 43 An important practical and fundamental factor which should also be noted when considering OER anode materials is that, even in the case of the parent metal, the anodic OER always occurs at an oxidised surface.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Redox and electrochemical water splitting catalytic properties of hydrated metal oxide modified electrodes

Doyle

Godwin

Brandon

et al. 2013

Phys. Chem. Chem. Phys.

523

565

View full text Add to dashboard Cite

This paper presents a review of the redox and electrocatalytic properties of transition metal oxide electrodes, paying particular attention to the oxygen evolution reaction. Metal oxide materials may be prepared using a variety of methods, resulting in a diverse range of redox and electrocatalytic properties. Here we describe the most common synthetic routes and the important factors relevant to their preparation. The redox and electrocatalytic properties of the resulting oxide layers are ascribed to the presence of extended networks of hydrated surface bound oxymetal complexes termed surfaquo groups. This interpretation presents a possible unifying concept in water oxidation catalysis -bridging the fields of heterogeneous electrocatalysis and homogeneous molecular catalysis. In contextOver the past 50 years considerable research efforts have been devoted to the realisation of efficient, economical and renewable energy sources. Metal oxide materials have played a large part in this drive with demonstrated applications at both the research and commercial level. Their use in areas such as batteries, fuel cells and water electrolysis has resulted in the development of materials with a diverse range of structural and chemical properties. In all cases, understanding the fundamental electrochemistry of the material can be invaluable for rational design and optimisation. This review focuses on the redox, charge transport and electrocatalytic properties of transition metal oxide electrodes as they pertain to the electrolytic splitting of water. Particular emphasis is placed on the nature of the active surface which is interpreted in terms of hydrated interlinked oxymetal complexes termed surfaquo groups. In this way, the review seeks to bridge the gap between heterogeneous electrocatalysis and homogeneous molecular catalysis for water oxidation, areas of considerable modern interest and activity.

show abstract

Section: Bulk Oxide/hydroxide Electrodesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Redox and electrochemical water splitting catalytic properties of hydrated metal oxide modified electrodes

Doyle

Godwin

Brandon

et al. 2013

Phys. Chem. Chem. Phys.

523

565

View full text Add to dashboard Cite

show abstract

“…41 Furthermore, manganese oxides are commonly used as supports in combined catalytic complexes for the oxidation of CO 42,43 and reduction of NOx. 44 Surface terminations and the thermodynamics of oxygen vacancy formation will play important roles in the catalytic activity of rutile MnO 2 , and we investigate each of these by first-principles simulations in this work.…”

Section: ■ Introductionmentioning

confidence: 99%

Rutile (β-)MnO₂ Surfaces and Vacancy Formation for High Electrochemical and Catalytic Performance

2014

View full text Add to dashboard Cite

MnO 2 is a technologically important material for energy storage and catalysis. Recent investigations have demonstrated the success of nanostructuring for improving the performance of rutile MnO 2 in Li-ion batteries and supercapacitors and as a catalyst. Motivated by this we have investigated the stability and electronic structure of rutile (β-)MnO 2 surfaces using density functional theory. A Wulff construction from relaxed surface energies indicates a rod-like equilibrium morphology that is elongated along the c-axis, and is consistent with the large number of nanowire-type structures that are obtainable experimentally. The (110) surface dominates the crystallite surface area. Moreover, higher index surfaces than considered in previous work, for instance the (211) and (311) surfaces, are also expressed to cap the rod-like morphology. Broken coordinations at the surface result in enhanced magnetic moments at Mn sites that may play a role in catalytic activity. The calculated formation energies of oxygen vacancy defects and Mn reduction at key surfaces indicate facile formation at surfaces expressed in the equilibrium morphology. The formation energies are considerably lower than for comparable structures such as rutile TiO 2 and are likely to be important to the high catalytic activity of rutile MnO 2 . ■ INTRODUCTIONEnergy storage for hybrid electric vehicles and renewable energy sources is a pressing technological challenge for which Li-ion batteries and supercapacitors are key candidate systems. The conventional Li-ion intercalation cathode, LiCoO 2 , faces challenges of toxicity and high cost. Current supercapacitors based on carbon cathodes are limited by their storage capacity. The demand for higher capacity and higher power energy storage has led to a surge in interest in nanostructured electrodes. 1 Nanostructuring has been shown to improve the energy storage properties of rutile MnO 2 for both Li-ion batteries 2,3 and supercapacitors. 4−6 However, the mechanisms for this improvement are not fully understood on the atomic-scale. In addition to its role as an electrode material, nanostructured rutile MnO 2 has been shown to give good performance as a catalyst, 7 with much recent interest in its potential role in the Li−O 2 battery. 8 Knowledge of the surface features of rutile MnO 2 at the atomic and electronic level would provide valuable information regarding its energy storage and catalytic mechanisms. With the clear impetus to better understand the performance of rutile MnO 2 in three technologies, Li-ion batteries, supercapacitors and catalysis, in this work we apply first-principles simulations to understand surface phenomena in this promising material.Rutile MnO 2 is the subject of extensive research for its applications in Li-ion batteries, but early work indicated that bulk samples did not allow significant Li-ion intercalation. 2,9,10

show abstract

“…[7][8][9][10][11][12] At present, a significant body of research exists on the application of non-noble transition metal oxides as OER anodes. Amongst the most promising materials are various intermetallic alloys, 13 electrodeposited nickel, 14 cobalt 15 and manganese oxides, 16 spinels including nickelites, 17 cobaltites 18 and ferrites, 19 perovskites, 20 and hematite photoanodes. 21 However, despite these intense efforts the mechanism of the OER at first row transition metal oxide surfaces remains controversial and the important question of a common mechanism which would facilitate a theory of electrocatalysis for oxygen evolution is therefore unresolved.…”

Section: Introductionmentioning

confidence: 99%

An electrochemical impedance study of the oxygen evolution reaction at hydrous iron oxide in base

Doyle

Lyons

2013

Phys. Chem. Chem. Phys.

231

209

View full text Add to dashboard Cite

The oxygen evolution reaction at multi-cycled iron oxy-hydroxide films in aqueous alkaline solution is discussed. Steady-state Tafel plot analysis and electrochemical impedance spectroscopy have been used to elucidate the kinetics and mechanism of oxygen evolution. Tafel slopes of ca. 60 mV dec À1 and 40 mV dec À1 are found at low overpotentials depending on the oxide growth conditions, with an apparent Tafel slope of ca. 120 mV dec À1 at high overpotentials. Reaction orders of ca. 0.5 and 1.0 are observed at low and high overpotentials, again depending on the oxide growth conditions. A mechanistic scheme involving the active participation of octahedrally coordinated anionic iron oxyhydroxide surfaquo complexes, which form the porous hydrous layer, is proposed. The latter structure contains considerable quantities of water molecules which facilitate hydroxide ion discharge at the metal site during active oxygen evolution. This work brings together current research in heterogeneous electrocatalysis and homogeneous molecular catalysis for water oxidation.

show abstract

Enhanced water electrolysis: Electrocatalytic generation of oxygen gas at manganese oxide nanorods modified electrodes

Cited by 148 publications

References 37 publications

Redox and electrochemical water splitting catalytic properties of hydrated metal oxide modified electrodes

Redox and electrochemical water splitting catalytic properties of hydrated metal oxide modified electrodes

Rutile (β-)MnO₂ Surfaces and Vacancy Formation for High Electrochemical and Catalytic Performance

An electrochemical impedance study of the oxygen evolution reaction at hydrous iron oxide in base

Contact Info

Product

Resources

About

Enhanced water electrolysis: Electrocatalytic generation of oxygen gas at manganese oxide nanorods modified electrodes

Cited by 148 publications

References 37 publications

Redox and electrochemical water splitting catalytic properties of hydrated metal oxide modified electrodes

Redox and electrochemical water splitting catalytic properties of hydrated metal oxide modified electrodes

Rutile (β-)MnO2 Surfaces and Vacancy Formation for High Electrochemical and Catalytic Performance

An electrochemical impedance study of the oxygen evolution reaction at hydrous iron oxide in base

Contact Info

Product

Resources

About

Rutile (β-)MnO₂ Surfaces and Vacancy Formation for High Electrochemical and Catalytic Performance