Enhanced surface wettability and innate activity of an iron borate catalyst for efficient oxygen evolution and gas bubble detachment
25 Jun 2019-Journal of Materials Chemistry (The Royal Society of Chemistry)-Vol. 7, Iss: 25, pp 15252-15261
TL;DR: In this paper, an amorphous iron borate film was deposited on nickel foam with significant catalytic activity and surface wettability, enabling fast gas bubble dissipation, and a low-adhesion oxygen evolution electrode with a porous and roughened surface was prepared.
Abstract: The development of facile methods to design efficient oxygen evolution electrocatalysts for electrochemical water splitting is an on-going challenge. Not only the sluggish kinetics of oxygen evolution has to be overcome, but also the adsorption of the gas bubble product which significantly contributes towards the energy consumption in water splitting. Here, we report an amorphous iron borate film deposited on nickel foam with significant catalytic activity and surface wettability which enables fast gas bubble dissipation. Through exposing a highly hydrophilic electrocatalyst surface via borate functionalization and the inclusion of Fe active sites, a low-adhesion oxygen evolution electrode with a porous and roughened surface, exhibiting significantly improved mass transfer and outstanding performance compared to unfunctionalized iron and iron hydroxide systems, is prepared. The proposed electrocatalyst shows strong oxygen evolution behavior by delivering current densities of 20 and 100 mA cm−2 at small overpotentials of 232 and 268 mV in 1.0 M KOH, respectively. The proposed electrode also displays good durability in particular at large current densities where vigorous gas bubble evolution occurs.
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TL;DR: In this article, a lattice-matching growth strategy is demonstrated for conductive MOF/layered double hydroxide (cMOF/LDH) heteronanotube arrays with highly ordered hierarchical porous structures enabling an ultraefficient oxygen evolution reaction.
Abstract: The conjugation of metal-organic frameworks (MOFs) into different multicomponent materials to precisely construct aligned heterostructures is fascinating but elusive owing to the disparate interfacial energy and nucleation kinetics. Herein, a promising lattice-matching growth strategy is demonstrated for conductive MOF/layered double hydroxide (cMOF/LDH) heteronanotube arrays with highly ordered hierarchical porous structures enabling an ultraefficient oxygen evolution reaction (OER). CoNiFe-LDH nanowires are used as interior template to engineer an interface by inlaying cMOF and matching two crystal lattice systems, thus conducting a graft growth of cMOF/LDH heterostructures along the LDH nanowire. A class of hierarchical porous cMOF/LDH heteronanotube arrays is produced through continuously regulating the transformation degree. The synergistic effects of the cMOF and LDH components significantly promote the chemical and electronic structures of the heteronanotube arrays and their electroactive surface area. Optimized heteronanotube arrays exhibit extraordinary OER activity with ultralow overpotentials of 216 and 227 mV to deliver current densities of 50 and 100 mA cm-2 with a small Tafel slope of 34.1 mV dec-1 , ranking it among the best MOF and non-noble-metal-based catalysts for OER. The robust performance under high current density and vigorous gas bubble conditions enable such hierarchical MOF/LDH heteronanotube arrays as promising materials for practical water electrolysis.
114 citations
TL;DR: The development of efficient and stable transition bimetallic chalcogenides to replace precious metal electrocatalysts for alkaline oxygen evolution reaction (OER) remains an ongoing challenge as mentioned in this paper.
Abstract: The development of efficient and stable transition bimetallic chalcogenides to replace precious metal electrocatalysts for alkaline oxygen evolution reaction (OER) remains an ongoing challenge. Her...
108 citations
TL;DR: In this article, the authors provide guidance in the development of noble-metal-free multicomponent nanointegration for sustainable energy conversion for photocatalysis, photo-electrocatalysis, and electrocatalysis.
Abstract: Global energy and environmental crises are among the most pressing challenges facing humankind. To overcome these challenges, recent years have seen an upsurge of interest in the development and production of renewable chemical fuels as alternatives to the nonrenewable and high-polluting fossil fuels. Photocatalysis, photoelectrocatalysis, and electrocatalysis provide promising avenues for sustainable energy conversion. Single- and dual-component catalytic systems based on nanomaterials have been intensively studied for decades, but their intrinsic weaknesses hamper their practical applications. Multicomponent nanomaterial-based systems, consisting of three or more components with at least one component in the nanoscale, have recently emerged. The multiple components are integrated together to create synergistic effects and hence overcome the limitation for outperformance. Such higher-efficiency systems based on nanomaterials will potentially bring an additional benefit in balance-of-system costs if they exclude the use of noble metals, considering the expense and sustainability. It is therefore timely to review the research in this field, providing guidance in the development of noble-metal-free multicomponent nanointegration for sustainable energy conversion. In this work, we first recall the fundamentals of catalysis by nanomaterials, multicomponent nanointegration, and reactor configuration for water splitting, CO2 reduction, and N-2 reduction. We then systematically review and discuss recent advances in multicomponent-based photocatalytic, photo-electrochemical, and electrochemical systems based on nanomaterials. On the basis of these systems, we further laterally evaluate different multicomponent integration strategies and highlight their impacts on catalytic activity, performance stability, and product selectivity. Finally, we provide conclusions and future prospects for multicomponent nanointegration. This work offers comprehensive insights into the development of cost-competitive multicomponent nanomaterial-based systems for sustainable energy-conversion technologies and assists researchers working toward addressing the global challenges in energy and the environment.
106 citations
TL;DR: An evident enhancement of the oxygen evolution reaction (OER) is demonstrated on a vanadate-modified iron-nickel catalyst synthesized by a successive ionic layer adsorption and reaction method, which suggests metallic oxo-anion modification as a versatile catalyst design strategy for advanced water oxidation.
Abstract: Surface chemistry is a pivotal prerequisite besides catalyst composition toward advanced water electrolysis Here, an evident enhancement of the oxygen evolution reaction (OER) is demonstrated on a vanadate-modified iron-nickel catalyst synthesized by a successive ionic layer adsorption and reaction method, which demonstrates ultralow overpotentials of 274 and 310 mV for delivering large current densities of 100 and 400 mA cm-2 , respectively, in 1 m KOH, where vigorous gas bubble evolution occurs Vanadate modification augments the OER activity by i) increasing the electrochemical surface area and intrinsic activity of the active sites, ii) having an electronic interplay with Fe and Ni catalytic centers, and iii) inducing a high surface wettability and a low-gas bubble-adhesion for accelerated mass transport and gas bubble dissipation at large current densities Ex situ and operando Raman study reveals the structural evolution of β-NiOOH and γ-FeOOH phases during the OER through vanadate-active site synergistic interactions Operando dynamic specific resistance measurement evidences an accelerated gas bubble dissipation by a significant decrease in the variation of the interfacial resistance during the OER for the vanadate-modified surface Achievement of a high catalytic turnover of 012 s-1 suggests metallic oxo-anion modification as a versatile catalyst design strategy for advanced water oxidation
59 citations
References
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TL;DR: In this paper, the authors report a protocol for evaluating the activity, stability, and Faradaic efficiency of electrodeposited oxygen-evolving electrocatalysts for water oxidation.
Abstract: Objective evaluation of the activity of electrocatalysts for water oxidation is of fundamental importance for the development of promising energy conversion technologies including integrated solar water-splitting devices, water electrolyzers, and Li-air batteries. However, current methods employed to evaluate oxygen-evolving catalysts are not standardized, making it difficult to compare the activity and stability of these materials. We report a protocol for evaluating the activity, stability, and Faradaic efficiency of electrodeposited oxygen-evolving electrocatalysts. In particular, we focus on methods for determining electrochemically active surface area and measuring electrocatalytic activity and stability under conditions relevant to an integrated solar water-splitting device. Our primary figure of merit is the overpotential required to achieve a current density of 10 mA cm–2 per geometric area, approximately the current density expected for a 10% efficient solar-to-fuels conversion device. Utilizing ...
4,808 citations
TL;DR: It is established that Fe(3+) in Ni(1-x)Fe(x)OOH occupies octahedral sites with unusually short Fe-O bond distances, induced by edge-sharing with surrounding [NiO6] octahedra, which results in near optimal adsorption energies of OER intermediates and low overpotentials at Fe sites.
Abstract: Highly active catalysts for the oxygen evolution reaction (OER) are required for the development of photoelectrochemical devices that generate hydrogen efficiently from water using solar energy. Here, we identify the origin of a 500-fold OER activity enhancement that can be achieved with mixed (Ni,Fe)oxyhydroxides (Ni(1-x)Fe(x)OOH) over their pure Ni and Fe parent compounds, resulting in one of the most active currently known OER catalysts in alkaline electrolyte. Operando X-ray absorption spectroscopy (XAS) using high energy resolution fluorescence detection (HERFD) reveals that Fe(3+) in Ni(1-x)Fe(x)OOH occupies octahedral sites with unusually short Fe-O bond distances, induced by edge-sharing with surrounding [NiO6] octahedra. Using computational methods, we establish that this structural motif results in near optimal adsorption energies of OER intermediates and low overpotentials at Fe sites. By contrast, Ni sites in Ni(1-x)Fe(x)OOH are not active sites for the oxidation of water.
1,850 citations
TL;DR: The as-prepared three-dimensional structured electrodes developed by electrodepositing amorphous mesoporous nickel–iron composite nanosheets directly onto macroporous nickel foam substrates is the most efficient oxygen evolution electrode in alkaline electrolytes reported to the best of the knowledge.
Abstract: Development of efficient and affordable oxygen evolution catalysts is essential for large-scale electrolytic water splitting. Here, the authors report mesoporous nickel–iron composite nanosheets loaded on macroporous nickel foam substrates, and evaluate their electrocatalytic oxygen evolution in basic media.
1,583 citations
TL;DR: The growth of NiSe nanowire film on nickel foam (NiSe/NF) in situ by hydrothermal treatment of NF using NaHSe as Se source is presented.
Abstract: Active and stable electrocatalysts made from earth-abundant elements are key to water splitting for hydrogen production through electrolysis. The growth of NiSe nanowire film on nickel foam (NiSe/NF) insitu by hydrothermal treatment of NF using NaHSe as Se source is presented. When used as a 3D oxygen evolution electrode, the NiSe/NF exhibits high activity with an overpotential of 270mV required to achieve 20mAcm(-2) and strong durability in 1.0M KOH, and the NiOOH species formed at the NiSe surface serves as the actual catalytic site. The system is also highly efficient for catalyzing the hydrogen evolution reaction in basic media. This bifunctional electrode enables a high-performance alkaline water electrolyzer with 10mAcm(-2) at a cell voltage of 1.63V.
1,376 citations
TL;DR: The high OER activity and simple synthesis make these Ni-based catalyst thin films useful for incorporating with semiconductor photoelectrodes for direct solar-driven water splitting or in high-surface-area electrodes for water electrolysis.
Abstract: Water oxidation is a critical step in water splitting to make hydrogen fuel. We report the solution synthesis, structural/compositional characterization, and oxygen evolution reaction (OER) electrocatalytic properties of ∼2–3 nm thick films of NiOx, CoOx, NiyCo1–yOx, Ni0.9Fe0.1Ox, IrOx, MnOx, and FeOx. The thin-film geometry enables the use of quartz crystal microgravimetry, voltammetry, and steady-state Tafel measurements to study the electrocatalytic activity and electrochemical properties of the oxides. Ni0.9Fe0.1Ox was found to be the most active water oxidation catalyst in basic media, passing 10 mA cm–2 at an overpotential of 336 mV with a Tafel slope of 30 mV dec–1 with oxygen evolution reaction (OER) activity roughly an order of magnitude higher than IrOx control films and similar to the best known OER catalysts in basic media. The high activity is attributed to the in situ formation of layered Ni0.9Fe0.1OOH oxyhydroxide species with nearly every Ni atom electrochemically active. In contrast to pr...
1,306 citations