3D Self-Supported Porous NiO@NiMoO 4 Core−Shell Nanosheets for Highly Efficient Oxygen Evolution Reaction (original) (raw)
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Nanochemistry Research, 2021
Recently, the concerns about depletion of fossil fuels and also the environmental pollution arisen from burning of them have driven scientists to quest for clean and sustainable energy resources. Some advantages of hydrogen have made it as an alternative energy resource to fossil fuels. Electrochemically splitting of water is considered as one of the main techniques to produce high-purity hydrogen. Fabrication of cost-effective electrocatalysts for oxygen evolution reaction (OER) in a water splitting process is vital for large-scale practical applications. Herein, we present an affordable and straightforward method for synthesis of NiO nanoparticles supported on Ni foam for oxygen evolution reaction (OER). A single-step annealing process is carried out at the different temperatures to achieve an optimal temperature, at which an electrocatalyst with a tailored morphology and high electrocatalytic activity is obtainable. The best electrocatalytic activity is showed by the electrode fabricated at 400 °C, which delivers current density of 10 mA/cm2 at 1.59 mV potential versus reversible hydrogen electrode (RHE) under alkaline condition. Various material characterization tests accompanied by electrochemical measurements are employed to clarify the cause of the excellent electrocatalytic activity of the electrode fabricated at 400 °C.
Royal Society Open Science
Highly porous 3d transition metal oxide nanostructures are opening up the exciting area of oxygen evolution reaction (OER) catalysts in alkaline medium thanks to their good thermal and chemical stability, excellent physiochemical properties, high specific surface area and abundant nanopores. In this paper, highly porous Co-doped NiO nanorods were successfully synthesized by a simple hydrothermal method. The porous rod-like nanostructures were preserved with the added cobalt dopant ranging from 1 to 5 at% but were broken into aggregated nanoparticles at higher concentrations of additional cobalt. The catalytic activity of Co-doped NiO nanostructures for OER in an alkaline medium was assayed. The 5%Co-NiO sample showed a drastically enhanced activity. This result could originate from the combination of advantageous characteristics of highly porous NiO nanorods such as large surface area and high porosity as well as the important role of Co dopant that could provide more catalytic acti...
The design and fabrication of earth-abundant and highly efficient water oxidation electrocatalysts are important for water splitting systems associated with the energy conversion and storage. In this work, we report an intercalation strategy to expand interlayer spacing of the layered structure and thus achieve great enhancement for water oxidation activity. Layered-structured nickel benzoate hydroxide nanobelts arrays on nickel foam (benzoate-Ni(OH) 2 /NF) are prepared by a one-step hydrothermal method. As-prepared benzoate-Ni(OH) 2 /NF exhibits outstanding oxygen evolution performance with the need of only 242 mV overpotential to drive a current density of 60 mA cm −2 in 1.0 M KOH, 126 mV lower than that for Ni(OH) 2 / NF. This catalyst electrode also has good stability with the maintenance of its catalytic activity for 27 h. ■ INTRODUCTION Water electrolysis is currently acknowledged as an attractive approach for hydrogen production, which can well relieve the global energy crisis and environmental deterioration caused by increased depletion of fossil fuels. 1,2 However, electrocatalytic water splitting is seriously limited by the intrinsically sluggish kinetics of oxygen evolution reaction (OER) as the energy intensive step. 3,4 Hence, effective catalysts are demanded to accelerate the OER process and thus decrease the overpotential requirement. Ru and Ir oxides are the most active OER catalysts, but they suffer from scarcity, high cost, and instability during long-term electrolysis in alkaline medium, which hinders their large-scale applications. 5,6 Accordingly, extensive efforts have been devoted to the development of high-efficiency alternatives made from cost-effective materials. Layered metal hydroxides (LMHs) with brucite-like structures have emerged as promising earth-abundant materials with excellent electrochemical activity, 7−12 and various strategies have been proposed to further improve the electrochemical performance of LMHs. 13−17 Jin and co-workers reported layered α-cobalt hydroxide intercalated by large charge-balancing anions for the expansion of its interlayer spacing, and the larger interlayer distance allows for more accessible surface areas leading to enhanced capacitive performance. 17 Some work also demonstrates that LMHs with expanded interlayer spacing catalyze water oxidation more efficiently. 18−21 Additionally, previous reports have verified that more effective electrocatalysis can be achieved by directly growing catalyst nanoarrays on current collectors because of decreased series resistance, more exposed active sites, and facilitated diffusion of electrolytes. 22,23 Our recent work also indicates that benzoate anions are effective intercalators for layered cobalt hydroxide nanoarrays toward efficient OER electrocatalysis. 24 Given the Ni is more earth-abundant than Co, it is interesting to investigate the intercalation effect of benzoate anions on the OER activity of Ni-based LMHs nanoarrays, which, however, has not been explored before. In this work, we report layered nickel hydroxide intercalated by benzoate ions (0.7 nm in length) via a simple hydrothermal process to expand its interlayer spacing. Such benzoate-intercalated layered nickel hydroxide nanobelts arrays on nickel foam (benzoate-Ni(OH) 2 /NF) show greatly enhanced OER performance. Behaving as a 3D durable electrocatalyst for water oxidation in 1.0 M KOH, benzoate-Ni(OH) 2 /NF requires the overpotential of only 242 mV to afford 60 mA cm −2 , and much increased overpotential (368 mV) is demanded for Ni(OH) 2 / NF. Also, its catalytic activity can be maintained for at least 27 h.
Nanomaterials (Basel, Switzerland), 2017
Earth-abundant and low-cost catalysts with excellent electrocatalytic hydrogen evolution reaction (HER) activity in alkaline solution play an important role in the sustainable production of hydrogen energy. In this work, a catalyst of Ni(P, O)x·MoOx nanowire array on nickel foam has been prepared via a facile route for efficient alkaline HER. Benefiting from the collaborative advantages of Ni(P, O)x and amorphous MoOx, as well as three-dimensional porous conductive nickel scaffold, the hybrid electrocatalyst shows high catalytic activity in 1 M KOH aqueous solution, including a small overpotential of 59 mV at 10 mA cm-2, a low Tafel slope of 54 mV dec-1, and excellent cycling stability.