Presenter Information

Meron Samuel Metaferia

Department of Chemistry and Biochemistry, Duquesne University

Abstract

In this study we have electrochemically fabricated the naturally abundant and stable electrocatalysts Ni-Fe, Ni-Co, Co-Fe-double hydroxides and Ni-Fe-Co-triple hydroxides, for efficient splitting of water to oxygen and hydrogen. Oxygen-evolution reaction (OER) activity of these electrocatalysts electrodeposited on different substrates were examined in an alkaline solution of potassium (KOH). The substrates used were Ni-foam, electrodeposited Ni-Co-oxide on Ni-foam and pressed porous Ni-Co oxide under varying electrodeposition bath composition, electrodeposition time under potential and current controls. The results clearly showed the pronounced effect of substrate on the electro-catalytic activity of these double and triple hydroxides. The synergetic effect of multiple hydroxides and the substrate is responsible for such enhanced electrocatalytic activity. We found that Ni-Fe-Co-triple hydroxide electrodeposited for total of 10 min under potential control at – 1.0/SCE on pressed porous Ni-Co-oxide sheet acted as an exceptional electrocatalyst for OER during water splitting reaction. This electrocatalyst generated a current density of ~ 100.0 mA cm-2 at an oxygen overpotential of 0.270 volt (= 1.5 V vs RHE) in 1.0 M KOH at electrolyte temperature of 25oC. However, the triple hydroxide deposited for 7 min generated 81.0 mA cm-2 at the same overpotential and electrolyte temperature. However, among the double and triple hydroxides deposited on pressed porous Ni-Co oxide substrate under current control at – 250 mA/cm2 for 100 sec, the Co-Fe double hydroxide showed better performance generating a current density of ~ 27.0 mA/cm2 at an oxygen overpotential of 0.270 volt (= 1.5 V vs RHE) in 1.0 M KOH electrolyte at room temperature. Thus, indicating that the activity of double or triple hydroxides synthesized under potential control electrodeposition were found higher compared to samples synthesized by current control perhaps due to too thinner film formation in100 sec deposition time in the later.

School

Bayer School of Natural and Environmental Sciences

Advisor

Dr. Shahed Khan

Submission Type

Paper

Included in

Life Sciences Commons

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Electrochemical Synthesis of Electrocatalysts Ni-Fe, Ni-Co, Co-Fe double and Ni-Co-Fe Triple Hydroxides for Efficient Water Splitting to Oxygen and Hydrogen

In this study we have electrochemically fabricated the naturally abundant and stable electrocatalysts Ni-Fe, Ni-Co, Co-Fe-double hydroxides and Ni-Fe-Co-triple hydroxides, for efficient splitting of water to oxygen and hydrogen. Oxygen-evolution reaction (OER) activity of these electrocatalysts electrodeposited on different substrates were examined in an alkaline solution of potassium (KOH). The substrates used were Ni-foam, electrodeposited Ni-Co-oxide on Ni-foam and pressed porous Ni-Co oxide under varying electrodeposition bath composition, electrodeposition time under potential and current controls. The results clearly showed the pronounced effect of substrate on the electro-catalytic activity of these double and triple hydroxides. The synergetic effect of multiple hydroxides and the substrate is responsible for such enhanced electrocatalytic activity. We found that Ni-Fe-Co-triple hydroxide electrodeposited for total of 10 min under potential control at – 1.0/SCE on pressed porous Ni-Co-oxide sheet acted as an exceptional electrocatalyst for OER during water splitting reaction. This electrocatalyst generated a current density of ~ 100.0 mA cm-2 at an oxygen overpotential of 0.270 volt (= 1.5 V vs RHE) in 1.0 M KOH at electrolyte temperature of 25oC. However, the triple hydroxide deposited for 7 min generated 81.0 mA cm-2 at the same overpotential and electrolyte temperature. However, among the double and triple hydroxides deposited on pressed porous Ni-Co oxide substrate under current control at – 250 mA/cm2 for 100 sec, the Co-Fe double hydroxide showed better performance generating a current density of ~ 27.0 mA/cm2 at an oxygen overpotential of 0.270 volt (= 1.5 V vs RHE) in 1.0 M KOH electrolyte at room temperature. Thus, indicating that the activity of double or triple hydroxides synthesized under potential control electrodeposition were found higher compared to samples synthesized by current control perhaps due to too thinner film formation in100 sec deposition time in the later.

 

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