апрель 2019

Oxygen evolution reaction at mo-modified nickel foam electrode in 25% KOH

Slis A. A. , Solodovnik T. V.
Химия и современные технологии
Abstract / Full Text

Slis A. A., Solodovnik T. V. Oxygen evolution reaction at mo-modified nickel foam electrode in 25% KOH / Химия и современные технологии : Метериалы ІХ Международной научно-технической конференции студентов, аспирантов и молодых ученых «Химия и современные технологии», 2019. – C. 73

Over the last years, the world consumption of energy has rapidly increased. In this case, the investigating of hydrogen energy is necessary as alternative source to nuclear-, hydropower or fossil fuels. Water electrolysis is considered as the prospective way to produce hydrogen of ultra-pure quality. The basic processes occurring during water electrolysis is hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). From the kinetic aspect of these reactions, the OER requires more energy and high working potentials (1.5-2.0 V) for formation of oxygen molecule. A lot of works are aimed to find the best electrocatalyst for OER by studying their properties (electrochemical efficiency, performance in different mediums, corrosion resistivity and price). IrO2 and RuO2 shows good electrocatalytic activity in acidic solution. However, these materials could not be considered as low cost catalysts for OER. On the other hand, in alkaline media some transition metals (e.g. Ni, Co, Fe and Mn), their oxides and oxyhidroxides presents reasonable results in anodic reaction. Ni and its alloys are commonly used as materials for alkaline water electrolysis. Ni foam is highly-valuable electrocatalyst material with high porosity and specific surface area, good electrical conductivity and high corrosion resistance.

This work reports on oxygen evolution reaction, studied at nickel foam electrode material. Electrocatalytic behaviour of oxidized and Mo-modified Ni foam samples was evaluated in 25% M KOH solution for the potential range: 1300-1800 mV vs. RHE. The performance of nickel foam electrodes was examined by a.c. impedance spectroscopy and galvanostatic measurements in a single-cell water electrolyser.

According to the results of impedance spectroscopy, it has been found that the surface properties of nickel foam as electrode in the OER process, can be significantly altered due to different types of processing. With the help of these modifications, the catalytic properties of the electrode can be enhanced in comparison with a pure electrode, without any treatments. Thus, the Mo-modified Ni foam electrode showed an almost 1.5 times better result than unmodified sample for the reaction of oxygen evolution. It follows that, changes in the properties of the electrochemical surface layer can greatly enhance the OER process.

These study have shown that Mo-modified Ni foam materials not only can achieve a significant increasing on the OER performance, but also can replace expensive materials as cheaper analogue for their mass production.