Exploring the Effect of Ball Milling on the Physicochemical Properties and Oxygen Evolution Reaction Activity of Nickel and Cobalt Oxides

Advanced Energy and Sustainability Research, vol. 5

Abstract

Ball milling is commonly used to reduce catalyst particle size. However, little attention is paid to further changes that ball milling can cause to the rest of the catalysts’ physicochemical properties, which can impact their intrinsic catalytic activity. The effect of ball milling on the physicochemical properties of NiCoO2, NiO, CoO, and NiO:CoO mixtures is reported and correlated with their electrochemical oxygen evolution reaction (OER) activity. It is also shown that particle fragmentation is an inherent consequence of ball milling, but some oxides can also experience a phase transformation. In the case of rocksalt‐structured CoO, it is partially or entirely transformed to spinel‐structured Co3O4. Additionally, NiCo2O4 with a spinel structure can be formed by ball milling NiO and CoO simultaneously (both rocksalt structures), but only in the absence of water. The changes impact the electrochemical activity of the initial oxides. Ball milled NiCoO2 exhibits the highest activity with a mean potential of 1.563 V at 10 mA cm−2, demonstrating the advantage of having Ni and Co in the same structure. Although NiCo2O4 is also a binary oxide, the results indicate that its metal coordination environment makes it intrinsically less active than NiCoO2 for the OER in alkaline media.

Authors 5

1. Sabita Bhandari Aachen Electrochemical Reaction Engineering

   RWTH Aachen University

   Affiliation as printed

   Electrochemical Reaction Engineering (AVT.ERT) RWTH Aachen University Forckenbeckstr. 51 Aachen 52074 Germany

   Electrochemical Reaction Engineering (AVT.ERT), RWTH Aachen University, Forckenbeckstr. 51, Aachen, 52074 Germany

2. Roland Schierholz

   Forschungszentrum Jülich

   Affiliation as printed

   Institute for Energy Technology Fundamental Electrochemistry (IET‐1) Forschungszentrum Jülich GmbH Jülich 52425 Germany

3. Rüdiger‐A. Eichel Aachen Institute of Physical Chemistry

   RWTH Aachen University · Forschungszentrum Jülich

   Affiliation as printed

   Institute for Energy Technology Fundamental Electrochemistry (IET‐1) Forschungszentrum Jülich GmbH Jülich 52425 Germany

   Institute of Physical Chemistry RWTH Aachen University Aachen 52074 Germany

   Institute of Physical Chemistry, RWTH Aachen University, Aachen, 52074 Germany

4. Ana Laura Luna corresponding

   Forschungszentrum Jülich

   Affiliation as printed

   Institute for Energy Technology Fundamental Electrochemistry (IET‐1) Forschungszentrum Jülich GmbH Jülich 52425 Germany

5. Anna K. Mechler corresponding Aachen Electrochemical Reaction Engineering

   RWTH Aachen University · Forschungszentrum Jülich · Jülich Aachen Research Alliance

   Affiliation as printed

   Electrochemical Reaction Engineering (AVT.ERT) RWTH Aachen University Forckenbeckstr. 51 Aachen 52074 Germany

   Institute for Energy Technology Fundamental Electrochemistry (IET‐1) Forschungszentrum Jülich GmbH Jülich 52425 Germany

   JARA‐ENERGY Aachen 52074 Germany

   Electrochemical Reaction Engineering (AVT.ERT), RWTH Aachen University, Forckenbeckstr. 51, Aachen, 52074 Germany

   Institute for Energy Technology Fundamental Electrochemistry (IET‐1) Forschungszentrum Jülich GmbH Jülich 52425 Germany