Transition Metal Oxides for the Oxygen Reduction Reaction: Influence of the Oxidation States of the Metal and its Position on the Periodic Table.
Electrocatalysts have been developed to meet the needs and requirements of renewable energy applications. Metal oxides have been well explored and are promising for this purpose, however, many reports focus on only one or a few metal oxides at once. Herein, thirty metal oxides, which were either commercially available or synthesized by a simple and scalable method, were screened for comparison with regards to their electrocatalytic activity towards the oxygen reduction reaction (ORR). We show that although manganese, iron, cobalt, and nickel oxides generally displayed the ability to enhance the kinetics of oxygen reduction under alkaline conditions compared with bare glassy carbon, there is no significant correlation between the position of a metal on the periodic table and the electrocatalytic performance of its respective metal oxides. Moreover, it was also observed that mixed valent (+2, +3) oxides performed the poorest, compared with their respective pure metal oxides. These findings may be of paramount importance in the field of renewable energy.
Department of Chemistry & Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 637371, Singapore, Singapore.
Rou Jun
RJ
Toh
Department of Inorganic Chemistry, University of Chemistry and Technology Prague, Technická 5, 166 28, Prague 6, Czech Republic.
Zdeněk
Z
Sofer
Department of Chemistry & Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 637371, Singapore, Singapore. pumera@ntu.edu.sg.
Martin
M
Pumera
catalysis; electrochemistry; metal oxides; oxygen reduction; transition metals