The oxygen evolution reaction (OER) is of fundamental importance for the development of renewable energies. Research on earth-abundant, efficient, and stable OER electrocatalysts is a key factor for the technological improvement of water-splitting systems. In this article, we demonstrate OER performance of olivine-type lithium earth-abundant transition-metal phosphates coated with reduced graphene oxide (rGO). We report on LiCoPO4/rGO and the solid solutions Li1-xCoyFe1-yPO4/rGO synthesized by a nonaqueous sol-gel microwave reaction. Interestingly, such conditions allow for the direct synthesis of substochiometric Li0.7Co0.75Fe0.25PO4/rGO compound with improved OER activity. The materials crystallize in the olivine orthorhombic phase with nanoplatelet-like shape with nanometer-size thickness and micrometer-size width. The substochiometric phase Li0.7Co0.75Fe0.25PO4/rGO exhibits the best OER activity in alkaline medium, generating a current density of 5 mA cm-2 at an overpotential of 0.39 V and a Tafel slope of 44.5 mV dec-1 in 6 M KOH with a low 51 μg cm-2 loading, outperforming previously reported results in terms of mass effectivity and Tafel slope.
|Number of pages||11|
|State||Published - 7 Sep 2018|
Bibliographical noteFunding Information:
The authors acknowledge Dr. Gregory Gershinsky for his kind assistance with HRSEM, Yulia Kostikov for the her kind assistance with English proofreading, Dr. Hagit Aviv for her kind assistance with Raman and David Keller for his kind assistance with optical measurements. This work is partially supported by the Planning & Budgeting Committee of the Council of High Education and the Prime Minister Office of Israel, in the framework of the INREP project.
© 2018 American Chemical Society.
- oxygen evolution reaction
- water splitting