▎ 摘　　要

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 jig cm(-2) loading, outperforming previously reported results in terms of mass effectivity and Tafel slope.