Novel Noble-Metal-Free Electrocatalyst for Oxygen Evolution Reaction in Acidic and Alkaline Media

This study focuses on the feasibility of using TMTiP (where TM is a 3d transition metal or a mixture of 3d transition metals, Cr, Mn, Fe, Co, and Ni; TiP denotes titanium phosphide) as the electrode material for the oxygen evolution reaction (OER) by systematic modification to the atomic ratio of the constituent metals. The catalytic activity of the electrode materials is expected to be governed by the d electrons of the transition metals; the electrical conductivity is provided by TiP even under highly acidic conditions. The OER activity followed a “volcano plot” as the TM was changed from Cr to Ni and assumed the maximum value for the composition cobalt titanium phosphide (CoTiP). The CoTiP electrode also exhibited excellent corrosion resistance and metallic conductivity (on the order of 10−6 Ω m) over the pH range 0–14. The OER activity of CoTiP was comparable to that of Pt but inferior to that of state-of-the-art IrO2 and RuO2.