Improving Electrocatalytic Activity of MoO₃ for the Oxygen Evolution Reaction by Incorporation of Li Ions

Several polymorphs of MoO₃ with different crystal and electronic structures provide many opportunities to find suitable electrocatalysts for water splitting hydrogen generation. So far, promising electrocatalytic activity for hydrogen evolution reaction (HER) has been found for α-MoO₃ (orthorhombic), while the polymorph has shown a poor oxygen evolution reaction (OER) activity. In this work, it is found that the intrinsic OER activity of α-MoO₃ is remarkably improved by incorporating guest ions of lithium-ion (Li⁺). α-MoO₃ nanoparticles were deposited on a carbon fiber paper (α-MoO₃/CFP) by chemical vapor transport and a subsequent lithiation process was applied to prepare lithiated α-MoO₃/CFP (Li-α-MoO₃/CFP), showing the robust η₁₀ of 458 mV. The improved OER activity in the lithiated electrode is attributed to the incorporation of Li⁺ into the MoO₃, which increases the electron carrier density and the corresponding electrical conductivity, thereby improving the interfacial charge transfer kinetics as well as activating a large number of ECSA.