In-situ tracking of phase conversion reaction induced metal/metal oxides for efficient oxygen evolution

Due to the unique interface and electronic structure, metal/metal oxide composite electrocatalysts have been designed and exploited for electrocatalytic oxygen evolution reaction (OER) in alkaline solution. However, how to fabricate metal/metal oxides with abundant interfaces and well-dispersed metal phases is a challenge, and the synergistic effect between metal and metal oxides on boosting the electrocatalytic activities is still ambiguous. Herein, by controlling the lithium-induced conversion reaction of metal oxides, metal/metal oxide composites with plentiful interfaces and excellent electrical interconnection are fabricated, which can enhance the active sites, and accelerate the mass transfer during the electrocatalytic reaction. As a result, the electrocatalytic oxygen evolution activities of the as-fabricated metal/metal oxide composite catalysts including NiCo/NiCo 2 O 4 , NiMn/NiMn 2 O 4 and CoMn/CoMn 2 O 4 are greatly improved. The catalytic mechanism is also explored using the in-situ X-ray and Raman spectroscopic tracking to uncover the real active centers and the synergistic effect between the metal and metal oxides during water oxidation. Density functional theory plus U (DFT + U) calculation confirms the metal in the composite can optimize the catalytic reaction path and reduce the reaction barrier, thus boosting the electrocatalytic kinetics.