Vibronic Superexchange in Double Perovskite Electrocatalyst for Efficient Electrocatalytic Oxygen Evolution

Perovskites are prototype electrocatalyts benefiting from their high terrestrial availability and high stability. Electronic state regulation plays a key role in promising higher electrocatalytic efficiencies. Herein, we highlighted a vibronic superexchange in double perovskite to synergistically optimize e_g electron filling state and increase the formation of active species on the surface of catalysts. Vibronic superexchange of Ni³⁺-O-Mn³⁺ in La₂NiMnO₆ nanoparticles brings the optimal e_g electron filling state of Mn and Ni ions toward unity. Moreover, a vibronic superexchange interaction of Ni³⁺-O-Mn³⁺ induces strong Jahn-Teller distortion of MnO₆ and NiO₆ octahedra, elongating metal-O bonds, which helps to form the active species of Mn/Ni hydroxide/oxide on the surface of catalysts. Surprisingly, La₂NiMnO₆ nanoparticles exhibit superior oxygen evolution reaction (OER) catalytic performance with higher current density and lower Tafel slope than its bulk counterpart. Our finding will be a promising pathway to develop advanced precious-metal-free catalysts.