Elucidating the construction and modulation of built-in electric field in the oxygen evolution reaction

The construction of a built-in electric field (BIEF) is considered to be an effective strategy for enhancing catalyst performance due to its critical role in optimizing adsorption of reactants and key intermediates, as well as its positive impact on interface behavior. Herein, a strategy is developed to elucidate the correlation between oxygen evolution reaction activity and the BIEF and its strength by constructing and enhancing the BIEF through incorporating manganese into Co3O4@NiFe-LDH p-n heterojunction. This Co3O4@NiFe-LDH p-n heterojunction generates a BIEF that effectively regulates electronic structure, facilitates rapid electron transfer, induces alterations in the chemical microenvironment, and modulates intermediate adsorption energy. Notably, when hetoroatomic Mn is incorporated into the p-n heterojunction, particularly encapsulated within NiFe-LDH, a more pronounced enhancement for BIEF is observed. Benefiting from this strong BIEF, Co3O4@Mn/NiFe-LDH exhibits excellent OER activity and stability with an overpotential of only 209 mV at 50 mA cm−2, a Tafel slope of 57 mV dec−1, and stable operation for 110 h at approximately 10 mA cm−2. Moreover, density functional theory (DFT) calculations further confirms that the construction and reinforcement of the BIEF can effectively accelerate the electron transfer rates, adjust the metal d-band center, optimize intermediates adsorption properties, and reduce the reaction energy barriers.