Modulating Built-In Electric Field Via N-Doped Carbon Dots for Robust Oxygen Evolution at Large Current Density.

Constructing a built-in electric field (BIEF) within heterostructures has emerged as a compelling strategy for advancing electrocatalytic oxygen evolution reaction (OER) performance. Herein, the p-n type nanosheet array heterojunction NiP-NCDs-Co(OH)-NF are successfully prepared. The variation in interaction affinity between nitrogen within N-doped carbon dots (NCDs) and Ni/Co induces charge redistribution between Co and Ni in the NiP-NCDs-Co(OH)-NF-3 heterostructure, thereby enhancing the intensity of the BIEF, facilitating electron transfer, and markedly improving OER activity. The optimized electrocatalyst, NiP-NCDs-Co(OH)-NF-3, demonstrates a remarkably low overpotential of 389 mV at 500 mA cm, alongsides a small Tafel slope of 65 mV dec, expansive electrochemical active surface area (ECSA), low impedance, outstanding stability exceeding 425 h at 500 mA cm, and a Faradaic efficiency of up to 96%. In situ Raman spectroscopy and density functional theoretical (DFT) calculations elucidate the OER mechanism, revealing that the enhanced BIEF optimizes the adsorption energy of Co to OH and weakened the desorption energy of oxygen during the reaction. The work ponieeringly employed the NCDs as a regulator of the BIEF, effectively tuning field intensity and achieving superior electrocatalytic OER performance under large current density, thus charting new pathways for the development of high-efficiency oxygen evolution electrocatalysts.