A mesoporous C,N-co doped Co-based phosphate ultrathin nanosheet derived from a phosphonate-based-MOF as an efficient electrocatalyst for water oxidation

Abstract

The discovery of efficient and durable earth-abundant electrocatalysts for water splitting is highly desirable and is still a great challenge. Herein, we report a facile and simple approach to prepare amorphous, mesoporous C,N co-doped Co-phosphate ultrathin nanosheets via the one-step pyrolysis of a Co-based phosphate precursor with different kinds of coordinated atoms and a 2D layered structure. The resulting material supported on glassy carbon (GC) exhibited an excellent OER activity with a low overpotential of 291 mV, which is 21 mV lower than that of IrO₂ catalyst on GC (312 mV) in the same alkaline solution, to afford 10 mA cm⁻². Besides, this electrocatalyst showed fast kinetics with a Tafel slope of 57 mV decade⁻¹ in a 1.0 M KOH electrolyte, and the polarization curve after continuous 2000 CV cycles showed a negligible difference, indicating its good stability in alkaline media. The highly efficient catalytic performance with long-term stability for OER could be attributed to the following advantages: C,N co-doping facilitates the charge transfer; the amorphous structure and ultrathin 2D nanosheet structure enhance the activity site density; mesoporous structure facilitates the diffusion of O₂. This study provides a new strategy for the design and synthesis of heteroatom-doped high performance electrocatalysts for water oxidation based on MOFs with different types of coordination atoms, such as N and O atoms in the MOFs precursor.