Engineering CoP/FeP4 heterostructures on epitaxially grown ultra-thin two-dimensional MOFs via competitive coordination for high-durability electrochemical supercapacitors

Abstract

Two-dimensional (2D) ultra-thin structures represent ideal precursor materials for supercapacitors, owing to their large surface area that exposes abundant metal active sites and shortens ion diffusion pathways, thereby facilitating electrochemical reactions. Herein, a 2D Co MOF (urea) material with precisely defined geometries is constructed via urea molecule induced structural topology control. Urea participates in coordination competition, actively promoting the 2D growth of the material. Through subsequent controlled phosphating, 2D/3D P-CM (urea)/CFP heterostructures are successfully fabricated. The designed heterostructures effectively regulate interfacial charge states, generating abundant active sites and accelerating charge transfer kinetics. The as-fabricated electrode material exhibits a remarkably high specific capacitance of 2353.8 F g⁻¹ at a current density of 2 mA cm⁻² and excellent rate capability. Density functional theory calculations are performed to reveal the mechanism of enhanced electrochemical performance. The assembled P-CM (urea)/CFP//AC asymmetric supercapacitor presents outstanding electrochemical performance such as a high energy density of 41.9 Wh kg⁻¹ at a power density of up to 711.4 W kg⁻¹, and remarkably high cycling stability with 95.1% capacitance retention after 10 000 charge–discharge cycles. These findings highlight the effectiveness of integrating morphological and electronic modulation for material optimization in energy storage applications.