Cobalt-doped Fe₂O₃@CoFe-Layered Double Hydroxides heterostructures for enhanced supercapacitor and oxygen evolution reaction

Abstract

Hematite (Fe₂O₃) is a promising electrode material for supercapacitors owing to its high theoretical specific capacitance and structural tunability. However, its practical application is hindered by intrinsically poor electrical conductivity. In this work, we designed and synthesized novel cobalt-doped Fe₂O₃@CoFe-layered double hydroxide (LDH) heterostructures via a two-step hydrothermal method. Density functional theory (DFT) calculations reveal that cobalt doping and the construction of heterointerfaces effectively optimize the electronic structure and enhance electrical conductivity, leading to significantly improved electrochemical performance. The optimized electrode delivers a high specific capacity of 1202.2 F g⁻¹ at 1 A g⁻¹ and excellent cycling stability with 71.93% retention after 3000 cycles. Furthermore, an asymmetric supercapacitor assembled with this material achieves an energy density of 41.47 Wh kg⁻¹ at a power density of 705.59 W kg⁻¹, along with outstanding long-term stability (74.72% capacity retention after 3000 cycles). The material also exhibits remarkable oxygen evolution reaction (OER) catalytic activity, requiring a low overpotential of 255 mV to reach 10 mA cm⁻². This study provides new insights into the deliberate incorporation of cobalt and heterostructure engineering for the rational design of integrated energy storage and conversion systems.