Multi-layered MXene-supported Cu@Fe–N–C with mSiO2 protection for Oxygen Reduction Reaction, supercapacitors, and water splitting

Abstract

The quest for cost-effective materials is vital to advancing energy storage and conversion technologies. In this study, a novel electrocatalyst, Cu@Fe–N–C@MXene, tailored for multifunctional applications, including oxygen reduction reaction (ORR), water splitting, and supercapacitors, is presented. A key innovation in this work is the incorporation of mesoporous silica (mSiO₂) protection, which effectively prevents fusion and aggregation of the Cu@Fe–N–C framework during high-temperature pyrolysis (920 °C), thereby preserving active site integrity and catalytic performance. The Cu@Fe–N–C structure, known for its potential to replace noble metals, was synthesized via a straightforward approach, while the multi-layered MXene support was prepared using HF/HCl etching and DMSO-assisted sonication, followed by controlled pyrolysis for composite integration. Comprehensive physicochemical characterizations confirmed the successful synthesis and structural stability of the composite. Electrochemical assessments demonstrated exceptional performance, including an onset potential of −0.031 V vs. Ag/AgCl for ORR with an electron transfer number of 3.35, overpotentials of 318 mV (HER) and 120 mV (OER) at 10 mA cm⁻², and Tafel slopes of 152 mV dec⁻¹ (HER) and 187 mV dec⁻¹ (OER). Additionally, a remarkable specific capacitance of 377 F g⁻¹ was achieved at 1 A g⁻¹. These results underscore the crucial role of mSiO₂ protection in maintaining structural integrity and enhancing catalytic efficiency, alongside the synergistic integration of MXene and Cu@Fe–N–C, making this composite a highly promising candidate for next-generation energy applications.