Porous Fe₂O₃ Modified by Nitrogen-Doped Carbon Quantum Dots/Reduced Graphene Oxide Composite Aerogel as a High-Capacity and High-Rate Anode Material for Alkaline Aqueous Batteries

Abstract

Carbon quantum dots (CQDs) as novel types of emerging materials have aroused tremendous attention in recent years. Herein, we report for the first time a new application of 3D CQD-based composite aerogels as excellent electrode materials for alkaline aqueous batteries. The scalable graphitic CQDs are prepared with high yields (>40%) and further utilized to fabricate the novel nitrogen-doped CQDs/reduced graphene oxide/porous Fe₂O₃ (N-CQDs/rGO/Fe₂O₃) composite aerogels with different contents of Fe₂O₃. Benefiting from the unique 3D network composite aerogel structure with a high surface area and hierarchical porous structure as well as the synergistic effect of high-capacity Fe₂O₃ and highly conductive and stable N-CQDs/rGO, the composite aerogels achieve enhanced electrochemical properties with ultrahigh specific capacity, admirable rate property, and superior cycling performance. Furthermore, the <i>N</i>-CQDs/rGO/Fe₂O₃-1 electrode (Fe₂O₃, 34.9 wt %) exhibits the best rate capability (72.1, 58.9, and 46.2% capacity retention at 5, 50, and 100 A g^-1, respectively) and cycle performance (80.4% capacity retention at 3 A g^-1 over 5000 cycles), while the N-CQDs/rGO/Fe₂O₃-3 electrode (Fe₂O₃, 62.3 wt %) displays the highest specific capacity (274.1 mA h g^-1 at 1 A g^-1). The current research provides a valuable guidance for developing high-performance 3D CQD-based composite aerogels for application in energy storage systems.