Hierarchical CuCo-Oxide/N-Doped Graphene-CNTs 3D Composite Material for High-performance Energy Storage and Environmental Sustainability

Abstract Developing cost-effective, high-performance materials for energy storage, environmental remediation, and electrocatalysis is crucial for sustainable technologies. Here, we report a novel CuCo-oxide/N-GCNT composite, synthesized via a scalable, solvent-free method, and evaluated for supercapacitors, catalytic reduction of 4-nitrophenol, HMF oxidation, and water splitting. The composite exhibited a high specific capacitance of 162.63 F/g at 1 A/g, an energy density of 22.5 Wh/kg, and a power density of 1267.3 kW/kg, with 88.08% retention after 10,000 cycles, demonstrating excellent supercapacitor stability. In environmental catalysis, the material enabled complete 4-nitrophenol reduction in 3 min with a pseudo-first-order rate constant (89.72 × 10 −2 s −1 ). It also achieved 98.7% HMF conversion and 68.6% FDCA yield using 70% t-BuOOH as an oxidant. As a bifunctional electrocatalyst, CuCo-oxide/N-GCNT delivered overpotentials of 258 mV (OER) and 185 mV (HER) at 100 mA/cm 2 , with Tafel slopes of 56.5 mV/dec (OER) and 84.0 mV/dec (HER). The enhanced performance is attributed to synergistic bimetallic interactions, high porosity, and uniform active site dispersion. This study establishes CuCo-oxide/N-GCNT as a sustainable, high-performance alternative to noble-metal catalysts for next-generation energy and environmental applications. Graphical Abstract