Journal ArticleVertically Aligned Carbon Nanotubes Grown on Copper Foil as Electrodes for Electrochemical Double Layer CapacitorsNwanno, Chinaza E (ORCID:0009000198676185); Gotame, Ram Chandra (ORCID:000900062314472X); Watt, John; Kuo, Winson (ORCID:0000000328217909); Li, Wenzhi (ORCID:0000000184422232)<p>This study reports a binder-free, catalyst-free method for fabricating vertically aligned carbon nanotubes (VACNTs) directly on copper (Cu) foil using plasma-enhanced chemical vapor deposition (PECVD) for electrochemical double-layer capacitor (EDLC) applications. This approach eliminates the need for catalyst layers, polymeric binders, or substrate pre-treatments, simplifying electrode design and enhancing electrical integration. The resulting VACNTs form a dense, uniform, and porous array with strong adhesion to the Cu substrate, minimizing contact resistance and improving conductivity. Electrochemical analysis shows gravimetric specific capacitance (Cgrav) and areal specific capacitance (Careal) of 8 F g−1 and 3.5 mF cm−2 at a scan rate of 5 mV/s, with low equivalent series resistance (3.70 Ω) and charge transfer resistance (0.48 Ω), enabling efficient electron transport and rapid ion diffusion. The electrode demonstrates excellent rate capability and retains 92% of its initial specific capacitance after 3000 charge–discharge cycles, indicating strong cycling stability. These results demonstrate the potential of directly grown VACNT-based electrodes for high-performance EDLCs, particularly in applications requiring rapid charge–discharge cycles and sustained energy delivery.</p>MDPI2025-10-0110646043Nanomaterials151915062079-4991https://doi.org/10.3390/nano151915062213923National Science Foundation