Advancing Dual‐Functional Phase Change Material With Copper Oxide‐Coated Carbon Nanofibers for Photothermal Energy Harvesting and Thermal Management in Electronic Devices

This research integrates copper oxide‐coated activated carbon nanofibers (CuO‐ACnF) into paraffin wax to synthesize a nano‐enhanced phase change material (NePCM) and evaluates its suitability for photothermal solar energy harvesting and direct thermal management of electronic devices. The synthesized CuO‐ACnF within the phase change material (PCM) serve as an optical path for incident photons, enhancing photothermal performance. Additionally, the CuO coating increases the specific surface area of the percolated heat transfer network of ACnF, further improving thermal conductivity. The study examines the impact of varying CuO‐ACnF content from 0.5 to 5 wt% on the thermophysical and photothermal properties of the NePCM. Results show significant improvements, with thermal conductivity increasing by 18.9% to 45.15%, while photothermal gains ranged from 35% to 67.4%. Enhanced latent heat capacity was observed at certain concentrations due to heterogeneous nucleation, demonstrating the potential of the synthesized material for combined thermal energy storage and photothermal applications. However, higher concentrations of CuO‐ACnF led to agglomeration, reducing photothermal performance due to photon trapping within the CuO‐ACnF networks. Additionally, the computational fluid dynamics (CFD) approach reveals that all synthesized NePCMs outperform pure PCM in managing critical temperature (80°C) of CPU heat sink, with enhanced latent heat and thermal conductivity significantly contributing to the delaying of critical temperatures.