Development of hemp fiber-reinforced epoxy composite with cobalt oxide nanoparticles for fuel cell and energy storage applications

• Hemp fibers reinforced with Co₃O₄ nanoparticles enhanced composite properties. • Sample F4 showed tensile, flexural, and fatigue strengths of 79.14, 81.35, 83.19 MPa. • Achieved 127 °C heat deflection temperature and 34.6 W/mK thermal conductivity. • Retained 35 % mass at 410 °C, showing high thermal stability. • Combines hemp fibers and Co₃O₄ nanoparticles for energy storage applicatio. As industries push towards more sustainable and efficient production methods, polymer composites offer significant benefits. This study presents a novel composite material developed by reinforcing Cannabis sativa (hemp) fibers with cobalt oxide (Co₃O₄) nanoparticles, varying from 4 to 20 g, in an epoxy matrix. The aim of the study was to improve key properties such as mechanical strength, thermal stability, fatigue resistance, and antibacterial capacity, which are critical for enhancing the efficiency, durability, and safety of energy storage devices. Among five formulations tested, the composite containing 180 g of hemp fiber and 16 g of cobalt oxide in 164 g of epoxy (Sample F4) demonstrated the best performance. It achieved a tensile strength of 79.14 MPa, flexural strength of 81.35 MPa, and fatigue strength of 83.19 MPa after 5000 cycles, significantly improving structural integrity and resilience under mechanical stress. Thermally, Sample F4 exhibited a heat deflection temperature of 127 °C, a 15 % increase compared to the lowest-performing sample, and a thermal conductivity of 34.6 W/mK, ensuring efficient heat dissipation. Thermogravimetric analysis revealed high thermal stability, with Sample F4 retaining 35 % of its mass at 410 °C. Although the antibacterial capacity was 13.7 % lower than the standard agent, it still provided effective protection against oxidative degradation. The novelty of this work lies in the integration of hemp fibers with cobalt oxide nanoparticles, which enhances the mechanical and thermal properties, making it a promising material for energy storage applications, including fuel cell casings, batteries, and supercapacitors.