Hematite/NiO/Graphene Composites: Enhancing Humidity Energy Harvesting Through Temperature Variations

Harvesting energy from humidity is a new approach that has emerged as a potential renewable energy source. However, there are drawbacks to current humidity-based energy-harvesting technologies, such as the absence of a long-term conversion mechanism in hygroscopic materials. In this study, we developed hematite/nickel oxide/graphene (hematite/NiO/Gr) on a cellulose-based substrate as the hygroscopic material for humidity-to-energy applications. We successfully synthesized a novel hematite/NiO/Gr composite using a cost-effective sonicated solution immersion method at different synthesis temperatures. Results indicated that the prepared hygroscopic material is hydrophilic, with a water contact angle of 67.83°. The fabricated humidity-to-energy device utilizing these hygroscopic materials yielded an output voltage of 3.87 ± 0.06 mV and a current density of 0.309 ± 0.05 nA/cm2. This research highlights the potential of cellulose-based hematite/NiO/Gr composites as promising hygroscopic materials that could be utilized in future large-scale green energy technologies.