Conductive coal-based nanocarbon for hydrovoltaic generator with enhanced electric power generation

The development of sustainable and cost-effective energy conversion technologies is imperative in the face of escalating global energy demands and environmental concerns. Hydrovoltaic power generation, which harnesses ambient water via solid–liquid interface interactions, offers a green pathway for low-grade energy harvesting. However, conventional carbon-based materials used in such systems often rely on petrochemical-derived precursors, limiting the scalability and environmental sustainability. Herein, we report a novel hydrovoltaic generator (CCHG) that fabricated with the low-cost and conductive coal-based nanocarbon (CCN). The CCN is uniformly deposited on the filter paper to form a water-permeable interface, enabling the directional water transport and evaporation-driven ion diffusion. The resultant CCHG device exhibits a voltage output of 0.53 V and a current of 62 μA with only 50 μL of water under ambient conditions. Integration of multiple units in series or parallel delivers up to 2.1 V and 240 μA, sufficient to drive the power commercial electronics such as LED arrays and timers. This work demonstrates a sustainable strategy for transforming coal from a combustion fuel to a value-added functional carbon material, opening the avenues for scalable, low-cost hydrovoltaic power generation systems in self-powered electronics and environmental sensing.