abstract

Moisture-enabled electricity generation (MEG) has emerged as a transformative paradigm for harvesting clean, sustainable energy from ubiquitous atmospheric humidity. This paper provides a comprehensive examination of the physical principles governing water adsorption energy harvesting, focusing on the fundamental mechanisms that convert molecular interactions between water and hygroscopic materials into usable electrical power. Through systematic analysis of ion diffusion, streaming potential, and electric double layer dynamics, we elucidate how functional group chemistry, nanoconfinement effects, and asymmetric material architectures govern charge separation and transport. Recent breakthroughs demonstrating power densities exceeding 1.5 mW cm⁻³, voltages above 1.0 V from single-cell devices, and novel hybrid systems integrating moisture harvesting with triboelectric or photovoltaic mechanisms are critically evaluated. We examine material innovations spanning carbon-based nanostructures, hydrogel-salt composites, metal-organic frameworks, and bioinspired systems that achieve unprecedented hygroscopicity and ion selectivity. Additionally, we analyze emerging device architectures including Janus structures, biomimetic aerogels, and self-adsorbing evaporative generators that address persistent challenges in continuous water supply and sustained output. Finally, we identify critical knowledge gaps in thermodynamic modeling, long-term durability, and scalable manufacturing while proposing future research directions including AI-assisted material discovery and hybrid energy systems. This review establishes that moisture-powered electricity, grounded in rigorous adsorption physics, stands poised to enable self-powered microelectronics, distributed sensing networks, and sustainable energy solutions independent of geographical constraints.