Atmospheric Water Sorption–Desorption as a Pathway for Green Energy Generation

Beyond the indispensable resource for living creatures, water has recently been explored as an eco-friendly source of energy, known as the hydrovoltaic technology. Of significant interest, the cyclic sorption/desorption of water molecules physically and chemically induces the gaseous/liquid–solid interactions with the substances, demonstrating potential for harnessing electricity. Existing efforts have focused on materials engineering and structural design of the energy generators, enhancing the generated electricity for real-life applications. Despite the substantial achievements, the principal interpretation of the process from water molecules to electricity establishes the foundation and serves as the guidance for device modification and performance enhancement. Herein, this review thoroughly discusses the energy conversion, from the introduction of water molecules to the generation of electricity, starting with an understanding of the sorption/desorption of water molecules. Mechanisms in charge creation from the interaction are then elucidated, where water molecules themselves serve as ions or stimulate ion dissociation from the substances. It continues with an overview of the existing advancements in sorption/desorption-induced electricity generation and practical demonstrations of the developed electricity. Based on the conversion procedure, insights for upcoming generator designs are proposed subsequently. Finally, present challenges to be addressed and perspectives on future development in the sorption/desorption-induced electricity are discussed in detail.