Fig. 1. Rational design of the NAH electricity generator from CO₂ adsorption.

a Schematic illustration of the prototype NAH electricity generator. The generator was intentionally designed with a symmetric structure between two electrical collectors to ensure a balanced chemical potential across the generator at the initial stage. b The process of ion separation induced electricity generation from CO₂ adsorption, it starts from (i) grafting PEI onto boron nitride nanosheets to get h-BN-NH₂ adsorbents, (ii) the CO₂ adsorption induces the ions releasing of cations (h-BN-NH₃⁺) and anions (HCO₃^-), (iii) the cations in hundred nanometer are spatially confined while the anions can freely transverse within the hydrogel channels, leading to precise ion separation. c TEM image of the as-exfoliated and functionalized h-BN-NH₂ nanosheets. d SEM image of the cross-section structure of the NAH composite. The red discs are the trapped h-BN-NH₂ nanosheets in hydrogel network. e Photograph of the NAH electricity generator.