Fig. 3: Mechanism of the electricity generation from CO₂ adsorption.

a Comparison of the adsorption isotherms (293.15 K) of CO₂ by h-BN-NH₂ nanosheets and bulk h-BN measured by Brunauer–Emmett–Teller (BET) analysis. b The pH value of h-BN-NH₂ water solution as a function of CO₂ adsorption time, which drops gradually because of the generation of HCO₃^- ions. Total solution: 100-mL water solution of h-BN-NH₂ nanosheets at 1 mg mL^-1. CO₂ feeding rate is 10 mL min⁻¹. c I–V curves of h-BN-NH₂ nanosheet water solution bubbled with CO₂ and N₂ respectively in an H-cell. The other side was fed with DI water. d MD simulation model of agarose channel for selective transport of h-BN-NH₃⁺ and bicarbonate ions. The channel size was set to be wide enough to eliminate size effects. The relative positions of h-BN-NH₃⁺ and HCO₃^- were investigated at t = 0 and t = 25 ns respectively, which shows that h-BN-NH₃⁺ get anchored while HCO₃^- freely move within and across the channel. e The electrostatic and van der Waals interaction energies between agarose and HCO₃^- compared with those of between agarose and h-BN-NH₃⁺ nanosheet. f Ion permeation rate comparison of negative ions (HCO₃^-) and positive ions (h-BN-NH₃⁺) under concentration gradient. A homemade diffusion setup was applied to confirm the simulation results with a hydrogel bridge in between two reservoirs containing h-BN-NH₂ and DI water. (further experimental details are provided in Supplementary Note 4).