fig17

Figure 17. (A) V_oc generated by biological generators made of different nanofibrils (NFs). (B) Optical and scanning electron microscope images of aerogel fabricated by directionally freezing. (C) Zeta potentials of biological NF dispersions. (D) Schematic of hydrated channels around and between NFs. (E) V_oc variation upon exposure to airflow with different velocities. (F) Structure of the conductive metal-organic framework layered on cellulose nanofibre and the assembled film. (G) Cross-sectional scanning electron microscopy image of the film. Scale bar, 5 µm. (H) Measured zeta potentials of the cellulose nanofibers at different pH values. (I) The streaming potential generated in the hybrid cellulose nanofibre @ conductive metal-organic framework film at different pH (where the NaCl concentration was fixed at 0.01 M) and different salt concentrations (where the pH value was fixed at 10). (J) The measured ionic thermoelectric voltage at a temperature gradient of 5 °C. (K) A schematic of ion distribution and transport in the charged nanochannels and the proposed mechanisms for voltage generation. (A-E) Reprint with permission Ref.^[100]. Copyright 2019, Wiley-VCH. (F-K) Reprint with permission Ref.^[103]. Copyright 2021, The Royal Society of Chemistry.