Fabricating high performance multi-functional hygroelectric generator through a biomimic approach

Biomimic “root” like aramid fiber (ANF) dendritic colloid is used to grasp functional fillers onto carbon nanotubes (CNTs) coated polyurethane foam, where graphene oxide (GO/ANF and reduced graphene oxide (rGO)/ANF dendritic colloids were respectively coated onto each end of the foam to prepare high-performance hygroelectric generator. Thanks to the high filler concentration on dendritic colloidal ANF and the overall device and direct contact between functional filler and water, a high concentration of charged ions is constructed on GO/ANF side with high oxygen functional groups. In contrast, rGO/ANF side would have a rather low concentration of charged ions, exerting an additional force on the directional diffusion of mobile charged ions. Thus, through creating large ion density difference, direct contact between water and active materials, and large specific area, excellent moisture–electric energy transformation (MEET) performance is illustrated, including ultra-high open-circuit voltage (0.96 V), short-circuit current (68.4 μA), energy density (≈ 225.4 μWh·cm −3 ), power density, and energy conversion efficiency (59.96%), where energy density is the highest among MEET devices reported. Besides, such foam can generate voltage under deformation so that they could be used as self-powered sensors. • A biomimic coating method was proposed to build a high ion concentration gradient. • This foam has excellent moisture–electric energy transformation (MEET) performance. • Experimental and fitting show that MEET properties was improved after adding salt. • Such foams generate voltage under deformation for self-powered sensors.