Hydrovoltaic effect of microbial films enables highly efficient and sustainable electricity generation from ambient humidity

All-Biobased Hydrovoltaic-Photovoltaic Electricity Generators for All-Weather Energy Harvesting

“…Beyond E P , a hydrovoltaic electric field ( E H ) also exists in the all-biobased HPEG (Figure S19 ). According to Figure S20 and the literature [ 9 , 16 ], a moisture gradient existed in the film. Upon exposure to the ambient moisture, cations (such as H + ) may dissociate from -COOH moieties in the G.s -PSII hybrid film (Figure S21 ).…”

“…Surprisingly, the electricity output decreased by only ~8.0% after 220 h ( Figure 2(e) ), indicating a steady performance of the G.s -PSII HPEG. The continuous electricity generation was mainly due to the water adsorption-desorption process [ 9 , 16 ]. Abundant pores created the interspace of films that were associated with the external environment.…”

“…Mobile cations diffuse into the interior of the film with water movement, which was shown to induce concentration gradients across cations [ 10 , 38 ] and the formation of a diffusion current and E H . Notably, the porous structure of a hybrid film was conductive to the adsorption of water molecules into the pores through interfacial interactions [ 16 , 39 ] and the diffusion outside the film through evaporation. Such a dynamic water adsorption-desorption process driven by the environmental energy effectively maintains the concentration gradients of charges (Figure S22 ).…”

Electricity Generation from Phase Transitions between Liquid and Gaseous Water

“…Impressively, Zhou group successfully utilized three types of cells from electroactive bacteria to fabricate whole‐cell film‐based MIGs (Figure 9e). [ 16 ] Furthermore, five critical elements of device performance have been identified in the sequence: hydrophilicity, ionization, conductivity, pore structure, and water movement. More hydrophilic groups can trigger stronger ionic dissociation, migration, and conductivity by supplying more mobile ions.…”

“…Reproduced with permission. [11,[14][15][16][17][18][19][20][21][22][23][24][25][26]73] Reproduced with permission. [73] Copyright 2013, Royal Society of Chemistry.…”