Moisture-enabled hydrovoltaic power generation with milk protein nanofibrils

Biologic materials have been shown to be good candidates for moisture-enabled hydrovoltaic power generation, but only those from specific bacterial cells have been explored. Herein, we report a moist-electric generator (PN-MEG) based on protein nanofibrils from milk /9-lactoglobulin. The as-developed device can generate an open -circuit voltage of up to 0.65 V and a short-current of 2.9 mu A. This device can generate a maximum power density of 38.88 mu W.cm? 2, which is one order of magnitude larger than those of previously reported analogous devices. The superior performance of this device is attributed to the remarkable hydrophilicity, high ionization and surface-to-volume ratio of protein nanofibrils. Density functional theory (DFT) calculations revealed that carboxyl groups were the favorable active sites in protein nanofibrils for binding water molecules. This study provides a novel perspective for common protein nanofibrils and paves the way for developing high-performance hydrovoltaic devices from biological materials.