A novel wood-based multifunctional composites incorporating with piezoelectric and moist-electric performance

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The multi-functionalization on wood and its derivant has gained more and more attention for its resource-rich, reproducible and biodegradable properties. In this work, a wood-based multifunctional composite displaying piezoelectric and moist-electric performance has been proposed. Oxidized wood porous material/MXene/ZnO (OWPM/MXene/ZnO) was firstly prepared by delignification, oxidation, impregnation with MXene and loading zinc oxide (ZnO), in which zinc oxide (ZnO) was loaded via hydrothermal synthesis method. It can be found that the negative charge on the porous surface in MXene-impregnated OWPM can attract Zn2+ by electrostatic adsorption, creating a large number of nucleation sites for the growth of ZnO, thus accelerating its nucleation rate. Moreover, the increase of ZnO loading can enhance the streaming current, so the obtained OWPM/MXene/ZnO moist-electrical generator (MEG) can generate an open-circuit voltage (VOC) of 0.75 V at a test humidity of 85 %RH, as well as can collect energy from hot steam with the VOC of about 0.4 V. Simultaneously, the heterojunction formed between ZnO and MXene further enhance the piezoelectric performance. Finally, a piezoelectric generator (PEG) with anisotropic piezoelectric sensing performance was prepared by the impregnation with polydimethylsiloxane (PDMS) in OWPM/MXene/ZnO and the following densification. It can generate a VOC up to 4.71 V when a force of 45 N was applied perpendicularly to the fiber direction. The four PEGs series connection can light up a LED. Consequently, the application performance of MEGs and PEGs based on wood materials highlight potential in energy harvesting field.