Preparation of GA cross-linked PVA/SA electrospinning nanofibrous membranes and their moisture-powered generation performance
With the development of society,the conversion and utilization of micro energy has received increasing attention.Moisture-powered generation is a technology that converts the energy of moisture into electricity to meet energy demand and reduce dependence on traditional energy sources.The moisture-powered generator prepared by electrospinning has a large specific surface area and great porosity,resulting in a high voltage output and fast response rate during moisture-powered generation.However,the fine nanofibers of the membrane lack structural stability after absorbing moisture,which can lead to a drastic decline in device performance.The cycling performance of the nanofibrous membrane as a moisture-powered generator can be enhanced through appropriate crosslinking.Therefore,in this paper,polyvinyl alcohol(PVA)and sodium alginate(SA)were used as raw materials,and different amounts of glutaraldehyde(GA)were added to cross-link and modify PVA and SA for the preparation of the spinning solution.GA crosslinking modified PVA/SA nanofiber film(G-PVA/SA)with certain water solubility resistance was prepared by electrospinning technology.The molecular structure,morphology,mechanical properties,moisture-powered generation properties and related applications of G-PVA/SA nanofiber films with different crosslinking degrees were tested and analyzed.The results show that GA can promote the effective cross-linking between PVA/SA molecules.With the increase of GA content,the degree of cross-linking between molecules increases,which leads to the increase of the fiber diameter,crystallinity and mechanical properties of the prepared G-PVA/SA nanofiber films.However,due to the decrease of hydrophilicity,the power generation performance of the moisture-powered generation device is slightly reduced.0%G-PVA/SA nanofiber film(2 cm×2 cm)can produce 0.42 V voltage at high humidity(RH=85%),and 2%G-PVA/SA nanofiber film can produce 0.38 V voltage.After three cycles,0%G-PVA/SA hygroscopic generation voltage decreases by 28.59%,while 2%G-PVA/SA nanofiber film hygroscopic generation voltage decreases by only 0.42%,and after 10 cycles,the open-circuit voltage remains at 0.36 V with a short-circuit current of 0.44 μA,which is only reduced by 6.5%and 4.4%,respectively.The cross-linking improves the water solubility resistance of G-PVA/SA nanofiber film and maintains the structural stability after moisture absorption.In addition,by adjusting the distance between the finger and the device,various levels of output voltage can be monitored,which can be used to estimate the approximate distance between the human body and an object.Meanwhile,placing the device within a face mask allows for monitoring of different breathing intensities and frequencies through various waveforms of electrical output,thereby enabling the moisture-powered generator to be utilized in numerous real-life applications.
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