GO Nanosheet-Wrapped ZnS-Nanoplate-Based Highly Efficient Wearable Piezoelectric Nanogenerator for Biomechanical Energy Harvesting, Portable Electronics, and Health Monitoring

In this work, we propose an easy, cost-effective, and efficient approach to wrap zinc sulfide (ZnS) nanostructures or other similar nanomaterials with graphene oxide (GO) nanosheets for energy harvesting. The ZnS nanoplates were wrapped with different concentrations of GO nanosheets (5, 10, 15, 20, and 25 wt %) by using the hydrothermal method. Field-emission scanning electron microscopy and powder X-ray diffraction were performed to study the surface morphology and crystal phase structure of each sample. The dielectric study revealed that the wrapping gradually enhanced the polarization density of ZnS nanostructures. Then, GOx-ZnS nanostructures were loaded in a polydimethylsiloxane (PDMS) polymer matrix (GOx-ZnS@PDMS) to develop flexible piezoelectric nanogenerator (FPENG) devices. Among all fabricated devices, the GO20-ZnS@PDMS-based FPENG device showed the highest electric output of ∼27 V and 50.9 μWcm–2. The GO20-ZnS@PDMS-based FPENG device was used to develop a highly efficient self-charging green power system, which effectively charged a series of capacitors (1, 2.2, and 4.7 μF) up to ∼5.8, 4, and 2.6 V, respectively. For practical implementation, wearable/portable electronic gadgets were operated. The efficiency of the fabricated FPENG device was found to be ∼21.56%. Further, the FPENG device was demonstrated for biomechanical energy harvesting, and it showed remarkable electrical output performance under various kinds of human body motions. This indicates that the GO20-ZnS@PDMS-based FPENG device can be used in futuristic real-time health monitoring applications. Therefore, the present work on a highly efficient wearable FPENG device can be used in many daily life applications.