Emulsion Electrospinning of Polytetrafluoroethylene (PTFE) Nanofibrous Membranes for High-Performance Triboelectric Nanogenerators

Pengfei Zhao; Navneet Soin; Kovur Prashanthi; Jinkai Chen; Shurong Dong; Erping Zhou; Zhigang Zhu; Anand Arcot Narasimulu; Carlo D Montemagno; Liyang Yu; Jikui Luo

doi:10.1021/acsami.7b18442

Emulsion Electrospinning of Polytetrafluoroethylene (PTFE) Nanofibrous Membranes for High-Performance Triboelectric Nanogenerators

ACS Appl Mater Interfaces. 2018 Feb 14;10(6):5880-5891. doi: 10.1021/acsami.7b18442. Epub 2018 Jan 30.

Authors

Affiliations

¹ Institute for Materials Research & Innovation (IMRI), School of Engineering, University of Bolton , Deane Road, Bolton BL3 5AB, United Kingdom.
² Ingenuity Lab, Department of Chemical and Materials Engineering, University of Alberta , Edmonton, Alberta T6G 2V4, Canada.
³ Key Laboratory of RF Circuit and System, Ministry of Education, Hangzhou Dianzi University , Hangzhou 310018, China.
⁴ School of Environmental and Materials Engineering, College of Engineering, Shanghai Polytechnic University , Shanghai 201209, P. R. China.
⁵ Southern Illinois University, Carbondale, Illinois 62901, United States.

PMID: 29346721
DOI: 10.1021/acsami.7b18442

Abstract

Electrospinning is a simple, versatile technique for fabricating fibrous nanomaterials with the desirable features of extremely high porosities and large surface areas. Using emulsion electrospinning, polytetrafluoroethylene/polyethene oxide (PTFE/PEO) membranes were fabricated, followed by a sintering process to obtain pure PTFE fibrous membranes, which were further utilized against a polyamide 6 (PA6) membrane for vertical contact-mode triboelectric nanogenerators (TENGs). Electrostatic force microscopy (EFM) measurements of the sintered electrospun PTFE membranes revealed the presence of both positive and negative surface charges owing to the transfer of positive charge from PEO which was further corroborated by FTIR measurements. To enhance the ensuing triboelectric surface charge, a facile negative charge-injection process was carried out onto the electrospun (ES) PTFE subsequently. The fabricated TENG gave a stabilized peak-to-peak open-circuit voltage (V_oc) of up to ∼900 V, a short-circuit current density (J_sc) of ∼20 mA m^-2, and a corresponding charge density of ∼149 μC m^-2, which are ∼12, 14, and 11 times higher than the corresponding values prior to the ion-injection treatment. This increase in the surface charge density is caused by the inversion of positive surface charges with the simultaneous increase in the negative surface charge on the PTFE surface, which was confirmed by using EFM measurements. The negative charge injection led to an enhanced power output density of ∼9 W m^-2 with high stability as confirmed from the continuous operation of the ion-injected PTFE/PA6 TENG for 30 000 operation cycles, without any significant reduction in the output. The work thus introduces a relatively simple, cost-effective, and environmentally friendly technique for fabricating fibrous fluoropolymer polymer membranes with high thermal/chemical resistance in TENG field and a direct ion-injection method which is able to dramatically improve the surface negative charge density of the PTFE fibrous membranes.

Keywords: PEO carrier; PTFE nanofiber; electrostatic force microscopy (EFM); emulsion electrospinning; ion injection; triboelectric nanogenerator.