In this work, the surface modification using a two-steps plasma etching has been developed for enhancing energy conversion performance in polytetrafluoroethylene (PTFE) triboelectric nanogenerator (TENG). Enhancing surface area by a powerful O₂ and Ar bipolar pulse plasma etching without the use of CF₄ gas has been demonstrated for the first time. TENG with modified surface PTFE using a sequential two-step O₂/Ar plasma has a superior power density of 9.9 W⋅m⁻², which is almost thirty times higher than that of a pristine PTFE TENG. The synergistic combination of high surface area and charge trapping sites due to chemical bond defects achieved from the use of a sequential O₂/Ar plasma gives rise to the intensified triboelectric charge density and the enhancement of power output of PTFE-based TENG. The effects of plasma species and plasma etching sequence on surface morphologies and surface chemical species were investigated by a field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). The correlation of surface morphology, chemical structure, and TENG performance was elucidated. In addition, the applications of mechanical energy harvesting for lighting, charging capacitors, keyboard sensing and operating a portable calculator were demonstrated.