Contact-electrification at solid–liquid interfaces (SL-CE) and contact-electro-catalysis (CEC) are two blooming research areas with promising applications in sustainable energy, sensing, and chemical processes. However, prior research has neglected the impact of electronic defects on the ability of high-performance tribo-materials, like fluorinated polymers, to perform SL-CE/CEC. Here, through first-principle calculations, the addition of surface functional groups to fluorinated ethylene propylene (FEP) enables the tuning of its molecular orbitals' positions, and displacing deep-level defect states from the HOMO-LUMO gap is shown. Thereafter, FEP films are modified accordingly by plasma etching; resulting in a significant performance improvement of up to 202% (charge) in SL-CE experiments, and up to 398% (kinetic rate) in CEC dye degradation. This study provides a theoretical and experimental framework to design high-performance materials for SL-CE and CEC, and insights into their physical mechanisms and defect passivation, which are all fundamental for the advancement of these fields.