The Absence of Redox Reactions for Palladium(II) and Copper(II) on Electrostatically Charged Teflon: Relevance to the Concept of “Cryptoelectrons”

Abstract

Die Hypothese einer Kontaktelektrifizierung durch den Transfer von Kryptoelektronen wurde geprüft, indem nach Hinweisen auf eine Reduktion von Pd2+ und Cu2+ durch statische Ladungen beim Reiben von Teflon gesucht wurde. Gemäß Röntgenphotoelektronenspektroskopie wird keines der beiden Ionen durch die statische Ladung reduziert (siehe Bild; schwarz: Pd2+ nach Adsorption; rot: Pd0 nach Reduktion mit Formaldehyd; grün: Pd2+/Pd0 nach partieller Reduktion während 2 h unter der XPS‐Sonde). Eine alternative Interpretation stellt die Rolle von Kryptoelektronen infrage.

The effects of dynamics on the triboelectrification of volcanic ash

“…Thus, determining the relative contributions of both mechanisms becomes problematic (although some work suggests that frictional processes added to fracture electrification may in fact reduce the overall magnitude of charging [ James et al ., ]). We do note, however, that evidence exists to suggest that triboelectric charging involves spallation at the molecular scale, supporting the idea that frictional charging and fragmentation charging are but manifestations of a single process [ Salaneck et al ., ; Piperno et al ., ]. With the available data, discerning the extent to which triboelectric charging and fractocharging contribute to the electrified state in a plume (or whether they are actually end‐members of a single process) remains difficult.…”

Friction, tribochemistry and triboelectricity: recent progress and perspectives

“…This was criticized by Piperno et al 109 who observed the mutual transfer of material 70 between PMMA and PTFE, increasing the capacity for cation adsorption on PTFE. Following these authors, "the static charge might be due to uncompensated ions rather than cryptoelectrons".…”

Triboelectric charging of insulating polymers–some new perspectives

“…When two polymers like Teflon and Lucite were rubbed together vigorously, it was found by Liu and Bard [33][34][35] and by Otero 36 that the surface charges developed can carry out different chemical redox reactions such as metal deposition, ion reduction and chemiluminescence, reactions which can be induced by electrons but not by ions. This conclusion was later challenged by Piperno et al 37 because it was shown that rubbing of these polymers results in transfer of material containing polar active species so that the surfaces are charged by ions. However, this issue is by no means resolved.…”

“…However, this issue is by no means resolved. For example, in the experiments by Piperno et al, 37 Teflon was irradiated with high pressure oxygen plasma prior to contact charging, which likely changed the surface composition. For comparison, it was found by Vandencasteele 38 et al that irradiation of Teflon with ten times weaker oxygen plasma for a much shorter time increased the surface oxygen level from 0 to 5%, decreased the surface fluorine from 66 to 36%, and increased the surface carbon from 34 to 59%.…”

“…37 The question now arises whether the degree to which the material transfer mechanism occurs depends on where the contact type resides on the contact continuum. Does the material transfer mechanism apply only when the degree of force or frictional energy exceeds a certain value, and an electron or ion transfer mechanism occurs below that value, as possibly is the case in cascading of beads over inclined polymer films?…”