Preparative Electrosynthesis of Strong Oxidizers at Boron‐Doped Diamond Electrode in Anhydrous HF

Abstract

The use of the boron-doped diamond electrode as as ufficiently stable electrode for electrochemical measurements/synthesis in liquid anhydroush ydrogen fluoride medium is reported. Electrooxidation of silver(I)h as been studied in this solventb yu sing classical transient electrochemical methods and impedance spectroscopy.I t has been found that faradaic currents relatedt os ilver(I) oxidation and the fluorine evolution reaction are reasonably separated at the potentials cale, whicha llows efficient electrosynthesis of Ag II F 2 ,apowerful oxidizer.I mpedance spectroscopy measurements provide insight into complex mechanism of AgF 2 formation.T he proceduref or electrosynthesis is provided for the first time in both galvanostatic and potentiostatic condition.With its Hammett acidityf unction, H 0 ,o fÀ15,1, [1] anhydrous hydrogen fluoridea cid (aHF) is classified as at ypical superacid. Immense protona ctivity,a sw ell as presence of fluorine atoms, lead to very high chemical reactivity of aHF;i ndeed, almost all metals and quartz are dissolved or etched in aHF.Am edieval alchemist learning of properties of aHF might possibly classify it as ac omponent of alkahest, that is, ad ream universal solvent. The necessity of using fluoropolymer materials for storing aHF,i ts very low boilingp oint of 19.4 8C, and pressure of gaseous HF steeply increasing with temperature (up to 20 atm at 130 8C, [2] and thus beyonds hear stress of thin-wall semitransparentf luoropolymer containers), add to difficulties of working with this compound.

Electrochemical Technologies for Detecting and Degrading Benzoquinone Using Diamond Films

“…Among those processes, the electrochemical oxidation (EO) has been the most employed method for treating organic pollutants applying different electrocatalytic materials . Boron‐doped diamond (BDD) anodes are widely used in EO due to their important characteristics that stand out from conventional electrodes, as well as their application to electro‐synthesize oxidants or compounds of high added value . In addition, its greater O 2 overpotential promotes the electrogeneration of higher amounts of physical adsorbed .…”

“…[11][12][13] Borondoped diamond (BDD) anodes are widely used in EO due to their important characteristics that stand out from conventional electrodes, [14][15][16][17][18] as well as their application to electro-synthesize oxidants or compounds of high added value. [19][20][21] In addition, its greater O 2 overpotential promotes the electrogeneration of higher amounts of physical adsorbed * OH radicals on its surface from water oxidation (Eq. 1), endorsing high pollutants degradation (Eq.…”

Electrosynthesis of Unique AgII Fluoride Quantum Antiferromagnets in Anhydrous HF

“…[23] related to the subsequent chemical reaction and it can be described by the model proposed recently by two of us. [23] By fitting the model to the experimental spectra ( Figure 6-Bottom) the following parameters were determined: resistance of the solution, R s , of 22.5 ± 0.35 Ω cm 2 , double layer capacity, C dl , of 22 ± 2 μF cm -2 , charge transfer resistance, R ct , of 151.4 ± 3.2 Ω cm 2 before and 118.6 ± 2.7 Ω cm 2 after electrosynthesis, and the homogeneous reaction rate constant, k, of Chemical synthesis crystal 1 [9] 6.6995 (14) 4.0116 (13) 180.05(7) Chemical synthesis crystal 2 [9] 6.7000(3) 4.0113 (2) 180.07(1) Electrosynthesis powder [this work] 6.670 (2) 3.9951 (14) 177.72 (10) 0.07 ± 0.002 s -1 before and 0.36 ± 0.01 s -1 after electrosynthesis. Using the model, it is possible to determine the average lifetime of the generated oxidizer (t 1/2 ):…”

“…[11] In our previous study, we have developed a method for electrosynthesis of polycrystalline silver(II) fluoride. [14] However, this method in its original setup failed to deliver single crystals. Figure 7 shows cyclic voltammetry curves recorded for BBD electrode in anhydrous hydrogen fluoride (aHF) with the addition of 500 mM silver(I) fluoride at 0°C.…”

“…[12] Following this insightful study, in our own recent work, we have shown that synthesis of even unstable and highly oxidizing Ag II salts is possible using Fluorine doped Tin Oxide (FTO) electrode. [13] However, work with aHF as a solvent, which is a sine qua non condition for preparation of silver(II) fluorides, requires the use of extremely chemically-resistant BDD as a working electrode, [14] as in Panizza's study. [12] Here we further advance our studies utilizing BDD electrode towards facile electrochemical preparation of two unique quantum magnets.…”