Electrosynthesis and catalytic activity of PbO₂‐fluorinated surfactant composites

Abstract

BACKGROUND: The effect of the potassium salt of nonafluorobutanesulfonic acid (C 4 F 9 SO 3 K) on the kinetic regularities of electrodeposition of lead dioxide (PbO 2) from nitrate electrolytes has been investigated. Obtained results concerning synthesis and physicochemical properties can contribute substantially to a fundamental understanding of the relationship between coating structure and catalytic activity, important to all fields of catalysis. RESULTS: The introduction of C 4 F 9 SO 3 K into the PbO 2 deposition electrolyte leads to insignificant inhibition of the Pb 2+ electrooxidation process, whereas the mechanism of the process does not change. Upon deposition of coatings from electrolytes containing surfactants, a composite coating is formed. Depending on the electrolyte composition and electrolysis conditions, the surfactant content in the composite can vary from 2.00 ± 0.05 to 17.00 ± 0.05 wt%. The inclusion of surfactants in the coating composition with subsequent overgrowth with PbO 2 leads to a decrease in the size of PbO 2 crystals and prevents the formation of polycrystalline blocks. The composite material is a PbO 2 matrix with submicron and nanoscale crystals into which surfactant particles are embedded. CONCLUSION: It was shown that the electrocatalytic activity of composite PbO 2-surfactant materials depends on the nature and content of the latter in the composite. The use of PbO 2 doped with C 4 F 9 SO 3 K as an anode leads to an inhibition of the process of oxygen evolution and an almost threefold increase in the rate of electrochemical conversion of 4-chlorophenol to aliphatic compounds.

Electrochemical oxidation of chloramphenicol with lead dioxide–surfactant composites

“…As can be seen from the obtained data, the formed coating consists of 93.1% of α‐phase PbO 2 in contrast to the similar one synthesized from nitrate electrolyte, which contains 73.3% of β phase (Velichenko, Luk'yanenko, Shmychkova, & Dmitrikova, 2020). However, the main effect on the phase composition in this case has the content of methanesulfonic acid in the electrolyte deposition, against which the effect of surfactant is not noticeable.…”

“…As in the case of coatings synthesized from nitrate solution (Velichenko, Luk'yanenko, Shmychkova, & Dmitrikova, 2020), the presence of surfactant in the deposition electrolyte leads to the loss of a clear direction of the individual faces of the crystals and an obvious reduction in their size (see Figure 1).…”

“…It is known that α‐PbO 2 has a more compact structure compared with β‐PbO 2 (Casellato et al, 2003). Usually, electrodeposited coating often consists of different phase structures of α‐PbO 2 /β‐PbO 2 (Velichenko, Luk'yanenko, Shmychkova, & Dmitrikova, 2020).…”

“…According to previous studies (Hu et al, 2021; Sanchez‐Montes et al, 2018), the most effective anodes are modified materials based on PbO 2 . A number of our recent publications have demonstrated the high electrocatalytic activity and stability of PbO 2 –surfactant composites deposited from nitrate electrolyte (Velichenko, Luk'yanenko, & Shmychkova, 2020; Velichenko, Luk'yanenko, Shmychkova, & Dmitrikova, 2020). However, it is impossible to synthesize mechanically stable coatings thicker than 100 μm from nitrate electrolytes.…”

“…It should be noted that a detailed study of the properties and electrocatalytic activity of lead dioxide–sodium dodecyl sulfate electrodes has so far been carried out in only three publications (Chen et al, 2020; Li et al, 2017; Velichenko, Luk'yanenko, Shmychkova, & Dmitrikova, 2020), and in all three coatings were deposited from nitrate electrolytes. There are no data in the literature on the coatings synthesized from methanesulfonate solutions.…”