Cerium Oxide on a Fluorinated Carbon-Based Electrode as a Promising Catalyst for Hypochlorite Production

Abstract

Sodium hypochlorite (NaOCl) is widely used as a disinfectant agent for water treatment and surface cleaning. A straightforward way to produce NaOCl is by the electrolysis of an aqueous sodium chloride (NaCl) solution. This process presents several side reactions decreasing its efficiency with hypochlorite reduction on the cathode surface being one of the main detrimental reactions. In this work, we have studied carbon-based electrodes modified with cerium oxide (CeO2), fluorine, and platinum nanoparticles as cathodes for hypochlorite production. Fluorination was carried out electrochemically; the polyol method was used to synthesize platinum nanoparticles; and the hydrothermal process was applied to form a CeO2 layer. Scanning electron microscopy, FTIR, and inductively coupled plasma (ICP) indicated the presence of cerium oxide as a film, fluorine groups on the substrate, and a load of 3.2 mg/cm2 of platinum nanoparticles and 2.7 mg/cm2 of CeO2. From electrochemical impedance spectroscopy, it was possible to demonstrate that incorporating platinum and fluorine decreases the charge transfer resistance by 16% and 28%, respectively. Linear sweep voltammetry showed a significant decrease in hypochlorite reduction when the substrate was doped with fluorine from −16.6 mA/cm2 at −0.6 V to −9.64 mA/cm2 that further reduced to −8.78 mA/cm2 with cerium oxide covered fluorinated electrodes. The performance of the cathode materials during hypochlorite production improved by 80% compared with pristine activated carbon cloth (ACC) electrodes. The improvement toward hindering NaOCl reduction is probably caused by the incorporation of a partial negative charge upon doping with fluorine.

Exploring the Mechanism of the Electrochemical Polymerization of CO2 to Hard Carbon over CeO2(110)

“…At this potential, water would also be reduced to hydrogen. However, even in water (pH 7), the onset for hydrogen evolution over CeO 2 is of the order of approximately −1.3 V vs SHE . Furthermore, the reaction is performed in DMF with minor amounts of water .…”

“…However, even in water (pH 7), the onset for hydrogen evolution over CeO 2 is of the order of approximately −1.3 V vs SHE. 116 Furthermore, the reaction is performed in DMF with minor amounts of water. 52 Accordingly, this side reaction is at least to some degree suppressed.…”

Enhanced Electrocatalytic Conversion of Nitrates to Ammonia: Fuel from Waste

“…Also, higher current density would raise the operating voltage, which is not suitable for ACC electrode due to its stability. [16] Henceforth, in subsequent tests of the cell, a lower current density of 20 mA cm À 2 was used to minimize HER activities.…”

“…from re-oxidation of the product. [16] In most cases, batch reactors are accompanied by a membrane to keep the reactants separated, in order to prevent re-oxidation of the product. [49] However, membranes are not preferable in industrial conditions, as it has to be replaced regularly, adding additional costs to the production processes.…”

“…[14,15] The anode was modified with platinum (Pt) catalysts to reduce oxidation of the carbon electrodes. [16][17][18] The device termed continuous membrane-free electrocatalytic device (CMED) is designed similar to a flow-through capacitive deionization (CDI) device with InÀ Pd modified cathode for transformation of NO 3 À to NH 3 , with a proton generating anode for the enhancement of NO 3 À reduction in a sustainable process.…”