Electrochemical and Corrosion Characterization of TiO2-RuO2/Ti Electrodes Modified with WO3

Electrocatalytic activity of electrodeposited CoOx thin film on low-carbon unalloyed steel substrate toward electrochemical oxygen evolution reaction (OER)

In this study, we report elaboration of a thin film of CoOx on a low carbon unalloyed steel substrate by electrochemical route and the study of its electrocatalytic performances with respect to the evolution reaction of oxygen (OER) in NaOH medium. The elaborated deposits were well-characterized using X-ray diffraction. Kinetic and thermodynamic parameters such as exchange current density, Tafel slope, reaction order with respect to OH- ions and apparent activation energy were studied. The CoOx displays satisfactory OER performance in an alkaline medium, with a low overvoltage of 362 mV at 10 mA/cm2 and a Tafel slope of 81 mV/dec at 293 K. The apparent kinetic activation energy (= 29.79 kJ/mol) was similar to those obtained for the reported catalytic electrode materials. The O2 gas obtained on the cobalt oxide electrode was 2.865 mmol/s.cm2, which is 28 times higher than that obtained for the platinum electrode (0.102 mmol/s.cm2). Chronoamperometry demonstrates a better electrochemical stability under a polarization potential of 2 V in 1 M NaOH for nearly 25 h. The low cost, the high OER performance, as well as the good stability of the CoOx electrode make it a promising candidate for the industrial-scale water electrolysis.

Electrochemical and Catalytic Properties of Carbon Dioxide-Activated Graphite Felt

The commercial graphite felt GFA 10 was subjected to an activation process with the use of CO₂ at 900 °C for 35 and 70 min. Pristine and heat-treated materials were characterized using various methods: low-temperature N₂ adsorption, SEM, and EDS. Voltammetric measurements of GFA samples (before and after activation) as the working electrode were carried out. Voltammograms were recorded in aqueous solutions of 4-chlorophenol and sodium sulfate as supporting electrolyte. The catalytic activity of GFA samples in the process of 4-chlorophenol oxidation with the use of H₂O₂ was also investigated. The influence of graphite felt thermal activation in the CO₂ atmosphere on its electrochemical and catalytic behavior was analyzed and discussed. Results of the investigation indicate that GFA activated in CO₂ can be applied as an electrode material or catalytic material in the removal of organic compounds from industrial wastewater. However, the corrosion resistance of GFA, which is decreasing during the activation, needs to be refined.

Research trends in the development of anodes for electrochemical oxidation of wastewater

The review focuses on the recent development in anode materials and their synthesis approach, focusing on their compatibility for treating actual industrial wastewater, improving selectivity, electrocatalytic activity, stability at higher concentration, and thereby reducing the mineralization cost for organic pollutant degradation. The advancement in sol–gel technique, including the Pechini method, is discussed in the first section. A separate discussion related to the selection of the electrodeposition method and its deciding parameters is also included. Furthermore, the effect of using advanced heating approaches, including microwave and laser deposition synthesis, is also discussed. Next, a separate discussion is provided on using different types of anode materials and their effect on active •OH radical generation, activity, and electrode stability in direct and indirect oxidation and future aspects. The effect of using different synthesis approaches, additives, and doping is discussed separately for each anode. Graphene, carbon nanotubes (CNTs), and metal doping enhance the number of active sites, electrochemical activity, and mineralization current efficiency (MCE) of the anode. While, microwave or laser heating approaches were proved to be an effective, cheaper, and fast alternative to conventional heating. The electrodeposition and nonaqueous solvent synthesis were convenient and environment-friendly techniques for conductive metallic and polymeric film deposition.

Evaluating the Effect of WO3 on Electrochemical and Corrosion Properties of TiO2-RuO2-Coated Titanium Anodes with Low Content of RuO2

The electrochemical and corrosion characterization of Ti0.97Ru0.03O2/Ti electrodes modified with WO3 was reported. Modification of Ti0.97Ru0.03O2/Ti electrodes with WO3 was previously described as improving the effectiveness of an azo dye degradation in a photoelectrochemical treatment. Thus, the effect of WO3 introduction to oxide film on electrode surface on electrochemical behaviour and stability of the modified electrodes was investigated. Moreover, corrosion behaviour of Ti0.97Ru0.03O2/Ti electrodes modified with WO3 was evaluated with the application of potentiodynamic polarization sweep method and open circuit potential measurement. Electrodes modified with WO3 revealed higher anodic and cathodic peak currents in K4[Fe(CN)6] solution (by 35% for 6%WO3 content) indicating higher electroactive surface area and faster electron transfer reaction. An increase in WO3 amount in the oxide layer caused an increase in the number of active sites determined in Na2SO4 and most of them (more than 80%) were located in the outer and more accessible surface. The investigation of the tested electrodes at high potentials at which oxygen evolution is observed, allowed their classification in the following order showing an increase in their activity towards oxygen evolution reaction: Ti0.97Ru0.03O2/Ti < Ti0.94Ru0.03O2-W0.03O3/Ti < Ti0.91Ru0.03O2-W0.06O3/Ti. Although the electrode modification with WO3 resulted in lower resistance to corrosion in Na2SO4 solution regarding corrosion potential, corrosion current densities were clearly lower in comparison with the non-modified electrode, especially after longer immersion in the solution. ASTs showed that even a small addition of WO3 increased the lifetime of the electrodes. The Ti0.97Ru0.03O2/Ti electrode modification with WO3 seemed to be advantageous for their application in electrochemical and photoelectrochemical degradation of organic pollutants.