Electrocatalytic Evolution of Oxygen Gas at Cobalt Oxide Nanoparticles Modified Electrodes

The electrocatalysis of oxygen evolution reaction (OER) at cobalt oxide nanoparticles (nano-CoOx) modified GC, Au and Pt electrodes has been examined using cyclic voltammetry. The OER is significantly enhanced upon modification of the electrodes with nano-CoOx, as demonstrated by a negative shift in the polarization curves at the nano-CoOx modified electrodes compared to that obtained at the unmodified ones. Scanning electron microscopy (SEM) revealed the electrodeposition of nanometer-size CoOx (average particle size of 200 nm) onto GC electrode. Optimization of the operating experimental conditions (i.e., solution pH and loading level of nano-CoOx) has been achieved to maximize the electrocatalytic activity of nano-CoOx modified electrodes. It has been found that the electrocatalytic activity of the nano-CoOx modified electrodes towards the OER is pH and loading level dependent, while it is substrate independent. The low cost as well as the marked stability of the thus-modified electrodes make them promising candidates in industrial water electrolysis proces

Flower-shaped gold nanoparticles: Preparation, characterization, and electro

The modification of a glassy carbon electrode with gold nanoparticles was pursued, characterized, and examined for electrocatalytic applications. The fabrication process of this electrode involved assembling the gold nanoparticles atop of amino group grafted glassy carbon electrode. The scanning electron microscopy indicated the deposition of gold nanoparticles in flower-shaped nanostructures with an average particle size of ca. 150 nm. Interestingly, the electrode exhibited outstanding enhancement in the electrocatalytic activity toward the oxygen evolution reaction, which reflected from the large negative shift (ca. 0.8 V) in its onset potential, in comparison with that observed at the bulk unmodified glassy carbon and gold electrodes. Alternatively, the Tafel plot of the modified electrode revealed a significant increase (∼one order of magnitude) in the apparent exchange current density of the oxygen evolution reaction upon the modification, which infers a faster charge transfer. Kinetically, gold nanoparticles are believed to facilitate a favorable adsorption of OH− (fundamental step in oxygen evolution reaction), which allows the charge transfer at reasonably lower anodic polarizations

Fabrication of CuOx-Pd Nanocatalyst Supported on a Glassy Carbon Electrode for Enhanced Formic Acid Electro-Oxidation

Formic acid (FA) electro-oxidation (FAO) was investigated at a binary catalyst composed of palladium nanoparticles (PdNPs) and copper oxide nanowires (CuOxNWs) and assembled onto a glassy carbon (GC) electrode. The deposition sequence of PdNPs and CuOxNWs was properly adjusted in such a way that could improve the electrocatalytic activity and stability of the electrode toward FAO. Several techniques including cyclic voltammetry, chronoamperometry, field-emission scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction were all combined to report the catalyst’s activity and to evaluate its morphology, composition, and structure. The highest catalytic activity and stability were obtained at the CuOx/Pd/GC electrode (with PdNPs directly deposited onto the GC electrode followed by CuOxNWs with a surface coverage, Г, of ca. 49%). Such enhancement was inferred from the increase in the peak current of direct FAO (by ca. 1.5 fold) which associated a favorable negative shift in its onset potential (by ca. 30 mV). The enhanced electrocatalytic activity and stability (decreasing the loss of active material by ca. 1.5-fold) of the CuOx/Pd/GC electrode was believed originating both from facilitating the direct oxidation (decreasing the time needed to oxidize a complete monolayer of FA, increasing turnover frequency, by ca. 2.5-fold) and minimizing the poisoning impact (by ca. 71.5%) at the electrode surface during FAO

Electrocatalysis of the Oxygen Evolution Reaction at Nickel Oxide Nanoparticles - Modified Electrodes

Electrocatalysis, the approach dealing with enhancing the rates of electrochemical reactions by altering the surface properties of the electrodes on which these reactions proceed has been a topic of rapidly increasing interest. An intensive effort has recently been invested to develop new electrocatalytic materials for several applications such as the anodic oxygen evolution reaction (OER). The OER is principal in water electrolysis, an auxiliary reaction in the production of several substances forming at the cathode, and a side reaction in a number of anodic processes, particularly in the production of chlorine and other oxidizing agents. The recent revolution in nanotechnology has stimulated the development of a large set of novel nano-sized materials for the OER. The use of nano-sized electrodes enhances the mass transport, enlarges the accessible active surface area, lowers the charged currents and reduces the deleterious effects of solution resistance. Herein, we report on the electrocatalytic applications of platinum (Pt), gold (Au) and glassy carbon (GC) electrodes modified with nickel oxide (NiOx) nanoparticles towards the OER. The modification of the electrodes with NiOx nanoparticles has been done electrochemically. The scanning electron microscope (SEM) and the Energy dispersive X-ray spectroscopy (EDXS) are used to evaluate the surface morphology and composition of the modified electrodes. Preliminary results revealed a significant enhancement in the electrocatalytic activity of the GC and Au electrodes towards the OER upon the modification with NiOx nanoparticles. This enhancement appeared in a cathodic shift of 750 mV and 550 mV in the onset potentials of the OER, respectively, on the NiOx-modified GC and Au electrodes