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CO2 is electrocatalytically reduced in aqueous solutions (NaHCO3 and Na2SO4 ) at polycrystalline gold (Au) both bare and modified with copper nanoparticles (nano-Cu) (nano-Cu/Au). Copper nanoparticles were deposited by the cycling of potential in the range (–0.2–0.7 V) for various potential cycles. The effect of the electrolyte, as well as the nano-Cu loading on the electroreduction of CO2, has been investigated. Nano-Cu/Au electrode has been voltammetrically and morphologically characterized. It has been found that the type of electrolyte, that is, NaHCO3 and Na2SO4, is critical in the electrochemical reduction of CO2 ; for instance, the CO2 reduction is obscured by hydrogen evolution in NaHCO3 solutions (pH 9.2) at both electrodes, that is, bare Au and nano-Cu/Au electrodes, the well-defined redox peak is obtained at both electrodes in Na2SO4 solution (pH 7), even though the pH of Na2SO4 is smaller. The extent of catalysis is based on the copper loading at the nano-Cu/Au electrode as well. [ABSTRACT FROM AUTHOR]

Cysteine monolayer has been assembled onto bare gold electrode (SAM/Au), and subsequently deoxyribonucleic acid (DNA) has been successfully immobilized at the SAM/Au electrode. The thus modified electrode is assigned DNA/SAM/Au. Modification steps of the electrode were followed electrochemically using K4[Fe(CN6)] electrochemical marker. Also, the build‐up of the modified electrode composition is followed using EDX and the crystallographic orientation is inspected using XRD. The electrochemical behavior of paracetamol (PC) at DNA/SAM/Au electrode is investigated. Interestingly, the sluggish irreversible behavior of PC at the bare gold electrode is converted to a quasi‐reversible one at DNA/SAM/Au electrode pointing to some interaction between the immobilized DNA and PC. The enhanced electrochemical behavior of PC at modified DNA/SAM/Au electrode is successfully used for a sensitive electrochemical determination of PC. Square wave voltammetry (SWV) was used for this purpose. The concentration of PC was in linear relation with the peak current at the optimum conditions within the range 10.0–110.0 μg mL−1 with correlation coefficient (R2) of 0.998. Also, the standard deviation (SD) and relative standard deviation (RSD) were calculated and found to be 0.817 and 1.52, respectively, indicating the significance of the present method. [ABSTRACT FROM AUTHOR]

Abstract: Poisoning of the poly-Pt electrode by low concentration ammonium ion was investigated in H2SO4 and HClO4 solutions and a significant poisoning was observed in H2SO4 solution. An extraordinary recovery of the poisoned electrode was achieved in HClO4 solution by cycling the electrode potential between the onset potentials of the hydrogen and oxygen evolution. The extent of recovery was marked using the oxygen reduction reaction (ORR) as a probing reaction. Ammonium ion poisoning of the electrodes in H2SO4 caused a significant contribution of the two-electron reduction of O2 to hydrogen peroxide, as indicated by the rotating ring-disk voltammetry. The Tafel slopes at the low and high current densities were also affected by the presence of ammonium ion in H2SO4 solution and an increase in the Tafel slope was recognized with increasing the concentration of ammonium ion. However, the Tafel slopes at the low and high current densities were hardly affected by the ammonium ion in HClO4 solution. [Copyright &y& Elsevier]

Abstract: The current study is concerned with the preparation and characterization of tantalum oxide-loaded Pt (TaO x /Pt) electrodes for hydrogen spillover application. XPS, SEM, EDX and XRD techniques are used to characterize the TaO x /Pt surfaces. TaO x /Pt electrodes were prepared by galvanostatic electrodeposition of Ta on Pt from LiF–NaF (60:40mol%) molten salts containing K2TaF7 (20wt%) at 800°C and then by annealing in air at various temperatures (200, 400 and 600°C). The thus-fabricated TaO x /Pt electrodes were compared with the non-annealed Ta/Pt and the unmodified Pt electrodes for the hydrogen adsorption/desorption (Hads/Hdes) reaction. The oxidation of Ta to the stoichiometric oxide (Ta2O5) increases with increasing the annealing temperature as revealed from XPS and X-ray diffraction (XRD) measurements. The higher the annealing temperature the larger is the enhancement in the Hads/Hdes reaction at TaO x /Pt electrode. The extraordinary increase in the hydrogen adsorption/desorption at the electrode annealed at 600°C is explained on the basis of a hydrogen spillover–reverse spillover mechanism. The hydrogen adsorption at the TaO x /Pt electrode is a diffusion-controlled process. [Copyright &y& Elsevier]

This work examines the electrocatalytic reduction of molecular oxygen at Pt nanoparticles (nano-Pt) electrodeposited onto poly- crystalline gold (poly-Au) electrode in O2-saturated 0.5 M KOH. Cyclic and hydrodynamic voltammetry techniques were used for the evaluation of the electrocatalytic activity of the nano-Pt modified poly-Au electrodes. The nano-Pt was electrodeposited onto unmodified poly-Au electrode (nano-Pt/Au) and poly-Au electrode modified with a submonolayer (Ausm) of a thiol compound (typically cysteine) (nano-Pt/Ausm). In the latter case, Pt nanoparticles were electrodeposited, preferentially, at the bare fraction of the poly-Au electrode free from cysteine [i.e., the Au(111) domains of the poly-Au] while the other facets (i.e., Au(100) and Au(110)) were under the protection of cysteine. The nano-Pt electrodeposited onto the Ausm is characterized by small average particle size (ca. 10 nm) compared to that electrodeposited Onto the unmodified Au electrode (ca. 50–100 nm). The nano-Pt/Ausm electrode offers a high electrocatalytic activity toward the oxygen reduction reaction (ORR) as compared with the nano-Pt/Au and bare polycrystalline Pt electrodes. A 60 mV positive shift of the onset potential of the ORR was obtained at the nano-Pt/Ausm electrode as compared to the bare Pt electrode. A proper design of the nano-Pt/Au binary catalyst is the key point which controls the catalytic activity of the proposed electrocatalyst. [ABSTRACT FROM AUTHOR]

Highlights: [•] N-hexadecylpyridinium bromide (PyC16Br) significantly inhibits the corrosion of mild steel in H2SO4 solution. [•] PyC16Br act as a mixed-type inhibitor in 0.5M H2SO4 solutions. [•] Halides markedly enhances the inhibition action when added to PyC16Br. [•] Both PyC16Br and PyC16Br/halide systems the adsorption obeys Temkin adsorption isotherm. [ABSTRACT FROM AUTHOR]

The present work investigates the electrocatalysis of oxygen evolution (OE) on a glassy carbon electrode modified with nickel oxide nanoparticles (NPs) (nano-Ni) in an alkaline solution. The nano-Ni is electrodeposited from an acidic sulfate electrolyte containing various additives, such as glucose, glycerol, and dimethyl glyoxime. The NPs are characterized morphologically and electrochemically using scanning electron microscopy and cyclic voltammetry. The elemental composition and electronic state of the modified electrodes were analyzed using X-ray photoelectron spectroscopy. A considerable enhancement in electrocatalytic activity, depending on the additives used, is observed. The study also explores the effect of nickel oxide loading to optimize the process. The highest cathodic shift in the onset potential of the oxygen evolution reaction is achieved with nickel oxide deposited in the presence of ethylene glycol., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)