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Nickel oxide nanoparticles (nano-NiO x ) of peculiar shape are prepared by sol–gel technique and its electrocatalytic activity is evaluated at different conditions. The thus prepared nanoparticles are annealed at three different temperatures, i.e., 200, 400 and 600 °C and anchored on glassy carbon (GC) electrode. Nano-NiO x modified GG (nano-NiO x /GC) electrodes are subjected to surface analysis techniques such as field emission scanning electron microscopy (FE-SEM) high resolution transmission electron micrograph (TEM) and X-ray diffraction (XRD). Electrochemical characterizations are performed using cyclic voltammetry and chronoamperometric techniques. The effects of annealing temperature on the morphological structure, surface concentration and subsequently on the electrochemical properties of nano-NiO x /GC are examined. Experimental results indicate that the grain size and electrochemical characteristics of the nano-NiO x /GC are significantly affected by the annealing temperature. The electrocatalytic oxidation of glucose at nano-NiO x /GC electrode is significantly enhanced especially with nano-NiO x annealed at 200 °C compared to those annealed at 400 and 600 °C. Nano-NiO x is believed to play a crucial role as a catalytic mediator to facilitate the charge transfer during the oxidation of glucose. [ABSTRACT FROM AUTHOR]

Abstract: A novel binary electrocatalyst fabricated from manganese and nickel oxides nanoparticles (MnO x and NiO x ), prepared by electrodeposition, is proposed as an anode for an amplified electrochemical oxidation of glucose in NaOH solutions. Cyclic voltammetry and scanning electron microscopy images were used to characterize these electrocatalysts. It has been found that the electrocatalytic activity critically depends on the order of the deposition of the two oxides. The NiO x /MnO x /GC electrode (MnO x deposited first) showed a superior electrocatalytic activity towards glucose oxidation compared to NiO x /GC, MnO x /GC or MnO x /NiO x /GC electrodes (NiO x deposited first). The extraordinary activity obtained at the NiO x /MnO x /GC electrode is attributed to the compilation of the better adsorption of glucose molecules on the MnO x sites and the increase of conductivity of the NiO x due to the increase of Ni3+ content. The results lead us to conclude that there is a synergism between the two oxides towards the electrooxidation of glucose. [Copyright &y& Elsevier]

Abstract: In this work, we study the effect of anodic oxidation of glassy carbon (GC) on the deposition of nickel oxide (NiO x ) nanoparticles and the electrocatalytic oxidation of glucose on the anodically oxidized GC modified with the NiO x . The GC is pretreated by anodic oxidation in 0.1M H2SO4 solution at different anodic potentials for different time periods. Different shape and size of NiO x nanoparticles are obtained when NiO x is deposited on anodically oxidized GC electrode. The purpose of the anodic oxidation is to manipulate the GC surface such that it gives higher surface concentration of C–O functional groups and higher surface area which leads to an extraordinary increase in the activity of NiO x towards glucose electrooxidation. Glucose electrooxidation is conducted in alkaline medium at GC/NiO x (GC is untreated) and GCox/NiO x (GC is treated) electrodes. Cyclic voltammetry (CV), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) are used for characterization of the above electrodes. The GCox/NiO x shows an excellent electrocatalytic activity toward glucose oxidation compared to GC/NiO x . The enhancement of the electrocatalytic activity obtained at the GCox/NiO x is discussed in the light of the obtained differences in characteristics of GCox/NiO x and increase in the surface concentration of C–O functional groups. [Copyright &y& Elsevier]

Nanoparticles of nickel oxide (nano-NiO x ) have been synthesized using electrochemical and sol-gel routes. Impacts of the synthesis route on the structural and electrochemical properties of NiO x nanoparticles modified glassy carbon electrode (nano-NiO x /GC) are studied. Cyclic voltammetry (CV), field emission scanning electron microscopy (FE-SEM), X-ray diffraction and transmission electron microscopy (TEM) have been used for the characterization of nano-NiO x /GC. The size of the particles using the sol-gel technique (NiO x-SG ) is uniform and have smaller particle size (~ 20 nm) than that obtained using the electrochemical route (NiO x-El , ~ 80 nm). The specific activity (given in mA per mg of the NiO x ) of the Ni(OH) 2 /NiOOH redox couple of the NiO x-SG is higher with higher reversibility compared with the NiO x-EL . Impacts of the synthesis route on the electrocatalytic properties of the thus prepared NiO x-SG and NiO x-El are tested by the glucose oxidation in alkaline solution as a probing reaction for the electrocatalytic activity. Enhancement of glucose electrocatalytic oxidation is discussed in the light of the difference in structural and electrochemical characteristics of both catalysts. [ABSTRACT FROM AUTHOR]

Abstract: This work addresses the electrocatalytic activity of a new catalyst composed of nickel and manganese binary oxides, prepared by electrodeposition, toward glucose electro-oxidation in alkaline medium. Cyclic voltammetry, scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) were used to characterize those electrocatalysts. It has been found that the electrocatalytic activity critically depends on the loading level and the order of deposition of the two oxides; the NiO x /MnO x /GC electrode (MnO x deposited first) showed an excellent electrocatalytic activity and stability toward glucose oxidation compared to NiO x /GC, MnO x /GC or MnO x /NiO x /GC electrodes (NiO x deposited first). At the present work conditions, it has found that, the optimum loading level is 60 cycles of MnO x followed by 10min deposition of nickel. At this loading level, it has been found that, the relation between I p /v 1/2 function and scan rate gives the characteristic feature of a catalytic process. [Copyright &y& Elsevier]

• A novel electrocatalytic NiFe 2 O 4 -nanoparticles (NFNPs) material was successfully fabricated via the citrate framework methodology. • Physicochemical tools including FT-IR, FE-SEM, XRD, TEM, HR-TEM, SAED BET, and EDX were studied to confirm the structure of NFNPs material. • CV at different scan-rate and glucose-contents followed by EIS were used to study the glucose electrooxidation. • NFNPs material as low-cost and simply prepared presents electrocatalyst towards the high-performance glucose oxidation in alkaline medium. Electrooxidation of glucose in alkaline media is a critical issue as a clean source for Fuel cell application. The using of noble metals as anodes obstructs the economic cost of the glucose fuel cells (GFC S). That is why the trend is towards the recent doped metal oxides designs as low-cost anodes electrocatalysts. Here, Nickel ferrite (NiFe 2 O 4) nanoparticles (NFNPs) were simply prepared by the formation of citrate framework followed by combustion and calcination as a promising anode for GFC S at high pH. The as-designed NFNPs were investigated in terms of FE-SEM, TEM, EDX, and XRD analyses. The crystallinity study confirms the formation of NiFe 2 O 4 cubic spinel with a crystallite size of around 13.7 nm. The surface morphology has a sponge-like structure with an irregular shape of pores. The diameters of sponge are varying, and the average is around ~ 572 nm. The successful formation of a porous network can be related to the releasing of considerable amounts of gaseous products during the combustion process at 180 °C and calcination process at 400 °C. The synthesized NFNPs showed enhanced electrocatalytic characteristics at different glucose contents up to 60.0 mM. Besides the high produced current, the enhanced stability and charge transfer were observed for the application of NFNPs in GEO. Image, graphical abstract [ABSTRACT FROM AUTHOR]