The modification of a glassy carbon (GC) electrode with platinum (PtNPs), gold (AuNPs), and nicke... more The modification of a glassy carbon (GC) electrode with platinum (PtNPs), gold (AuNPs), and nickel oxide (NiOx) nanoparticles was pursued to fabricate an efficient and stable anode for the formic acid electro-oxidation of (FAO). The deposition sequence of PtNPs and AuNPs was adjusted to optimize the electrocatalytic activity of the electrode. This could fortunately suppress the CO poisoning that usually deteriorates the catalytic activity of the anode during FAO. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy were used to evaluate the morphology and composition of the catalyst. Cyclic voltammetry measurements showed that the highest activity was obtained at the NiOx-Au-Pt/GC electrode (with PtNPs firstly deposited on the GC electrode followed by AuNPs then NiOx). Interestingly, the electrode has exhibited excellent stability which continued for more than 7h of continuous oxidation. While PtNPs furnished a suitable base for FA adsorption, AuNPs interrupte...
ABSTRACT The nickel oxide-platinum nanoparticles modified glassy carbon electrode (NiOx/Pt/GC) is... more ABSTRACT The nickel oxide-platinum nanoparticles modified glassy carbon electrode (NiOx/Pt/GC) is used as an effective anode for the oxidation of formic acid (FA), methanol (ME) and ethanol (ET) in 0.3 NaOH solutions. The loading of GC with NiOx and Pt is achieved electrochemically. The modified electrodes are characterized using cyclic voltammetry (CV) and scanning electron microscopy (SEM). The catalytic improvement observed at the NiOx/Pt/GC electrode for FAO, MEO, and ETO was not only confined in the large increase of the oxidation current but also in a negative shift in the onset potential of the oxidation reactions. The influence of temperature on the oxidation current is investigated and the apparent activation energy, Ea, for each fuel is calculated at a specific potential. Furthermore, the NiOx/Pt/GC electrode shows a satisfactory stability for FAO, MEO, and ETO in 0.3 M NaOH solution.
ABSTRACT Here we demonstrate a remarkable enhancement of the direct formic acid electro-oxidation... more ABSTRACT Here we demonstrate a remarkable enhancement of the direct formic acid electro-oxidation (FAO) to CO2 (dehydrogenation pathway, Ipd) at Pt nanoparticle modified GC (nano-Pt/GC) electrodes, in the presence of minute amount ( ppm) of vinyl acetate (VA), while suppressing the dehydration pathway (producing the poisoning intermediate CO, Ipind). An excellent electrocatalytic activity of the nano-Pt/GC electrocatalyst for FAO was found in the presence of VA (a possible contaminant) as revealed by comparing the intensity of the corresponding two oxidation peaks Ipd and Ipind) observed, respectively, at 0.25 and 0.75 V vs. Ag/AgCl/KCl(sat). The degree of enhancement of Ipd depends on the surface coverage () of VA at Pt nanoparticles. VA is believed to adsorb and consequently interrupt the surface contiguity of the Pt active sites favorable for CO poisoning. XPS measurements revealed a change in the electronic properties of Pt in presence of VA in such a way that favors the charge transfer during the FAO and/or facilitating the oxidative removal of the poisoning CO at lower potentials. Interestingly, VA (in ppm concentration) improves the electrode’s stability during FAO and also its catalytic tolerance against poisoning with chloride. Several indices were developed to measure the catalytic activity of the electrode in absence and presence of VA, and several techniques as FE-SEM, XRD, EDX, and XPS were employed in the revelation of the electrode’s morphology, crystal structure, composition, and binding energy.
ABSTRACT This study addresses the electrocatalytic oxidation of formic acid (FA) at nickel oxide ... more ABSTRACT This study addresses the electrocatalytic oxidation of formic acid (FA) at nickel oxide nanoparticles (nano-NiOx) modified Pt, Au, GC anodes. FA oxidation proceeds at the unmodified Pt electrode with the appearance of two oxidation peaks at 0.25 and 0.65 V corresponding to the direct oxidation of FA to CO 2 and the oxidation of the poisoning intermediate, CO, to CO 2 with a current ratio of the two peaks less than 0.2. Interestingly, this ratio jumps up to more than 50, upon modifying Pt with nano-NiOx. This highlights the essential role of NiOx in enhancing the direct oxidation of FA (at 0.25 V) at Pt substrate. On the other hand, unmodified GC and Au anodes as well as those modified with nano-NiOx exhibit no catalytic response toward FA oxidation. This highlights the essential role of the underlying substrate and depicts also that nano-NiOx behaves as a catalytic mediator which facilitates the charge transfer during the oxidation of FA at Pt anode. Optimization of the surface coverage of nano-NiOx at Pt is achieved, aiming at maximizing the rate of the direct oxidation pathway of FA while suppressing the indirect oxidation route producing the poisoning CO. Moreover, nano-NiOx/Pt anode maintains its high catalytic activity for a prolonged time of continuous oxidation of FA. textcopyright 2012 The Electrochemical Society.
ABSTRACT This study addresses the electrocatalytic oxidation of formic acid (FA) at binary cataly... more ABSTRACT This study addresses the electrocatalytic oxidation of formic acid (FA) at binary catalysts composed of Pt nanoparticles (nano-Pt) and nickel oxide nanoparticles (nano-NiOx) electrodeposited onto glassy carbon (GC) electrodes. Pt electrode shows two oxidation peaks at ca. 0.25 and 0.65 V vs. Ag/AgCl/KCl (sat.) corresponding to the direct (Ipd, favorable) and indirect (Ipind, unfavorable) oxidation pathways of FA, respectively. Nano-Pt/GC electrode shows a significantly higher catalytic activity toward FA oxidation than the bulk Pt electrode. Interestingly, further modification of the nano-Pt/GC electrode with nano-NiOx leads to a superb enhancement of Ipd with a concurrent suppression of Ipind. The catalytic activity of the various modified GC electrodes is probed by the ratio of Ipd/Ipind. This ratio increases from 0.2 at bulk Pt to 1.4 at nano-Pt/GC (i.e., ca. 7 times higher), and jumps up to more than 20 at the binary nano-NiOx/nano-Pt modified GC electrode, reflecting the superiority of the latter electrode toward FA oxidation to CO2. While nano-Pt furnishes a suitable base for FA adsorption, nano-NiOx acts as a catalytic mediator which facilitates the charge transfer during the direct oxidation of FA. The influence of the deposition sequence and the loading level of both species (i.e., Pt and NiO x) on the catalytic activity of the binary catalyst are investigated. textcopyright 2013 Elsevier Ltd. All rights reserved.
ABSTRACT Minute amount (∼1 ppm) of acrylonitrile (AcN), a possible contaminant, shows an unexpect... more ABSTRACT Minute amount (∼1 ppm) of acrylonitrile (AcN), a possible contaminant, shows an unexpected enhancement for the direct electro-oxidation of formic acid (FAO) at Pt nanoparticles modified GC (nano-Pt/GC) electrodes. This is reflected by a remarkable increase of the current intensity of the direct oxidation peak (Ipd, at ca. 0.3 V) in the presence of AcN, concurrently with a significant decrease of the second (indirect) oxidation current (Ipind, at ca. 0.7 V), compared to that observed in the absence of AcN (i.e., at the unpoisoned Pt electrode). The extent of enhancement depends on the surface coverage (θ) of AcN at the surface of Pt nanoparticles. AcN is thought to favor the direct FAO by disturbing the contiguity of the Pt sites, which is necessary for CO adsorption. Furthermore, XPS measurements revealed a change in the electronic structure of Pt in presence of AcN, which has a favorable positive impact on the charge transfer during the direct FAO.
The modification of a glassy carbon (GC) electrode with platinum (PtNPs), gold (AuNPs), and nicke... more The modification of a glassy carbon (GC) electrode with platinum (PtNPs), gold (AuNPs), and nickel oxide (NiOx) nanoparticles was pursued to fabricate an efficient and stable anode for the formic acid electro-oxidation of (FAO). The deposition sequence of PtNPs and AuNPs was adjusted to optimize the electrocatalytic activity of the electrode. This could fortunately suppress the CO poisoning that usually deteriorates the catalytic activity of the anode during FAO. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy were used to evaluate the morphology and composition of the catalyst. Cyclic voltammetry measurements showed that the highest activity was obtained at the NiOx-Au-Pt/GC electrode (with PtNPs firstly deposited on the GC electrode followed by AuNPs then NiOx). Interestingly, the electrode has exhibited excellent stability which continued for more than 7h of continuous oxidation. While PtNPs furnished a suitable base for FA adsorption, AuNPs interrupte...
ABSTRACT The nickel oxide-platinum nanoparticles modified glassy carbon electrode (NiOx/Pt/GC) is... more ABSTRACT The nickel oxide-platinum nanoparticles modified glassy carbon electrode (NiOx/Pt/GC) is used as an effective anode for the oxidation of formic acid (FA), methanol (ME) and ethanol (ET) in 0.3 NaOH solutions. The loading of GC with NiOx and Pt is achieved electrochemically. The modified electrodes are characterized using cyclic voltammetry (CV) and scanning electron microscopy (SEM). The catalytic improvement observed at the NiOx/Pt/GC electrode for FAO, MEO, and ETO was not only confined in the large increase of the oxidation current but also in a negative shift in the onset potential of the oxidation reactions. The influence of temperature on the oxidation current is investigated and the apparent activation energy, Ea, for each fuel is calculated at a specific potential. Furthermore, the NiOx/Pt/GC electrode shows a satisfactory stability for FAO, MEO, and ETO in 0.3 M NaOH solution.
ABSTRACT Here we demonstrate a remarkable enhancement of the direct formic acid electro-oxidation... more ABSTRACT Here we demonstrate a remarkable enhancement of the direct formic acid electro-oxidation (FAO) to CO2 (dehydrogenation pathway, Ipd) at Pt nanoparticle modified GC (nano-Pt/GC) electrodes, in the presence of minute amount ( ppm) of vinyl acetate (VA), while suppressing the dehydration pathway (producing the poisoning intermediate CO, Ipind). An excellent electrocatalytic activity of the nano-Pt/GC electrocatalyst for FAO was found in the presence of VA (a possible contaminant) as revealed by comparing the intensity of the corresponding two oxidation peaks Ipd and Ipind) observed, respectively, at 0.25 and 0.75 V vs. Ag/AgCl/KCl(sat). The degree of enhancement of Ipd depends on the surface coverage () of VA at Pt nanoparticles. VA is believed to adsorb and consequently interrupt the surface contiguity of the Pt active sites favorable for CO poisoning. XPS measurements revealed a change in the electronic properties of Pt in presence of VA in such a way that favors the charge transfer during the FAO and/or facilitating the oxidative removal of the poisoning CO at lower potentials. Interestingly, VA (in ppm concentration) improves the electrode’s stability during FAO and also its catalytic tolerance against poisoning with chloride. Several indices were developed to measure the catalytic activity of the electrode in absence and presence of VA, and several techniques as FE-SEM, XRD, EDX, and XPS were employed in the revelation of the electrode’s morphology, crystal structure, composition, and binding energy.
ABSTRACT This study addresses the electrocatalytic oxidation of formic acid (FA) at nickel oxide ... more ABSTRACT This study addresses the electrocatalytic oxidation of formic acid (FA) at nickel oxide nanoparticles (nano-NiOx) modified Pt, Au, GC anodes. FA oxidation proceeds at the unmodified Pt electrode with the appearance of two oxidation peaks at 0.25 and 0.65 V corresponding to the direct oxidation of FA to CO 2 and the oxidation of the poisoning intermediate, CO, to CO 2 with a current ratio of the two peaks less than 0.2. Interestingly, this ratio jumps up to more than 50, upon modifying Pt with nano-NiOx. This highlights the essential role of NiOx in enhancing the direct oxidation of FA (at 0.25 V) at Pt substrate. On the other hand, unmodified GC and Au anodes as well as those modified with nano-NiOx exhibit no catalytic response toward FA oxidation. This highlights the essential role of the underlying substrate and depicts also that nano-NiOx behaves as a catalytic mediator which facilitates the charge transfer during the oxidation of FA at Pt anode. Optimization of the surface coverage of nano-NiOx at Pt is achieved, aiming at maximizing the rate of the direct oxidation pathway of FA while suppressing the indirect oxidation route producing the poisoning CO. Moreover, nano-NiOx/Pt anode maintains its high catalytic activity for a prolonged time of continuous oxidation of FA. textcopyright 2012 The Electrochemical Society.
ABSTRACT This study addresses the electrocatalytic oxidation of formic acid (FA) at binary cataly... more ABSTRACT This study addresses the electrocatalytic oxidation of formic acid (FA) at binary catalysts composed of Pt nanoparticles (nano-Pt) and nickel oxide nanoparticles (nano-NiOx) electrodeposited onto glassy carbon (GC) electrodes. Pt electrode shows two oxidation peaks at ca. 0.25 and 0.65 V vs. Ag/AgCl/KCl (sat.) corresponding to the direct (Ipd, favorable) and indirect (Ipind, unfavorable) oxidation pathways of FA, respectively. Nano-Pt/GC electrode shows a significantly higher catalytic activity toward FA oxidation than the bulk Pt electrode. Interestingly, further modification of the nano-Pt/GC electrode with nano-NiOx leads to a superb enhancement of Ipd with a concurrent suppression of Ipind. The catalytic activity of the various modified GC electrodes is probed by the ratio of Ipd/Ipind. This ratio increases from 0.2 at bulk Pt to 1.4 at nano-Pt/GC (i.e., ca. 7 times higher), and jumps up to more than 20 at the binary nano-NiOx/nano-Pt modified GC electrode, reflecting the superiority of the latter electrode toward FA oxidation to CO2. While nano-Pt furnishes a suitable base for FA adsorption, nano-NiOx acts as a catalytic mediator which facilitates the charge transfer during the direct oxidation of FA. The influence of the deposition sequence and the loading level of both species (i.e., Pt and NiO x) on the catalytic activity of the binary catalyst are investigated. textcopyright 2013 Elsevier Ltd. All rights reserved.
ABSTRACT Minute amount (∼1 ppm) of acrylonitrile (AcN), a possible contaminant, shows an unexpect... more ABSTRACT Minute amount (∼1 ppm) of acrylonitrile (AcN), a possible contaminant, shows an unexpected enhancement for the direct electro-oxidation of formic acid (FAO) at Pt nanoparticles modified GC (nano-Pt/GC) electrodes. This is reflected by a remarkable increase of the current intensity of the direct oxidation peak (Ipd, at ca. 0.3 V) in the presence of AcN, concurrently with a significant decrease of the second (indirect) oxidation current (Ipind, at ca. 0.7 V), compared to that observed in the absence of AcN (i.e., at the unpoisoned Pt electrode). The extent of enhancement depends on the surface coverage (θ) of AcN at the surface of Pt nanoparticles. AcN is thought to favor the direct FAO by disturbing the contiguity of the Pt sites, which is necessary for CO adsorption. Furthermore, XPS measurements revealed a change in the electronic structure of Pt in presence of AcN, which has a favorable positive impact on the charge transfer during the direct FAO.
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