AuPt Bimetal has been successfully synthesized by electrodeposition method with potentiostat technique. By varying the concentration of Au ions in the solution they are able to control the morphology ...and composition of the synthesized sample. The morphology obtained from the AuPt synthesis is cauliflower. The effect of Au ion concentration in solution on the catalytic performance of AuPt, the greater the Au concentration, the greater the current density in the electrooxidation reaction. In addition, the concentration of Au ions in the solution affects the results of the deposition of Au and Pt elements. In the study of AuPt nanocatalysts with a 0.4 mM Au ion concentration in an electrolyte solution, it was shown to have good catalytic activity in the ethanol electrooxidation reaction, with the resulting current densities and If/Ib of 10.1 mA/cm2 and 43.53 mA/cm2, respectively. This is an implication of many Au compositions which are known to have the ability to absorb and oxidize CO to encourage an increase in current density and increase its catalytic activity.
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•Co-fueling increases the current densities of C3-alcohols maximally by 9.9 times.•Product evolutions are recorded with in situ NMR monitoring.•Charge distributions are quantitatively ...analyzed with EC-NMR technique.•Co-fueling enhances the adsorption of –OH and the cleavage of C-C-C bonds.
C3-alcohols can theoretically provide high current efficiencies in direct fuel cell applications because of their intrinsically large energy densities. However, during realistic reactions, molecular multiple carbon–carbon (CCC) bonds are hardly broken, severely reducing current efficiencies. Herein, directly with commercial Pt/C as the catalyst, the operation of co-fueling with formic acid significantly enhances the current efficiencies of two types of C3-alcohols, namely, isopropanol and 1,2-propanediol. Compared with the current densities of pure C3-alcohols, those of co-fueled C3-alcohols increase maximally by 9.9 times. The reason lies in the fact that the co-fueling design facilitates the breaking of CCC bonds, as elucidated by charge distributions that are obtained via electrochemical nuclear magnetic resonance analyses. Density-functional-theory computational results indicate that the generation of OH groups adsorbed on Pt surfaces is promoted in co-fueling experiments, reducing energy barriers for breaking progress. The co-fueling strategy is capable of optimizing C3-alcohol electrooxidations in direct fuel cells and deserves extensive study.
Glycerol electrooxidation reaction (GOR), as an attractive alternative to oxygen evolution reaction, not only produces value-added formic acid but also facilitates H2 production. However, its ...practical application suffers from the lack of efficient electrocatalysts with high activity at low potentials. Herein, sulfur doped manganese-cobalt hydroxide nanosheets on nickel foam (Mn-Co-S/NF) has been demonstrated as a promising electrocatalytic electrode for GOR, showing high current density at low potentials and high Faradaic efficiency for formate production. The combination of ex situ characterization, operando Raman analysis, and in situ electrochemical impedance spectroscopy measurement unveils that S doping leads to the formation of hierarchically porous structure with abundant oxygen vacancies during the reaction, enabling the surface reconstruction to proceed in an easier manner and to a higher degree. As a result, the reconstructed Mn-Co-S/NF possesses highly enhanced charge/mass transfer capability and enriched high valence Co active species. Impressively, in a practical flow electrolyzer, an industrial-level current density of 900 mA cm−2 can be achieved at a cell voltage of 2.0 V. It also exhibits H2 yield rate of 3.5 mmol cm−2 h−1 at 200 mA cm−2, realizing up to 30.2% energy saving efficiency compared to water electrolysis.
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•Mn-Co-S/NF exhibits high activity and high formate Faradaic efficiency for glycerol electroxidation.•S-doping promotes the surface reconstruction of Mn-Co-S/NF.•The glycerol electrolyzer shows higher energy saving efficiency for hydrogen production than overall water splitting.
Development of electrocatalysts with extended homogeneity and improved metal-support interactions is of urgent scientific need in the context of electrochemical energy applications. Herein, ...bimetallic Pt-Pd nanoparticles with good homogeneity are fabricated using a convenient solution phase chemical reduction method onto a reduced graphene oxide (rGO) support. X-ray diffraction studies revealed that Pt-Pd/rGO possesses the crystallite size of 3.1 nm. The efficacies of Pt-Pd/rGO catalyst (20 wt% Pt + 10 wt% Pd on rGO support, Pt:Pd atomic ratio = 1:1) towards ethanol electrooxidation reaction (EOR) are evaluated in acidic conditions by cyclic voltammetry using catalyst-coated glassy carbon electrode as a working electrode. With the better dispersion on rGO support the Pt-Pd/rGO nancomposite catalyst exhibit highest mass specific activity (0.358 mA/µg-Pt) which is observed to be 1.9 times of similarly synthesized 20 wt% Pt/rGO (0.189 mA/µg-Pt) and 2.5 times of commercial 20 wt% Pt/C (0.142 mA/µg-Pt), respectively. Apart from the observed improved EOR activity, the Pt-Pd/rGO catalyst exhibited better stability than Pt/rGO and Pt/C catalysts. Strong synergy offered by Pt, Pd and rGO support could contribute to the observed higher EOR activity of Pt-Pd/rGO.
•For glycerol electrooxidation the anodic limit of Pd-electrodes is superior to their ECSA.•The adsorption of glycerol appears to be not a dominant factor in its total electrooxidation route.•Role of ...molecular oxygen in electrooxidation of glycerol on Pd-modified electrodes was revealed.•The larger Pd-particles better catalyze glycerol oxidation.
Herein, a study dealing with a progress on palladium (Pd) electrocatalysts for an efficient glycerol electrooxidation in model aqueous and real fermentation solutions with special focus on some physicochemical parameters (e.g., the impact of adsorption stage of multiple species, presence of oxygen, influence of anodic limits and Pd-size) was conducted. During the course of investigations by tandem of an optical oxygen minisensor and cyclic voltammetry a significant impact of oxygen on the efficiency of glycerol electrooxidation on Pd electrocatalysts at alkaline pH in model aqueous and yeast fermentation media was revealed.
The obtained knowledge was used for the optimization of an assay utilizing Pd-sensing layers for glycerol determination and quantification in yeast fermentation medium. Received results showed a satisfactory agreement with a control measurement carried out by gas chromatography mass-spectrometry.
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With increasing energy demands worldwide, significant efforts have been made to develop superior electrocatalysts for efficient energy conversion systems. Among all the electrocatalysts exploited, ...Pt‐based bimetallic nanomaterials stand out by virtue of their high catalytic activity and relatively low cost due to the introduction of a nonprecious metal component. It should be noted that electrocatalytic reactions only take place on the surface of catalysts, so investigations of the surface composition of Pt‐based bimetallic nanomaterials are necessary for practical electrocatalysts. In this review, recent studies on controlling the surface composition of Pt‐based bimetallic catalysts for the oxygen reduction reaction, formic acid electrooxidation, and ethanol electrooxidation are summarized. The controlling strategies, including the chemical method and the electrochemical method, are discussed. The impacts of surface composition compositions on the electrocatalytic performance are also discussed. Finally, the challenges and future directions for controlling the surface composition of Pt‐based bimetallic nanomaterials are addressed.
The recent progress in controlling the surface composition of Pt‐based bimetallic (PtM) nanomaterials is discussed. These surfaces directly impact the corresponding electrocatalytic reactions, for example oxygen reduction reactions, ethanol oxidations, and formic acid oxidations. This study also provides guidelines for researchers to pursue more efficient strategies to rationally design highly activity and stabile electrocatalysts.
Platinum (Pt) nanoparticles were successfully prepared using square wave pulse deposition technique by varying the upper potential. The X-ray energy dispersive spectrum pattern confirmed the ...formation of Pt nanoparticles on the fluorine-doped tin oxide coated glass substrate. The results of scanning electron microscopy showed that the potential of 0.60 V was able to produced a large number of Pt particles with a unique morphology. The ethanol electrooxidation test conducted using cyclic voltammetry showed that Pt0.60v has the lowest charge transfer resistance value showing high catalytic activity which could be associated to the increase of particle number and its active sites that activated the redox reactions in the system.
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•Modified carbon paper (CP) electrodes have been used for naproxen electrooxidation.•Reduced graphene oxide (RGO) improved Pt nanoparticles (Pt NPs) dispersion on CP.•RGO on CP ...reduced the size of Pt NPs, contributing to increase the electroactivity.•NaCl containing media accelerated the naproxen kinetics electrooxidation.
This research study investigates the electrooxidation of naproxen (NPX), an anti-inflammatory pharmaceutical, on modified carbon paper (CP) electrodes. Electrochemical modification of CP electrodes was accomplished with Pt or reduced graphene oxide (RGO)-Pt coatings, resulting in the production of electroactive electrodes. RGO coatings synthesized by cyclic voltammetry (CV) for 10 scans provided the optimal coverage for the CP electrode surface. The deposition of Pt nanoparticles (Pt NPs) on the electrodes (CP or CP-RGO) by CV produced a good electrode surface coverage with 20 synthesis scans. The voltammetric analysis of the electrodes in 230 mg/L NPX solution showed oxidation peaks around 1.0 to 1.2 V. Moreover, the inclusion of RGO in the coating led to an increase in the current density of these oxidation peaks and a decrease of the electrode electron transfer resistance as measured by electrochemical impedance spectroscopy.
The electrolysis of NPX in different electrolytes (Na2SO4 and Na2SO4/NaCl) was conducted at 1.4 V, and the removal of NPX was analyzed using high-performance liquid chromatography. The CP-RGO-Pt electrode in Na2SO4/NaCl media showed the fastest NPX degradation kinetics, resulting in a 90 % degradation in only 90 min with low charge consumption (0.07 A·h·L-1). The smaller size of Pt NPs deposited on CP-RGO, as observed by field emission scanning electron microscopy and transmission electron microscopy, contributed to the higher electrochemical response in CV and a faster kinetic degradation of NPX.
Sluggish kinetics of the methanol oxidation reaction (MOR) at the anode of direct methanol fuel cells (DMFCs) is primarily due to adsorbed CO poisoning of precious metal catalysts. CeO2 is known to ...provide oxygen containing species to adjacent precious metal sites for facilitating CO removal during the MOR. In this work, highly dispersed Pd nanoparticles surrounded by CeO2 dots were deposited on a core–shell structured and nitrogen-doped mesoporous carbon sphere (NMCS) support, which exhibited encouraging electrocatalytic activity, CO tolerance, and stability for the MOR in alkaline media. The ratios of Pd to CeO2 were found crucial for overall catalytic performance enhancement. When compared to a commercial PtRu/C catalyst, an optimized Pd(20%)-CeO2(20%)/NMCS catalyst presented a comparable CO stripping onset potential, ∼6 times higher peak current density, and enhanced cyclic stability. The unique mesoporous carbon with nitrogen doping also benefits for uniform dispersion of Pd nanoparticles and CeO2 dots. In good agreement with experimental spectroscopy analysis, density functional theory calculations suggest that the strong electronic interactions between Pd and surrounding CeO2, as well as nitrogen dopants in supports, dramatically reduce the adsorption energy of CO at the Pd surface, therefore enhancing CO tolerance of the Pd-CeO2/NMCS catalyst and further improving MOR activity. Using a polymer fiber membrane-based alkaline DMFC, the Pd(20%)-CeO2 (20%)/NMCS anode catalyst further demonstrated encouraging performance when a NiCo2O4 catalyst was used for the oxygen cathode.
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