Ethanol Electrooxidation In Alkaline Media Research Articles

Nickel Flower/Conducting Polymer Composite for Effective Ethanol Electrooxidation in Alkaline Medium

Nickel Flower/Conducting Polymer Composite for Effective Ethanol Electrooxidation in Alkaline Medium

Mild Synthesis of Planar PdPtAuAgCuIr Nanocrystals with Granular Edges for Improved Ethanol Electrooxidation

AbstractWe report a mild, one‐pot synthesis of PdPtAuAgCuIr multimetallic nanocrystals with controlled shapes and explore their applications as the electrocatalysts for ethanol electrooxidation in alkaline medium. The success of current synthesis relies on the co‐reduction of six metal precursors in the presence of octadecylammonium chloride and ascorbic acid at an elevated temperature. The resulting products are featured with an in‐plane core‐shell structure, together with the trigonal/hexagonal plate decorated with granular edges. When serving as EOR electrocatalysts, the carbon‐supported PdPtAuAgCuIr nanocrystals exhibit more than five‐fold increase in mass activity as compared to that of commercial Pt/C, as well as improved reaction kinetics and long‐term durability. DFT calculations disclose that the reduced energy barrier renders the Pd‐based multimetallic catalyst in catalytic performance. The present study provides a feasible strategy to create multimetallic nanocrystals with controlled two‐dimensional morphology under ambient conditions, shedding light for rational design over advanced fuel cell catalysts composed of multimetallic alloy.

Rare-earth modified Pt-Sn catalysts obtained via bromide anion exchange for enhanced ethanol electrooxidation in alkaline medium

Rare-earth modified Pt-Sn catalysts obtained via bromide anion exchange for enhanced ethanol electrooxidation in alkaline medium

Electrocatalytic performance of Pd-based electro-catalysts supported on CNTs for isopropanol and ethanol electro-oxidation in alkaline medium

Palladium carbon nanotubes and palladium-niobium carbon nanotubes electro-catalysts were successfully prepared through the alcohol reduction method. The composition and morphology of the synthesized electro-catalysts were examined using different physicochemical characterization techniques such as Field Emission Scanning Electron Microscopy, High-Resolution Transmission Electron microscopy, and X-ray photoelectron spectroscopy. High-Resolution Transmission Electron microscopy revealed hollow tubular structures showing multi-walled carbon nanotubes with palladium-niobium nanoparticles deposited on their surface with an average particle size of 5.02 nm. The electrochemical behavior of palladium carbon nanotubes and palladium-niobium carbon nanotubes for isopropanol and ethanol electro-oxidation were investigated through cyclic voltammetry, chronoamperometry, and electrochemical impedance spectroscopy techniques. Palladium-niobium carbon nanotubes bimetallic electro-catalyst demonstrated better poisoning tolerance and the highest electrocatalytic activity through low Tafel slopes, low onset potentials, and fast charge transfer kinetics compared to palladium carbon nanotubes monometallic and the commercial palladium on carbon. The addition of niobium modified the structure of palladium through the electronic effect, weakening the binding strength of carbonaceous species on the surface of palladium and thus increasing its electrocatalytic activity. The obtained results provided essential insights into palladium-niobium carbon nanotubes as promising electro-catalysts for direct alcohol fuel cells.

Alkaline ethanol oxidation on porous Fe/Pd–Fe nanostructured bimetallic electrodes

In this work, to prepare nanostructured and porous Fe/Pd–Fe bimetallic catalysts, the iron coating is applied firstly onto the copper substrate by the electrochemical deposition method. Subsequently, iron-zinc alloy coating is deposited on the underlayer iron. Eventually, by immersing this alloy coating in an alkaline solution containing palladium ions, the palladium will replace the zinc, resulting in porous Fe/Pd–Fe catalysts. The X-ray diffraction (XRD) technique was used for the characterization of the physical properties of the as-prepared electrocatalysts. Their electrocatalytic activity was studied by electrochemical methods such as cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS). The XRD results showed that the zinc element was the main component of the Fe/Zn-Fe alloy and was replaced by palladium as a result of leaching-galvanic replacement. The electrochemical investigations showed that a new porous Fe/Pd-Fe bimetallic catalyst had higher electro-catalytic activity and stability than pure Pd and Fe electrodes for ethanol electro-oxidation in alkaline media. The superiority of the Fe/Pd–Fe catalyst is related to the high surface area and a synergistic effect between Fe and Pd in Fe/Pd–Fe catalysts. Therefore, the nanostructured Fe/Pd–Fe catalysts can be proposed as potential anode materials for alkaline ethanol fuel cells. A new porous Fe/Pd–Fe bimetallic catalyst shows higher electro-catalytic activity and stability than pure Pd and Fe electrodes for ethanol electro-oxidation in alkaline media. The superiority of the Fe/Pd–Fe catalyst is related to the high electrochemical surface area and a synergistic effect between Fe and Pd in Fe/Pd–Fe catalysts

Activated Carbon Supported Ni-Co Layered Double Hydroxides Nanowires: An Effective and Low-Cost Electrocatalyst for Ethanol Electro-Oxidation in Alkaline Media

Developing nanostructured electrocatalysts by utilizing low-cost, non-noble metals with good activity and stability to replace noble metals such as Pt and Pd has gained significant interest in the area of sustainable energy production technologies. To that effect, we adopted a facile synthesis route to synthesize NiCo-LDH (layered double hydroxides) nanowires with activated carbon (AC) as support using a one-pot hydrothermal synthesis method. The role of AC on the activity of NiCo-LDH catalyst was studied. The activity of the electrocatalysts was characterized using Cyclic Voltammetry (CV), Electrochemical Impedance Spectroscopy (EIS), and Chronoamperometry (CA) techniques. The NiCo-LDH/AC, with Ni:Co molar ratio of 1:2, exhibited a good electrocatalytic activity of 12.5 mA cm−2 at 1.1 V vs SCE (saturated calomel electrode) at a scan rate of 50 mV s−1 and retained a remarkable cyclic stability of 74.4% even after 200 cycles in 0.1 M NaOH and 1 M EtOH. The better electrocatalytic activity of NiCo-LDH/AC catalyst can be ascribed to the presence of extremely active sites and porous structures as well as a good electron transfer conductivity of AC. The facile synthesis of NiCo-LDH/AC and its attractive performance highlights its potential application as an anodic electrocatalyst in direct ethanol fuel cells (DEFCs).

Design and Synthesis of Palladium/Black Phosphorus–Graphene Hybrids as High-Performance Catalysts for Ethanol Electrooxidation in Alkaline Media

In this study, a series of Pd-supported black phosphorus–graphene (Pd/BP-G) catalysts are prepared to explore their electrocatalytic performances in the electrooxidation of ethanol in alkaline media. The characterization results show that BP is combined with activated graphene to form a P–C bond and a P–O–C bond heterojunction. Pd nanoparticles equally anchor on the BP-G hybrid, and Pd/BP-G exhibited enhanced electrocatalytic activity for the ethanol oxidation reaction in alkaline media. The electrochemically active surface area and mass activity for the Pd/BP-G catalyst reached 210.4 m2·gPd–1 and 3960.0 mA·mgPd–1, which are 9.54 and 5.86 times higher than those of commercial Pd/C, respectively. Further studies show that Pd/BP-G catalysts have reliable stabilities and faster reaction kinetics. These results indicate that the prepared Pd/BP-G catalysts have great application potentials in direct ethanol fuel cells.

Fabrication of dendritic PdCu alloy supported on 3D N-doped hollow graphene for efficient ethanol electrooxidation.

Fabricating highly efficient Pd-based nanocatalysts with a well-defined structure is desired for the commercialization of direct ethanol fuel cell (DEFC). Herein, a series of hierarchical three-dimensional N-doped hollow graphene spheres (NHGS) supported dendritic PdCu alloy catalysts PdxCu(d)-NHGS (x: Cu/Pd theoretical molar ratio of 4, 2, and 1) are assembled by one-pot ascorbic acid reduction-immobilization method. Aiming to maximize the Pd utilization and realize the efficient ethanol electrooxidation, this novel electrocatalyst offers potent activity sites and promotes electron and ion kinetics simultaneously. Characterization indicates that the as-obtained Pd4Cu(d) alloy nanoparticles with average sizes of approximately 55 nm are evenly dispersed on the NHGS supporting materials obtained by using the SiO2 nanospheres template strategy. Three catalysts all exhibit enhanced electrocatalytic activity, of which the Pd4Cu(d)-NHGS shows the highest mass current activity (2683 mA mgPd-1), which is 2.59 times of the commercial Pd/C toward ethanol electrooxidation in alkaline medium. Based on the results, we believed that the Pd4Cu(d)-NHGS could exhibit extensive application prospect in alkaline DEFC.

Synthesis, characterization and performance of a novel Ni–Co/GO-TiO2 for electrooxidation of methanol and ethanol

In order to find out electrocatalysts based on non-precious metals, Ni–Co/GO-TiO2 composite with different amounts of nickel and cobalt is prepared and the impacts of TiO2 nanoparticles on GO support are highlighted. Composition, morphology and textural features of the synthesized materials are characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, N2 adsorption-desorption isotherms and field emission scanning electron microscopy equipped with energy-dispersive X-ray analysis. The electrochemical activity of the prepared catalysts toward methanol and ethanol electrooxidation in alkaline media is investigated by cyclic voltammetry, electrochemical impedance spectroscopy, and chronoamperometry. Results confirmed that adding TiO2 nanoparticles to graphene oxide can increase the surface area, porosity and electrochemically active surface area of the support material. The composition with the equal amount of nickel and cobalt precursors exhibited the highest current density for methanol and ethanol electrooxiation equal to 121.07 and 145.28 mA/cm2, respectively. Stability test results demonstrated that this sample maintains 94.1% and 87.5% of initial current density after 7200 s for the electrooxidation of ethanol and methanol in 1.0 M KOH, respectively. All results confirm the synergic effect of Ni and Co for the alcohols oxidation in alkaline media and equal amount of Ni and Co leads to the best catalytic performance with the highest current density, lowest impedance and maximum stability.

Developing an efficient approach for preparation of high-performance visible-light assisted ethanol electro-oxidation materials based on Pd, Pt and Pd–Pt nanoparticles supported on iron doped titania nanotube films

Electrochemical anodization and electrodeposition have been used to synthesize highly ordered iron doped titania nanotubes (FeT) loaded with palladium (Pd), platinum (Pt) and Pt–Pd nanoparticles, followed by characterization by FE-SEM and XRD analyses. Higher photoelectrocatalytical activity is shown by the electrodeposited nanotube samples compared with undeposited-FeT sample under identical conditions, according to the photoelectrochemical experiments. The electrochemical behavior of the synthetic electrodes was studied by investigation of ethanol electrocatalytic oxidation in an alkaline medium in the absence or presence of light irradiation. The results of electrochemical studies indicated that Pt–Pd/FeT/Ti was more catalytically active than Pt/FeT/Ti and Pd/FeT/Ti in ethanol electrooxidation in alkaline media both in the dark and under light irradiation. Furthermore, the catalytic activities of nanotube based catalysts were considerably enhanced under light irradiation due to the interaction of electrocatalysis and photocatalysis. The peak current density of ethanol oxidation using sample FeT2 under light irradiation is about 1.45 times the corresponding value in the dark.

Pd electrodeposition on a novel substrate of reduced graphene oxide/ poly(melem-formaldehyde) nanocomposite as an active and stable catalyst for ethanol electrooxidation in alkaline media

Palladium nanoparticles (Pd NPs) were successfully electrodeposited on a reduced graphene oxide/poly(melem-formaldehyde) nanocomposite (rGO/PMF) NC as a catalyst for ethanol electrooxidation in alkaline media; melem was used as a nitrogen-rich source in the substrate structure for the first time. The specific surface area and average pore diameter of (rGO/PMF) NC were 481.61 m2 gr−1 and 10.23 nm, respectively. High nitrogen doping and structural defects improved the dispersion and anchoring of Pd NPs on (rGO/PMF) NC. The onset potential (Eonset) of Pd/(rGO/PMF) NC was shifted negatively to 110 mV, in comparison to Pd/rGO. Also, the current density and electrochemical active surface area (EASA) of Pd/(rGO/PMF) NC were enhanced to 44 mA cm−2 and 67.58 m2 gr−1, respectively, as compared to Pd/rGO. Furthermore, the stability of Pd/(rGO/PMF)NC was indicated against ethanol oxidation intermediates during 7000 s. This work also produced a superior graphene-based material for direct ethanol fuel cell anode catalysts applications.

High-performance Pd nanocatalysts based on the novel N-doped Ti3C2 support for ethanol electrooxidation in alkaline media

In this article, the novel N-doped Ti3C2 support Pd-based catalyst (Pd/N-Ti3C2-28 h) is successfully prepared by suitable HF-etching and NH3.H2O doping, which possess the conspicuous lamellar morphology and uniform metal Pd distribution. The Pd/N-Ti3C2-28 h with N-doping has the higher content of Pd (~5.33 at%) than that of without N-doping (~1.38 at%) under the same mass of Pd loading. Being explored as the catalyst for ethanol electrooxidation in alkaline medium, the Pd/N-Ti3C2-28 h catalyst exhibits the higher electrochemically active surface areas, ethanol oxidated current densities (~36.71 mA.cm−2) and electrochemical stability than those of the Pd/Ti3C2-28 h, the other Pd/N-Ti3C2 catalysts with different HF-etching time (20,24 and 32 h), and the commercial Pd/C (j = ~12.73 mA.cm−2). Such excellent electrocatalytic performance can be ascribed to synergy of obvious layer-structure of the Ti3C2 support and the NH3.H2O doping, which lead to the higher binding energy and more electron transfer of the metal Pd and Ti3C2, thereby improving the Pd loading on the Ti3C2. And the current densities after 200 redox cycles of Pd/Ti3C2-28 h can retain 78.3% of the maximum capacity, demonstrating the high cycle stability. Thus, the Pd/N-Ti3C2-28 h can become the potential candidates as the anode catalyst for the ethanol electrooxidation in alkaline medium.

Formation of Cu@Pd core@shell nanocatalysts with high activity for ethanol electro-oxidation in alkaline medium

In this work, the formation of Cu@Pd core–shell nanoparticles was studied by optimizing the reduction of Cu2+ to Cu0 used as cores, and by increasing the amount of Pd precursor, labelling these materials as Cu@Pd I to IV, respectively. X-ray diffraction, UV–vis tests, and X-ray photoelectron spectroscopy (XPS) revealed the formation and progressive growth of Cu@Pd nanoparticles with the increase of the Pd content. High-resolution transmission electron microscopy (HR-TEM) and line-scan energy-dispersive spectroscopy (EDX line-scan) tests indicated that the Cu@Pd IV was the sample that displayed a better formation of a core@shell structure, having an average particle size of 5.9 nm. Electrochemical tests were performed using a synthesized Pd/C nanomaterial (15.7 nm) as reference electrocatalyst for the ethanol oxidation reaction (EOR), and the effect of the fuel and electrolyte concentrations were analyzed. The highest activity was obtained with 3 M ethanol + 2 M KOH, where Cu@Pd IV displayed an onset potential (Eonset) of −0.6 V vs. NHE and an oxidation peak potential (Ep) of 0.11 V. This Ep was 400 mV lower to that achieved by Pd/C at the same conditions. In addition, Cu@Pd IV presented the highest current density (6.78 mA cm−2, 1.6 times higher than Pd/C).

Promoted electrocatalytic performance of palladium nanoparticles using doped-NiO supporting materials toward ethanol electro-oxidation in alkaline media

Electrocatalyst support materials play significant role in the performance, durability and commercialization of fuel cells. This research work describes the preparation of metal oxide (nickel oxide (NiO), cobalt (Co) and copper (Cu) doped NiO) support materials on meshed titanium (Ti) substrate via a simple electro-deposition method for their application as novel support material for palladium (Pd) catalyst. Field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) techniques are employed to study morphology, composition and structure of fabricated electrodes, respectively. The electrocatalytic performance of fabricated electrodes toward ethanol oxidation reaction (EOR) in alkaline solution is examined by the cyclic voltammetry (CV), chronoamperometry (CA) techniques. Low peak potential (−0.2 V), increased peak current density (62.54 mA cm−2) and large electrochemical active surface area (16.02 m2 g−1) were remarkable properties of Pd/Cu–NiO/Ti electrode. The results of other electrochemical measurements, CO-striping voltammetry, long-term stability and electrochemical impedance spectroscopy (EIS) revealed that the Pd/Cu–NiO/Ti electrode has the privileged electrocatalytic performance for EOR relative to other prepared electrodes. Accordingly, the Pd/Cu–NiO/Ti can be considered as a hopeful electrode for ethanol electro-oxidation reaction in DEFCs.

Comparative study of catalyst effect on ethanol electrooxidation in alkaline medium: Pt- and Pd-based catalysts containing Sn and Ru

The ethanol oxidation reaction (EOR) on Pd:M- and Pt:M-based nanocatalysts (M = Sn or Ru) was investigated by using electrochemical and chromatographic methods. These carbon-supported materials were prepared by the microwave-assisted method. The experimental bulk compositions of the Pt-based catalysts were very close to the nominal composition, and all the catalysts displayed the Pt or Pd fcc crystalline structure with crystallite sizes ranging from 1.6 to 6.8 nm. The Pd-based catalysts presented much higher catalytic activity and stability than the Pt-based ones. Electrolysis (HPLC) showed that the Pd:M catalysts are good materials for C2 (acetaldehyde and acetic acid) by-product production and improve the yields of ethanol consumption as compared to the poor activity of the Pt:M catalyst in basic medium. In alkaline medium, the co-catalyst did not lead to the huge differences observed in acidic medium. Pd:Ru/C proved to be the best catalyst for EOR in basic medium, surpassing the activity of Sn, which is known as the most active catalyst for this reaction in acidic medium.

The Performance of a Novel PdFe/B-N-G Catalys for Ethanol Electro-oxidation in Alkaline Medium

The Performance of a Novel PdFe/B-N-G Catalys for Ethanol Electro-oxidation in Alkaline Medium

Hierarchical Nanostructured Pd/Co3N‐Ni3N as an Efficient Catalyst for Ethanol Electrooxidation in Alkaline Media

AbstractCreating synergistic active sites via combination of palladium (Pd) or platinum (Pt) with oxophilic metal compounds has been extensively investigated as a promising approach for developing active and robust electrocatalysts toward the ethanol oxidation reaction (EOR). Among the metal compounds of choice, transition metal nitrides are highly appealing but less well explored candidates. Herein, the synthesis of a carbon fiber cloth (CFC)‐supported Pd/Co3N‐Ni3N nanocomposite catalyst using a hydrothermal method followed by ammonization treatment and electrochemical deposition is reported. The study found that incorporation of Co3N‐Ni3N of metallic nature can effectively improve the durability of Pd catalyst toward the EOR in alkaline condition and meanwhile preserve good electrical conductivity of the electrocatalyst. Furthermore, the high surface area of nanostructured Co3N‐Ni3N promises the exposure of abundant accessible active sites and a favorable reactant/product mass transfer kinetics. Benefiting from these favorable attributes, the Pd/Co3N‐Ni3N/CFC catalyst exhibits high activity and improved durability toward the EOR in alkaline conditions, which compares favorably with most self‐supported EOR electrocatalysts reported up to date.

Precise size and dominant-facet control of ultra-small Pt nanoparticles for efficient ethylene glycol, methanol and ethanol oxidation electrocatalysts

Control of the structure and shape of platinum nanocrystals has recently attracted much attention, mostly due to their specific properties and related catalytic functionalities. However, the realization of platinum nanocrystals with controlled sizes and dominant facet types remains a significant challenge. In this study, platinum nanoparticles with controllable sizes and dominant facets are produced via a simple, organic agent-free, rapid, clean and direct chemical reduction method. The effects of initial solution pH on the sizes and dominant facets of the platinum nanoparticles are investigated and the mechanism for different sizes and facets are examined. Electrocatalytic analyses show that the catalytic activities and stabilities of the synthesized platinum nanoparticles are related to their sizes and dominant facets, and these nanoparticles display great potential as substitutes for commercial Pt/C in the effective catalysis of ethylene glycol, methanol, and ethanol electrooxidation in alkaline medium. Among the present platinum nanoparticles, the nanoparticles synthesized in pH 3 initial conditions, with small average size and (111)-dominant facets, display the best electrocatalytic activity and stability.

PdxFey alloy nanoparticles decorated on carbon nanofibers with improved electrocatalytic activity for ethanol electrooxidation in alkaline media

We prepared bimetallic PdxFey alloy nanoparticles/carbon nanofiber composites with different Pd/Fe mole ratios and showed their advantage as a potential anode catalyst in ethanol fuel cells.

Composition-Graded Cu–Pd Nanospheres with Ir-Doped Surfaces on N-Doped Porous Graphene for Highly Efficient Ethanol Electro-Oxidation in Alkaline Media

Tuning the compositions and structures of Pd-based nanomaterials and their supports has shown great potentials in facilitating the sluggish ethanol oxidation reaction (EOR) in alkaline direct ethan...