Electrochemical Oxidation Of Methanol Research Articles

Electrochemical Deposition of Pd@Pd(OH)2 Core-Shell Nanoparticles onto Glassy Carbon from a Deep Eutectic Solvent (Reline) and their Use as Electrocatalyst for the Methanol Oxidation Reaction

Pd@Pd(OH)2 core–shell nanoparticles were potentiostatically electrodeposited onto a glassy carbon electrode, GCE, from Pd(II) ions dissolved in the reline deep eutectic solvent. It is shown that the GCE/Pd@Pd(OH)2-modified electrode displays a high catalytic activity towards the methanol electrochemical oxidation reaction (MOR) in alkaline solution, revealing a mass activity of (2370 ± 450) mA mgPd−1 at the peak potential (for CVs recorded at 0.1 V s−1), much greater than those reported to date for other nanoparticles, namely: Pd, Cu1Pd2, Pd4Ag1, PdFe, PtPdPt, Pt or Pt2Ru1, synthesized by means of technically complicated, expensive and time-consuming methods or electrodeposited from aqueous media. In particular, the steady-state current reported for PdNPs electrodeposited from aqueous media towards MOR depicted values around 3 mA mgPd−1, while those from DES (this work) reached values around 42 mA mgPd−1. Furthermore, it is shown that the Pd@Pd(OH)2 nanoparticles displayed excellent poisoning tolerances, from 2 to 8, depending on the applied potential scan rate and anodic switching potential, which remains practically constant after 200 voltammetric cycles.

Electrochemical Oxidation of Methanol and Ethanol at Rh@Pt and Ru@Pt Catalysts

The influence of the amount of Pt deposited onto Rh and Ru nanoparticles on the oxidation of methanol and ethanol has been compared in H2SO4(aq) at ambient temperature and in a proton exchange membrane (PEM) cell at 80 °C. In H2SO4(aq), Rh@Pt and Ru@Pt show similar enhancements in activities over Pt for both methanol and ethanol oxidation. However, differences in the optimum Pt coverage indicate that compression of the Pt lattice by Rh plays a dominate role, while ligand effects are more important for Ru@Pt. In the PEM cell, the Ru core enhanced activities significantly for both methanol and ethanol, while activities were suppressed by the Rh core. This may arise from dominance of ligand and/or bifunctional effects for the Ru@Pt catalyst at 80 °C. Data from the PEM cell showed that the stoichiometry for ethanol oxidation at Ru@Pt was higher than for Rh@Pt, indicating a higher selectivity for the complete oxidation to CO2.

Half-Sphere Shell Supported Pt Catalyst for Electrochemical Methanol Oxidation

Bi-functional effect, elevated mass transport and increased durability have been combined within one catalyst for electrochemical methanol oxidation reaction. It has niobium (Nb) doped titanium dioxides (TiO2) nanosized half-sphere shell (HSS) as the substrate material deposited with small amount of Pt nanoparticles. These specially designed HSS nanostructure has significantly increased surface areas which are suitable for Pt nanoparticles to be deposited onto them to form the catalyst denoted as Pt/Nb-TiO2 HSS. It exhibits a remarkably high methanol oxidation activity of 0.21 V vs RHE which is 0.05 V lower than HiSPEC10000 PtRu/C catalyst, due to the substrate’s strong metal support interactions effect, bi-functional effect and the special structure. These HSS nanostructures have also increased the methanol diffusion and mass transport within the anode to give a maximum power output of 0.0931 W of cathode polarization in miniature direct methanol fuel cell (DMFC). It also acts as protection shells, which minimises the dissolution of Pt metal nanoparticles to prevent its diffusion through the membrane.

Nickel boride and cobalt boride coated stainless steel gauze for enhanced electrochemical oxidation of methanol

Ni-Co-B catalyst consisting of different ratios of Ni and Co was successfully synthesized via a simple electroless deposition method on stainless steel (SS) gauze substrate. Among various ratios, the Ni-Co-B of the ratio (0.09 M/0.01 M, designated as Ni-Co-B-MR1) exhibited higher electrochemical response towards methanol oxidation in alkaline medium with a highest current density about 11.3 mA/cm2 at a potential of − 0.65 V. The electrode exhibited improved CO tolerance for methanol oxidation reaction (MOR) in alkaline medium. The surface morphology and composition of the SS gauze coated with Ni-Co-B-MR1 catalyst was analysed using SEM and energy dispersive X-ray analysis. XRD confirms the presence of orthorhombic nickel boride and cobalt boride structure. The XPS analysis confirms the active presence of nickel boride and cobalt boride on SS gauze coated with Ni-Co-B-MR1 catalyst. The BET surface area of SS gauze coated with Ni-Co-B-MR1 catalyst was 1.21 m2 g−1. The single direct methanol fuel cell with SS gauze coated with Ni-Co-B-MR1 electrode produces a current density of about 0.1 mA/cm2 and power density about 10 mW/cm2, respectively.

Bi‐Co‐Cu Metal Oxide Foam as Significant Electrocatalyst for Methanol Electrooxidation

AbstractTransition metals and metal oxides are carrying out vibrant role in electrooxidation of methanol. Unfortunately, the unclear cognition of methanol oxidation reaction (MOR) mechanism hampers the development of high performance electrocatalysts. Thus, in this report, a fascinating MOR mechanism has been studied using CoCuBi oxide foam structure, where the (220) plane of CoCuBi oxides are playing an exciting role in an unprecedented mechanism. Interestingly, the (220) plane belongs to the families of plane, where transition metal oxides prefer Eley‐Rideal (ER) mechanism with concomitant reduction in the poisoning effect due to CO. The synergetic effect of these planes triggers the excellent current density of 118 mA/cm2 with 50% retention of activity even after 10 h stability test. X‐ray photoelectron spectroscopy (XPS) and X‐ray diffraction (XRD) studies revealed different oxidation states of metal ions indicating formation of mixed oxides along with different phase formation in CoCuBi foam structure. More excitingly, CoCuBi nanocomposites show remarkable electrochemical methanol oxidation to form specific product such as formate, which is strongly confirmed by proton NMR spectroscopy.

Pd-NiO-Y/CNT nanofoam: a zeolite-carbon nanotube conjugate exhibiting high durability in methanol oxidation.

A Pd-NiO-based catalyst hybridized with zeolite-Y and multiwalled carbon nanotubes has been found to show a remarkable mass activity in the electrochemical oxidation of methanol with long term durability up to 80 000 s.

Effective Electrochemical Activation of Oleate-Residue-Fouled Pt Nanoparticle Catalysts for Methanol and Formic Acid Oxidation.

Platinum plays a crucial role in the field of basic electrochemistry, regeneration energy, and so on. Pt nanomaterials with well-controlled size and shape could be easily obtained from metal–oleate complexes. However, these nanoparticles (NPs) were electrochemically inactive because of the attached organic residue. This work has been reported as a robust method to remove the residues from the surface of Pt nanoparticle catalysts by the electrochemical treatment in alkaline media. After the electrochemical activation, the Pt nanoparticle catalysts show good catalytic behavior toward the electrochemical oxidation of methanol and formic acid.

New Insights into Layered Graphene Materials as Substrates to Regulate Synthesis of Ni-P Nanomaterials for Electrocatalytic Oxidation of Methanol and Water.

The doping ring-core nickel phosphide/graphene nanomaterial is obtained by H2 reduction of the flower-like nickel phosphates/graphene oxide (NiPOGO) and sea urchin-like nickel phosphates/chemically converted graphene (NiPOG) substrates. The obtained structure of nickel phosphates depends on the influence of different kinds of oxygen-containing groups on the graphene substrate. The substrate can also affect the particle size and distribution of nickel phosphate nanoparticles. The substrate can adjust the particle size, distribution, and exposed growth direction of nickel phosphide. These materials with high activity are employed as electrochemical catalysts for methanol oxidation reactions, which is ∼7 times that of pure nickel phosphide, and there is a very small Tafel slope of 47 mV decade-1 in the water oxidation reaction. Our results highlight that the substrate structure is essential to catalytic materials for electrochemical oxidation of methanol and water.

Synthesis of Hollow Pt-Ni Nanoboxes for Highly Efficient Methanol Oxidation

In direct methanol fuel cell technology, highly stable electrochemical catalysts are critically important for their practical utilization at the commercial scale. In this study, sub ~10 nm hollow Pt-Ni (1:1 at. ratio) nanoboxes supported on functionalized Vulcan carbon (Pt-Ni/C-R2) were synthesized through a facile method for the efficient electrooxidation of methanol. Two reaction procedures, namely, a simultaneous reduction and a modified sequential reduction method using a reverse microemulsion (RME) method, were adopted to synthesize solid Pt-Ni NPs and hollow nanoboxes, respectively. To correlate the alloy composition and surface structure with the enhanced catalytic activity, the results were compared with the nanocatalyst synthesized using a conventional NaBH4 reduction method. The calculated electroactive surface area for the Pt-Ni/C-R2 nanoboxes was 190.8 m2.g−1, which is significantly higher compared to that of the Pt-Ni nanocatalyst (96.4 m2.g−1) synthesized by a conventional reduction method. Hollow nanoboxes showed 34% and 44% increases in mass activity and rate of methanol oxidation reaction, respectively, compared to solid NPs. These results support the nanoreactor confinement effect of the hollow nanoboxes. The experimental results were supported by Density Functional Theory (DFT) studies, which revealed that the lowest CO poisoning of the Pt1Ni1 catalyst among all Ptm-Nin mixing ratios may account for the enhanced methanol oxidation. The synthesized hollow Pt-Ni/C (R2) nanoboxes may prove to be a valuable and highly efficient catalysts for the electrochemical oxidation of methanol due to their low cost, numerous catalytically active sites, low carbon monoxide poisoning, large electroactive surface area and long-term stability.

Development of Nickel-BTC-MOF-Derived Nanocomposites with rGO Towards Electrocatalytic Oxidation of Methanol and Its Product Analysis

In this study, electrochemical oxidation of methanol to formic acid using the economical and highly active catalytic Nickel Benzene tricarboxylic acid metal organic framework (Ni-BTC-MOF) and reduced graphene oxide (rGO) nanocomposites modified glassy carbon electrode GCE in alkaline media, which was examined via cyclic voltammetry technique. Nickel based MOF and rGO nanocomposites were prepared by solvothermal approach, followed by morphological and structural characterization of prepared samples through X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), and energy dispersive X-ray (EDX) analysis. The electrochemical testing of synthesized materials represents the effect of the sequential increase in rGO concentration on electrocatalytic activity. The Ni-BTC/4 wt % rGO composite with a pronounced current density of 200.22 mA/cm2 at 0.69 V versus Hg/HgO electrode at 50 mV/s was found to be a potential candidate for methanol oxidation in Direct Methanol Fuel Cell (DMFC) applications. Product analysis was carried out through Gas Chromatography (GC) and Nuclear Magnetic Resonance (NMR) spectroscopy, which confirmed the formation of formic acid during the oxidation process, with approximately 62% yield.

Electrochemical oxidation of methanol on highly dispersed Pt nanoparticles supported on NiAl layered double hydroxide/carbon nanotubes composite

Platinum catalysts play a major role in the large scale commercialization of direct methanol fuel cells (DMFCs). Here, we present a procedure to create a nanostructural NiAl Layered Double Hydroxide/Carbon Nanotubes composite (NiAl-LDH/CNTs) containing a small amount (2.6 μg) of platinum nanoparticles (Pt NPs). It is found that Pt/NiAl-LDH/CNTs electrocatalyst exhibits higher electrocatalytic activity, better anti-poisoning ability and stability for methanol oxidation comparing to pure Pt and commercial Pt/ CNTs catalyst. Such an enhancement is probably attributed to the synergistic effect of Ni- NiAl LDH and the uniform loading of Pt NPs on the LDH layers. The morphology and structure of composites were characterized by scanning electron microscopy, atomic force microscopy, energy dispersive spectroscopy and electrochemical methods. It was found that the Pt NPs are formed on the surface of NiAl-LDH/CNTs with small particle size, high loading density, and uniform dispersion.

Cellulose nanocrystal/clay based macroion nanogel as support for stable platinum catalyst for electrochemical oxidation of methanol in alkaline medium

Nanogels are well known for their ability to encapsulate metal nanoparticles. However, only few reports exist on the application of such metal nanoparticle-loaded nanogels as electrocatalyst. Here, the formation of a self-assembled macroion nanogel-based complex using sustainable nanomaterials and its functional application as catalyst support for methanol oxidation in alkaline medium is reported. Physico-chemical and morphological investigations of the nanogel showed the formation of micro-nano particles, suggesting the presence of good ionic interactions. Prepared complex was utilized to host catalytically active platinum nanoparticles. On calcination, Pt-loaded nanogels showed good activity towards methanol oxidation in alkaline medium. Further, based on linear sweep voltammetry, it was proposed that for the current system reported here, reaction intermediates formed in methanol oxidation during the cyclic voltammetry analysis get removed from the catalyst surface during the forward scan, instead of the reverse scan. The proposed hypothesis was further supported by impedance analysis and the potential range for removal of intermediates was determined, which was found to be 0.1 V – 0.2 V in alkaline medium during the forward scan. Thus, it has been successfully demonstrated that such catalytic nanoparticle-encapsulated complexes have good electrochemical activity.

The electrocatalytic oxidation of methanol using a new modified electrode based on NiCo2O4 nanoparticles incorporated into zeolite-4A

In this work, a new catalyst based on carbon paste (CP) modified by spinel NiCo2O4 nanoparticles and zeolite-4A was proposed and used for the electrochemical oxidation of methanol. NiCo2O4@zeolite-4A was obtained through the calcination of the physical mixture of NiCo2O4 and zeolite-4A. Their physicochemical properties were characterized by X-ray diffraction (XRD), scanning electron microscopy-energy dispersive X-ray spectra (SEM-EDS), and FT-IR techniques. The electrocatalytic performance of modified electrode based on NiCo2O4@zeolite-4A was tested using cyclic voltammetry (CV) and chronoamperomerty (CA). The result of cyclic voltammetry indicated a significant rise in the oxidation current on the surface of NiCo2O4@zeolite-4A/CPE modified electrode. The rate constant for the catalytic reaction (k) of methanol was calculated by means of a chronoamperometric technique. To sum up, the incorporation of NiCo2O4 nanoparticles into zeolite-4A provided the binary electroactive sites for catalysis of methanol oxidation as it exhibited a long-term stability for catalytic reaction, and thus a promising application.

Hollow PtPd Nanorods with Mesoporous Shells as an Efficient Electrocatalyst for the Methanol-Oxidation Reaction.

Tailoring the morphology and composition of platinum-based electrocatalysts is of significant importance for the development of highly efficient direct methanol fuel cells. Herein, we report a dual-templating method for the design of hollow PtPd nanorods with mesoporous shells (mPtPd HNRs). We found that F127 micelles favored the formation of mesoporous structures and that SiO2 nanorods served as a hard template for the creation of cavities. The well-developed mesopores, hollow structures, and bimetallic composition of the mPtPd HNRs afforded a sufficient number of active sites to facilitate the electrochemical oxidation of methanol, thereby leading to enhanced activity and stability. This strategy allowed for the reliable preparation of mesoporous hollow platinum-based electrocatalysts with desired compositions and morphologies for catalytic applications.

Self-standing hollow porous AuPt nanospheres and their enhanced electrocatalytic performance

In this paper, we present a template method to fabricate AuPt hollow nanospheres by depositing Au inner layer and dendritic Pt outer layer onto PS template. The as-prepared AuPt hollow nanospheres can form self-standing hollow nanostructures under thermal treatment which is confirmed by small-angle X-ray scattering results. We believe that the self-standing structural features of them result from different thermal stability of Au and Pt elements. The small-angle X-ray diffraction measurements and X-ray photoelectron spectroscopy of binding energies certify the existing interaction between Au and Pt. It is suggested that Pt mole contents of AuPt hollow nanospheres can be varied by changing H2PtCl4 concentration during chemical deposition process. The methanol electrochemical oxidation reaction indicates these as-prepared AuPt hollow nanospheres possessing excellent potential applications on catalysts. Moreover, synthesis of multilayer hollow porous nanospheres such as Pt@Au@Pt proves that our method greatly enriches the species of the self-standing, hollow and porous functional nanomaterials.

Ni–Zn–P catalyst supported on stainless steel gauze for enhanced electrochemical oxidation of methanol for direct methanol fuel cell application

Ni–Zn–P catalyst of different chemical compositions is successfully synthesized via simple electroless deposition method on stainless steel (SS) gauze substrate. The electrocatalytic properties of Ni–Zn–P/SS gauze is investigated towards methanol oxidation in an alkaline medium. The Ni80Zn12P8 catalyst coated on SS gauze exhibits higher and more durable electrocatalytic activities with an excellent current density (10.2 mA cm−2) at a negative potential (−0.6 V). The modified electrode is characterized by SEM, and EDX techniques to determine the surface morphology and composition of the catalyst deposited. XRD confirms the presence of hexagonal Ni2P, tetragonal Zn3P2, and cubic Ni–P structure. The surface properties investigated using XPS analysis indicate the presence of the nickel phosphide and zinc phosphide linkage. The BET surface area for Ni80Zn12P8 catalyst coated SS gauze is 6.661 m2g−1. The current density and power density obtained from single fuel cell performance on Ni80Zn12P8/SS electrode for 1 M methanol are 0.107 mA cm−2 and 9.5 mW cm−2, respectively.

Hydrothermal Syntheses of NiO−GO Nanocomposite on 3D Nickel Foam as a Support for Pt Nanoparticles and its Superior Electrocatalytic Activity towards Methanol Oxidation

AbstractIn this project, Pt/NiO−GO nanocatalyst is grown on nickel foam (NF) and, its catalytic activity towards electrochemical oxidation of methanol in acidic media is studied. The first step is devoted to the synthesis of NiO−GO support by a hydrothermal method. Then Pt nanoparticles (∼34.3 nm) are electrodeposited on this supporting material. Hydrothermal and electrochemical deposition conditions are optimized. Surface of modified NF was inspected for physical characterization and Chemical composition by some techniques such as field emission scanning electron microscopy (FESEM), energy‐dispersive X‐ray spectra (EDS), and X‐ray diffraction (XRD). In the electrochemical section, the catalytic performance of Pt/NiO−GO/NF towards methanol oxidation is investigated by cyclic voltammetry and chronoamperometry measurements. The electrochemical impedance spectroscopy (EIS) is elected to deliberate charge transfer resistance on the catalyst surface. Mass activity, electrochemical surface area (ECSA) and durability of prepared catalysts are compared with commercial Pt/C. Deliberations prove the superiority of Pt/NiO−GO/NF towards methanol oxidation in acidic media. The Superior quality of synthesized nanocatalyst that is attributed to the synergetic effect of the NiO−GO support material and Pt nanoparticles, indicate that Pt/NiO−GO/NF can be successfully used as the anode in the direct methanol fuel cell (DMFC).

Electrooxidation of saturated C1-C3 primary alcohols on platinum: Potential-resolved product analysis with electrochemical real-time mass spectrometry (EC-RTMS)

Electrochemical real-time mass spectrometry (EC-RTMS) is a novel technique for the real-time monitoring of gaseous and liquid products of electrochemical reactions, independent of their vapor pressure, with excellent temporal and potential resolution. The scope of this manuscript is to provide details on the interpretation of data for this new technique and on the assignment of mass signals to reaction products by studying three model reactions. The bulk products of the electrochemical oxidation of methanol, ethanol and 1-propanol are characterized by EC-RTMS during potentiodynamic measurements, and the capabilities of the method in detecting reaction products in real time are demonstrated. The importance of proton affinity for the detection of reaction products is highlighted.

Ultrathin-Polyaniline-Coated Pt-Ni Alloy Nanooctahedra for the Electrochemical Methanol Oxidation Reaction.

Controlling the morphology and composition of nanocatalysts constructed from metals and conductive polymers has attracted attention owing to their great potential for the development of high-efficiency catalysts for various catalytic applications. Herein, a facile synthetic approach for ultrathin-polyaniline-coated Pt-Ni nanooctahedra (Pt-Ni@PANI hybrids) with controllable PANI shell thicknesses is presented. Pt-Ni nanooctahedra/C catalysts enclosed by PANI shells with thicknesses from 0.6 to 2.4 nm were obtained by fine control over the amount of aniline. The various Pt-Ni@PANI hybrids exhibited electrocatalytic activity toward the methanol oxidation reaction that is highly dependent on the thickness of the PANI shell. Pt-Ni@PANI hybrids with the thinnest PANI shells (0.6 nm) showed markedly improved electrocatalytic performance for the methanol oxidation reaction compared with Pt-Ni@PANI hybrids with thicker PANI shells, Pt-Ni nanooctahedra/C, and commercial Pt/C due to synergistic benefits of ultrathin PANI shells and Pt-Ni alloy.

Methanol Electrooxidation at Electrodes Made of Exfoliated Graphite/Nickel/Palladium Composite

This paper try to answer the question, if the exfoliated graphite/nickel/palladium (EG/Ni/Pd) composite can be regarded as a potential anode material in direct methanol fuel cells (DMFCs). For this purpose, process of electrochemical oxidation of methanol on electrode made of EG/Ni/Pd was investigated. Electrochemical investigations were conducted in alkaline medium by cyclic voltammetry and potentiostatic techniques. Informations on catalytic activity of the examined composite were acquired from the comparison of current charges calculated for methanol oxidation peaks. The investigations revealed that electrochemical activity of EG/Ni/Pd composite enhances along the potential cycling. Current charges of methanol oxidation peaks increase with number of conducted cycles up to 26th cycle. The increment in electrochemical activity impacts on the decline in methanol concentration in the investigated electrolyte. The results of electrochemical investigations for EG/Ni/Pd composite were compared to that acquired for EG/Pd. The difference in total organic carbon (TOC) before and after the selected cycles of electrochemical process at EG/Ni/Pd electrode were the source of information on degree of methanol oxidation. Process comprised of 50 cycles of methanol electrooxidation resulted over 50% decrease in its concentration. The interpretation of electrochemical investigations were supported by scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and X-ray photoelectron spectroscopy (XPS) analysis.Graphical