Electrochemical Oxidation Of Methanol Research Articles

An Electrochemical Investigation of Methanol Oxidation on Thin Films of Nickel Oxide and Its Composites with Zirconium and Yttrium Oxides

The present work is focused on the fabrication of NiO-ZrO2/FTO and NiO-Y2O3/FTO thin films via a simple dip-coating method. The films are deposited from precursor solutions of Ni(CH3COO)2·2H2O, Zr(CH3COO)4, Y(CH3COO)3·H2O in methanol. The synthesized films, after proper characterization, are employed for electrochemical oxidation of methanol. The analytical techniques such as X-ray diffraction (XRD), Raman, and Infrared (IR) spectroscopy reveal the successful formation of crystalline thin films of mixed metal oxide without any additional impurities. Further, X-ray photoelectron spectroscopy (XPS) results, confirm the composition and oxidation state of all the elements present in thin films. The field emission scanning electron microscopy (FESEM) further aided to identify the uniformity and porous nature of composite thin films while the energy-dispersive X-ray spectroscopy (EDS) confirms the targeted elemental composition of the prepared thin films is in good agreement with precursors. The electrochemical oxidation of methanol results reveals that NiO-Y2O3/FTO and NiO-ZrO2/FTO thin films showed current densities of 6.2 mA/cm2 and 10 mA/cm2 at 0.65 V, respectively, against Ag/AgCl/3M KCl using 0.6 M methanol solution. Furthermore, Chronoamperometric (CA) results show good stability of NiO-ZrO2/FTO and NiO-Y2O3/FTO thin films with observed current decay of 10% and 6.8% of the initial current density, respectively. Moreover, the effect of scan rate and concentration of metals in a catalyst was also investigated. The Electrochemical impedance studies (EIS) further support electrochemical results, where the lower charge transfer resistance (Rct) values are recorded for composite thin films as compared to the pure metal oxide thin films (NiO/FTO, ZrO2/FTO, and Y2O3/FTO).

Electrolysis of Ethanol and Methanol at PtRu@Pt Catalysts

Electrolysis of ethanol in a proton exchange membrane (PEM) cell is an attractive method for generating hydrogen from renewable resources. However, the most active anode catalysts, such as PtRu, produce acetic acid as the main product, which makes the process very inefficient. Core–shell nanoparticles can improve efficiency by providing more selective cleavage of the C–C bond at a Pt shell. Here, the influence of the amount of Pt deposited onto a commercial PtRu/C catalyst has been investigated for electrochemical oxidation of ethanol and methanol, in aqueous H2SO4 at ambient temperature and in a PEM electrolysis cell at 80 °C. It is shown that addition of a Pt shell improves voltammetric activity markedly for both methanol and ethanol oxidation, while half-wave potentials in the PEM cell are shifted to higher potentials as the Pt coverage is increased. However, limiting currents for ethanol oxidation in the PEM cell are increased, and it is shown that the distribution of products shifts strongly towards CO2, which provides more efficient production of hydrogen.

CoFe2O4 NPs supported on graphitic carbon nitride as inexpensive electrocatalysts for methanol oxidation reaction

Electrochemical methanol oxidation (MOR) is considered an efficient route for generating clean energy with low pollutant emissions. In this study, we synthesized graphitic carbon nitride (GCN/g-C3N4) supported CoFe2O4 with different weights (100, 200, and 300 mg) of GCN by using the hydrothermal synthesis method; the synthesized cost-effective electrocatalysts have been denoted as g-CF1, g-CF2, and g-CF3 respectively. The electrochemical performance of the synthesized catalysts was studied using cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS) techniques. In an alkaline medium, the g-CF2 electrocatalyst showed the best MOR activity, a larger electrochemically active surface area, and better stability compared to those of pure GCN, g-CF1, and g-CF3 electrocatalysts.

Synthesis of AuNPs decorated multi-valent Cu-Ni oxide nanoplates for electrochemical oxidation of methanol

Cu-Ni oxide nanocomposite was synthesized via solvothermal method with nickel (II) nitrate and copper nitrate as Ni and Cu resource respectively. AuNPs/oxide nanocomposite was obtained by dispersing the oxide into the pre-synthesized Au colloid. Transmission electron microscope (TEM) shows that the synthesized oxides are nanoplate morphology. Interplanar distance from the high resolution TEM (HRTEM) image shows that the Ni and Cu in the oxide are multivalent state. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) characterization further proves that the Ni and Cu are multivalent state, and the Au is Au0 form in the nanocomposte. EDS-mapping images confirm large numbers of AuNPs are uniformly absorbed onto the ultra-thin multivalent Cu-Ni oxide nanoplate. The electrochemical properties of multivalent oxide (m-v oxide) with or without AuNPs decoration are investigated in 0.1 M potassium chloride electrolyte with 2.0 mM Ferri/Ferro-Cyanide. When employed for the electrochemical catalysis in methanol oxidation reaction (MOR), the AuNPs/m-v oxide exhibits better electrochemistry performance than m-v oxide. The current density of AuNPs/m-v oxide (21.1 mA/cm2) is 3.4 times bigger than that of m-v oxide/GCE (6.2 mA/cm2). What’s more, it shows good electrochemical stability and lower slope of the Tafel plot (41.87 mV/dec).

Efficient Synthesis of Pdir Nanocatalysts with Controllable Surface Composition for Electrochemical Oxidation of Methanol

Efficient Synthesis of Pdir Nanocatalysts with Controllable Surface Composition for Electrochemical Oxidation of Methanol

Engineering PtCu nanoparticles for a highly efficient methanol electro-oxidation reaction.

Achieving a highly efficient and durable methanol electro-oxidation catalyst in acid media is critical for the practical utilization of direct methanol fuel cells (DMFCs) at the commercial scale. Herein, we report a facile and effective one-pot strategy for the synthesis of carbon-supported PtCu alloy nanoparticles (PtCu NPs) with a Pt-rich surface, small particle size and uniform dispersion. The as-prepared PtCu NPs with the optimal alloy composition (Pt2Cu) exhibit a significantly improved electrochemical methanol oxidation reaction performance in terms of a high activity, superior CO tolerance and remarkable durability, in contrast to those of commercial Pt/C catalysts in acid media. Particularly, the Pt2Cu/C catalyst exerts a 4.5 times enhancement in the mass activity and a larger If/Ib value compared to those of commercial Pt/C (Pt/Ccomm). The enhanced catalytic activities can be ascribed to the high utilization of Pt and the high index facets of the surface. Also, the addition of Cu downshifts the d-band center of Pt and improves the CO tolerance during the methanol oxidation reaction process. This work provides an efficient strategy for designing desired Pt-based alloys for various catalytic reactions.

Understanding the high performance of PdSn–TaN(tantalum nitride)/C electrocatalysts for the methanol oxidation reaction: coupling nitrides and oxophilic elements

Palladium-modified transition metal nitrides (TaN) are investigated as electrochemical methanol oxidation reaction (MOR) catalysts. Combined in situ ATR-SEIRAS and DFT results demonstrate PdSn–TaN/C as an effective material to enhance MOR activity.

Preparation of Au@Pd Core-Shell Nanorods with fcc-2H-fcc Heterophase for Highly Efficient Electrocatalytic Alcohol Oxidation.

Controlled construction of bimetallic nanostructures with a well-defined heterophase is of great significance for developing highly efficient nanocatalysts and investigating the structure-dependent catalytic performance. Here, a wet-chemical synthesis method is used to prepare Au@Pd core-shell nanorods with a unique fcc-2H-fcc heterophase (fcc: face-centered cubic; 2H: hexagonal close-packed with a stacking sequence of "AB"). The obtained fcc-2H-fcc heterophase Au@Pd core-shell nanorods exhibit superior electrocatalytic ethanol oxidation performance with a mass activity as high as 6.82 A mgPd-1, which is 2.44, 6.96, and 6.43 times those of 2H-Pd nanoparticles, fcc-Pd nanoparticles, and commercial Pd/C, respectively. The operando infrared reflection absorption spectroscopy reveals a C2 pathway with fast reaction kinetics for the ethanol oxidation on the prepared heterophase Au@Pd nanorods. Our experimental results together with density functional theory calculations indicate that the enhanced performance of heterophase Au@Pd nanorods can be attributed to the unconventional 2H phase, the 2H/fcc phase boundary, and the lattice expansion of the Pd shell. Moreover, the heterophase Au@Pd nanorods can also serve as an efficient catalyst for the electrochemical oxidation of methanol, ethylene glycol, and glycerol. Our work in the area of phase engineering of nanomaterials (PENs) opens the way for developing high-performance electrocatalysts toward future practical applications.

Electrodeposited palladium as efficient electrocatalyst for hydrazine and methanol electro-oxidation and detection

Electrodeposited palladium was used as an electrocatalyst for electrochemical oxidation of hydrazine and methanol and the development of a sensitive platform for their detection. The electrochemical behavior of the electrode was evaluated by cyclic voltammetry (CV) while electroanalytical properties were determined by means of differential pulse voltammetry (DPV). The electrodeposited Pd catalyst exhibited good electrocatalytic activity towards the oxidation of hydrazine in neutral solution and methanol oxidation in alkaline solution. Under optimized DPV conditions, the electrodeposited Pd electrode shows good sensing capability in hydrazine and methanol detection.

Fabrication of Metal (Cu and Cr) Incorporated Nickel Oxide Films for Electrochemical Oxidation of Methanol

Methanol electrochemical oxidation in a direct methanol fuel cell (DMFC) is considered to be an efficient pathway for generating renewable energy with low pollutant emissions. NiO−CuO and Ni0.95Cr0.05O2+δ thin films were synthesized using a simple dip-coating method and tested for the electro-oxidation of methanol. These synthesized electrocatalysts were characterized by X-ray diffraction spectroscopy (XRD), X-ray photoelectron spectroscopy (XPS), Scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDS), and Raman spectroscopy. Different electrochemical techniques were used to investigate the catalytic activity of these prepared electrocatalysts for methanol oxidation, including linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS), and chronoamperometry (CA). In the presence of 0.3 M methanol, the current densities of NiO−CuO and Ni0.95Cr0.05O2+δ thin films were found to be 12.2 mA·cm−2 and 6.5 mA·cm−2, respectively. The enhanced catalytic activity of NiO−CuO and Ni0.95Cr0.05O2+δ thin films may be a result of the synergistic effect between different metal oxides. The Chronoamperometry (CA) results of the mixed metal oxide thin films confirmed their stability in basic media. Furthermore, the findings of electrochemical impedance spectroscopy (EIS) of mixed metal oxide thin films demonstrated a lower charge transfer resistance as compared to the pure NiO, CuO, and Cr2O3 thin films.

The bimetallic heterostructure Pt-Au nanoparticle array on Indium Tin Oxide electrode by electrodeposition and their high activity for the electrochemical oxidation of methanol

The stability of Pt-based catalyst for methanol oxidation reaction (MOR) is the main hot topic to the commercial applications of direct methanol fuel cells (DMFCs) at present. In this article, a novel bimetallic heterostructure Pt-Au nanoparticles array catalyst on Indium Tin Oxide (ITO/AuNPs/PtNPs) for direct methanol fuel cells was synthesized through a facile two-step electrodeposition. Compared to ITO/PtNPs electrode, ITO/AuNPs/PtNPs delivers excellent activity and operational durability towards MOR. The turn over number (TON) of the as-prepared ITO/AuNPs/PtNPs is estimated as ~2.4 times higher than value of ITO/PtNPs at 0.06 V. The ability of resistance to CO poisoning for ITO/AuNPs/PtNPs is also evaluated, the If/Ib ratio of ITO/AuNPs/PtNPs and ITO/PtNPs is 2.0, 1.2, respectively. The enhanced properties of ITO/AuNPs/PtNPs for activity and durability can be ascribed to a high specific surface area, which could effectively promote the oxidation of methanol on Pt. Furthermore, Au can also greatly promote the transformation from CO-likes to CO2 on Pt sites. The synergetic effects provide a guarantee for highly efficient methanol oxidation for ITO/AuNPs/PtNPs.

In Situ Replacement Synthesis of Co@NCNT Encapsulated CoPt3 @Co2 P Heterojunction Boosting Methanol Oxidation and Hydrogen Evolution.

Simultaneous boosting electrochemical methanol oxidation reaction (MOR) for direct methanol fuel cells and production of hydrogen is meaningful but challenging. Herein, a sea urchin-shaped cobalt-embedded N-doped carbon nanotubes (Co@NCNT) encapsulated CoPt3 @Co2 P heterojunction (CoPt3 @Co2 P/Co@NCNT) is fabricated. Theoretical calculations confirm that electrons at the interfaces transfer from CoPt3 to Co2 P, where electron hole region on CoPt3 is beneficial to improving the MOR activity, whereas accumulation region on Co2 P favors to the optimization of H2 O and H* absorption energies for hydrogen evolution reaction (HER). Benefitting from its interfacial electronic reconfiguration, the CoPt3 @Co2 P/Co@NCNT heterojunction exhibits excellent electrocatalytic performances for MOR and HER, in which the mass activity (2981mAmgPt -1 ) for MOR is 14.2 times than that of Pt/C (20%), and the smallest overpotentials only requires 19 mV to deliver a current density of 10mAcm-2 for HER. Moreover, the electrolyzer employing CoPt3 @Co2 P/Co@NCNT for anodic MOR and cathodic H2 production only requires a low voltage of 1.43 V at 10mAcm-2 with impressive long-life cycling stability, which is obviously better than that of commercial Pt/C//RuO2 . This study offers a novel strategy for other organics oxidation reaction coupled with HER catalyzed production of hydrogen.

Cu(OH)2-Ni(OH)2 engulfed by zeolite-Y hydroxyl nest and multiwalled carbon nanotube for effective methanol oxidation reaction

Cu(OH)2-Ni(OH)2 supported on zeolite-Y and combined with multi-walled carbon nanotube (MWCNT), M(OH)2-Y-CNT (M = Cu, Ni) was found to be an excellent multicomponent hybrid system for methanol oxidation reaction (MOR). The formation of metal hydroxyl nest interconnected through MWCNT produced a high current density of 5.5 A/mg with significant durability up to 11.1 h. The electrochemical oxidation of methanol was found to be significant with maximum current density when the Cu:Ni ratio was 3:1. The surface hydroxyl group of zeolite-Y and -COOH functional group of MWCNT interacted strongly with Cu(OH)2 and Ni(OH)2 and provided a strong metal to surface interaction. From the temperature programme desorption (TPD) study and pyridine adsorption FTIR analysis, it was evident that both the acidity and basicity of Cu(OH)2-Ni(OH)2-Y catalyst was influenced by the MWCNT and consequently helped in MOR. Modification with MWCNT also lead to the change in the binding energy values of Cu and Ni and thereby effected the overall MOR activity of the electrocatalyst. The MOR activity of the hybrid material was tested by modifying the glassy carbon working electrode (GCE) as well in Pt working electrode. The MOR activity was found to be much better with Pt-electrode in comparison to GCE in terms of current density, durability and stability. The Pt-electrode modified with the hybrid M(OH)2-Y-MWCNT exhibited high CO tolerance in comparison to commercial Pt/ C electrocatalyst.

Cu-Ce0.8Sm0.2O2-δ anode for electrochemical oxidation of methanol in solid oxide fuel cell: Improved activity by La and Nd doping

CuCe0.8La0.1Sm0.1O2-δ and CuCe0.8Nd0.1Sm0.1O2-δ are studied as anode materials for solid oxide fuel cells with methanol as fuel. The oxygen surface exchange and bulk diffusion coefficients of Ce0.8Sm0.2O2-δ both increase with La and Nd doping. The CH3OH temperature-programmed surface reaction results show that the addition of La and Nd accelerates the chemical oxidation of CH3OH. Furthermore, compared with CuCe0.8Sm0.2O2-δ, the anodes with La and Nd show higher resistance to coking in CH3OH atmosphere. The Cu-based cermet anode exhibits a low catalytic activity for the electrochemical oxidation of H2, and a single cell supported by a Ce0.8Sm0.2O2-δ‑carbonate composite electrolyte with CuCe0.8Sm0.2O2-δ anode exhibits a maximum power density of 160 mW cm−2 at 650 °C using dry hydrogen as fuel. However, the maximum power density reaches 550 mW cm−2 when CH3OH is used as fuel, and further increases to 730 and 830 mW cm−2 with the addition of La and Nd in the anode, respectively. The results indicate that with the promotion of the oxygen activity, the Cu-based cermet is a promising anode material for solid oxide fuel cells using CH3OH as fuel.

Monitoring electrochemical methanol oxidation and CO coverage using Pt deposited SPR sensor platform

Monitoring electrochemical methanol oxidation and <scp>CO</scp> coverage using Pt deposited <scp>SPR</scp> sensor platform

Pt/Ni Catalyst Supported by Composite of Graphene and Polyaniline Microtubes Boosting Methanol Electrochemical Oxidation

The development of durable and efficient anode electrocatalysts is crucial for direct methanol fuel cells. In this paper, polyaniline (PANI) microtubes are firstly prepared by removing the polystylene (PS) core from PANI coated electrospun PS. The catalyst of PtNi/PANI@rGO is built by two steps: graphene oxide (GO) is mixed with PANI microtubes to obtain PANI@GO and then PANI@GO is used as a support material to load PtNi nanoparticles by reductive reaction while GO is reduced into rGO. The morphology, electronic structure and chemical structure of the catalysts are characterized by SEM, TEM, XPS and Raman spectroscopy, respectively. The electrochemical analysis of electrochemical impedance spectroscopy, cyclic voltammetry and chronoamperometric measurement are performed to analyze the electrocatalytic performance. The electrochemical results indicate that as-synthesized PtNi/PANI@rGO has the high activity toward methanol oxidation, and its mass activity is 1.7, 1.3 and 4.1 times higher than that of PtNi/PANI, PtNi/rGO and commercial Pt/C catalysts, respectively. The PANI microtubes not only improve the electron transfer kinetic but also help avoid the accumulation of graphene layers. The doping of Ni into Pt changes the surface electronic structure to elevate the catalytic activity and helps effectively improve the resistance to CO poisoning.

Laser-assisted decoration of carbon nanotubes with palladium nanoparticles for application in electrochemical methanol oxidation

Multi-walled carbon nanotubes (MWCNTs) were decorated with palladium nanoparticles (Pd NPs) by laser-ablation of a physical mixture of MWCNTs and Pd NPs without using any reducing agent. The morphology and composition of MWCNT/Pd were analysed by complementary techniques involving Fourier transform infrared spectrometry, transmission electron microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy. Using cyclic voltammetry and chronoamperometry, the electrocatalytic activity and stability of CNT/Pd were evaluated for the electrochemical oxidation of methanol in a basic medium. Comparative investigations were provided with laser-ablated Pd NPs (LA Pd) catalyst concerning catalytic activity and stability. MWCNT/Pd exhibited remarkably high catalytic activity (104.20 mA mg−1) in comparison to the LA Pd catalyst (14.41 mA mg−1). The catalyst was found to exhibit long-term stability even after 3600 s of operation and high resistance towards CO poisoning. It is suggested that the MWCNT/Pd would be valuable as an active electrocatalyst for its commercial applications in direct methanol fuel cells.

Design of new anodic bimetallic nanocatalyst composed of Ni–Cu supported by reduced carbon quantum dots for the methanol oxidation reaction

The direct methanol fuel cell (DMFC), as the ideal fuel cell system which produces the electric power by the direct conversion of the methanol fuel at the fuel cell anode. The main advantage of this kind of fuel cell is the ease of fuel transportation, an energy-dense yet reasonably stable liquid at all environmental conditions. The DMFC relies upon the oxidation of methanol on a catalyst layer to form carbon dioxide. Up to now, different particles ad nanoparticles have been used as an anodic catalysts in various researches. In this work, bimetallic nanoparticles of NiCu dispersed on reduced carbon quantum dots (RCQDs) were prepared using the facile electrochemical procedure. The electrochemical oxidation of methanol on a Ni–Cu/RCQDs/GCE electrode was studied in 0.50 M KOH using cyclic voltammetry (CV), chronoamperometry (CA), and impedance spectroscopy (EIS). The beginning potential for electro-oxidation of methanol was observed at lower voltages for Ni-Cu/RCQD/GCE related to Ni-Cu/GCE and Ni-NPs/GCE. Also, the peak current density for the oxidation of methanol for Ni-Cu/RCQD/GCE showed a high amount of 90.41 mA.cm-2, which is threefold of Ni-Cu/GCE catalyst. EIS studies were applied to study the charge transfer rate. The charge transfer resistance for the electrochemical oxidation of methanol for Ni-Cu/RCQD/GCE was obtained 25 Ω while this amount for Ni-Cu/GCE was ca. 313 Ω.

Synthesis of Core@Shell Cu‐Ni@Pt‐Cu Nano‐Octahedra and Their Improved MOR Activity

AbstractFabrication of 3d metal‐based core@shell nanocatalysts with engineered Pt‐surfaces provides an effective approach for improving the catalytic performance. The challenges in such preparation include shape control of the 3d metallic cores and thickness control of the Pt‐based shells. Herein, we report a colloidal seed‐mediated method to prepare octahedral CuNi@Pt‐Cu core@shell nanocrystals using CuNi octahedral cores as the template. By precisely controlling the synthesis conditions including the deposition rate and diffusion rate of the shell‐formation through tuning the capping ligand, reaction temperature, and heating rate, uniform Pt‐based shells can be achieved with a thickness of &lt;1 nm. The resultant carbon‐supported CuNi@Pt‐Cu core@shell nano‐octahedra showed superior activity in electrochemical methanol oxidation reaction (MOR) compared with the commercial Pt/C catalysts and carbon‐supported CuNi@Pt‐Cu nano‐polyhedron counterparts.

Synthesis of Core@Shell Cu-Ni@Pt-Cu Nano-Octahedra and Their Improved MOR Activity.

Fabrication of 3d metal-based core@shell nanocatalysts with engineered Pt-surfaces provides an effective approach for improving the catalytic performance. The challenges in such preparation include shape control of the 3d metallic cores and thickness control of the Pt-based shells. Herein, we report a colloidal seed-mediated method to prepare octahedral CuNi@Pt-Cu core@shell nanocrystals using CuNi octahedral cores as the template. By precisely controlling the synthesis conditions including the deposition rate and diffusion rate of the shell-formation through tuning the capping ligand, reaction temperature, and heating rate, uniform Pt-based shells can be achieved with a thickness of <1 nm. The resultant carbon-supported CuNi@Pt-Cu core@shell nano-octahedra showed superior activity in electrochemical methanol oxidation reaction (MOR) compared with the commercial Pt/C catalysts and carbon-supported CuNi@Pt-Cu nano-polyhedron counterparts.