Electro-Catalytic Oxidation of Methanol on a Ni–Cu Alloy in Alkaline Medium

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).

A review on advances in green treatment of glycerol waste with a focus on electro-oxidation pathway

Over the past decades, research efforts are being devoted into utilizing the biomass waste as a major source of green energy to maintain the economic, environmental, and social sustainability. Specifically, there is an emerging consensus on the significance of glycerol (an underutilised waste from biodiesel industry) as a cheap, non-toxic, and renewable source for valuable chemicals synthesis. There are numerous methods enacted to convert this glycerol waste to tartronic acid, mesoxalic acid, glyceraldehyde, dihydroxyacetone, oxalic acid and so on. Among these, the green electro-oxidation technique is one of the techniques that possesses potential for industrial application due to advantages such as non-toxicity process, fast response, and lower energy consumption. The current review covers the general understanding on commonly used techniques for alcohol (C₁ & C₂) conversion, with a specific insight on glycerol (C₃) electro-oxidation (GOR). Since catalysts are the backbone of chemical reaction, they are responsible for the overall economy prospect of any processes. To this end, a comprehensive review on catalysts, which include noble metals, non-noble metals, and non-metals anchored over various supports are incorporated in this review. Moreover, a fundamental insight into the development of future electrocatalysts for glycerol oxidation along with products analysis is also presented.

Investigation of electrocatalytic activity of NiTPPBr6 on the graphite electrode for oxidation of methanol, ethanol, 1-propanol and 2-propanol

Due to the importance of producing clean energy through systems such as alcoholic fuel cell, methanol, ethanol, 1-propanol, and 2-propanol, these alcohols were oxidized at the modified graphite electrode by NiTPPBr6 / NiTPPBr8 as a clean electrocatalyst in an alkaline media. This process investigated by various techniques such as cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS), in all cases showed Cottrell type behavior with the diffusion of coefficients of 2.04 × 10[Formula: see text], 1.3 × 10[Formula: see text] 8.3 × 10[Formula: see text] cm[Formula: see text] s[Formula: see text] for the corresponding alcohols respectively. Likewise, the catalytic rate constant for methanol oxidation was found to be 2.9 × 108 cm3mol[Formula: see text] s[Formula: see text] through chronoamperometric measurements. Interestingly, the order in activity for oxidation of the alcohols introduced with the electrocatalyst was: 2-propanol [Formula: see text] 1-propanol [Formula: see text] ethanol [Formula: see text] methanol and was unlike previous studies in which the oxidation current was reduced by increasing the number of carbon atoms from methanol to propanol.

Electrocatalytic Oxidation of Methanol by a Polymeric Ni Complex-Modified Electrode Prepared by a One-Step Cold-Plasma Process

In this work, a polymeric nickel complex-modified indium tin oxide (ITO) electrode was prepared by a one-step cold-plasma process of acrylic-Ni complex precursors. Also, the work provides the electrocatalytic oxidation of methanol by a polymeric Ni complex-modified electrode prepared by a simple one-step cold-plasma process. The acrylic-Ni complex precursors were synthesized by complexation of nickel (II) chloride, and acrylic acid in a small amount of water; subsequently we added N,N′-methylene-bis-acrylamide as a crosslinking agent to the complex solution. We characterized the prepared polymeric Ni complex-modified (Ni-modified) catalytic electrode by X-ray photoelectron spectroscopy, field emission scanning electron microscopy, and electrochemical methods. Electrochemical characterization showed stable redox behavior of Ni(III)/Ni(II) couples. Cyclic voltammetric experiments have shown that electrocatalytic oxidation of methanol can occur on Ni-modified catalytic electrodes, while not observed on bare ITO. As a result, this work provides the simple and easy preparation of electrocatalysts by one-step plasma process for methanol fuel cell.

Ultrafast Growth of a Cu(OH)2-CuO Nanoneedle Array on Cu Foil for Methanol Oxidation Electrocatalysis

A swift potentiostatic anodization method for growing a 5-7 μm tall nanoneedle array of Cu(OH)₂-CuO on Cu foil within 100 s has been developed. This catalytic electrode when screened for methanol oxidation electrocatalysis in 1 M KOH with 0.5 M methanol, delivered a current density as high as 70 ± 10 mA cm^-2 at 0.65 V versus Hg/HgO which is superior to the performance of many related catalysts reported earlier. The observed activity enhancement is attributed to the formation of both Cu(OH)₂-CuO nanoneedle arrays of high active surface area over the metallic Cu foil. In addition, the Cu(OH)₂-CuO/Cu electrode had also exhibited excellent stability upon prolonged potentiostatic electrocatalytic oxidation of methanol while retaining the charge-transfer characteristics. Growth of such highly ordered assembly of Cu(OH)₂-CuO nanoneedles within a minute has never been achieved before. When compared to its oxygen evolution reaction activity, the addition of 0.5 M methanol has lowered the overpotential at 10 mA cm^-2 by 334 mV, which is significant. This encourages the use of methanol as a sacrificial anolyte for energy-saving production of H₂ from water electrolysis.

The one-pot synthesis of CuNi nanoparticles with a Ni-rich surface for the electrocatalytic methanol oxidation reaction

The use of fuel cells is one of the most promising renewable energy strategies, but they still suffer from many limitations. The high mass enthalpy of hydrogen as a fuel comes at the cost of inconveniences and risks associated with storage, transportation and utilization, while the high performance of Pt catalysts in commercial fuel cells is limited by their high cost, low earth abundance, and poor stability as a result of CO intermediate poisoning. To circumvent these dilemmas, direct methanol fuel cells (DMFCs) were developed, using methanol as a fuel and Ni as the anode catalyst. Thanks to the condensed form of the fuel, DMFCs are considered as the most promising fuel-cell solution for portable electronic devices. Usually, other elements have to be introduced into Ni-based catalysts to modify the active sites to provide better alternatives to pristine Ni metal in terms of activity and stability. In this study, we provide a mild synthetic method for the preparation of CuNi alloy nanoparticles. The proper alloying ratio leads to the suitable modification of the electronic structure of Ni, which promotes the MOR catalytic reaction on the NiCu alloy. The NiCu alloy catalyst exhibits a mass current density of 1028 mA mg_metal^-1 for the MOR at 1.55 V (vs. RHE), which is among the best values obtained from similarly prepared Ni-based catalysts.

Electrochemical Oxidation of Urea on NiCu Alloy Nanoparticles Decorated Carbon Nanofibers

Bimetallic Cu3.8Ni alloy nanoparticles (NPs)-anchored carbon nanofibers (composite NFs) were synthesized using a simple electrospinning machine. XRD, SEM, TEM, and TGA were employed to examine the physiochemical characteristics of these composite NFs. The characterization techniques proved that Cu3.8Ni alloy NPs-anchored carbon NFs were successfully fabricated. Urea oxidation (UO) processes as a source of hydrogen and electrical energy were investigated using the fabricated composite NFs. The corresponding onset potential of UO and the oxidation current density (OCD) were measured via cyclic voltammetry as 380 mV versus Ag/AgCl electrode and 98 mA/cm2, respectively. Kinetic study indicated that the electrochemical oxidation of urea followed the diffusion controlled process and the reaction order is 0.5 with respect to urea concentration. The diffusion coefficient of urea using the introduced electrocatalyst was found to be 6.04 × 10−3 cm2/s. Additionally, the composite NFs showed steady state stability for 900 s using chronoamperometry test.

NiCo alloy nanoparticles electrodeposited on an electrochemically reduced nitrogen-doped graphene oxide/carbon-ceramic electrode: a low cost electrocatalyst towards methanol and ethanol oxidation

NiCo alloy nanoparticles on the electrochemically reduced nitrogen-doped graphene oxide/carbon-ceramic electrode: a low cost electrocatalyst towards methanol and ethanol oxidation.

Facile Synthesis of Cu/NiCu Electrocatalysts Integrating Alloy, Core-Shell, and One-Dimensional Structures for Efficient Methanol Oxidation Reaction

The design and development of low-cost Pt-free, high-active, and durable noble-metal-free electrocatalysts for methanol electrooxidation is highly desirable but remains a challenge. Herein, unique Cu/NiCu nanowires (NWs) integrating alloy, core-shell, and one-dimensional structures are prepared by a facile one-pot strategy. It is found that the Ni-Cu surface alloying structure can effectively change the charge distribution of the atomic configuration, the core-shell structure can be optimized with the usage of Ni and Cu, and the one-dimensional structure can effectively enhance the charge transfer between the electrode surface and the active sites, making the prepared NWs promising electrocatalysts. Detailed catalytic investigations showed that the obtained Cu/NiCu NWs exhibit an enhanced electrocatalytic performance for methanol oxidation reaction (MOR). The optimized Cu/NiCu NWs in this work show a mass current density of 867.1 mA mg_metal^-1 at 1.55 V (vs. RHE) for MOR, which is far higher than those of Ni-based previously reported electrocatalysts. This work opens up a new pathway for the design and engineering of noble-metal-free alloy electrocatalysts with enhanced activity and durability.

Co-sputter deposited nickel-copper bimetallic nanoalloy embedded carbon films for electrocatalytic biomarker detection

We report the fabrication of a nickel (Ni)-copper (Cu) bimetallic nanoalloy (∼3 nm) embedded carbon film electrode with the unbalanced magnetron (UBM) co-sputtering technique, which requires only a one-step process at room temperature. Most of each nanoalloy body was firmly embedded in a chemically stable carbon matrix with an atomically flat surface (Ra: 0.21 nm), suppressing the aggregation and/or detachment of the nanoalloy from the electrode surface. The nanoalloy size and composition can be controlled simply by individually controlling the target powers of carbon, Ni and Cu, which also makes it possible to localize the nanoalloys near the electrode surface. This electrode exhibited excellent electrocatalytic activity for d-mannitol, which should be detected with a low detection limit in urine samples for the diagnosis of severe intestinal diseases. With a Ni/Cu ratio of around 64/36, the electrocatalytic current per metal area was 3.4 times larger than that of an alloy film electrode with a similar composition (∼70/30). This improved electrocatalytic activity realized higher stability (n = 60, relative standard deviation (RSD): 4.6%) than the alloy film (RSD: 32.2%) as demonstrated by continuous measurements of d-mannitol.

Investigation of thermal, structural and dynamical properties of (Aux–Cuy–Niy)N=32,108,256 ternary nanosystems: effect of Au addition to Cu–Ni bimetallic nanoclusters via MD simulation

In this work, we have investigated the heating and cooling processes for ternary metallic nanoclusters with different Au mole fractions using molecular dynamics simulation.

Hierarchical nickel oxide nanosheet@nanowire arrays on nickel foam: an efficient 3D electrode for methanol electro-oxidation

Hierarchical nickel oxide nanosheet@nanowire arrays hydrothermally grown on nickel foam behave as an efficient 3D anode for electro-catalytic oxidation of methanol in alkaline media.

Physioelectrochemical and DFT investigation of metal oxide/p-type conductive polymer nanoparticles as an efficient catalyst for the electrocatalytic oxidation of methanol

Poly tyramine–NiO as an efficient electrocatalyst was prepared by in situ electropolymerization of tyramine in the presence of the SDS under ultrasonic irradiation.

Cu-Ni nano-alloy: mixed, core-shell or Janus nano-particle?

Bimetallic nanoparticles like Cu-Ni are particularly attractive due to their magnetic and catalytic properties; however, their properties depend strongly on the structure of the alloy i.e. mixed, core-shell or Janus. To predict the alloy structure, this paper investigates the size and shape effects as well as the surface segregation effect on the Cu-Ni phase diagram. Phase maps have been plotted to determine the mixing/demixing behavior of this alloy according the particle shape. Cu-Ni nanoalloy can form a mixed particle or a Janus one depending on the synthesis temperature. Surface segregation is also considered and reveals a nickel surface-enrichment. Finally, this paper provides a useful roadmap for experimentalists.