Electrooxidation Of Alcohols Research Articles

Some features of alcohols electrooxidation process on Pd, Rh and PdRh catalysts

PdRh/C catalyst and electrodeposited Pd, Rh and PdRh particles on glassy carbon electrode were studied in methanol and ethanol oxidation reactions in comparison with Pt-containing catalysts. Some features of this process have been described: (1) the appearance of oxidation peak in acidic and neutral media is possible only when polarization on CV is prolonged to hydrogen adsorption region where the surface OH-group formation occurred and surface oxides are reduced; (2) the CV-responses of model systems (electrodeposited Pd, Rh, PdRh) corresponding to alcohol oxidation increase and deform even during relaxation period when polarization is switched off; (3) experiments with addition of corresponding aldehydes (formaldehyde, acetaldehyde) to alcohol solution with stabilized CV responses showed that only increase in currents but not deformation of CV occurred. The addition of acid residue did not change the response noticeably. The formation of the same electroactive species, gem-diolate, for both alcohol and aldehyde electrooxidation mechanisms was supposed.

Synthesis of Pt nanoparticles with the aid of PVA for highly active and stable alcohol electro-oxidation

Synthesis of Pt nanoparticles with the aid of PVA for highly active and stable alcohol electro-oxidation

Facilitation of PdPb nanoalloy anchored on rGO/MOF-derived δ-Ga2O3 nanorod for electrocatalytic oxidation of methanol, ethanol and ethylene glycol

A wrinkled rGO modified nanorod gallium oxides (Ga2O3) anchored PdPb nanoalloys composite (PdPb@rGO/Ga2O3) was prepared using GO/Ga-MOF as the precursor by facile hydrothermal, calcination and reduction approach, and then applied as an electrocatalyst for alcohols electrooxidation. Electrochemical tests show that the fabricated PdPb@rGO/Ga2O3 exhibits superior electrocatalytic activity and high anti-CO poisoning capability for methanol, ethanol and ethylene glycol oxidation reactions (MOR, EOR and EGOR), outperforming Pd@rGO/Ga2O3 and commercial Pd/C. Specifically, the bimetallic electrocatalyst owns the highest forward peak current density of 115.84 mA cm−2, 146.97 mA cm−2 and 226.59 mA cm−2, which is 4.69, 5.08 and 8.38 times of Pd/C for MOR, EOR and EGOR, respectively. After 3600 s CA test, the retained current density of PdPb@rGO/Ga2O3 achieves the initial 59.24%, 71.13% and 81.71% towards MOR, EOR and EGOR, respectively. The remarkable performance is attributed to the electronic effects of PdPb nanoalloys, which can improve the electronic structure of Pd d-band, while the surface decoration of Pb/PbO NPs can dramatically adsorb more oxy-species and accelerate the oxidative removal of CO(ads). Moreover, the oxidation mechanisms of three alcohols and the removal processes of CO(ads) on the Pd surface are analyzed in detail.

Alcohols electrooxidation coupled with H2 production at high current densities promoted by a cooperative catalyst

Electrochemical alcohols oxidation offers a promising approach to produce valuable chemicals and facilitate coupled H2 production. However, the corresponding current density is very low at moderate cell potential that substantially limits the overall productivity. Here we report the electrooxidation of benzyl alcohol coupled with H2 production at high current density (540 mA cm−2 at 1.5 V vs. RHE) over a cooperative catalyst of Au nanoparticles supported on cobalt oxyhydroxide nanosheets (Au/CoOOH). The absolute current can further reach 4.8 A at 2.0 V in a more realistic two-electrode membrane-free flow electrolyzer. Experimental combined with theoretical results indicate that the benzyl alcohol can be enriched at Au/CoOOH interface and oxidized by the electrophilic oxygen species (OH*) generated on CoOOH, leading to higher activity than pure Au. Based on the finding that the catalyst can be reversibly oxidized/reduced at anodic potential/open circuit, we design an intermittent potential (IP) strategy for long-term alcohol electrooxidation that achieves high current density (>250 mA cm−2) over 24 h with promoted productivity and decreased energy consumption.

Self-Supported Pdni Dendrite on Ni Foam for Improving Monohydric Alcohol and Polyhydric Alcohols Electrooxidation

Self-Supported Pdni Dendrite on Ni Foam for Improving Monohydric Alcohol and Polyhydric Alcohols Electrooxidation

Alcohol oxidation with high efficiency and selectivity by nickel phosphide phases

Ni12P5nanoparticles are used for electro-oxidation of various alcohols through a preferred reaction path, by O–H activation, that supresses futher oxidation to CO2and produces valuable chemicals.

Defect engineering of Ni3S2 nanosheets with highly active (110) facets toward efficient electrochemical biomass valorization

Creating S vacancies in Ni3S2 can effectively modulate the electronic structure and surface properties, which adjusts the adsorption behaviors during benzyl alcohol electro-oxidation thereby dramatically boost the catalytic activity.

Electrochemical Surface Reconstruction of Cu2s to Synthesize Cuo with Oxygen Vacancies for Benzyl Alcohol Electro-Oxidation in a Wide Voltage Range

Electrochemical Surface Reconstruction of Cu2s to Synthesize Cuo with Oxygen Vacancies for Benzyl Alcohol Electro-Oxidation in a Wide Voltage Range

Pd17Se15 alloy on Se spheres with a high anti-poisoning ability for alcohol fuel electrooxidation.

The electron-deficient effect of Pd in the Pd17Se15 catalyst effectively weakens the adsorption of CO poisoning species and enhances the electrocatalytic performance of alcohol electrooxidation in an alkaline medium.

Ni3s4–Nis-Rgo as a Promising Catalyst for Alcohol Electrooxidation

Ni3s4–Nis-Rgo as a Promising Catalyst for Alcohol Electrooxidation

Accelerating Anode Reaction with Electro-oxidation of Alcohols over Ru Nanoparticles to Reduce the Potential for Water Splitting.

Generating hydrogen by water electrolysis is a promising and sustainable approach to the production of a green energy carrier, but the sluggish kinetics of the oxygen evolution reaction (OER) at anode leads to a high working potential. Replacing OER with electro-oxidation of organics driven at a low potential offers an effective way to accelerate the sluggish anode reaction, and thus increase hydrogen evolution in water-splitting. Herein, we have prepared a Ru nanoparticles on N-doped carbon nanotubes (Ru-NPs@NCNTs) to implement electro-oxidation of benzyl alcohol toward reducing the anodic potential in watersplitting. The potential of the anode reaction is remarkably decreased from 1.76 to 1.19 V vs RHE at a current density of 10 mA cm-2 with the assistance of a Ru-NPs catalyst. Furthermore, 100% selectivity and 95% yield of valuable benzaldehyde were achieved simultaneously. The Ru-NPs also exhibits good durability and wide applicability to other alcohols. The high performance of Ru-NPs is mainly attributed to the unique horizontal adsorption configuration of benzyl alcohol with surface atoms of the catalyst, shortening the distance between the •OH group and Ru atoms, and increasing the activation rate of the •OH group. This work presents a feasible strategy to boost water-splitting performance and concurrently produce value-added organics under mild conditions.

Facile synthesis of low-dimensional PdPt nanocrystals for high-performance electrooxidation of C 2 alcohols

Low-dimensional noble-metal materials (LDNMs) with different structural advantages have been considered as the high-performance catalysts for C2 alcohol electrooxidation. However, it is still a great challenging to precisely construct nanomaterials with low-dimensional composite structure thus to take advantages of various dimension, especial without the surfactant participation. Most studies focus on the modulation of the single dimensional nanocatalysts, the correlation between electrocatalytic performances and low-dimension composite have been rarely reported. Herein, we engineered a simple one-step approach to design multi-low-dimensional PdPt nanomaterials by using different Pd precursors. The low-dimensional PdPt nanocrystals (NCs) composed of zero dimension (0D) dendrite-like nanoparticles and two dimension (2D) nanosheets were obtained by using Pd(OAc)2, and meanwhile the 2D PdPt nanosheet assemblies (NAs) were synthesized by the introduction of NaPdCl4. Specifically, benefitting from the unique low-dimension structures with fast electron/mass transfer, and optimized electronic and synergistic effect, the multi-low-dimensional 0D-2D PdPt NCs showed the highest ethanol oxidation reaction (EOR)/ethylene glycol oxidation reaction (EGOR) mass activities, which were much higher than 2D PdPt NAs. The 0D-2D PdPt NCs also exhibited the highest structural stability. Generally, this work could inspire more advanced designs for surfactant-free synthesis and promote the fundamental engineering on nanocatalysts with low-dimension composite structure for electrocatalytic fields.

One-pot synthesis of porous Pd-polypyrrole/nitrogen-doped graphene nanocomposite as highly efficient catalyst for electrooxidation of alcohols

Herein, a ternary-nanocomposite Pd-polypyrrole/nitrogen-doped graphene (Pd-PPy/NGE) has been prepared facilely by the one-pot method. In simple terms, PPy was in-situ polymerized on the surface of NGE with PdCl42- as the oxidant, and simultaneously Pd nanopaticles were loaded on the surface of PPy or embedded in PPy particles. The obtained Pd-PPy/NGE nanocomposite exhibits promising electrocatalytic properties toward the oxidation reaction of alcohols in alkaline medium. Especially, the optimized Pd-PPy/NGE (1:50) catalyst possesses mass activity of 2176.7, 1192.7 and 498.9 mA mgPd-1 toward ethylene glycol, methanol and ethanol electrooxidation, respectively, which are 4.3, 6.7 and 2.9 times of those for commercial Pd/C catalyst. Moreover, the Pd-PPy/NGE (1:50) also shows higher anti-poisoning ability and operating stability than the Pd/C catalyst. The promising electrocatalytic performance of the Pd-PPy/NGE (1:50) for alcohols oxidation can be ascribed to the well dispersion of Pd nanoparticles, the porous and stable three dimentional structure of the composite, and the synergistic effect between different components. The structural randomness of the conducting polymer and the potential synergistic effect between the metal nanoparticles and various supports would provide broad development space for these composites as electrocatalysts in direct alcohol fuel cell.

Influence of structure on the electrooxidation rate of six C-4 alcohols

Alcohols are of great interest both for fuel cells and for the preparation of aldehydes. The electrooxidation of six C-4 alcohols (1-, 2- and iso-butanol, crotyl, cis-2-buten-1,4-diol and erythritol on gold in alkaline medium has been studied by cyclic voltammetry (CV), the Electrochemical Quartz Crystal Microbalance (EQCM) and Electrochemical Impedance Spectroscopy (EIS). Furthermore, molecular dynamics calculations were used for determining the probability of solvation of the alcoholic head, g(r), as a function of the distance, r, to the alcoholic head. This probability was found to be maximum at r = 2 Å The six alcohols fell into two groups. One group, namely 1-, 2- and iso-butanol, showed first-order electrooxidation kinetics at concentrations <20 mM, without poisoning of the electrode surface. These alcohols, as well as including crotyl, showed relative low reactivity (It was estimated as the ratio of the charge of peak b1 in a given alcohol to that of iso-butanol, the less active alcohol) correlation against the Radial Distribution Function (RDF) at a given distance (g(2 Å)), in total agreement with our hypothesis about the effect of the hydrophobicity of the analyte on the reactivity of the electrode. The second group, formed by crotyl, cis-2-buten-1,4-diol and erythritol, were almost 10 times more reactive, had a kinetic order near 0.5, showed adsorption on the gold surface, and their activity correlated better with their boiling points, that is, with their dipolar character. So, in the electrooxidation of unsaturated alcohols there is adsorption of residues and/or reaction products, which does not affect their high reactivity.

Reversible Ketone Hydrogenation and Dehydrogenation for Aqueous Organic Redox Flow Batteries

Aqueous soluble organic (ASO) redox-active materials have recently shown great promise as alternatives to transition metal ions to be employed as energy-bearing active materials in redox flow batteries for large-scale energy storage because of their structural tunability, cost-effectiveness, availability, and safety features. Development so far however has been limited to a small palette of organics that are aqueous soluble and tend to display the necessary redox reversibility within the water stability window. There is however noticeably much larger number of organic molecules that exhibit some degree of irreversible redox activities. In this presentation, we show how the molecular engineering of fluorenone enables the alcohol electro-oxidation needed for reversible ketone hydrogenation and dehydrogenation at room temperature without the use of a catalyst. Flow batteries based on these fluorenone derivative anolytes operate efficiently and exhibit stable long-term cycling at ambient and mildly increased temperatures in a non-demanding environment. These results suggest the potential for identifying other atypical organic redox molecules for energy storage. Reference: Feng et al., Science 372, 836–840 (2021)

Nitroxyl Radical/Copper-Catalyzed Electrooxidation of Alcohols and Amines at Low Potentials.

Nitroxyl radicals, such as 2,2,6,6-tetramethylpiperidine N-oxyl (TEMPO), can catalyze the electrochemical oxidation of alcohols and amines. Because the oxidation current obtained in this process depends on the concentration of alcohols and amines, this process can be applied to their sensing. However, the relatively high oxidation potentials required by nitroxyl radicals can induce interfering oxidation currents from various reductive substances in biological samples, which affects the accuracy of analyte measurements. In this study, we examined the electrooxidation of alcohols and amines at a low potential by applying cooperative oxidation catalysis using a nitroxyl radical and a copper salt. Nortropine N-oxyl (NNO), which showed higher catalytic activity than TEMPO was used as the nitroxyl radical. An increase in the oxidation current was observed at the low potential, and this increase depended on the alcohol concentration. In the case of the electrooxidation of amines, a positive correlation between oxidation current and amine concentration was observed at low amine concentrations. Therefore, low-potential cooperative catalysis can be applied to alcohol and amine electrooxidation for the development of accurate sensors suitable for clinical settings.

Catalytic activity of platinized titanium and titanium coated with ruthenium oxide in the processes of electrooxidation of ethyl alcohol in alkaline media

AbstractBACKGROUNDThis study investigates the catalytic activity of platinized titanium and titanium coated with ruthenium oxide in the processes of electrooxidation of ethyl alcohol in alkaline phosphate electrolyte and potassium hydroxide electrolyte in non‐flowing membraneless fuel cells proposed by the authors. In these systems, an interface between the phases formed, which played the role of a membrane. Cyclic voltammetry, pulse chronoamperometry and gas–liquid chromatography were used to study the corrosion resistance and catalytic activity of ethanol oxidation on the selected electrodes. Platinized titanium and titanium coated with ruthenium oxide, involving a thin layer of platinum or ruthenium oxide on a perforated titanium mesh, were investigated.RESULTSIt is found that the oxidation of ethyl alcohol proceeds more actively on the surface of titanium coated with ruthenium oxide in alkaline phosphate electrolyte, with the formation of acetaldehyde as the main reaction product. In potassium hydroxide electrolyte, acetaldehyde and acetic acid are formed on the surface; two and four electrons are released, respectively. This indicates the C2 reaction pathway of ethanol oxidation. In contrast, the oxidation of ethyl alcohol in potassium hydroxide electrolyte proceeds more actively on the platinized titanium with the formation of acetaldehyde.CONCLUSIONSThe results obtained show that titanium electrode coated with ruthenium oxide is promising in phosphate electrolyte, but platinized titanium electrode is promising in potassium hydroxide electrolyte in the proposed non‐flowing membraneless alcohol fuel cells. © 2021 Society of Chemical Industry (SCI).

Controlled synthesis of mono- and bimetallic Pt-based catalysts for electrochemical ethanol oxidation

Poisoning tolerance of Pt-based catalyst is an important parameter for the designing of direct electrochemical fuel cells (EFCs) based on electrooxidation of alcohols (i.e. methanol, ethanol). Applicability of direct ethanol EFCs is still challenging taking into account the lack of effective electrocatalysts which are able to produce high faradic current densities and high stability towards strong adsorption of C1 and C2 oxidation products. As we present here, mono- and bimetallic Pt-based electrocatalysts have been synthesized on a carbon black support for the elecotrooxidation of ethanol in acidic media. Depending of the molar ratio between poly-n-vinylpyrrolidone (PVP, acting as protecting agent) and Pt, nanoparticle size distribution has been controlled, obtaining an optimal condition of Pt loading and electroactive surface area (ECSA) for the PVP/Pt ratio = 1. The electrochemical behavior of electrocatalyst Pt/Re/CB-1 shows a negligible variation in the ECSA (98.3 m2 g−1) in comparison with the monometallic electrodes (90.2 m2 g−1). In contrast, addition of Ir tends to reduce the ECSA by agglomeration of some nanoparticles and decreasing its electrochemical performance. Incorporation of Re in the alloy promotes bond breaking of the intermediates adsorbed on surface, specifically adsorbed C2 molecules, releasing great number of the active sites from the Pt surface, minimizing the deactivation with cycling and providing remarkable stable catalyst with high specific current densities with the addition of small amounts of Re.

Molecular Engineering to Tune the Ligand Environment of Atomically Dispersed Nickel for Efficient Alcohol Electrochemical Oxidation

AbstractAtomically dispersed metals maximize the number of catalytic sites and enhance their activity. However, their challenging synthesis and characterization strongly complicates their optimization. Here, the aim is to demonstrate that tuning the electronic environment of atomically dispersed metal catalysts through the modification of their edge coordination is an effective strategy to maximize their performance. This article focuses on optimizing nickel‐based electrocatalysts toward alcohol electrooxidation in alkaline solution. A new organic framework with atomically dispersed nickel is first developed. The coordination environment of nickel within this framework is modified through the addition of carbonyl (CO) groups. The authors then demonstrate that such nickel‐based organic frameworks, combined with carbon nanotubes, exhibit outstanding catalytic activity and durability toward the oxidation of methanol (CH3OH), ethanol (CH3CH2OH), and benzyl alcohol (C6H5CH2OH); the smaller molecule exhibits higher catalytic performance. These outstanding electrocatalytic activities for alcohol electrooxidation are attributed to the presence of the carbonyl group in the ligand chemical environment, which enhances the adsorption for alcohol, as revealed by density functional theory calculations. The work not only introduces a new atomically dispersed Ni‐based catalyst, but also demonstrates a new strategy for designing and engineering high‐performance catalysts through the tuning of their chemical environment.

Shape-dependent catalytic properties of electrochemically synthesized PdPt nanoparticles towards alcohols electrooxidation

Tuning the composition and structure of alloys is significantly important to unveil their relationship between structure and functions, and thus help to design catalysts with high performance. In this work, PdPt octahedral and concave cubic nanoparticles (OH-PdPt NPs and CC-PdPt NPs) were synthesized firstly by developed electrochemical methods. EDS and XPS studies revealed that the as-synthesized PdPt NPs have similar composition both in bulk and surface. The alloy nanoparticles show surface structure dependent enhanced activity and stability for methanol, ethanol and glycerol electrooxidations (MOR, EOR and GOR). The {hk0} high-index facets enclosed CC-PdPt NPs show higher activity towards MOR and EOR which is 7.0-fold and 3.4-fold respectively higher than commercial Pt/C. However, {1 1 1} low-index facets enclosed OH-PdPt NPs show superior activity towards GOR, which is 4.5-fold higher than commercial Pt/C. The selective enhancing catalytic ability of PdPt NPs towards different alcohol electrooxidations could be attributed to the synergetic effect and modified electronic structure of Pd and Pt, as well as the important effects of surface atomic configuration. DFT calculations suggest that the higher activity of methanol and ethanol oxidation on high-index {hk0} facets is due to the faster decomposition process and lower oxidation barrier on the step sites. Nevertheless, the strong adsorption of COCHOHCO* on step sites leading to a much higher oxidation barrier, indicating the step sites of {hk0} facets are not beneficial for glycerol oxidation.