Ethanol Oxidation Research Articles

Pro‐catalytic Role of Transition Metal/Metal Oxide Blend Low Pd Catalysts for Ethanol Oxidation: Diminution of Activation Energy and Promoting Electrode Kinetics at Low Temperature

AbstractIn this investigation the effect of temperature on catalytic oxidation of ethanol on multi‐metallic PdCoNi/C nano‐composite bearing reduced palladium loading, have been studied over the temperature range 20 °C to 80 °C. The structure, composition and surface morphology of the catalyst regime were determined through the respective techniques like XRD, EDX and TEM while electro‐catalytic parameters were evaluated by the help of voltammetry, chronoamperometry, impedance spectroscopy and ion‐chromatography. The apparent activation energies (Ea) of ethanol oxidation reaction (EOR) were drastically reduced over PdCoNi/C compared to Pd/C reflecting the energy efficiency of ternary matrix furnished with only 35 % Pd loading and the rest 65 % being cheaper transition metals. The long term poisoning rates warrant improved stability of PdCoNi/C and also figure out the robustness of the catalyst even at 20 °C. The Ea value is remarkably reduced, rendering appreciable mass activity in terms of current density per mg of Pd at each of the temperatures studied. The incorporation of transition metals Co and Ni onto Pd becomes particularly effective in orienting the EOR proceed through carbonate pathway as reflected by the columbic efficiency in terms of oxidation product yield ~5 times higher, compared to single Pd catalyst throughout the temperature range.

Effective Photocatalytic Ethanol Reforming into High-Value-Added Multicarbon Compound Coupled with H2 Production Over Pt-S3 Sites at PtSA-ZnIn2S4 Interface.

Selective photocatalytic production of high-value acetaldehyde concurrently with H2 from bioethanol is an appealing approach to meet the urgent environment and energy issues. However, the difficult ethanol dehydrogenation and insufficient active sites for proton reduction within the catalysts, and the long spatial distance between these two sites always restrict their catalytic activity. Here, guided by the strong metal-substrate interaction effect, an atomic-level catalyst design strategy to construct Pt-S3 single atom on ZnIn2S4 nanosheets (PtSA-ZIS) is demonstrated. As active center with optimized H adsorption energy to facilitate H2 evolution reaction, the unique Pt single atom also donates electrons to its neighboring S atoms with electron-enriched sites formed to activate the O─H bond in *CH3CHOH and promote the desorption of *CH3CHO. Thus, the synergy between Pt single atom and ZIS together will reduce the energy barrier for the ethanol oxidization to acetaldehyde, and also narrow the spatial distance for proton mass transfer. These features enable PtSA-ZIS photocatalyst to produce acetaldehyde with a selectivity of ≈100%, which will spontaneously transform into 1,1-diethoxyethane via acetalization to avoid volatilization. Meanwhile, a remarkable H2 evolution rate (184.4µmolh-1) is achieved with a high apparent quantum efficiency of 10.50% at 400nm.

Modulating the exposed facets of Pd-Pb intermetallic compounds via morphology engineering for efficient multifunctional electrocatalysts

To develop Pd-based intermetallic compounds (IMCs) nanomaterials with specific morphologies for exposing specific facets is essential yet full of challenges for highly efficient electrocatalysts. Herein, we utilized morphology engineering to successfully acquire Pd-Pb concave nanocubes (Pd-Pb CNCs) with Pd3Pb IMC phase and exposing (200) facet mainly. The Pd-Pb CNCs catalyst displays the ultrahigh activity of 4.01 A mgPd-1 for ethanol oxidation reaction (EOR), surpassing than that of Pd-Pb nanoparticles with Pd3Pb IMC phase but exposing (111) facet mainly, and far exceeding than commercial Pd/C. Density functional theory simulation manifests that the excellent EOR activity for Pd-Pb CNCs is attributed to the weakened reaction intermediates adsorption on catalyst surface. Importantly, the Pd-Pb CNCs are also with excellent reactivities for methanol oxidation reaction and glycerol oxidation reaction, indicating potentials as outstanding multifunctional electrocatalysts. This work may not only furnish a simple strategy for fabricating Pd-based IMCs exposing specific facets, but also promote their high-efficient applications in alcohol oxidation reactions and beyond.

Constructing molecule-metal relay catalysis over heterophase metallene for high-performance rechargeable zinc-nitrate/ethanol batteries

Zinc-nitrate batteries can integrate energy supply, ammonia electrosynthesis, and sewage disposal into one electrochemical device. However, current zinc-nitrate batteries still severely suffer from the limited energy density and poor rechargeability. Here, we report the synthesis of tetraphenylporphyrin (tpp)-modified heterophase (amorphous/crystalline) rhodium-copper alloy metallenes (RhCu M-tpp). Using RhCu M-tpp as a bifunctional catalyst for nitrate reduction reaction (NO 3 RR) and ethanol oxidation reaction in neutral solution, a highly rechargeable and low-overpotential zinc-nitrate/ethanol battery is successfully constructed, which exhibits outstanding energy density of 117364.6 Wh kg −1 cat , superior rate capability, excellent cycling stability of ~400 cycles, and potential ammonium acetate production. Ex/in situ experimental studies and theoretical calculations reveal that there is a molecule-metal relay catalysis in NO 3 RR over RhCu M-tpp that significantly facilitates the ammonia selectivity and reaction kinetics via a low energy barrier pathway. This work provides an effective design strategy of multifunctional metal-based catalysts toward the high-performance zinc-based hybrid energy systems.

Modulating Electronic Structure and Atomic Insights into the Novel Hierarchically Porous PdCuFe Trimetallic Alloy Aerogel for Efficient Oxygen Reduction.

The high cost of noble Pd/Pt required for the oxygen reduction reaction (ORR) in the cathode restricts the wide applications of fuel cells. In this study, the synthesis of a novel Pd3CuFe0.5 aerogel electrocatalyst is successfully demonstrated using self-assembly and lyophilization techniques, employing a mild reducing agent. The resulting aerogel electrocatalyst exhibits a distinctive 3D network structure, possessing a substantial BET-specific surface area of 75.19 m2g-1. It is worth noting that the optimized Pd3CuFe0.5 aerogel demonstrates exceptional ORR performance with a high half-wave potential of 0.92V versus RHE, a significant limiting current density of 7.6mAcm-2, and the excellent electrocatalytic stability, superior to the reported noble metal electrocatalysts, with the ORR activity decays only 4.9% after 16000 s. In addition, the Pd3CuFe0.5 aerogel electrocatalyst shows superior cycling stability for ≈120h at a charge/discharge current density of 10mAcm-2, indicating its promising application in fuel cells. Furthermore, the resulting composite aerogel possesses excellent hydrogen evolution reaction and ethanol oxidation reaction activity. The density functional theory calculations show that the partial oxidation of Pd3CuFe0.5 aerogel leads to a negative shift of the d-band center, which energetically optimizes the binding strength of *O intermediates, therefore accelerating the ORR activity.

Excessive Ethanol Oxidation Versus Efficient Chain Elongation Processes

PurposeChain elongation is a metabolic feature that consists of the elongation of short-chain fatty acids to longer and more valuable acids when ethanol is available. To lower the operational costs, the process can also be performed using mixed microbial cultures. However, certain microorganisms in the mixed cultures can use the ethanol provided in competing reactions, which is usually termed excessive ethanol oxidation (EEO). Although minimizing ethanol use is essential, there is a lack of studies analyzing the extent, causes, and solutions to excessive ethanol oxidation processes.MethodsTo address this knowledge gap, ethanol, and acetic acid mixtures, at a molar ratio of 5 to 2, were fermented, and the following were analyzed: the fermentation profile at different (1) pH and (2) headspace gas compositions, (3) a 16S analysis of the headspace gas composition fermentations, and (4) a thermodynamic analysis of the reactions involved.Results and Conclusions: All fermentations, except the ones at the lowest pH (5.3), exhibited a significant EEO activity that reduced the yield of chain-elongated products. It was demonstrated that neither the inhibition of methanogenic activity nor the increased H2 partial pressure is an efficient method to inhibit EEO. It was also shown that CO2 can act as an electron acceptor for EEO, promoting the growth of acetogenic bacteria. In the absence of CO2, sulfate was used as an electron acceptor by sulfate-reducing bacteria to facilitate EEO. Methods such as low pH operation with in-line extraction, and the use of alternative sulfur salts, are proposed to increase the ethanol use efficiency in chain elongation processes.Graphical

Probing the Behavior of Composition‐Tunable Ultrathin PtNi Nanowires for CO Oxidation and Small‐Molecule Electrocatalytic Reactions

AbstractWe have successfully synthesized ultrathin nanowires of pure Pt, Pt99Ni1, Pt9Ni1, and Pt7Ni3 using a modified room‐temperature soft‐template method. Analysis of both methanol oxidation reaction (MOR) and ethanol oxidation reaction (EOR) results found that the Pt7Ni3 samples yielded the best performance with specific activities of 0.36 and 0.34 mA/cm2 respectively. Additionally, formic acid oxidation reaction (FAOR) tests noted that both Pt and PtNi nanowires oxidize small organic molecules (SOMs) via an indirect pathway. CO oxidation data suggests little measurable performance without any pre‐reduction treatment; however, after annealing in H2, we detected significantly improved CO2 formation for both Pt9Ni1 and Pt7Ni3 motifs. These observations highlight the importance of pre‐treating these nanowires under a reducing atmosphere to enhance their performance for CO oxidation. To explain these findings, we collected extended x‐ray adsorption fine structure (EXAFS) spectroscopy data, consistent with the presence of partial alloying with a tendency for Pt and Ni to segregate, thereby implying the formation of a Pt‐rich shell coupled with a Ni‐rich core. We also observed that the degree of alloying within the nanowires increased after annealing in a reducing atmosphere, a finding deduced through analysis of the coordination numbers and calculations of Cowley's short range order parameters.

Relative Kinetic Study of Oxidation of Ethanol by Potassium Dichromate and Potassium Permanganate in Aqueous Acidic Media

Relative Kinetic Study of Oxidation of Ethanol by Potassium Dichromate and Potassium Permanganate in Aqueous Acidic Media

Palladium chalcogenide nanosheets with p-d orbital hybridization for enhanced alcohol electro-oxidation performance

Ethanol oxidation reaction (EOR) is an important energy conversion process. Herein, we have proposed palladium chalcogenide nanosheets to improve C-C bond cleavage ability for EOR. The mass activity of the Te-Pd nanosheets (NSs)/C, which is higher than Se-Pd NSs/C and S-Pd NSs/C (6.9 A mg−1 and 5.3 A mg−1), has achieved 10.0 A mg−1, 12.5-fold higher than commercial Pd/C (0.8 A mg−1) and 8.3 times higher than Pd NSs/C (1.2 A mg−1). The Faradaic efficiency of C1 pathway for EOR on the Te-Pd NSs/C can improve to 56.6% compared with Pd NSs/C (25.7%) at 0.8 VRHE. Density functional theory calculations reveal that the orbital hybridization between Pd and Te weakens the adsorption energy of intermediates and reduces the energy barrier of the rate-determining steps in the C1 pathway. Besides, these palladium chalcogenide NSs can also serve as efficient electrocatalysts for ethylene glycol oxidation reaction and methanol oxidation reaction.

Effect of SnO2 and Rh modifications on CO-stripping kinetics and ethanol oxidation mechanism of Pt electrode

Effect of SnO2 and Rh modifications on CO-stripping kinetics and ethanol oxidation mechanism of Pt electrode

Slowly Removing Surface Ligand by Aging Enhances the Stability of Pd Nanosheets toward Electron Beam Irradiation and Electrocatalysis.

Surface ligands play an important role in shape-controlled growth and stabilization of colloidal nanocrystals. Their quick removal tends to cause structural deformation and/or aggregation to the nanocrystals. Herein, we demonstrate that the surface ligand based on poly(vinylpyrrolidone) (PVP) can be slowly removed from Pd nanosheets (NSs, 0.93±0.17 nm in thickness) by simply aging the colloidal suspension. The aged Pd NSs show well-preserved morphology, together with significantly enhanced stability toward both e-beam irradiation and electrocatalysis (e.g., ethanol oxidation). It is revealed that the slow desorption of PVP during aging forces the re-exposed Pd atoms to reorganize, facilitating the surface to transform from being nearly perfect to defect-rich. The resultant Pd NSs with abundant defects no longer rely on surface ligand to stabilize the atomic arrangement and thus show excellent structural and electrochemical stability. This work provides a facile and effective method to maintain the integrity of colloidal nanocrystals by slowly removing the surface ligand.

Slowly Removing Surface Ligand by Aging Enhances the Stability of Pd Nanosheets toward Electron Beam Irradiation and Electrocatalysis

AbstractSurface ligands play an important role in shape‐controlled growth and stabilization of colloidal nanocrystals. Their quick removal tends to cause structural deformation and/or aggregation to the nanocrystals. Herein, we demonstrate that the surface ligand based on poly(vinylpyrrolidone) (PVP) can be slowly removed from Pd nanosheets (NSs, 0.93±0.17 nm in thickness) by simply aging the colloidal suspension. The aged Pd NSs show well‐preserved morphology, together with significantly enhanced stability toward both e‐beam irradiation and electrocatalysis (e.g., ethanol oxidation). It is revealed that the slow desorption of PVP during aging forces the re‐exposed Pd atoms to reorganize, facilitating the surface to transform from being nearly perfect to defect‐rich. The resultant Pd NSs with abundant defects no longer rely on surface ligand to stabilize the atomic arrangement and thus show excellent structural and electrochemical stability. This work provides a facile and effective method to maintain the integrity of colloidal nanocrystals by slowly removing the surface ligand.

The analytical performance of Saccharomyces cerevisiae and Bacillus megaterium microbial consortium as recognition element in ethanol biosensor

Abstract. Nurdiani, Iswantini D, Nurhidayat N, Wahyuni WT, Kartono A. 2023. The analytical performance of Saccharomyces cerevisiae and Bacillus megaterium microbial consortium as recognition element in ethanol biosensor. Biodiversitas 24: 5928-5936. Alcohol, particularly ethanol, is commonly found in human food and plays a significant role in degenerative diseases and disability. Accurate measurement of alcohol in food products is essential to ensure adherence to the Muslim halal rule. However, existing alcohol biosensor that relies on a single microbe has limitations in measuring a wide range of ethanol concentrations. To address this issue, a microbial consortium is needed to expand the measurable range. Therefore, this study aimed to develop an innovative biosensor to widen the range of measured ethanol concentrations based on the microbial consortium of Saccharomyces cerevisiae YSAPMI.2 and Bacillus megaterium BSAPMI.1. The performance of the biosensor was evaluated using the cyclic voltammetry method. The results showed that the linear range, linearity, coefficient of determination, sensitivity, and response time, were 0.02-6.0%, 0.9968, 0.9936, 83.157 µA (%)-1, and 11 seconds. The LoD ??and LoQ theoretical values ??of the method obtained in the ethanol oxidation reaction were 0.060% and 0.182%, respectively. The confirmatory test for the LoD value of 0.01% yielded a positive response, while the confirmed LoQ value of 0.02% showed good precision and accuracy. The biosensor had precise %RSD values of 0.568, 1.338, and 4.632% for the high, medium, and low ethanol concentrations, respectively. The accuracy reflected as the recovery percentage was in the range of 90.27-111.07%. The biosensor was relatively specific and had no interferences with common ethanol compounds including methanol, sodium chloride, formic acid, and glucose. The stability obtained with biofilm showed a better result reaching 88% in 70 days. Based on the result, this microbial consortium biosensor could widen the range of measured ethanol concentrations and should be further developed to create a prototype for an accurate and practical analysis.

Bimetallic Pd–Co Aerogel Three-Dimensional Architecture: Developing Self-Assembled Materials for Advanced Ethanol Oxidation

Bimetallic Pd–Co Aerogel Three-Dimensional Architecture: Developing Self-Assembled Materials for Advanced Ethanol Oxidation

Effect of manganese addition to Ni-Cu oxides on properties and activity in the oxidation of volatile organic compounds

Transition metal oxides are suitable for the total oxidation of harmful volatile organic compounds. The effect of Mn addition to Ni-Cu oxides was investigated to determine the optimum cation composition for achieving high catalytic performance in the total oxidation of ethanol and toluene, which were chosen as model volatile organic compounds. Single component (Ni, Cu, Mn), binary Ni-Cu, and ternary (Ni-Cu-Mn) oxide catalysts with various Ni:Cu and Ni:Cu:Mn molar ratios were prepared by precipitation of aqueous nitrate solutions followed by calcination at 500 °C in air. The catalysts were characterized by AAS, powder XRD, Raman spectroscopy, N2 adsorption, H2-TPR, and XPS spectroscopy. The addition of Mn to Ni-Cu oxides led to the formation of Ni-Cu-Mn mixed oxides with spinel structure and Ni-Mn mixed oxides (Ni6MnO8, NiMnO3). On the other hand, the Ni-Cu catalysts contained a mixture of NiO and CuO. In the H2-TPR experiments, the Ni-Cu-Mn oxides were reduced at lower temperatures compared to the binary Ni-Cu catalysts. The catalytic performance of Ni-Cu-Mn oxide catalysts was higher than that of the Ni-Cu catalysts. As the Mn concentration increased, the concentration of metal-bound oxygen raised, while the concentration of oxygen vacancies slightly decreased. A linear correlation was revealed between the surface concentrations of oxygen vacancies determined by XPS and specific reaction rates in ethanol and toluene oxidation over the Ni-Cu and Ni-Cu-Mn catalysts. For the Ni-Cu-Mn mixed oxides and the mixture of Ni and Cu oxides, a synergistic effect was found in the oxidation of both model compounds.

Pd/PdO doped WO3 with enhanced selectivity and sensitivity for ppb level acetone and ethanol detection

Ethanol and acetone sensors have a wide variety of applications across different industries. However, it is necessary to improve the performance of such sensors and to understand the underlying mechanisms. In this study, Pd/PdO-WO3 nanoblocks are synthesized via hydrothermal growth and calcination. The Pd and PdO contents of the materials are tuned by varying the Pd doping concentration and annealing temperature. The gas sensing performance of the nanoparticles is investigated, which shows that Pd doping increases the sensitivity and reduces the optimum operating temperature. At 200 °C, Pd/PdO-WO3 nanoblocks with different PdO ratios exhibit good sensitivity to acetone and ethanol. However, because PdO is an active catalyst for ethanol oxidation, the oxygen sensitivity increases as the PdO ratio increases. The prepared sensors exhibit good stability and excellent selectivity against a variety of interferents, and the detection limit of the target gas is 100 ppb. The chemical and electronic sensitization of Pd/PdO lowers the activation barrier and improves the gas sensing response. This study demonstrates that the selectivity of a gas sensor can be regulated by controlling the electronic states of the active species.

Efficient alcohol electro-oxidation based on a 3D Ni(II)-MOF with centrosymmetric Ni6 cluster

Designing economical and efficient anode catalysts is critical for the commercial use of direct alcohol fuel cells (DAFCs). In this work, a novel Ni(II)-based metal–organic framework (MOF), {[Ni3(μ3-OH)(TMBTI)(1,4-bib)(H3O)}n (H6TMBTI = 2,4,6-trimethylbenzene-1,3,5-triylisophthalate, 1,4-bib = 1,4-bis(1-imidazoly)benzene) (CTGU-38, CTGU = China Three Gorges University), was successfully synthesized through solvothermal method. Structural analyses reveal that the CTGU-38 possesses a unique Ni6(μ3-OH)2(COO)12 cluster and 3D porous framework with a rare (6,16)-connected topology. Further electrochemical experiments demonstrate that the CTGU-38 exhibits good electrocatalytic oxidation performance towards various alcohol fuel molecules, including the methanol oxidation reaction (MOR), ethanol oxidation reaction (EOR), n-propanol oxidation reaction (NPOR), and isopropanol oxidation reaction (IPOR), with peak current densities ranging from 26.9 to 54.46 mA cm−2 in alkaline solution. These results indicate that the CTGU-38 appears to be a potential non-noble metal-based electrocatalyst for DAFCs, and this work provides new insights into the design of more efficient electrocatalysts at the atomic scale for energy conversion.

NiO coupled with CeO2 as an efficient electrocatalysts for ethanol oxidation in hybrid water splitting

Replacing oxygen evolution reaction (OER) by ethanol oxidation reaction (EOR) is an effective strategy to reduce energy consumption in water splitting. Thus, a heterostructure composed of NiO nanosheets and CeO2 nanorods (NRs) (NiO@CeO2) are preapred by hydrothermal method as an efficient electrocatalyst for EOR. Characterization and electrochemical results suggest that NiO@CeO2 shows enhanced EOR performance due to the synergistic effect, which deliver current density (j) of 10 mA cm-2 at only 1.37 V, much smaller than that of NiO and CeO2. So, NiO@CeO2-based electrode shows a low cell voltage (1.39 V@ 10 mA cm-2) for overall water splitting (OWS).

Kinetically Controlled Nucleation Enabled by Tunable Microfluidic Mixing for the Synthesis of Dendritic Au@Pt Core/Shell Nanomaterials.

The nucleation stage plays a decisive role in determining nanocrystal morphology and properties; hence, the ability to regulate nucleation is critical for achieving high-level control. Herein, glass microfluidic chips with S-shaped mixing units are designed for the synthesis of Au@Pt core/shell materials. The use of hydrodynamics to tune the nucleation kinetics is explored by varying the number of mixing units. Dendritic Au@Pt core/shell nanomaterials are controllably synthesized and a formation mechanism is proposed. As-synthesized Au@Pt exhibited excellent ethanol oxidation activity under alkaline conditions (8.4 times that of commercial Pt/C). This approach is also successfully applied to the synthesize of Au@Pd core/shell nanomaterials, thus demonstrating its generality.

Composition engineering of carbon nanotubes supported PtxRhRu ultrafine nanocatalysts for ethanol electro-oxidation: Elucidating the role of trimetallic sites

The practice of direct ethanol fuel cells (DEFCs) is hindered by insufficient activity of anode Pt-based catalyst for ethanol oxidation reaction (EOR), while alloying Rh and Ru to Pt is hopeful to solve the problem by simultaneously enhancing CC cleavage and decreasing poisoning; and Ru owning better stability and activity than usually doped Sn in alkaline electrolyte. Nevertheless, Pt-Rh-Ru catalysts were rarely reported. In this work, to avoid random trials, the “composition engineering” strategy was applied to design PtxRhRu catalysts. The optimal x range was predicted by DFT. Then, carbon nanotubes supported PtxRhRu ultrafine nanoparticles (PtxRhRu/CNTs) were synthesized and characterized. The synthetic mechanism was also studied. EOR tests show that, in line with the forecast, Pt4RhRu/CNTs (∼1.9 nm) exhibit the highest activity (5.85 mA·cm−2), 6.97 times of commercial Pt/C, and higher than most reports. The selectivity, stability and durability are also excellent. DFT analysis reveals the role of Pt-Rh-Ru site for the first time, that the optimal route on PtxRhRu is changed. New route clearly enhances complete ethanol oxidation and reduces poisoning. Bifunctional mechanism on Pt-Rh-Ru site was also confirmed. This study may provide new perspective for material design; the products are also promotive for DEFCs into practice.