Activity For Ethanol Oxidation Research Articles

Synthesis of Gold Nanoparticles over CoAl Mixed Oxide for Ethanol Oxidation Reaction.

Catalytic total oxidation is an effective technique for the treatment of industrial VOCs principally resulting from industrial processes using solvents and usually containing mono-aromatics (BTEX) and oxygenated compounds (acetone, ethanol, butanone). The aim of this work is to deposit gold nanoparticles on CoAl mixed oxide issued from layered double hydroxide (LDH) precursor by using the deposition precipitation (DP) method, which is applied with two modifications, labeled method (A) and method (B), in order to enhance the interaction of the HAuCl4 precursor with the support. Method (A) involves the hydrolysis of the HAuCl4 precursor after addition of the support, while in method (B), the gold precursor is hydrolyzed before adding the support. The two methods were applied using as support the CoAl mixed oxide and the LDH precursor. Samples were characterized by several physical chemical techniques and evaluated for ethanol total oxidation. Method (B) allowed the ethanol oxidation activity to be enhanced for the resulting Au/CoAlOx catalysts thanks to the high surface concentration of Co2+ and improved reducibility at low temperature. The presence of gold permits to minimize the formation of by-products, notably, methanol, allowed for a total oxidation of ethanol at lower temperature than the corresponding support.

Supported palladium nanocubes reduced by graphene oxide and surface-cleaned for enhanced electrocatalytic activity

Highly dispersed Pd nanocubes (Pd NCs) supported on the surface of partially reduced graphene oxide (pRGO) were successfully prepared by a facile procedure. GO was used as reductant and support without any other external reducing agent been introduced, and potassium iodide (KI) was used as capping agent for morphology control respectively. Catalytic activities for ethanol oxidation and methanol oxidation were greatly enhanced after excess iodine on the surface of Pd NCs was removed by being surface-treated with NaBH4 solution.

The Effect of SnO<sub>2</sub> and Rh on Pt Nanowire Catalysts for Ethanol Oxidation

In this study, we synthesized Pt-Rh nanowires (NWs) through chemical reduction of metallic precursors using formic acid at room temperature, excluding the use of surfactants, templates, or stabilizing agents. These NWs were supported on two substrates: carbon (Vulcan XC-72R) and carbon modified with tin oxide (SnO<sub>2</sub>) via the sol-gel method (10 wt.% SnO<sub>2</sub>). We explored the electroactivity of Pt/SnO<sub>2</sub>/C, Pt-Rh/C, Pt-Rh/SnO<sub>2(commercial)</sub>/C (commercial SnO<sub>2</sub>), and Pt-Rh/SnO<sub>2</sub>/C NWs toward electrochemical oxidation of ethanol in acidic media using various techniques, including CO-stripping, cyclic voltammetry, derivative voltammetry, chronoamperometry, and steady-state polarization curves. Physical characterization involved X-ray diffraction and transmission electron microscopy. The synthesized NWs exhibit higher ethanol oxidation activity than the commercial Pt/C (Johnson Matthey™) catalyst. Rh atoms are hypothesized to enhance complete ethanol oxidation, while the NW morphology improves ethanol adsorption at the catalyst surface for subsequent oxidation. Additionally, the choice of support material plays a significant role in influencing the catalytic activity. The superior catalytic activity of Pt-Rh/SnO<sub>2</sub>/C NWs may be attributed to the facile dissociation of the C-C bond, low CO adsorption (electronic effect due to Rh presence), and the bifunctional mechanism facilitated by the oxophilic nature of the SnO<sub>2</sub> support.

Ni-based metal organic frameworks doped with reduced graphene oxide as an effective anode catalyst in direct ethanol fuel cell

Direct ethanol fuel cells (DEFCs), with their boosted energy density and efficiency, are poised to supplant secondary batteries in the near future. However, the pricy and low-durability of Pt-based anode catalyst used in these cells have hampered the development of this technology. We successfully created a Ni-MOF @ nickel foam (NF) to operate as an anode for a DEFC. We next enhanced the electrical conductivity of these produced electrodes with graphene and tested them towards ethanol oxidation in a basic solution. The study looked at the electrodes' surface shape, crystalline structure, chemical and electrical properities, among other things. Furthermore, the electrochemical activity and durability of the prepared electrodes were examined. These tests demonstrated the successful formation of the MOF @ the surface of the NF, with and without reduced graphene oxide. The produced materials outperformed plain Ni foam in terms of ethanol oxidation activity, and the graphene doping significantly enhanced this activity. A 0.35 V onset potential was obtained, with current output increasing concurrently with ethanol oxidation up to 0.5 M before stabilizing. The superior activity was attributed to the prepared electrodes' perfect nano-sheet structure, high porosity, and outstanding mass and charge transport characteristics. The addition of reduced graphene oxide enhanced charge transfer and thus improved the overall performance.

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.

Bimetallic Au–Pd nanoparticles decorated electrospun spinel CoFe2O4 nanostructures as efficient electrocatalysts for ethanol fuel oxidation in alkaline media

Spinel-based materials are promising candidates as electro-catalysts for the oxidation of alcohol fuels. In the present study, electrospun CoFe2O4 spinel nanostructures were prepared by electrospinning technique and the subsequent thermal treatment processes. Then, the bimetallic Au–Pd–CoFe2O4 composite as electro-catalysts were synthesized by precipitation method. The surface morphology, composition and structure of the resulting composite nanostructures were studied by FE-SEM, EDS, TEM, XPS, XRD and FT-IR. The catalytic performance of resultant composite has been examined in ethanol electro-oxidation reactions under alkaline conditions. The effect of different Au:Pd ratios on the electrocatalytic performance of Au–Pd–CoFe2O4 composite nanostructures for ethanol oxidation was evaluated. The synthesized composite Au–Pd–CoFe2O4 (APCo22) illustrates a superior ethanol oxidation activity in comparison to other electrocalysts, and the peak current of this spinel-type electro-catalysts is 9.89 times that of Pd–CoFe2O4 with a scan rate of 50 mVs−1, which is due to the synergistic effect of Au and Pd on CoFe2O4. Furthermore, the remarkable electrochemical property can be due to the production of OH−, which leads to the species present on the surface of the electro-catalysts during the activation process.

Using Sparfloxacin-Capped Gold Nanoparticles to Modify a Screen-Printed Carbon Electrode Sensor for Ethanol Determination.

Alcohol is a dangerous substance causing global mortality and health issues, including mental health problems. Regular alcohol consumption can lead to depression, anxiety, cognitive decline, and increased risk of alcohol-related disorders. Thus, monitoring ethanol levels in biological samples could contribute to maintaining good health. Herein, we developed an electrochemical sensor for the determination of ethanol in human salivary samples. Initially, the tetra-chloroauric acid (HAuCl4) was chemically reduced using sparfloxacin (Sp) which also served as a stabilizing agent for the gold nanoparticles (AuNPs). As-prepared Sp-AuNPs were comprehensively characterized and confirmed by UV-visible spectroscopy, X-ray diffraction, field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS), and elemental mapping analysis. The average particle size (~25 nm) and surface charge (negative) of Sp-AuNPs were determined by using dynamic light scattering (DLS) and Zeta potential measurements. An activated screen-printed carbon electrode (A-SPE) was modified using Sp-AuNPs dispersion, which exhibited greater electrocatalytic activity and sensitivity for ethanol (EtOH) oxidation in 0.1 M sodium hydroxide (NaOH) as studied by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). DPV showed a linear response for EtOH from 25 µM to 350 µM with the lowest limit of detection (LOD) of 0.55 µM. Reproducibility and repeatability studies revealed that the Sp-AuNPs/A-SPEs were highly stable and very sensitive to EtOH detection. Additionally, the successful electrochemical determination of EtOH in a saliva sample was carried out. The recovery rate of EtOH spiked in the saliva sample was found to be 99.6%. Thus, the incorporation of Sp-AuNPs within sensors could provide new possibilities in the development of ethanol sensors with an improved level of precision and accuracy.

ZnO/TiO2 Composite Thin-Film Photocatalysts for Gas-Phase Oxidation of Ethanol

The aim of this project is to investigate the photocatalytic activity of ZnO/TiO2 composite films for the gas-phase oxidation of ethanol. Pure TiO2, pure ZnO, and their composites were formulated using a sol-gel synthesis method, and the resulting powders were cast and dried as thin films in a flat-plate ultraviolet light-emitting diode (UV LED) reactor. P25 TiO2 and commercially available ZnO were also used for comparison. The structural, morphological, and optical characteristics of the materials were characterized. The photocatalytic oxidation of ethanol vapors in air after 24 h of reactor operation was used to assess the relative photocatalytic activity of the ZnO/TiO2 composite films. Our results show that as ZnO content increased in the coupled semiconductor materials, the apparent photocatalytic activity decreased. In this study, pure ZnO (both sol-gel and purchased) had the least photocatalytic activity for vapor-phase ethanol oxidation in our test apparatus. For gas-phase photocatalysis, surface area was shown to be a critical feature for photocatalytic activity. However, the inherent photocatalytic activity of the materials was not decoupled from the effects of surface area in this study.

Performance of BiCu2O modified Pd/C as an anode electrocatalyst for direct ethanol fuel cell system

BiCu2O Modified Pd/C nanocatalyst was synthesised via an eco-friendly method for fuel cell application. The obtained nanomaterials' structural composition, and electrochemical properties were investigated using chemical and physical techniques such as impedance spectroscopy (EIS), X-ray diffraction (XRD), high resolution-scanning electron microscopy (HR-SEM), and cyclic voltammetry (CV). The preparation of the BiCu2O Modified Pd/C catalyst was successfully verified by microscopic techniques, as shown by the presence of mixed nanostructures, Pd and BiCu2O coexisting. EIS measurements confirmed a smaller electron charge-transfer (160 Ω) for the prepared Pd/C-BiCu2O nanocatalyst. From the Pd oxide peaks, the electrochemical active surface area (EASA) values for Pd/C-BiCu2O and Pd/C were estimated to be 432.1 cm2 mg−1 and 79.2 cm2 mg−1, respectively. The resulting BiCu2O Modified Pd/C nanocatalyst showed increased ethanol oxidation activity (If/Ib=1.1) and was more resistant to poisoning by advanced oxidation species. Under passive conditions at 1 M ethanol in 1 M KOH, improved cell performance (cell output = 120 mW) with a high density of current (105 mAcm−2) and power density (25.7 mWcm−2) relative to the commercial Pd/C were obtained. The study opens and forges novel possibilities in the search for new carbon co-catalysts for direct ethanol fuel cell (DEFC) application because of the simplified green processing and the cost of the precursor and the Pd-based catalyst produced. The work involves using difficult waste streams produced by various agro-industrial operations to create high surface material for use in producing commodities with added value. This work will also help address climate action, clean and affordable energy crisis.

N-doped carbon-stabilized PdNiCu nanoparticles derived from PdNi@Cu-ZIF-8 as highly active and durable electrocatalyst for boosting ethanol oxidation

Controlling the component, tailoring the size and designing the carbon supporting materials are three promising strategies to improve electrocatalytic activity. Herein, a monatomic Cu carrier (CuCN) with larger specific surface area was used to anchor PdNi alloy nanoparticles by a facile one-step reduction method. Physical characterization revealed that the PdNi nanoparticles in the synthesized material possess good dispersion, which is mainly attributed to the high specific surface area of CuCN-900.Electrochemicalresults revealed that CuCN supported PdNi nanoparticles (Pd1Ni1/CuCN-900) nanohybrids had superior durability and catalytic activity for ethanoloxidation (EOR) compared with that of other PdxNiy/CuCN and commercial Pd/C. Rotating disk electrode (RDE) results further demonstrated that Pd1Ni1/CuCN-900 has a faster kinetic process of EOR than commercial Pd/C. DFT calculation implies that OH adsorption is preferentially near the Ni atom, the OH species on Ni1Pd1 surface play an important role in the process of EOR. This is of great research implications for finding new carbon carriers and regulating catalyst components to improve the catalytic efficiency of PdNi catalysts.

Mesoporous PtPb Nanosheets as Efficient Electrocatalysts for Hydrogen Evolution and Ethanol Oxidation

AbstractUsing a one‐pot hydrothermal method with ethylenediamine, we have synthesized mesoporous PtPb nanosheets that exhibit exceptional activity in both hydrogen evolution and ethanol oxidation. The resulting PtPb nanosheets have a Pt‐enriched structure with up to 80 % atomic content of Pt. The synthetic method generated a significant mesoporous structure, formed through the dissolution of Pb species. These advanced structures enable the mesoporous PtPb nanosheets to achieve a current density of 10 mA cm−2 with an extreme low overpotential of 21 mV for hydrogen evolution under alkaline conditions. Furthermore, the mesoporous PtPb nanosheets exhibit superior catalytic activity and stability for ethanol oxidation. The highest catalytic current density of PtPb nanosheets is 5.66 times higher than that of commercial Pt/C. This research opens up new possibilities in designing mesoporous, two‐dimensional noble‐metal‐based materials for electrochemical energy conversion with excellent performance.

Uncovering a Kind of Natural Galvanic Cell to Spontaneously Synthesize a Variety of Carbon-Supported Core–Shell Nanoparticles for Efficient Electrocatalysis

Here, we uncover a kind of natural galvanic cell to spontaneously synthesize a variety of McMs′/C NPs for efficient electrocatalysis. In these galvanic cells, the negative and positive electrodes are the owned functional groups (e.g., C–O–C, C–OH, COOH, etc.) and supported noble-metal NPs (e. g., Au, Pt, Pd, etc.) of carbon black, and the electrolyte is the solution of shell precursors. Such galvanic cells are capable of spontaneously synthesizing uniform McMs′/C NPs such as AucPts/C, AucPds/C, AucAgs/C, AucRus/C, PtcAgs/C, PdcRus/C, etc. As an example, as-prepared AucPds/C exhibits over 4-fold specific activity in the electrocatalytic ethanol oxidation compared to referenced Pd/C.

Mesoporous PtPb Nanosheets as Efficient Electrocatalysts for Hydrogen Evolution and Ethanol Oxidation.

Using a one-pot hydrothermal method with ethylenediamine, we have synthesized mesoporous PtPb nanosheets that exhibit exceptional activity in both hydrogen evolution and ethanol oxidation. The resulting PtPb nanosheets have a Pt-enriched structure with up to 80% atomic content of Pt. The synthetic method generated a significant mesoporous structure, formed through the dissolution of Pb species. These advanced structures enable the mesoporous PtPb nanosheets to achieve a current density of 10 mA/cm2 with an extreme low overpotential of 21 mV for hydrogen evolution under alkaline conditions. Furthermore, the mesoporous PtPb nanosheets exhibit superior catalytic activity and stability for ethanol oxidation. The highest catalytic current density of PtPb nanosheets is 5.66 times higher than that of commercial Pt/C. This research opens up new possibilities in designing mesoporous, two-dimensional noble-metal-based materials for electrochemical energy conversion with excellent performance.

Unveiling the effect of shapes and electrolytes on the electrocatalytic ethanol oxidation activity of self-standing Pd nanostructures

Morphologically controlled Pd-based nanocrystals are the most efficient strategies for improving the electrocatalytic ethanol oxidation reaction (EOR) performance; however, their morphological-EOR activity relationship and effect of electrolytes at a wide pH range are still ambiguous. Here, we have synthesized porous self-standing Pd clustered nanospheres (Pd-CNSs) and Pd nanocubes (Pd-NCBs) for the EOR in acidic (H2SO4), alkaline (KOH), and neutral (NaHCO3) electrolytes compared to commercial spherical-like Pd/C catalysts. The fabrication process comprises the ice-cooling reduction of Pd precursor by sodium borohydride (NaBH4) and l-ascorbic acid to form Pd-CNSs and Pd-NCBs, respectively. The EOR activity of Pd-CNSs significantly outperformed those of Pd-NCBs, and Pd/C in all electrolytes, but the EOR activity was better in KOH than in H2SO4 and NaHCO3. This is due to the 3D porous clustered nanospherical morphology that makes Pd active centers more accessible and maximizes their utilization during EOR. The EOR specific/mass activities of Pd-CNSs reached (8.51 mA/cm2/2.39 A/mgPd) in KOH, (2.98 mA/cm2/0.88 A/mgPd) in H2SO4, and (0.061 mA/cm2/0.0083 A/mgPd) in NaHCO3, in addition to stability after 1000 cycles. This study affirms that porous 3D spherical Pd nanostructures are preferred for the EOR than those of 0D spherical-like and multi-dimensional cube-like nanostructures.

Ni sulfide nano-sheets as an efficient standalone electrode in direct ethanol fuel cells

BackgroundDirect alcoholic fuel cells such as DEFCs “direct ethanol fuel cells” have a high energy density and can potentially replace secondary batteries in portable applications. Two main challenges of the DEFCs are the low efficiency and the precious/expensive Pt-based electrodes. MethodsIn this study, a standalone nickel sulfide electrode was grown on the surface of nickel foam via hydrothermal method followed by hydrothermal ion exchange. Significant FindingsThe prepared electrodes have a highly porous nanosheet structure and demonstrated high ethanol oxidation activity. The electrode showed high stability and excellent mass transfer properties with a constant generation of current density of 100 mAcm−2 at 0.5 V, two times that of the Ni-layered double hydroxide and ten times that of nickel foam. The superior activity was due to the enhanced charge transfer of the nickel sulfide (confirmed by EIS (electrochemical impedance spectroscopy)) and the improved mass transfer of the highly porous nanosheet structure.

The Role of a Sn Promoter on an Anodic Pt Electrocatalyst Prepared over H2 O2 -Functionalized Carbon Supports for Direct Ethanol Fuel Cell (DEFC) Applications.

Multiwalled carbon nanotubes and Vulcan carbon were functionalized with a 30 %v/v hydrogen peroxide solution and employed as supports for Pt and PtSn catalysts prepared by the polyol method. PtSn catalysts with a Pt loading of 20 wt.% and a Pt : Sn atomic ratio equal to 3 : 1 were evaluated in the ethanol electrooxidation reaction. The effects of the oxidizing treatment on the surface area and the surface chemical nature were analyzed through N2 adsorption, isoelectric point, and temperature-programmed desorption measurements. Results showed that the H2 O2 treatment affects the surface area of the carbons to a great extent. Characterization results indicated that the performance of the electrocatalysts strongly depends both on the presence of Sn and on the support functionalization. PtSn/CNT-H2 O2 electrocatalyst displays a high electrochemical surface area and enhanced catalytic activity for ethanol oxidation in comparison to other catalysts in the present study.

Efficient Oxidation of Ethanol at Ru@Pt Core-Shell Catalysts in a Proton Exchange Membrane Electrolysis Cell

Efficient electrochemical oxidation of ethanol in fuel cells and electrolysis cells is important for generating power and hydrogen, respectively, from renewable resources. PtRu alloys are most widely employed as catalysts because they provide high activities at low potentials. However, they produce acetic acid as the main product from ethanol, which results in low faradaic and overall efficiencies. In contrast, Pt provides high selectivity for the complete oxidation of ethanol to CO2, but low activities. Ru@Pt core–shell nanoparticles can improve efficiency by delivering higher activity than Pt and enhanced formation of CO2 relative to PtRu. Here, Ru@Pt catalysts have been prepared by depositing Pt onto a commercial carbon-supported Ru catalyst. The influence of the amount of Pt deposited has been investigated in H2SO4(aq) at ambient temperature and in a proton exchange membrane cell at 80 °C. Activities for ethanol oxidation were intermediate between those for commercial Pt and PtRu catalysts, providing higher currents than Pt at low potentials, and higher currents than PtRu at high potentials. Faradaic yields of CO2 (38%–48%) were greatly increased relative to the PtRu alloy catalyst (11%). This will optimize the efficiency of ethanol oxidation in PEM electrolysis and fuel cells.

Rh–Cu alloy nano-dendrites with enhanced electrocatalytic ethanol oxidation activity

The application of direct ethanol fuel cell (DEFC) has been bottlenecked by the sluggish ethanol oxidation reaction (EOR). Efficient electrocatalysts for the C−C bond cleavage are essential to promote EOR with high efficiency and C1 selectivity. Here, we prepared Rh–Cu alloy nano-dendrites (RhCu NDs) with abundant surface steps through controlled co-reduction, which exhibited significantly enhanced activity and C1 selectivity (0.47 mA cm−2(ECSA), 472.4 mA mgRh−1, and 38.9%) than Rh NDs (0.32 mA cm−2(ECSA), 322.1 mA mgRh−1, and 21.4%) and commercially available Rh/C (0.18 mA cm−2(ECSA), 265.4 mA mgRh−1, and 14.9%). Theoretical calculations and CO-stripping experiments revealed that alloying with Cu could modulate the surface electronic structures of Rh to resist CO-poisoning while strengthening ethanol adsorption. In situ Fourier transform infrared spectroscopy (FTIR) indicated that the surface steps on RhCu NDs further promoted the C−C bond cleavage to increase the C1 selectivity. Therefore, optimizing the surface geometric and electronic structures of nanocrystals by rational composition and morphology control can provide a promising strategy for developing practical DEFC devices.

Facile-synthesis and shape-adjustment of irregular gravel-like PtPd nanocatalysts by three-dimensional hyperbranched polyamide (HBPA) with enhanced activity in ethanol oxidation

Direct ethanol fuel cells (DEFCs) technology as a promising clean-energy, is obstructed by unsatisfactory activity of ethanol oxidation reaction (EOR) nanocatalysts. Traditional shape-controllers usually lead to regular nanoparticles. Three-dimensional dendrimers, like hyperbranched polyamide (HBPA), however, have superiorities to form irregular morphologies, due to their multitudinous terminal functional groups and irregular interior cavities. Considering the lack of researches, herein, a novel HBPA was utilized to facilely and controllably synthesize irregular gravel-like PtPd nanoparticles (g-PtPd-NPs) with rich active sites. The synthetic mechanism was studied by both experiments and density functional theory calculations. N atoms of HBPA were proven essential. In EOR tests, the activity of g-PtPd-NPs was 2.05-fold of commercial Pt/C, and higher than PtPd catalysts of control sets and reports. The durability was excellent, too. This study is promotive for DEFCs into practice, and may enlighten more nanomaterials' synthesis.

ZIF-67-Derived NiCo-Layered Double Hydroxide@Carbon Nanotube Architectures with Hollow Nanocage Structures as Enhanced Electrocatalysts for Ethanol Oxidation Reaction.

The rational design of efficient Earth-abundant electrocatalysts for the ethanol oxidation reaction (EOR) is the key to developing direct ethanol fuel cells (DEFCs). Among these, the smart structure is highly demanded for highly efficient and stable non-precious electrocatalysts based on transition metals (such as Ni, Co, and Fe). In this work, high-performance NiCo-layered double hydroxide@carbon nanotube (NiCo-LDH@CNT) architectures with hollow nanocage structures as electrocatalysts for EOR were prepared via sacrificial ZIF-67 templates on CNTs. Comprehensive structural characterizations revealed that the as-synthesized NiCo-LDH@CNTs architecture displayed 3D hollow nanocages of NiCo-LDH and abundant interfacial structure between NiCo-LDH and CNTs, which could not only completely expose active sites by increasing the surface area but also facilitate the electron transfer during the electrocatalytic process, thus, improving EOR activity. Benefiting from the 3D hollow nanocages and interfacial structure fabricated by the sacrificial ZIF-67-templated method, the NiCo-LDH@CNTs-2.5% architecture exhibited enhanced electrocatalytic activity for ethanol oxidation compared to single-component NiCo-LDH, where the peak current density was 11.5 mA·cm-2, and the jf/jb value representing the resistance to catalyst poisoning was 1.72 in an alkaline environment. These results provide a new perspective on the fabrication of non-precious metal electrocatalysts for EOR in DEFCs.