Ethanol Electro-oxidation Reaction Research Articles

D-Band Engineering in Pd-Based Nanowire Networks for Further Enhancement in Ethanol Electrooxidation Reaction.

The development of highly efficient electrocatalysts for the ethanol oxidation reaction (EOR) is essential for the commercialization of direct ethanol fuel cells, yet challenges remain. In this study, a one-pot solution-phase method to synthesize Pd nanowire networks (NNWs) with very high surface-to-volume ratio having numerous twin and grain boundaries is developed. Using the same method, the Pd lattice is further engineered by introducing Ag and Cu atoms to produce AgPd, and CuPd alloy structure which significantly shifts the Pd d-band center upward and downward, respectively due to strain and ligand effects. Theoretical analysis employing density functional theory (DFT) demonstrates that such modification of the d-band center significantly influences the adsorption energies of reactants on the catalytic surface. Owing to their notably high surface-to-volume ratio and the presence of multiple twin and grain boundaries, Pd NNWs demonstrate significantly enhanced electrocatalytic activity toward EOR, ≈7.2 times greater than that of commercial Pd/C. Remarkably, compared to Pd NNWs, AgPd, and CuPd NNWs display enlarged and reduced electrocatalytic activity toward EOR, respectively. Specifically, Ag4Pd7 NNWs achieve a remarkable mass activity of 9.00Amgpd -1 for EOR, which is 13.6 times higher than commercial Pd/C.

Synthesis of AuPt Bimetal and its Catalytic Properties in Ethanol Electrooxidation Reaction

AuPt Bimetal has been successfully synthesized by electrodeposition method with potentiostat technique. By varying the concentration of Au ions in the solution they are able to control the morphology and composition of the synthesized sample. The morphology obtained from the AuPt synthesis is cauliflower. The effect of Au ion concentration in solution on the catalytic performance of AuPt, the greater the Au concentration, the greater the current density in the electrooxidation reaction. In addition, the concentration of Au ions in the solution affects the results of the deposition of Au and Pt elements. In the study of AuPt nanocatalysts with a 0.4 mM Au ion concentration in an electrolyte solution, it was shown to have good catalytic activity in the ethanol electrooxidation reaction, with the resulting current densities and If/Ib of 10.1 mA/cm2 and 43.53 mA/cm2, respectively. This is an implication of many Au compositions which are known to have the ability to absorb and oxidize CO to encourage an increase in current density and increase its catalytic activity.

Recent Approaches for Cleaving the C─C Bond During Ethanol Electro-Oxidation Reaction.

Direct ethanol fuel cells (DEFCs) play an indispensable role in the cyclic utilization of carbon resources due to its high volumetric energy density, high efficiency, and environmental benign character. However, owing to the chemically stable carbon-carbon (C─C) bond of ethanol, its incomplete electrooxidation at the anode severely inhibits the energy and power density output of DEFCs. The efficiency of C─C bond cleaving on the state-of-the-art Pt or Pd catalysts is reported as low as 7.5%. Recently, tremendous efforts are devoted to this field, and some effective strategies are put forward to facilitate the cleavage of the C─C bond. It is the right time to summarize the major breakthroughs in ethanol electrooxidation reaction. In this review, some optimization strategies including constructing core-shell nanostructure with alloying effect, doping other metal atoms in Pt and Pd catalysts, engineering composite catalyst with interface synergism, introducing cascade catalytic sites, and so on, are systematically summarized. In addition, the catalytic mechanism as well as the correlations between the catalyst structure and catalytic efficiency are further discussed. Finally, the prevailing limitations and feasible improvement directions for ethanol electrooxidation are proposed.

Enhanced electrocatalytic performance of PtNi bimetallic alloys on carbon nanotube for ethanol oxidation reaction

In this paper, Ni-Pt bimetallic alloy nanoparticles were loaded on carbon nanotubes to prepare Ni-Pt nanoparticles/carbon nanotubes composites (Ni-Pt NPs/CNTs) as excellent catalytic materials for ethanol electro-oxidation reaction (EOR). X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and special aberration corrected transmission electron microscope (STEM) were used to characterize its morphology and structure. The activity and stability of the composite were measured by cyclic voltammetry (CV) and chronoamperometry (CA). The catalytic performance was explored by adjusting the ratio of Ni to Pt. Performance test results showed that the Ni-Pt alloy formed 10–15 nm spherical particles and dispersed uniformly on the surface of carbon nanotubes. The Ni1Pt1 NPs/CNTs composite showed excellent performance for EOR. Its mass activity of ethanol electro-oxidation was 620 mA·mg−1Pt, which was 5.08, 18.2 times higher than that of commercial Pt/C and Pt black catalyst, respectively.

Analysis of Reaction Rate and Product Selectivity of Ethanol Electrolytic Oxidation Reaction in the Flow Reactor

Introduction In recent years, the development of the electrolysis hydrogen production process has been vigorously promoted due to the widespread use of hydrogen energy. However, oxygen, a byproduct of the anode reaction, has not been utilized. On the other hand, chemical products are produced industrially by electro-organic synthesis, and if the anode reaction could be used directly as a chemical synthesis reaction, the overall benefit would be further enhanced. At the same time, the high selectivity and controllability of the electrochemical process make it possible to produce highly selective chemical products by anodic reactions. The objective of this study is to develop a process for simultaneous electrolytic hydrogen production at the cathode and highly selective acetaldehyde production at the anode. Experimental A schematic diagram of the experimental setup is shown in Figs. 1 and 2. Platinum electrodes were placed on silicone gaskets with flow channels, and the gaskets were sandwiched between silicone gaskets, PTFE plates, and stainless-steel endplates. A cation exchange membrane NR-212 was placed in the center to separate the reactions at the two electrodes. A 0 to 0.5 mol/L sulfuric acid solution containing 0.01 to 1.0 mol/L ethanol or a 0 to 0.5 mol/L sulfuric acid solution containing 0.01 to 1.0 mol/L acetaldehyde was supplied to the anode, and a 0 to 0.5 mol/L sulfuric acid solution was supplied to the cathode. Results and Discussion The experimental results are analyzed based on the premise of surface reaction rate limitation and steady-state conditions. As shown in Fig. 3, the ethanol conversion increased with rise in A/v (ratio of electrode area to flow rate), reaching its maximum value at A/v of 88.4 min/cm. This can be attributed to the difficulty in discharging bubbles generated from the electro-oxidation reaction as the A/v was raised. To ensure that the reactions occurred under reaction rate-limiting conditions, acetaldehyde electro-oxidation experiments were conducted with feed concentrations of 0 to 0.5 M sulfuric acid solutions containing 1.0 M acetaldehyde at the anode, and 0 to 0.5 M sulfuric acid solutions at the cathode, an A/v of 88.4 min/cm, and a potential difference of 1.0 V. The reaction rate was also affected by the reduction in the hydroxide ion concentration due to the increased sulfuric acid concentration, leading to the lower measured reaction rates. In the result of Fig. 4, it can be inferred that when the concentration of sulfuric acid was below 0.1 M, the reaction rate was governed by diffusion. Subsequently, acetaldehyde electro-oxidation experiments were performed under acetaldehyde concentrations ranging from 0.01 to 1 M, a sulfuric acid concentration of 0.1 M, the fixed A/v, and potential differences between 0.8 and 1.2 V to elucidate the impact of reactant concentration on the reaction rate. The results in Fig. 5 demonstrate that while the reaction rates increased with raising the acetaldehyde concentration, it eventually approached a plateau, attributable to the saturation of active sites with acetaldehyde on the Pt electrode.The results of ethanol electro-oxidation experiments were shown in Figs. 6 and 7, decrease in acetaldehyde selectivity was observed with a feed concentration of a 0.1 M sulfuric acid solution, attributable to the formation of acetic acid and carbon dioxide as byproducts. Subsequently, in comparison to sulfuric acid concentrations below 0.2 M, under the conditions of 0.5 M sulfuric acid concentration and low conversion, the acetaldehyde selectivity exhibited a gradual decline as the conversion increased. This indicates that the influence of sulfuric acid concentration on the oxidation reaction of acetaldehyde to acetic acid was more significant than that on the oxidation reaction of ethanol to acetaldehyde. A plausible explanation for this phenomenon is that the oxidation of acetaldehyde is considerably inhibited by the adsorption of sulfate ions to the active sites, as it is associated with a second-order reaction of adsorbed species concentration. Consequently, altering the sulfuric acid concentration results in changes in the ethanol electro-oxidation reaction selectivity. Conclusions The selectivity of ethanol electro-oxidation reaction was significantly influenced by potential difference and electrolyte concentration. Notably, acetic acid was not produced at potential differences below 0.8 V. Sulfuric acid concentration affected reaction selectivity, with a greater impact on acetaldehyde-to-acetic-acid oxidation. Despite the higher selectivity observed at 0.6 V, the reaction rate was low. Employing an appropriate potential difference and electrolyte concentration can facilitate achievement both of higher selectivity and an enhanced reaction rate. Optimal conversion was achieved at an A/v of 88.4 min/cm, while the maximum acetaldehyde selectivity of approximately 95 % was observed at an applied voltage of 1.2 V and 0.5 M sulfuric acid concentration. Figure 1

The determination of the electrochemically active surface area and its effects on the electrocatalytic properties of structured nickel electrodes produced by additive manufacturing

Additively manufactured (AM) nickel electrodes offer a great potential as an efficient solution for oxygen evolution catalysts in alkaline electrolyzers, since advanced fabrication methods allow the design of high surface area electrodes. The accurate determination of the electrochemical active surface area (ECSA) is a key step in the evaluation of the intrinsic catalytic activity of complex electrodes. In this work, we fabricated Ni electrodes with different macroscopic lattice structures using laser powder bed fusion of metals (PBF-LB/M). The selected designs allow exploring the effects of the electrode geometry on the electrochemical performance. X-ray photon spectroscopy (XPS) and a non-contact optical profilometer (NCOP) were used to investigate the composition and surface morphology of the electrodes. The ECSA was determined by three different approaches. 1. Linear and non-linear allometric fitting of the double layer capacitance from voltammetric experiments. 2. Integration of the Ni2+/Ni3+ transition, also from voltammetry. 3. Assessing double layer capacitance determined from electrochemical impedance spectroscopy (EIS) at open circuit potential (OCP) and the adsorption capacitance for the oxygen evolution reaction (OER) intermediates. Comparing these methods, large deviations in the resulting ECSAs were found, motivating a comprehensive discussion. In addition, four different reactions were investigated, ferri-ferrocyanide redox system, hydrogen evolution, ethanol electrooxidation, and oxygen evolution reaction. The obtained results demonstrate the potential of AM to tailor electrode performance by altering electrode geometry. The findings underline the importance of the ECSA determination for the comparison of the electrocatalytic activity in different electrodes.

Anchoring bimetallic PtAu nanoparticles on hierarchical zeolite as efficient electrocatalyst for the enhancement of ethanol electrooxidation

Zeolite materials as nanoreactor are promising candidates as catalysts for the oxidation of alcohol fuels. In the present work, the hierarchical zeolite was prepared via a hydrothermal technique. Then, the bimetallic Pt-Au-zeolite composite as electrocatalysts were synthesized by co-precipitation route. The surface morphology, composition and structure of the resulting composite were investigated by FE-SEM, EDS, XRD, XPS, BET&BJH and FT-IR. The catalytic performance of the composite has been examined in ethanol electrooxidation reactions under alkaline media. Pt-Au-zeolite exhibits superior selectivity for the electrooxidation of the ethanol, outperforming both conventional Au and Pt nanoparticles supported on zeolite crystals catalyst. The peak electrooxidation current of ethanol with Pt-Au-zeolite catalyst is 3.63 times that of Pt-zeolite with a scan rate of 50 mVs−1, which is due to the synergistic effect of Au and Pt in zeolite framework. It could be attributed to the incorporation of Au and Pt into zeolite framework, which was beneficial to the charge transferring the surface of Pt-Au-zeolite electrocatalyst and facilitated the ethanol oxidation. Besides, the significant electrochemical activity can be due to the production of OH–, which leads to the species present on the surface of the electrocatalysts during the activation process that controlled by the zeolite framework.

Synthesis of Pd-Cu/TPPCu electrocatalyst for direct ethanol fuel cell applications

In this study, the electro-oxidation reaction of ethanol over Pd–Cu supported on Cu porphyrin (TPPCu) was investigated. The catalyst was synthesized using the microwave-assisted polyol method and physicochemically characterized by XRD, XPS, SEM, EDS, TEM, EDAX, UV–Vis, FTIR, and RBS. A Cu-enriched catalyst with Cu3Pd, Pd,Cu, and TPPCu phases was identified using XRD and XPS. However, according to the RBS results, the catalytic surface was enriched with Pd, indicating that the interaction between TPPCu and Pd–Cu allowed the presence of Pd on the surface, thus enhancing the catalytic response of the material. This synthesis prevented the deprotonation of porphyrin on the electrocatalyst, as confirmed by XPS analysis. Electrochemical studies based on cyclic voltammetry and electrochemical impedance spectroscopy were used to investigate the response of the catalyst to variations in the scan rate and increasing ethanol concentration. The electrochemical response of PdCu/TPPCu improved with an increasing number of cycles, indicating improved mass transport, thus improving its electrochemical response and tolerance to CO contamination. This catalyst exhibited a high electroactive surface area of 49.4 m2/g, which could be related to the presence of TPPCu as a support. The behavior of the catalyst on the anode of a fuel cell fed with ethanol, bioethanol, and bioethanol residues was evaluated.Graphical

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.

Insights into the Rate-Determining Step of the Ethanol Electro-oxidation Reaction on the Pd(111) Surface through Ab Initio Molecular Dynamics Simulations

Insights into the Rate-Determining Step of the Ethanol Electro-oxidation Reaction on the Pd(111) Surface through Ab Initio Molecular Dynamics Simulations

Highly active and durable PdFe/Cu nanocatalysts prepared by liquid phase synthesis for ethanol electrooxidation reaction

In the face of environmental pollution and an energy shortage, how to reduce the cost of a noble metal catalyst in clean energy such as the fuel cell system and improve its electrocatalytic performance is one of the hot issues in this field. Here, a facile stepwise co-reduction route for synthesizing a series of PdFe/Cu catalysts with surface reconstruction is investigated and the ethanol oxidation reaction (EOR) performance is explored. The greater exposure of Pd active sites makes it excellent in EOR in alkaline media compared to the homemade and commercial Pd black catalyst. The mass activity of PdFe/Cu (794.97 mA mg−1Pd) is 2.52 times that of the Pd black catalyst (315.64 mA mg−1Pd). This kind of PdFe/Cu catalyst shows enhanced mass current density (255.66 mA mg−1Pd) after the 1800 s chronoamperometry test and only exhibits a decay of 1.4% after accelerated 500-cycle measurement. The enhanced EOR performance may be due to the change in the electronic structure of Pd caused by synergistic and strain effects among Pd, Fe, and Cu. This work provides an effective and kindly strategy to synthesize electrocatalysts with superior activity and durability in relation to EOR.

Pd Nanoparticle-Decorated Novel Ternary Bi2O2CO3-Bi2MoO6-CuO Heterojunction for Enhanced Photo-electrocatalytic Ethanol Oxidation.

Recently, photo-electrooxidation of fuel using a noble metal-semiconductor junction has been one of the most promising approaches in fuel cell systems. Herein, we report the development of a Pd-supported Bi2MoO6-Bi2O2CO3-CuO novel ternary heterojunction for ethanol oxidation in alkali in the presence and absence of visible light. Various spectroscopic and microscopic characterization techniques confirm strong coupling between palladium nanoparticles and Bi2MoO6-Bi2O2CO3-CuO ternary heterojunction supports. The photo-electrocatalytic efficacy of the synthesized catalysts was inspected by cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS). The CV study reveals that the forward peak current density (in mA mg-1 of Pd) of the synthesized quaternary heterojunction was about 1482.5, which is 2.4, 4, and 4.6 times higher than that of Pd/CuO (608.3), Pd/Bi2MoO6-Bi2O2CO3 (368.3), and similarly synthesized Pd catalyst (321.5) under visible light radiation. The best heterojunction catalyst shows 2.21-fold higher peak current density in visible light compared to that in dark. CA study reveals that after operation for 6000 s, the current density of the quaternary electrode is 1.5 and 3.4 times greater than that of Pd/CuO and Pd/C catalysts, respectively. The greater photocurrent response, lower photoluminescence (PL) emission intensity, and smaller semicircle arc in the Nyquist plot of the quaternary catalyst demonstrate the efficient segregation and higher charge transfer conductance of photogenerated charges to facilitate the photo-electrooxidation process of ethanol. The stability test shows that the quaternary catalyst loses only 9.8 and 7.7% of its maximum current density after 500 cycles of CV operation in the dark and light, respectively, indicating that light energy is more beneficial in establishing high stability. The dramatic enhancement of the photo-electrocatalytic activity of the quaternary electrode is owing to the lower band gap, high ECSA, enhanced charge separation of photogenerated carriers (e--h+), and all cocatalytic support of Bi2MoO6, Bi2O2CO3, and CuO in Pd/ Bi2MoO6-Bi2O2CO3-CuO under visible light radiation. The morphology and structure of the used quaternary catalyst are tested using FESEM and PXRD. Finally, ex situ FTIR spectroscopy and HPLC techniques help understand the ethanol electrooxidation reaction mechanism.

Conductive core/shell polymer nanofibres as anode materials for direct ethanol fuel cells

A conductive polymer-supported electrocatalyst in the form of fibrous mat has been developed that can be employed as a polymer-based electrode for direct ethanol fuel cells (DEFCs) with promoting effects to the state-of-the art Pd based catalysts. A series of conductive polyaniline (PANI)-containing polymer fibres-supported Pd electrocatalytic electrodes were successfully prepared and tested for the ethanol electro-oxidation reaction (EOR) in alkaline medium. The polymer support was a robust fibrous mat, where the fibres possessed a core-shell configuration. The core part was produced via electrospinning using a mixture of polyacrylonitrile (PAN) and 1-butyl-3-methylimidazolium chloride [BMIm]Cl ionic liquid (IL). The shell was a PANI layer deposited via the chemical polymerisation of aniline monomer. Pd was then electrodeposited on the fibres and the catalysts were tested for the EOR via cyclic voltammetry (CV) in a half-cell configuration and in a temperature range between 25 and 60 °C. The activity of the catalysts tested was measured in terms of activation energy and forward peak current density in the CV and compared to that of glassy carbon (GC)-supported Pd/PANI/PAN/IL fibrous catalysts. The polymer fibre-catalyst samples showed a higher active surface area and significantly lower activation energy than the GC-based ones. Even though the GC-supported catalysts showed a higher activity in terms of current, the Pd/(PAN/IL)-core/PANI-shell fibrous mats were active as well and, in some cases, demonstrated a promoting effect of PANI on Pd for EOR and a much better stability and robustness compared to the former. Furthermore, a series of promoting metals were investigated for these mats, such as Ag, Bi and Cu, with Ag and Bi demonstrating promoting effects compared to monometallic Pd/(PAN/IL)-core/PANI-shell mats in terms of both activation energy and peak current density. This work demonstrates a promising strategy in the arena of development of polymeric mats as anode electrodes for DEFCs, exploiting the benefits of PANI in terms of ease of synthesis, catalyst poisoning prevention, cost and promoting effects.

Integrating Low Pt-Based Ternary NiRuPt Nanoalloy on Hybrid TiO2-Based Oxide–Carbon Composite for Enhanced Ethanol Oxidation

Ternary NiRuPt nanoscale alloy on hybrid Ti0.9Ir0.1O2-C composite is herein reported to overcome the high cost and tenuous catalytic efficiency of anode catalysts in direct ethanol fuel cells. The small-size NiRuPt alloy is anchored on the Ti0.9Ir0.1O2-C surface via a NaBH4-ethylene glycol-assisted coreduction route. Benefiting from advantages of favorable structure and synergistic effects of compounds, the NiRuPt/Ti0.9Ir0.1O2-C catalyst exhibits high electrocatalytic performance for the ethanol electro-oxidation reaction (EOR) with mass activity of 720.75 mA mgMetal-1 and specific activity of 2.15 mA cm-2, which are 2.25- and 5-fold increases compared to those of the Pt/C (E-TEK) catalyst. The as-synthesized EOR catalyst also shows impressive anti-CO-poisoning ability and great electrocatalytic stability after 5000-cycling ADT. This work can open up an efficient strategy for designing multicomponent catalysts to reduce Pt content and enhance the catalytic performance of electrocatalysts in renewable energy-related technologies.

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.

Unexpected Negative Performance of PdRhNi Electrocatalysts toward Ethanol Oxidation Reaction.

Direct ethanol fuel cells (DEFCs) need newly designed novel affordable catalysts for commercialization. Additionally, unlike bimetallic systems, trimetallic catalytic systems are not extensively investigated in terms of their catalytic potential toward redox reactions in fuel cells. Furthermore, the Rh potential to break the ethanol rigid C-C bond at low applied potentials, and therefore enhance the DEFC efficiency and CO2 yield, is controversial amongst researchers. In this work, two PdRhNi/C, Pd/C, Rh/C and Ni/C electrocatalysts are synthesized via a one-step impregnation process at ambient pressure and temperature. The catalysts are then applied for ethanol electrooxidation reaction (EOR). Electrochemical evaluation is performed using cyclic voltammetry (CV) and chronoamperometry (CA). Physiochemical characterization is pursued using X-ray diffraction (XRD), transmission electron microscope (TEM), energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS). Unlike Pd/C, the prepared Rh/C and Ni/C do not show any activity for (EOR). The followed protocol produces alloyed dispersed PdRhNi nanoparticles of 3 nm in size. However, the PdRhNi/C samples underperform the monometallic Pd/C, even though the Ni or Rh individual addition to it enhances its activity, as reported in the literature herein. The exact reasons for the low PdRhNi performance are not fully understood. However, a reasonable reference can be given about the lower Pd surface coverage on both PdRhNi samples according to the XPS and EDX results. Furthermore, adding both Rh and Ni to Pd exercises compressive strain on the Pd lattice, noted by the PdRhNi XRD peak shift to higher angles.

Electrodeposition of CoxNiy Thin Film and Its Catalytic Activity for Ethanol Electrooxidation

Platinum is often used as a catalyst in ethanol electrooxidation. Still, it has many disadvantages being expensive and its active site can be poisoned by CO. Transition metal of Co and Ni can become a catalyst in alcohol electrooxidation at a lower cost to synthesize. In this work, bimetallic CoNi were successfully prepared by electrodeposition method with different Co/Ni ratios to enhance ethanol electrooxidation. Samples of CoNi are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), and electrochemical impedance spectroscopy (EIS). XRD diffractogram confirmed the formation of CoNi. Morphology of CoNi in SEM characterization showed that CoNi with ratio 5:1 has the more dispersed particle and the greatest surface area. EDX characterization indicated that the relative weight of different Co/Ni ratios, the composition wt.% Co is 81.15% and wt.% Ni is 18.85% in CoNi 5:1, wt.% Co is 60.96% and wt.% Ni is 30.94% in CoNi 2:5, while wt.% Co is 50.19%, and wt.% Ni is 49.81% in CoNi 5:5. EIS characterization showed that CoNi with ratio of 5:1 has faster electron kinetics. Electrooxidation of ethanol used cyclic voltammetry (CV) method. The best results from the ethanol electrooxidation reaction were obtained for CoNi with a ratio of 5:1 because of the greatest surface area that showed in scanning electron microscopy and fast electron transfer kinetics compared to others ratio of CoxNiy.

Controllable Synthesis of PtIrCu Ternary Alloy Ultrathin Nanowires for Enhanced Ethanol Electrooxidation.

Rational design and controllable synthesis of catalysts with unique structure and composition are effective ways to promote electrocatalytic ethanol oxidation, thus contributing the direct ethanol fuel cells to gain ground. Herein, 2.5 nm-thin PtIrCu ternary alloy ultrathin nanowires (UNWs) with high-density planar defects are synthesized via oriented attachment with the assistance of H2. By adjusting the contents of Ir and Cu atoms, we find that the structure of the products changed from nanowires (NWs) to nanoparticles with the increase of Ir content. Density functional theory calculations show that when Cu atoms are replaced by Ir atoms, the vacancy formation energy of Pt atoms is increased, making the Pt atoms difficult to be activated by H2, which is not conducive to the formation of a one-dimensional structure. The optimal Pt43Ir32Cu25 UNWs achieve excellent ethanol electrooxidation reaction activity (1.05 A·mg-1Pt and 1.67 mA·cm-2), for it can significantly reduce the onset potential and improve the ability of CO anti-poisoning. The significant improvement in catalytic performance is attributed to the synergistic effect of the alloy and the NW structure with high-density planar defects.

In-situ FTIR spectroscopy investigation of carbon-supported PdAuNi electrocatalysts for ethanol oxidation

• Adding Au and Ni to Pd/C enhances its ethanol oxidation performance. • In-situ FTIR studies suggest acetate is the ethanol oxidation final product. • Adding Ni and Au to Pd/C does not enhance the ethanol CO 2 selectivity. • The SBIPA method produces the ethanol most active catalyst. This work demonstrates novel in situ measurements of direct ethanol fuel cells (DEFCs), and shows that the synthesis procedure can exert a substantial influence over their activity, with exceptional activity demonstrated for a trimetallic PdAuNi/C catalyst prepared via NaBH 4 -2-propanol reduction (SBIPA). Furthermore, in situ Fourier transform infrared (FTIR) spectroscopy shows that the final ethanol electrooxidation reaction (EOR) over all catalysts investigated is acetate, thereby yielding valuable insights into the reaction mechanism. DEFCs present a sustainable net-zero technological solution which can supply diverse energy needs without increasing greenhouse gas (GHG) emissions. Ethanol can be produced from biomass precusors, and therefore its direct application in fuel cells can mitigate climate change and ensure environmental sustainability. In this work, PdAuNi/C catalysts are synthesized via three synthetic routes and applied in EOR. The catalysts are charachrterised via X-ray diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS). Their electrocatalytic performance is evaluated by cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS). SBIPA exhibits excellent electrocatalytic results with an oxidation current peak of 9.6 A/mg Pd . This is 4 times greater than that recorded for its monometallic counterpart prepared via the same procedure. It is, also, over twice as great as the other two trimetallic samples prepared by alternative protocols. Although adding Au and Ni to Pd significantly enhances EOR activity, it does not increase the CO 2 yield of EOR.

Square-wave pulse electrodeposition of gold nanoparticles for ethanol electrooxidation

Gold nanoparticles with precisely controlled sizes for electrocatalyst in ethanol electrooxidation reaction were synthesized using a one-step square-wave pulse deposition technique in an additive-free electrolyte.