Electrocatalytic Activity For Ethanol Oxidation Research Articles

Efficient stabilizing agent-free synthesis of gold nanoparticles via square-wave pulse deposition for enhanced catalytic performance in ethanol electrooxidation

The pressing environmental concerns and the depletion of fossil fuel reserves necessitate a transition toward sustainable energy sources. Ethanol, a renewable biomass-derived fuel, is a promising alternative due to its availability and high energy density. This study investigates the synthesis of gold nanoparticles (AuNPs) via a square-wave pulse deposition technique, aiming to enhance catalytic activity for ethanol electrooxidation. By varying pulse durations, we were able to exert precise control over AuNP size and distribution without stabilizing agents. Characterization using field emission scanning electron microscopy and X-ray diffraction techniques confirmed the formation of clustered nanoparticles of metallic gold phase. Electrochemical characteristics analyses revealed that AuNPs synthesized with a 900 ms pulse duration exhibited the lowest charge transfer resistance and the highest electrochemically active surface area. The electrocatalytic performance test of these AuNPs demonstrated an anodic current density of 2.5 mA cm-2 and a Tafel slope of 78 mV dec-1, indicating superior catalytic performance and reaction kinetics. Additionally, the AuNPs showed high resistance to poisoning, as evidenced by a low jb/jf ratio of 0.28 and stable chronoamperometric response. These findings underscore the potential of this synthesis method for producing high-performance electrocatalysts utilized in exploiting ethanol's potential as an environmentally friendly energy carrier.

Facile and innovation synthesis of Zn-Mn-Co-LDH/polypyrrole and its application in investigating ethanol oxidation in an alkaline medium

Overvoltage and low current are observed for ethanol electrooxidation on the surface of many unmodified electrodes. Therefore, it is desirable to use a suitable catalyst for ethanol electrooxidation to increase the current. This research introduces a new sensor to catalyze ethanol oxidation in an alkaline environment. This new Zn-Mn-Co LDH/PolyPyrrole/GCE nanocomposite sensor exhibits high catalytic activity for ethanol electrooxidation. It changes the oxidation potential of ethanol to a less positive potential. To identify this proposed sensor, X-ray diffraction (XRD), Brauner Emmett-Teller (BET), X-ray photoelectron spectroscopy (XPS), FT-IR spectroscopy, field emission scanning electron microscopy (FESEM), thermal analysis (TGA), high-resolution transmission electron microscopy (HR-TEM) and cyclic voltammetry techniques were used. Ethanol electrooxidation was investigated by cyclic voltammetry technique. The effects of scan rate and ethanol concentration on the ethanol oxidation peak have been investigated. The proposed sensor showed long-term stability. This prepared nanocomposite can be used as an anode catalyst for ethanol fuel cells.

Electrodeposition of Zn Zn-doped Cu Cu2O in Acidic and Alkaline Solution and Its Catalytic Activity for Ethanol Electrooxidation

In this study, Zn-doped Cu2O films were synthesized by electrodeposition technique in acidic (pH 4) and alkaline (pH 10) solution. Catalytic activity of the film was evaluated toward ethanol electrooxidation which was carried out using cyclic voltammetry technique. X-ray diffraction (XRD) analysis showed the formation of cubic structure of Cu2O from both conditions. Morphological characterization conducted under a field-emission scanning electron microscope exhibited that Cu2O particles electrodeposited in the acidic condition were smaller compared to those obtained in the alkaline condition. The photoelectrochemical responses, which were recorded using a linear sweep voltammetry technique, showed that the highest photocurrent density was 31.5 mA.cm-2 that obtained at 0.76 V vs. Ag/AgCl using Zn-doped Cu2O film prepared in the acidic condition. The film also possesses a low resistance charge transfer as measured by the electrochemical impedance spectroscopy (EIS) technique. These electrochemical characteristics resulted in a high catalytic performance of the Zn-doped Cu2O film on the ethanol electrooxidation as shown by the high anodic current of 22 mA.cm-2 at 0.968 V. These results indicated that the Zn-doped Cu2O film electrodeposited in the acidic condition has a good catalytic activity towards ethanol electrooxidation process.

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.

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.

Amorphous NiCo2O4 decorated Pd/C as electrocatalysts for boosting ethanol oxidation reaction in alkaline media

The electrocatalytic efficiency and stability have become the most significant topics in the catalytic application of fuel cells. In this work, the carbon-supported amorphous NiCo2O4 decorated Pd composite nanoparticles (Pd/NiCo2O4/C) was fabricated by means of the facile hydrothermal and reduction to investigate the electrocatalytic performance. The cyclicvoltammetry measurements show that the larger electrochemical active surface area (135.00 m2 g−1), increased peak current density (160.99 mA cm−2) and lower onset potential (−0.70 V) are obtained in Pd/NiCo2O4/C catalysts compared to the commercial Pd/C with the Pd loading (10 wt.%), indicating that a significantly enhanced electrocatalytic activity for ethanol oxidation in Pd/NiCo2O4/C catalysts. More importantly, the Pd/NiCo2O4/C catalyst also presents the long-time stability during the ethanol oxidation reaction. The X-ray powder diffraction, X-ray photo-electron spectroscopy and transmission electron microscopy measurements were carried out to further demonstrate that there exists the strong chemical interaction between Pd and amorphous NiCo2O4 nanoparticles, which leads to the formation of the more electrochemical active sites via redistributing the electronic structure of Pd and boosting anti-poisoning ability of intermediates. Our study provides a high-performance and promising electrocatalytic material, which can be applied to the direct ethanol fuel cells.

Ternary PdCoP nanoparticles with nanopore structures: synergic boosting of electrocatalytic activity for ethanol oxidation.

PdCoP nanoparticles (PdCoP NPs) with nanopore structures were synthesized by a facile one-pot solvothermal approach. Due to their unique geometric structures and the electronic and synergistic effects among multiple components, the optimized PdCoP NPs (PdCoP-NPs-1) show superior mass activity (5.97 A mgPd-1) for the ethanol oxidation reaction under alkaline conditions.

Multicomponent nanoporous Al–Ni–Cu–Pt–Pd–Co as highly stable anode catalysts in a flexible room-temperature pure ethanol–powered solid-state fuel cell

Developing highly active and durable anodic catalysts with low noble-metal content for ethanol electrooxidation is important for boosting the performance of direct room-temperature ethanol fuel cells. Herein, we use a general and scalable dealloying method to prepare a series of nanoporous multicomponent alloys with different alloy compositions. It is found that the subsurface alloy composition play an important role on the catalytic activity of the surface noble metals due to the surface strain and electronic effect. By screening, we find that the AlNiCuPtPdCo senary combination exhibits the highest electrocatalytic activity for ethanol oxidation in alkaline media. On the cathode electrode, a highly ORR active, durable, and ethanol-tolerant Co@N–C catalyst derived from MOF is used. Impressively, the designed solid-state room-temperature ethanol fuel cell using such anodic and cathodic catalysts can work immediately with the addition of pure ethanol, delivering a high power density of ~9.20 mW cm−2 with 1 mL ethanol. The flexible fuel cell can also work repeatedly when the added ethanol is consumed.

Enhanced electrochemical performance of Pt–Sn–In/C nanoparticles for membraneless fuel cells

Carbon-supported ternary Pt70Sn10In20, Pt70Sn15In15 and Pt70Sn20In10/C electrocatalysts were synthesized by co-impregnation method for the electrooxidation of ethanol in membraneless fuel cells. The resulting catalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDX) analyses compared to Pt50Sn50, Pt50In50 and Pt100/C catalysts produced in the same way. The results revealed that all catalysts showed a similar particle morphology and the lattice constant of Pt–Sn–In was between Pt–Sn and Pt–In. Cyclic voltammetry (CV) and chronoamperometry (CA) showed that the Pt–Sn–In catalyst has improved electrocatalytic activity for ethanol oxidation compared to Pt–Sn and Pt–In catalysts, which is in agreement with the results of the single cell test. The improvement in activity is due to a greatly increased electrochemically active surface and the promoting function of indium.

Mechanistic Insights for Photoelectrochemical Ethanol Oxidation on Black Gold Decorated Monoclinic Zirconia

Surface decoration of metal oxides by metals for enhancing their electrocatalytic properties for organic conversions has attracted a lot of researchers' interest due to their high abundancy, inexpensiveness, and high stability. In the present work, a process for the synthesis of black gold (BG) using a citrate assisted chemical route and m-ZrO2 by a hydrothermal method at 200 °C has been developed. Further, different concentrations of black gold are being used to decorate the surface of zirconia by exploitation of surface potential of zirconia and gold surfaces. The catalyst having 6 mol % concentration of black gold shows excellent electrocatalytic activity for ethanol oxidation with low oxidation peak potential (1.17 V) and high peak current density (8.54 mA cm-2). The current density ratio (jf/jb) is also high (2.54) for this catalyst indicating its high tolerance toward poisoning by intermediate species generated during the catalytic cycle. The enhanced electrocatalytic activity can be attributed to the high tolerance of gold toward CO poisoning and high stability of the ZrO2 support. The black gold decorated zirconia catalyst showed enhanced activity during photoelectrochemical studies when the entire spectrum of light falls on the catalyst. Ultrafast transient studies demonstrated plasmonic excitation of metallic free electrons and subsequent charge separation in the black gold-ZrO2 heterointerface as the key factor for enhanced photoelectrocatalytic activity.

Effect of Pd on the Electrocatalytic Activity of Pt towards Oxidation of Ethanol in Alkaline Solutions

The understanding of electrocatalytic activity and poisoning resistance properties of Pt and Pd nanoparticles, recognized as the best electrocatalysts for the ethanol oxidation reaction, is an essential step for the commercialization of direct ethanol fuel cells (DEFCs). In this paper, mono and bimetallic Pt and Pd nanoparticles with different atomic ratios have been synthesized to study their electrocatalytic properties for an ethanol oxidation reaction in alkaline solutions. The different nanoparticles were physiochemically characterized by transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The electrochemical characterization was performed by cyclic voltammetry and chronoamperometry measurements. The electrochemical measurements indicate that Pt nanoparticles have much higher electrocatalytic activity for ethanol oxidation than Pd nanoparticles. The studies with bimetallic PtPd nanoparticles showed a significant impact of their composition on the ethanol oxidation. Thus, the highest electrocatalytic activity and poisoning resistance properties were obtained for Pt3Pd2 nanoparticles. Moreover, this study demonstrates that the poisoning of the catalyst surface through ethanol oxidation is related to the prevalence of the acetaldehyde–acetate route and the polymerization of acetaldehyde through aldol condensation in the alkaline media.

Easy approach for decorating of poly 4-aminithiophenol with Pd nanoparticles: an efficient electrocatalyst for ethanol oxidation in alkaline media

In this work, a polymer composite based on poly 4-aminothiophenol (p-ATP) is prepared via a facile electrochemical route and is used as an appropriate support for Pd nanoparticles. The morphological studies reveal that a nanofiber structure patterned on the multiwalled carbon nanotubes (MWCNT) structure is obtained for the synthesized catalyst viz. Pd/p-ATP/MWCNT. The Pd/p-ATP/MWCNT catalyst delivers a mass activity of 3245 $$ \mathrm{mA}\ {\mathrm{mg}}_{\mathrm{Pd}}^{-1} $$ manifesting its superb electrocatalytic activity for ethanol oxidation in the alkaline media. The vital role of the polymeric substrate on the electrocatalytic activity of Pd nanoparticles is established by comparing the catalytic performance of Pd/p-ATP/MWCNT with Pd/MWCNT. Finally, the superb activity of the synthesized catalyst is explicated according to the mechanism of ethanol oxidation on the synthesized catalyst.

Tunable Concave Surface Features of Mesoporous Palladium Nanocrystals Prepared from Supramolecular Micellar Templates.

Concave metallic nanocrystals with a high density of low-coordinated atoms on the surface are essential for the realization of unique catalytic properties. Herein, mesoporous palladium nanocrystals (MPNs) that possess various degrees of curvature are successfully synthesized following an approach that relies on a facile polymeric micelle assembly approach. The as-prepared MPNs exhibit larger surface areas compared to conventional Pd nanocrystals and their nonporous counterparts. The MPNs display enhanced electrocatalytic activity for ethanol oxidation when compared to state-of-the-art commercial palladium black and conventional palladium nanocubes used as catalysts. Interestingly, as the degree of curvature increases, the surface-area-normalized activity also increases, demonstrating that the curvature of MPNs and the presence of high-index facets are crucial considerations for the design of electrocatalysts.

Electrocatalytic oxidation and detection of ethanol on an electroplated Pt/3D honeycomb-like nano-Au/Au disk electrode

The dynamic gas bubble template method was used to potentiostatically electrodeposit three-dimensional honeycomb-like porous nano‑gold (AuH) at −3 V vs SCE on a gold disk electrode in an aqueous bath containing 50 mM HAuCl4 and 3 M NH4Cl (AuH/Au). Then, Pt was potentiostatically deposited at −1 V vs SCE on the AuH/Au electrode in 0.1 M aqueous KCl containing 4 mM H2PtCl6 to yield a Pt/AuH/Au electrode. Scanning electron microscopy, X-ray diffraction pattern and cyclic voltammetry were employed to characterize the relevant electrodes. The Pt/AuH/Au electrode of large specific surface area exhibits high electrocatalytic activity for ethanol oxidation in 0.5 M aqueous H2SO4 or 1 M aqueous KOH. The Pt/AuH/Au electrode in 0.5 M aqueous H2SO4 shows a linear amperometric response to ethanol concentration from 0.05 mM to 43.3 mM with a sensitivity of 75.7 μA cm−2 mM−1, a limit of detection (LOD, S/N = 3) of 2.3 μM, and good selectivity, which is used to analyze ethanol in white-spirit/red-wine real samples with satisfactory results.

Investigation of the electrocatalytic activity for ethanol oxidation of Pt nanoparticles modified with small amount (≤5 wt%) of CeO2

Pt is still the state of the art electrocatalyst for the oxidation of ethanol but it is poisoned by the CO-intermediates resulting in a slow ethanol oxidation reaction kinetic. Here, we show that the electrocatalytic activity of unsupported Pt nanoparticles for the ethanol electro-oxidation in acid medium can be significantly enhanced by the addition of small amounts of CeO2 nanoparticles (≤5wt%). Comparative studies on bare Pt, Pt-CeO21wt% and Pt-CeO2—5wt% catalysts composed of Pt nanoparticles with different sizes (from 10 to >40nm for bare Pt, and from 6 and 20nm for the Pt-CeO2 composites) revealed an increase of the microstrain with the decrease of the Pt's average particle size. Besides, there is a strong electronic interaction between the Pt and CeO2 nanoparticles, demonstrated by a systematic shift of the Pt 4f7/2 peak to lower binding energy with the addition of CeO2. Chronoamperometric data showed that the steady state current density normalized to Pt's electrochemical surface area for ethanol electro-oxidation is mainly governed by the microstrain, and it decreases with increasing strain. This trend is explained in terms of a more facile activation of the ethanol molecule at the surface of less strained Pt nanoparticles. Thus, the best performance was obtained with Pt-CeO2 1wt% formed by Pt nanoparticles with an average size of 18nm, reaching 1.0A·m−2 after 900s at 0.6V vs SCE.

Core–shell titanium dioxide /carbon nanofibers decorated nickel nanoparticles as supports for electrocatalytic oxidation of ethanol

Abstract Recently alcohol fuel cells has been increased consideration because of their environmental friendliness, high energy conversion efficiency and low emissions. Many effort have been made to improve the electro-oxidation performance of alcohols such as methanol, ethanol and propanol. In this work, a new method for ethanol oxidation based on core–shell titanium dioxide / carbon nanofibers (TiO2@C NFs), TiO2 as a core and carbon as a shell, decorated Ni nanoparticles (NiNPs) is presented. TiO2@C NFs were prepared by mixing the electrospinning technique and hydrothermal method. Nickel nanoparticles were electrodeposed on the surface of TiO2@C NFs denoted as TiO2@C- Ni. The catalyst was characterized by SEM and electrochemical methods. Performance of ethanol oxidation was investigated in aqueous NaOH solutions by chronoamperometry and cyclic voltammetry. The electrochemical measurements showed that this electrode is effective and has good electrocatalytic activity for ethanol oxidation and the structures of nanofibers have important effect on the electrooxidation of ethanol. The synergy between Ni, carbon shell and TiO2 support, boost ethanol oxidation on TiO2@C- Ni. Keywords: Ethanol electrooxidation; Electrospinning; Nickel nanoparticles; Core–shell titanium dioxide /carbon nanofibers

Synthesis and facile structure-adjusting of Pd–Pt nanocrystal electrocatalysts with improved activity for ethanol oxidation reaction

Illustration of the synthesis of the nanospheroid-, nanoflower- and nanoworm-Pd–Pt NCs and their electrocatalytic activity for ethanol oxidation.

Three-dimensional Graphene-Carbon Nanotubes Composite-Supported PtSn Catalysts with a Tunable Microstructure to Enhance Electrocatalytic Activity for Ethanol Oxidation

Three-dimensional Graphene-Carbon Nanotubes Composite-Supported PtSn Catalysts with a Tunable Microstructure to Enhance Electrocatalytic Activity for Ethanol Oxidation

Hollow Graphitized Carbon Nanocage Supported Pd Catalyst with Excellent Electrocatalytic Activity for Ethanol Oxidation

Low cost, high activity and reliable stability are significant to the commercialization of fuel cell electrocatalysts. However, the synthesis of non-Pt anode catalysts with low cost, excellent performance and reliable stability is still a great challenge. Herein, we developed hollow graphitized carbon nanocages for improving the electrocatalytic performance of Pd nanoparticles (NPs) toward ethanol oxidation. A mild method was utilized for the preparation of hollow graphitized carbon nanocages (CN) using magnesium oxide as a sacrificial template without high-temperature processing. The CN can act as high-efficiency support for the distribution of Pd NPs. Pd NPs decorated on CN exhibited high catalytic performance with the current density of 2411.5 mA mg–1 for ethanol oxidation reaction, which is 1.84 and 4.42 times higher than reduced graphene oxide (1308.5 mA mg–1) and C (545.2 mA mg–1) as supports, respectively. The Pd/CN with excellent catalytic performance can be attributed to the CN, including the lar...

Electrocatalytic Property of Pt Atomic Layers on Pd Nanocrystals for Ethanol Oxidation

Platinum is actually the irreplaceable catalyst for proton-exchange-membrane fuel cells (PEMFCs) and direct-alcohol fuel cells (DAFCs). Due to the high price and rare reserve, further improving the activity while decreasing the loading of Pt catalyst in membrane-electrolyte-assembly (MEA) of fuel cells is crucial. Single atomic Pt layer even single Pt atom catalysts are the most promising and challenging strategy. In this study, catalysts of Pt atomic layers from sub-monolayer to multilayers on Pd tetrahexahedral nanocrystals (THH Pd@Ptn NCs) with high-index faceted and {111}-faceted Pd NCs were prepared through Pt galvanic displacement of UPD Cu. The results demonstrate that the catalytic activity for ethanol electrooxidation is very low on Pt monolayer (THH Pd@Pt1 NCs), while the highest activity is measured on Pt 2-layers (THH Pd@Pt2 NCs) amongst the THH Pd@Ptn NCs (n<1, =1-5) studied. The catalytic activity of THH Pd@Pt2 NCs is even higher than that of pure THH Pt NCs. Through in-situ CO-probe FTIR spectroscopic study, it has revealed that both the interaction of Pt layer with Pd nanoparticle (the strain and ligand effects) and the structure of surface atom arrangement play important roles in manipulating the activity of Pt catalyst. The study has thrown insight into design and preparation of high-active and ultra-low loading Pt catalysts for fuel cell applications. Acknowledgement: This work was supported by Natural Science Foundation of China (21573183, 21621091).