Ethanol Electrooxidation Research Articles

High-efficient electrooxidation of ethylene glycol and ethanol on PdSn alloy loaded by versatile poly(3,4-ethylenedioxythiophene)

Developing a novel catalyst with lower noble-metal loading and higher catalytic efficiency is significant for promoting the widespread application of direct alcohol fuel cells (DAFCs). In this work, poly(3,4-ethylenedioxythiophene) (PEDOT) supported the PdSn alloy (PdSn/PEDOT) were simply synthesized and their electrocatalytic performance toward the oxidation of ethylene glycol and ethanol (EGOR and EOR) were investigated in alkaline media, respectively. In comparison with other control catalysts, the optimized Pd4Sn6/PEDOT catalyst exhibits the highest mass activity (7125/4166 mA mgPd−1) and specific activity (26/15 mA cm−2) towards EGOR/EOR. The mass activity of Pd4Sn6/PEDOT for EGOR and EOR are 11.9 and 10.9 times higher than commercial Pd/C, respectively. Moreover, chronoamperometry (CA) and successive cyclic voltammetry (CV) tests show that the CO resistance ability and durability of the Pd4Sn6/PEDOT catalyst were superior to Pd4Sn6, Pd/PEDOT and commercial Pd/C catalysts, which can be attributed to the d-band center of Pd can be effectively downshifted and the interface strain effect between electrons caused by the conjugated structure between PEDOT groups. This work provides an effective strategy for the development of highly efficient anode catalysts of DAFCs.

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.

MoO3/WO3/rGO as electrode material for supercapacitor and catalyst for methanol and ethanol electrooxidation.

The potential of metal oxides in electrochemical energy storage encouraged our research team to synthesize molybdenum oxide/tungsten oxide nanocomposites (MoO3/WO3) and their hybrid with reduced graphene oxide (rGO), in the form of MoO3/WO3/rGO as a substrate with relatively good electrical conductivity and suitable electrochemical active surface. In this context, we presented the electrochemical behavior of these nanocomposites as an electrode for supercapacitors and as a catalyst in the oxidation process of methanol/ethanol. Our engineered samples were characterized by X-ray diffraction pattern and scanning electron microscopy. As a result, MoO3/WO3 and MoO3/WO3/rGO indicated specific capacitances of 452 and 583 F/g and stability of 88.9% and 92.6% after 2000 consecutive GCD cycles, respectively. Also, MoO3/WO3 and MoO3/WO3/rGO nanocatalysts showed oxidation current densities of 117 and 170 mA/cm2 at scan rate of 50 mV/s, and stability of 71 and 89%, respectively in chronoamperometry analysis, in the MOR process. Interestingly, in the ethanol oxidation process, corresponding oxidation current densities of 42 and 106 mA/cm2 and stability values of 70 and 82% were achieved. MoO3/WO3 and MoO3/WO3/rGO can be attractive options paving the way for prospective alcohol-based fuel cells.

Nickel Flower/Conducting Polymer Composite for Effective Ethanol Electrooxidation in Alkaline Medium

Nickel Flower/Conducting Polymer Composite for Effective Ethanol Electrooxidation in Alkaline Medium

GO modification with PANI-PpPDA as support material for Pd-Ni and its application for ethanol electrooxidation

Among different renewable energy sources, fuel cells emerged to be a promising solution. However, due to limitations such as high cost and low stability of current commercial catalysts, several approaches are considered to modify them. Graphene oxide (GO) modification via a facile in-situ polymerization of aniline (ANI) and p-phenylenediamine (pPDA) in the presence of GO sheets is the main goal of this study. Pd and Ni as active metals are chemically deposited on the support material. The prepared substrates and catalysts are examined by various structural and electrochemical tests. This study shows that GO-PANI-PpPDA support material has favorable characteristics with 32.64 % higher surface area compared to GO. High surface area and porosity lead to more loading and uniform distribution of metallic particles. GO-PANI-PpPDA/Pd-Ni exhibited superior eligible properties including 29.28 % higher electrochemically active surface area compared to GO/Pd-Ni. This nanohybrid has the lowest charge transfer resistance, highest current density, stability and durability and it loses 5.67 % of the initial current after 15 h. This method shows promising results as an advanced strategy to synthesize low-cost and high-performance Pd-based electrocatalysts on the modified GO.

Mild Synthesis of Planar PdPtAuAgCuIr Nanocrystals with Granular Edges for Improved Ethanol Electrooxidation

AbstractWe report a mild, one‐pot synthesis of PdPtAuAgCuIr multimetallic nanocrystals with controlled shapes and explore their applications as the electrocatalysts for ethanol electrooxidation in alkaline medium. The success of current synthesis relies on the co‐reduction of six metal precursors in the presence of octadecylammonium chloride and ascorbic acid at an elevated temperature. The resulting products are featured with an in‐plane core‐shell structure, together with the trigonal/hexagonal plate decorated with granular edges. When serving as EOR electrocatalysts, the carbon‐supported PdPtAuAgCuIr nanocrystals exhibit more than five‐fold increase in mass activity as compared to that of commercial Pt/C, as well as improved reaction kinetics and long‐term durability. DFT calculations disclose that the reduced energy barrier renders the Pd‐based multimetallic catalyst in catalytic performance. The present study provides a feasible strategy to create multimetallic nanocrystals with controlled two‐dimensional morphology under ambient conditions, shedding light for rational design over advanced fuel cell catalysts composed of multimetallic alloy.

Porous hemispherical Au@PdAg catalysts for enhancing ethanol electrooxidation

Direct ethanol fuel cell can convert chemical energy into electric energy directly, and has the advantages of being free from Carnot cycle and being friendly to environment, so it has a broad application prospect. However, the insufficient activity and toxicity resistance of anodic catalysts limit their commercial application, mainly due to the limited adsorption sites and the toxic inactivation of catalysts resulting from the production of toxic intermediates (COads) during the ethanol oxidation reaction (EOR) process. In this study, the Au@PdAg porous hemispherical catalyst assembled by nanotubes was successfully prepared by soft template method and co-reduction method using dioctadecyl dimethyl ammonium chloride (DODAC) as surfactant, and its EOR performance was tested. Au@Pd1.0Ag1.0 has the highest mass current density with a peak value of 4048.8 mAmgPd−1, which is 7.8 times of Pd/C (JM). After 5000 s stability test, the residual current density value is still 863.4 mAmgPd−1. The results showed that the introduction of the oxygenophilic metal Ag was conducive to the formation of OHads and the oxidation of COads. The porous structure of the nanotube assembly facilitates electron transfer and provides more adsorption sites, which makes the catalyst show good electrocatalytic activity and anti-CO poisoning ability.

Square-Wave Pulse Deposition of Pt Nanoparticles for Ethanol Electrooxidation

Platinum (Pt) is often used as an electrocatalyst in the electrooxidation of ethanol. There have been many attempts to improve the catalytic properties of platinum-based catalysts to achieve satisfactory results. The solutions are manipulating the size and shape of Pt. In this study, Pt will be deposited using the square wave pulse deposition method at upper potential variations. The Pt samples were characterized by scanning electron microscopy (SEM), X-ray diffraction, energy dispersive X-ray, and electrochemical impedance spectroscopy. The results of SEM show that the morphology of Pt at potentials of 0.3 V, 0.5 V, and 1.0 V produces a dendritic nanothorn morphology, while 1.25 V and 1.50 V produce a nanoleaf morphology. The lowest charge transfer resistance value is at Pt1.0V with the smallest size. The highest yield of ethanol electrooxidation was at Pt1.0V reaching 8.82 mA/cm2.

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.

Interface Engineering of PdPt Ultrafine Ethanol Electro-Oxidation Nanocatalysts by Bacterial Soluble Extracellular Polymeric Substances (s-EPS) to Break through Sabatier Principle.

Unsatisfactory performance of ethanol oxidation reaction (EOR) catalysts hinders the application of direct ethanol fuel cells (DEFCs), while traditional alloy catalysts (like PdPt) is cursed by Sabatier principle due to countable active site types. However, bacterial soluble extracellular polymeric substances (s-EPS) owning abundent functional groups may help breacking through it by contrusting different active sites on PdPt and inducing them to play synergy effect, which is called interface engineering. Using s-EPS to engineer catalysts is more green and consumes lower energy compared to chemical reagents. Herein, PdPt alloy nanoparticles (≈2.1nm) are successfully in situ synthesized by/on s-EPS of Bacillus megaterium, an ex-holotype. Tryptophan residuals are proved as the main reductant. In EOR, PdPt@s-EPS shows higher activity (3.89mAcm-2) than Pd@s-EPS, Pt@s-EPS, Pt/C and most reported akin catalysts. Its stability and durability are excellent, too. DFT modelling further demonstrates that, interface engineering by s-EPS breaks through Sabatier principle, by the synergy of diverse sites owning different degrees of d-p orbital hybridization. This work not only makes DEFCs closer to practice, but provides a facile and green strategy to design more catalysts.

RhCuBi Trimetallenes with Composition Segregation Coupled Crystalline‐Amorphous Heterostructure Toward Ethanol Electrooxidation

AbstractThe inefficiency of Pt and Pd benchmark catalysts in achieving complete ethanol oxidation, coupled with their inherent susceptibility to poisoning, poses a significant obstacle to the advancement of direct ethanol fuel cells. In this study, the development of self‐supported and ultrathin RhCuBi trimetallenes, demonstrating exceptional performance in ethanol electrooxidation through segregation and interface engineering is presented. The distinctive RhBi‐rich crystalline/RhCu‐rich amorphous heterostructure of RhCuBi trimetallenes creates a wealth of highly active interfacial sites for the ethanol oxidation reaction (EOR). This results in an impressive 43.3% Faradaic efficiency for the C1 pathway and a peak mass activity of 1.11 A mgRh−1 at 0.68 V versus reversible hydrogen electrode. Moreover, RhCuBi trimetallenes retain 60% of their initial mass activity after 8.5 h of constant potential electrolysis, outperforming commercial Pd and Pt catalysts (<3%). In/ex situ infrared spectroscopy directly reveals the generated C1 products and the key CH3CO* intermediates for EOR on RhCuBi trimetallenes. Theoretical calculations confirm that the RhBi alloy, particularly the lattice‐stretched crystalline/amorphous interfacial sites, facilitates the adsorption/activation of ethanol and the dehydrogenation of CH3CO* toward the C1 pathway of EOR. This breakthrough offers promising prospects for enhancing the efficiency and stability of ethanol electrooxidation in fuel cell applications.

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.

Facile Synthesis of High-Entropy Alloy Nanowires for Electrocatalytic Alcohol Oxidation.

Considering the structural and compositional advantages of high-entropy alloy (HEA) as high-efficient electrocatalysts, we here present a facile method to prepare high-entropy alloy nanowires with seven elements in an aqueous solution. The as-synthesized PdPtCuAgAuPbCo nanowires possess dispersed one-dimensional morphology and exhibit enhanced electrocatalytic performance with the mass activity of 9.9 A mgPd+Pt -1 toward ethanol electrooxidation. The HEA nanowires also perform superior stability, resistance to CO poisoning, and good electrocatalytic activities toward other alcohols (e. g., ethylene glycol and methanol) oxidation. The synthesis strategy is easy to operate with low cost and has wide application prospects for preparing desired electrocatalysts for fuel cells.

Electrocatalytic Oxidation of Methanol and Ethanol with 3d-Metal Based Anodic Electrocatalysts in Alkaline Media Using Carbon Based Electrode Assembly.

Homogeneous electrocatalytic systems based on readily available, earth-abundant, inexpensive base metals Ni, Co, and Cr have been formulated for the electro-oxidation of alcohols (methanol and ethanol) that constitute a key half-cell component of direct alcohol fuel cells (DAFCs). Notably, excellent results were obtained for both methanol as well as ethanol electro-oxidation while operating with a half-cell assembly based on all-non-noble working and counter electrode systems consisting of glassy carbon and graphite rod, respectively. Using NaOH as the supporting electrolyte, Ni/Co/Cr metal salts and their bis(iminopyridine) complexes have been used as anodic electrocatalysts for the alcohol half-cell reactions, and among them, catalytic systems based on Co outperformed the corresponding systems based on Ni and Cr. The system comprising CoCl2.·6H2O [10 mM] + NaOH [6 M] at room temperature emerged as the best electrocatalyst for both methanol [5 M] electro-oxidation (ca. 522.5 ± 13.5 mA cm-2 at 1.4 V) and ethanol [5 M] electro-oxidation (ca. 209 ± 25 mA cm-2 at 1.34 V). It was observed that regardless of the starting alcohol, the end product is carbon dioxide, all of which gets trapped as sodium carbonate (up to 97% yield), thereby mitigating any possible hazards of greenhouse gas emission. Inferences obtained from FETEM, FESEM, and EDS analysis of both the electrolyte solution and residues deposited on the electrode surface provide evidence for the mostly homogeneous nature of the reaction mixture with the molecular catalyst being the major contributor toward the electrocatalytic activity apart from the minor role played by trace heterogeneous particles. The current cell assembly operating with non-noble working and counter electrodes utilizing a catalytic system based on an earth-abundant, base metal salt/complex that not only results in good half-cell current densities for high-energy power-source DAFCs but also generates high-value sodium carbonate offers an exciting avenue.

Energy conversion using Pd-based catalysts in direct ethanol fuel cell

Direct Ethanol Fuel Cells DEFCs are considered one of the promising renewable energy sources, as they can produce electrical energy directly from the ethanol electrooxidation reaction. The efficiency of ethanol electrooxidation is a big question from research point of view. In this work, Pd is used as catalyst for the electrooxidation in alkaline media aiming to improve the catalytic activity for ethanol electrooxidation reaction, and consequently the DEFC performance, more than using a Pt-based catalyst. In this research, Pd was used as an alternative for Pt-based catalyst. Additionally, it can be recorded that the alloying of Pd with Sn will enhance the efficiency through increasing the surface area of the PdSn catalysts.

Development of PtNi/C and PtSnNi/C Nanocatalysts for Energy Convertion from Ethanol Electrooxidation

Literature describes the importance in studying morphological and structural electrocatalysts features since they influence catalytic activity toward ethanol electrooxidation. Thus, this work consists in studying the relation between structural/composition features and catalytic activity toward ethanol electrooxidation from Pt, PtSn, PtNi and PtSnNi alloys nanoparticles supported on Vulcan Carbon XC72R. These nanoparticles were obtained by the impregnation reduction method at 130 ºC, employing a mixture of water/ethylene glycol (75/25 v/v) with different amounts of Pt, Sn and Ni. The nanostructured catalysts obtained were characterized by Rutherford Backscattering Spectroscopy (RBS), X-Ray Diffraction (XRD), High Resolution Transmission Electronic Microscopy (HRTEM) and Cyclic Voltammetry (CV). Preliminary results showed that the impregnation reduction is a reasonable method to obtain Pt-based nanoparticles with a composition control. XRD analysis showed that tin and nickel addition promoted a crystal lattice dilation and contraction, respectively. Besides, the simultaneous addition of Sn and Ni to Pt did not significantly affect the reticular lattice value. Moreover, crystallite size is diminished with Ni or Ni and Sn addition. PtSn, PtNi and PtSnNi/C nanoparticles have higher catalytic activity than Pt/C toward ethanol electrooxidation, which was verified by a significant current density values increase and an onset potential decrease. The best catalytic activity was observed to PtNi/C electrocatalyst.

Trimetallic PdRhPt Porous Nanooctahedra as Highly Active and Cost‐Effective Electrocatalysts for Ethanol Electrooxidation

AbstractThe development of highly active and cost‐effective electrocatalysts for the ethanol oxidation reaction (EOR) is imperative for the prospective application of direct ethanol fuel cells (DEFCs). In this study, we successfully synthesized porous octahedral nanoarchitectures comprising Pd, Rh, and Pt, through a straightforward one‐step co‐reduction aided by additional Ag precursors and other surface capping agents. The in‐situ galvanic replacement played a pivotal role in shaping hollow structures within the prepared PdRhPt porous octahedra, designated as PdRhPt‐POct. By strategically employing both composition and structure engineering, PdRhPt‐POct exhibited remarkably enhanced activity and stability toward EOR. Specifically, the mass activity of PdRhPt‐POct, reaching 8.11 A mg−1Pd+Pt, surpassed that of the majority of state‐of‐the‐art EOR electrocatalysts, owing to increased efficiency in C−C bond breaking and enhanced anti‐poisoning properties. This work introduces new prospects for designing and producing unique hollow‐structured multi‐metal nanocrystals as high‐performance EOR catalysts.

CuNi2O4/MWCNTs nanocatalyst for methanol and ethanol electro-oxidation

The widespread use of cheap and efficient catalysts in energy storage and production in electrochemical processes led our research team to the synthesis and evaluation of CuNi2O4/MWCNTs nanocatalyst for alcohol oxidation. Nanocatalyst was characterized in terms of structure and morphology by X-ray diffraction analysis (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and energy-dispersive X-ray analysis (EDAX). The ability of CuNi2O4/MWCNTs was evaluated with cyclic voltammetry (CV) and linear sweep voltammetry (LSV) analyses in the oxidation process of methanol and ethanol alcohols in alkaline media. The optimal concentration of methanol and ethanol for CuNi2O4/MWCNTs and CuNi2O4 was obtained to investigate the methanol oxidation reaction and ethanol oxidation reaction processes. The mechanism of these processes was also evaluated in detail. The stability of both nanocatalysts was investigated by performing several consecutive CVs and in 3600 s by chronoamperometric analysis. The results showed the good stability of this catalyst. The synergistic effect of placing CuNi2O4 on the surface of carbon nanotubes improved the oxidation process of methanol and ethanol. In general, the proposed catalyst can be an efficient, stable, and cheap option and at the same time very stable for use in alcohol fuel cells.

Silver Nanowires-Based Flexible Gold Electrode Overcoming Interior Impedance of Nanomaterial Electrodes.

In the development of nanomaterial electrodes for improved electrocatalytic activity, much attention is paid to the compositions, lattice, and surface morphologies. In this study, a new concept to enhance electrocatalytic activity is proposed by reducing impedance inside nanomaterial electrodes. Gold nanodendrites (AuNDs) are grown along silver nanowires (AgNWs) on flexible polydimethylsiloxane (PDMS) support. The AuNDs/AgNWs/PDMS electrode affords an oxidative peak current density of 50mAcm-2 for ethanol electrooxidation, a value ≈20 times higher than those in the literature do. Electrochemical impedance spectroscopy (EIS) demonstrates the significant contribution of the AgNWs to reduce impedance. The peak current densities for ethanol electrooxidation are decreased 7.5-fold when the AgNWs are electrolytically corroded. By in situ surface-enhanced Raman spectroscopy (SERS) and density functional theory (DFT) simulation, it is validated that the ethanol electrooxidation favors the production of acetic acid with undetectable CO, resulting in a more complete oxidation and long-term stability, while the AgNWs corrosion greatly decreases acetic acid production. This novel strategy for fabricating nanomaterial electrodes using AgNWs as a charge transfer conduit may stimulate insights into the design of nanomaterial electrodes.

PdOs bimetallene for energy-saving hydrogen production coupled with ethanol electro-oxidation

The replacement of sluggish oxygen evolution reaction by more thermodynamically favorable ethanol oxidation reaction (EOR) is a promising strategy for coproduction of hydrogen and valuable chemicals in energy-saving mode. Here, we propose the synthesis of highly curved PdOs bimetallene, which possesses high active sites atomic utilization and conductivity. Furthermore, alloy effect can regulate electronic structure and optimize adsorption energy of reactants. Therefore, PdOs bimetallene exhibits superior performance for hydrogen evolution reaction (HER) and EOR under basic solutions, with overpotential of 36 mV at 10 mA/cm2 and mass activity of 1.51 mA/μgPd, respectively. In the EOR-HER coelectrolysis system, PdOs bimetallene requires low voltage of 0.801 V for concurrent production of hydrogen and acetate at 50 mA/cm2, which greatly reduces energy consumption compared to conventional water electrolysis (1.976 V). This method provides a promising strategy for designing bimetallic electrocatalysts toward simultaneous energy-saving generation of hydrogen and high-value chemicals by replacing sluggish oxygen evolution reaction with more favorable EOR.