Ethanol Oxidation Reaction Research Articles

Ternary CuZnPd Nanoalloys Achieving the Synergy of an Electronic Interaction and Bifunctional Catalysis for Efficient Ethanol Electrooxidation

Rationally constructing nanoalloys achieving the synergy of multiple interactions among different constituents could substantially enhance the electrocatalytic performance of an active metal for a given chemical reaction. In this context, we design and synthesize well-controlled ternary CuZnPd alloy nanoparticles, in which the Cu atoms modify the electronic configuration of Pd atoms through the ligand effect or the lattice strain effect, while the Zn atoms clean their neighboring Pd sites through a bifunctional mechanism, and the synergy of these two benefits endows the ternary CuZnPd alloy nanoparticles with exceptional electrocatalysis for a room-temperature ethanol oxidation reaction (EOR). In specific, at an appropriate 1/1/1 molar ratio for Cu/Zn/Pd, the as-prepared ternary CuZnPd alloy nanoparticles exhibit both the highest specific activity and mass activity of 17.3 mA cm–2 and 11.8 A mg–1, respectively, which outperform those of their CuPd, ZnPd alloy counterparts and the commercial Pd/C catalyst, as well as the majority of recently reported Pd-based catalysts. Density functional theory calculations verify that the key CO* and CH3CHO* intermediates generated during the EOR have the lowest adsorption energy on the ternary CuZnPd alloy nanoparticles, which is responsible for their boosted EOR electrocatalysis.

Efficient Electrooxidation of Ethanol on Annular Cu@Pt–Ru Ternary Metal Catalyst

Many efforts have been made to develop efficient electrocatalysts for ethanol fuel cells. However, the commonly used Pt‐based catalysts still have some shortcomings, such as low catalytic activity, severe CO poisoning, and poor stability. Herein, the preparation of Cu@Pt–Ru catalysts with high activity against CO poisoning by using an electrochemical method is reported. Because of its interatomic electronic effects, the Cu@Pt6.98Ru1 catalyst exhibits high electrocatalytic performance for the ethanol oxidation reaction. The mass activity reaches 641 mA mgPt−1, which are 2.9, 5.13, and 8.8 times those of CuPt, PtRu/C, and Pt/C catalysts, respectively. The specific activity reaches 3.19 mA cm−2, which are 1.77, 2.06, and 2.4 times those of CuPt, PtRu/C, and Pt/C catalysts, respectively. The catalytic activity remains relatively high after 2000s. The results have proven that the successful introduction of Cu and Ru into the Pt lattice would improve the catalytic activity and stability and increase its ability to resist CO poisoning of the catalyst.

Self-standing foam-like Pd-based alloys nanostructures for efficient electrocatalytic ethanol oxidation

In this work, self-standing binary porous PdM (M = Ni, Fe and Co) foam-like nanostructures are rationally designed by a rapid and one-step aqueous-solution method, including ice co-reduction of metal precursors using sodium borohydride. Amongst the tested PdM nanostructures, the PdNi nanostructures delivered a superior alkaline ethanol oxidation reaction (EOR) activity and stability than those of PdFe, PdCo, and commercial Pd/C catalysts. The EOR mass activity of PdNi (4.81 A/mgPd) was 1.32, 1.51, and 24.05-folds of PdFe (3.62 A/mgPd), PdCo (3.19 A/mgPd) and Pd/C (0.2 A/mgPd), respectively based on equal Pd mass loading. This was attributed to the lower synergetic effect of PdNi, which enhanced activation/dissociation of H2O to afford OH- species required for fast EOR kinetics; meanwhile, porous foam-like nanostructure improved electron mobility and increased accessible active sites. This study reveals that low synergism in porous PdM nanocrystals is beneficial for augmenting the EOR activity, which may allow the design of other binary Pd-based alloys for various electrocatalytic reactions.

Self-supporting trimetallic PtAuBi aerogels as electrocatalyst for ethanol oxidation reaction

The creation of anodic ethanol oxidation reaction catalysts with superior all-around performance for direct ethanol fuel cells (DEFCs) has continued to attract the attention of researchers. An ultrathin trimetallic PtAuBi aerogel with branching, rough-surfaced 1D nanowires that self-assemble into a 3D porous network structure has been created in this study. It has a mass activity (MA) of 8045 mA mgPt−1 in an alkaline medium, which is 7.56 times greater than that of commercial Pt/C (1064 mA mgPt−1). Notably, the catalytic activity and resistance to CO poisoning of PtAuBi aerogels are improved by the addition of an efficient “active additive” Au. The results analysis reveals that the increased performance of PtAuBi aerogel is mostly attributable to the integrated function of the 3D porous network structure, the downward shift of the Pt d-band center, and the synergistic effect of the “Pt–Bi” and/or “Pt–Au” dual active sites.

Bimetallic AgPt Nanoalloys as an Electrocatalyst for Ethanol Oxidation Reaction: Synthesis, Structural Analysis, and Electro-Catalytic Activity.

In the present work, the chemical synthesis of AgPt nanoalloys is reported by the polyol method using polyvinylpyrrolidone (PVP) as a surfactant and a heterogeneous nucleation approach. Nanoparticles with different atomic compositions of the Ag and Pt elements (1:1 and 1:3) were synthesized by adjusting the molar ratios of the precursors. The physicochemical and microstructural characterization was initially performed using the UV-Vis technique to determine the presence of nanoparticles in suspension. Then, the morphology, size, and atomic structure were determined using XRD, SEM, and HAADF-STEM techniques, confirming the formation of a well-defined crystalline structure and homogeneous nanoalloy with an average particle size of less than 10 nm. Finally, the cyclic voltammetry technique evaluated the electrochemical activity of bimetallic AgPt nanoparticles supported on Vulcan XC-72 carbon for the ethanol oxidation reaction in an alkaline medium. Chronoamperometry and accelerated electrochemical degradation tests were performed to determine their stability and long-term durability. The synthesized AgPt (1:3)/C electrocatalyst presented significative catalytic activity and superior durability due to the introduction of Ag that weakens the chemisorption of the carbonaceous species. Thus, it could be an attractive candidate for cost-effective ethanol oxidation compared to commercial Pt/C.

Ultrafine PtRh-Co3O4 ternary alloy nanoparticles with enhanced electrocatalytic activity and long-term stability for alcohol electro-oxidation

To date, the development of structure-sensitive electrocatalysts is crucial, consisting of oxophilic metals and a conductive support with Pt-rich surfaces. In this study, PtRh-Co3O4 ternary alloy nanoparticles (∼2–3 nm) were uniformly distributed on carbon (PtRh-Co3O4/C) via a co-chemical reduction method. The chemical inertness and oxophilicity of Rh, along with the abundant oxygen defects of Co3O4, contributed to improving the kinetics of the methanol oxidation reaction (MOR) and ethanol oxidation reaction (EOR) in PtRh-Co3O4/C by promoting the scission of C-C and C-H bonds. PtRh-Co3O4/C displayed high intrinsic activity for both MOR (6.8 mA/cm2Pt) and EOR (3.17 mA/cm2Pt) due to the strong electronic, ligand, and bifunctional effects. Even after 7000 potential cycles, it retained 81% (MOR) and 84% (EOR) of its initial value, indicating extended stability. Compared to other Pt-based benchmark catalysts, PtRh-Co3O4/C exhibited higher CO tolerance, extended activity, and stability, making it a promising electrocatalyst with competitive performance for alcohol electro-oxidation.

One-pot synthesis of ultrafine trimetallic PtPdCu alloy nanoparticles decorated on carbon nanotubes for bifunctional catalysis of ethanol oxidation and oxygen reduction

Bifunctional catalysts for ethanol oxidation reaction (EOR) and oxygen reduction reaction (ORR) with high noble-metal utilization are highly beneficial to direct ethanol fuel cells (DEFCs). This study developed a ternary bifunctional catalyst composed of ultrafine PtPdCu alloy nanoparticles and carbon nanotubes (CNTs) support through a facile surfactant-free solvothermal route. The carboxyl terminal groups on CNTs ensure the confined growth of PtPdCu alloys (∼5 nm) and suppress Ostwald ripening of metallic active sites during electrochemical cycling. Consequently, PtPdCu/CNTs exhibits high mass activity (1.95 A mg−1) and specific activity (4.08 mA cm−2) toward EOR, which are 7.8 and 8.9 times higher, respectively, than those of commercial Pt/C. Furthermore, PtPdCu/CNTs displays superior stability toward EOR compared with its bimetallic counterparts (PtPd/CNTs and PtCu/CNTs). In addition, PtPdCu/CNTs exhibits the highest half-wave potential of 0.888 V among all electrocatalysts, indicating high ORR activity. Density functional theory calculations reveal that Pd and Cu mediate the electronic structure of Pt, leading to enhanced catalytic activity of PtPdCu/CNTs. The excellent catalytic property of PtPdCu/CNTs can also be attributed to the bifunctional effects of Pd/Cu and the interaction between metal and the carbon support. The proposed material is a contribution to the family of efficient ternary-alloy electrocatalysts for fuel cells.

A fast and inexpensive strategy to fabricate ZnO–Cu composites as non-precious electrocatalysts for ethanol oxidation reaction in alkaline media

A fast and inexpensive strategy to fabricate ZnO–Cu composites as non-precious electrocatalysts for ethanol oxidation reaction in alkaline media

Palladium nanoparticles anchored on MXene-based N-doped porous carbon nanosheets as an advanced electrocatalyst for ethanol oxidation

Pd-based electrocatalysts with advanced activity and durability can greatly accelerate the commercial process of direct ethanol fuel cells (DEFCs). However, Pd nanoparticles (NPs) are easily aggregated and deactivated during the ethanol oxidation reaction (EOR), which will restrict their electrocatalytic efficiency during the long-term running. To solve these problems, we develop new sandwich-like MXene-based N-doped porous carbon (NPCM) through carbonizing and acid etching of ZIF/MXene composite nanosheets. The derived NPCM nanosheets possess a highly ordered nano-porous and N-doped structure, which can be used as competitive catalyst supports to highly disperse Pd NPs and effectively avoid the aggregation and deactivation of Pd NPs. Meanwhile, the as-synthesized Pd/NPCM can offer more activity sites and more space for electrocatalysis reaction, leading to excellent CO tolerance. Thanks to the combination of MXene and ZIF, the designed Pd/NPCM electrocatalyst can offer connected channels for the fast diffusion of reactants and products. Impressively, the Pd/NPCM electrocatalyst exhibits a mass activity of 2237 mA·mgPd−1, which is 1.90 and 6.37 folds that of Pd/ZIF (1179 mA mgPd−1) and Pd/C (351 mA mgPd−1) electrocatalyst, respectively. This work not only explores a novel strategy for preparing advanced electrocatalyst support materials but also opens up their wide applications in DEFCs.

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.

Role of ZSM-5/AC hybrid support on the catalytic activity of Pd-Ag electrocatalysts towards ethanol oxidation: An experimental and kinetic study

Ethanol is a promising future fuel for Direct Alcohol Fuel Cells (DAFCs) and one of the significant half-cell reactions of this type of FC is ethanol oxidation reaction (EOR). However, the high cost, low selectivity of the catalyst towards complete oxidation of ethanol to CO2, and poor electrode kinetics are the key challenges in commercializing this technology. The way to mitigate these issues is to design affordable, stable, and highly efficient electrocatalysts. In this prospect, we developed a zeolite-carbon (ZSM-5/AC) supported Pd-Ag binary alloy catalysts via a simple co-impregnation followed by co-reduction method. The influence of ZSM-5/AC composite support and its composition on the activity of bimetallic Pd-Ag catalyst has been studied in detail. The PdAg/ZSM-5/AC electrocatalyst with 1:3 wt ratio of ZSM-5:AC exhibited better catalytic performance (10.9 mA cm−2) and tolerance towards intermediate species than PdAg/AC and Pd/AC electrocatalysts. The larger jf/jb (forward to backward current density ratio) of 2.8 for PdAg/ZSM-5/AC indicates lower carbonaceous species accumulation on the zeolite-modified electrode. Additionally, the material possessed a good long-term cyclic stability up to 500 cycles. The high activity observed for PdAg/ZSM-5/AC could be attributed to synergism between bimetallic catalysts and high surface area zeolite support. Overall, the study reveals that the Pd-Ag bimetallic and ZSM-5/AC are potentially efficient electrocatalyst and support, respectively, for the ethanol oxidation reaction in DEFC application.

Cation Exchange between CdSe Nanocrystals and Pd2+ Cations in Different Solvent Environments toward Phase-Dependent Ethanol Oxidation Electrocatalysis.

The cation-exchange strategy has shown great potential to create a large variety of inorganic nanostructures. We herein report the cation-exchange reactions between CdSe nanocrystals and Pd2+ cations in different solvent environments and identify three features not sufficiently noticed before: (i) the exchange between Cd2+ and Pd2+ cations could be fully achieved in both aqueous and organic solvents and is also independent of its parent CdSe crystal structures; (ii) the exchange between Cd2+ and Pd2+ cations in aqueous solvent results in amorphous Pd-Se exchanged products, while in organic solvent, it leads to a cubic Pd17Se15 phase; and (iii) the exchanged Pd17Se15 product exhibits better electrocatalysis for ethanol oxidation reaction in an alkaline medium relative to its amorphous counterpart and the commercial Pd/C catalyst.

Lead as an effective facilitator for ethanol electrooxidation on Rh catalyst in alkaline media: RhPb/C vs RhRu/C

Rh-based catalysts have attracted much attention due to their ability to efficiently break CC bonds in ethanol oxidation reaction(EOR), while pure Rh catalyst have low EOR activity. It is important to improve the EOR activity of Rh-based catalyst. Herein, we have been successfully synthesized carbon supported Rh, Rh-Pb, and Rh-Ru alloy catalysts. The catalytic activity of RhPb/C for ethanol oxidation is 0.96 mA/cm2, which is 8 times than that of Rh/C. The steady-state current density of RhPb/C at 0.5 V is 17 and 20 times higher than that of RhRu/C and Rh/C, respectively. The results show that adding a small portion of lead significantly enhanced the Rh-based catalyst activity, stability, and anti-poisoning ability during EOR in alkaline media. Moreover, the Tafel slope of RhPb/C catalyst for EOR is 118 mVdec−1, which is similar with that of Pt/C(116 mVdec−1), while the Tafel slope of RhRu/C is 77 mVdec−1, similar to that of Rh/C(87 mVdec−1). The CO-stripping potential of RhRu/C, Rh/C and RhPb/C is 0.535 V, 0.573 V and 0.601 V, respectively. Combined with the cyclic voltammetry, chronoamperometry, CO-stripping and Tafel analysis, it is concluded that for RhRu/C catalyst, the improvement of EOR is mainly attributed to the bifunctional mechanism, while for RhPb/C catalyst, the ensemble effect and the electronic effect of Pb is essential to the improvement of EOR.

Heterostructure PtNi supported by Pd nanosheets high-performance catalysts for multifunctional fuel cell

Platinum (Pt) based catalysts have multiphase structure, such as two-dimensional (2D) nanosheets structure, with a large specific surface area and high atomic utilization ratio, and a large contact area with carbon support, which promotes the combination of catalyst and support, and improves the activity of catalyst. However, there are still many difficulties in the synthesis of 2D polymetallic alloy nanosheet catalysts. Herein, we synthesized palladium nanosheets (Pd NSs) catalyst with smooth surface structure via solvothermal method, smooth surface structure palladium platinum nanosheets (PdPt NSs) and palladium platinum nickel island particle nanosheets (PdPtNi IPNSs) catalyst. Compared with commercial TKK-Pt/C, the prepared PdPtNi IPNSs catalyst has better catalytic performance for oxygen reduction reaction (ORR), ethanol oxidation reaction (EOR) and methanol oxidation reaction (MOR). This work provides a simple and feasible strategy for the synthesis of stable and efficient polymetallic 2D alloy nanostructured catalysts.

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.

Electro-reforming of bioethanol produced by sugar fermentation on a Pt-Ni anodic catalyst supported on graphene nanoplatelets

A study of the electro-reforming of bioethanol produced through sugar fermentation using a Pt-Ni supported on graphene nanoplatelets (Pt-Ni/GNPs) anodic catalyst is presented here. The physicochemical characterization of the anodic catalyst showed a good dispersion and small sizes of the metallic crystallite. Then, the evolution of the electrochemical activity over time of three bioethanol batches with different initial sugar concentrations of 150, 200 and 250 g·L−1 was explored in a Proton Exchange Membrane (PEM) electrolysis cell. A general growth in the ethanol concentration over time was observed for all the bioethanol batches, along with an improvement in the electrochemical activity, principally associated to ethanol oxidation reaction (EOR). Additionally, the presence of non-fermented sugar and other molecules formed during fermentation exhibited a negative contribution in the electrochemical activity. The bioethanol batch with an initial sugar concentration of 200 g·L−1 presented the best compromise between bioethanol production, fermentation time and electrochemical activity, achieving competitive current densities (∼285 mA·cm−2 at 1.2 V) and energy consumption values (21.6 kWh·kgH2−1 at 100 mA·cm−2) to those from other publications using synthetic ethanol-water solutions. These results demonstrated the interest of the used Pt-Ni/GNPs anodic catalyst for the renewable hydrogen production via direct electro-reforming of liquid biofuels.

Quantum Catalytic Performance for the Hydrogen Evolution Reaction and the Ethanol Oxidation Reaction in Topological Edge States of SrPd and BaPd Semimetal Monolayers: A Theoretical Study

Quantum Catalytic Performance for the Hydrogen Evolution Reaction and the Ethanol Oxidation Reaction in Topological Edge States of SrPd and BaPd Semimetal Monolayers: A Theoretical Study

Interface synergism and engineering of Pd/Co@N-C for direct ethanol fuel cells

Direct ethanol fuel cells have been widely investigated as nontoxic and low-corrosive energy conversion devices with high energy and power densities. It is still challenging to develop high-activity and durable catalysts for a complete ethanol oxidation reaction on the anode and accelerated oxygen reduction reaction on the cathode. The materials’ physics and chemistry at the catalytic interface play a vital role in determining the overall performance of the catalysts. Herein, we propose a Pd/Co@N-C catalyst that can be used as a model system to study the synergism and engineering at the solid-solid interface. Particularly, the transformation of amorphous carbon to highly graphitic carbon promoted by cobalt nanoparticles helps achieve the spatial confinement effect, which prevents structural degradation of the catalysts. The strong catalyst-support and electronic effects at the interface between palladium and Co@N-C endow the electron-deficient state of palladium, which enhances the electron transfer and improved activity/durability. The Pd/Co@N-C delivers a maximum power density of 438 mW cm−2 in direct ethanol fuel cells and can be operated stably for more than 1000 hours. This work presents a strategy for the ingenious catalyst structural design that will promote the development of fuel cells and other sustainable energy-related technologies.

Free–templated synthesis of N–doped PtCu porous hollow nanospheres for efficient ethanol oxidation and oxygen reduction reactions

Hollow metal–based nanoparticles usually possess improved electrocatalytic properties, but challenge in their tedious and complicated synthetic protocols. In this paper, a one–step template–free method is newly developed, whereby the N–doped PtCuCo polycrystalline nanospheres can be spontaneously transformed to the N–doped PtCuCo porous hollow nanospheres. Specifically, the Kirkendall voids form with the rapid removal of transition metals in the starting nanoparticles by a special diffusion–oxidation–complexation effect. The N–doped Pt7Cu hollow nanospheres with ultrathin porous shells are formed after removing the surface oxides. A large electrochemical surface area of 97.9 m2 gPt–1 is established with the formation of abundant open channels in the hollow nanospheres. With the synergetic effect of the introduction of Cu, N components and the high Pt utilization, the N–doped Pt7Cu porous hollow nanospheres demonstrate greatly enhanced electrocatalytic mass activities of 2.14 A mgPt–1 and 1.42 A mgPt–1 toward ethanol oxidation and oxygen reduction reactions, respectively.

NiO nanocrystal anchored on pitaya peel-derived carbon laminated mesoporous composites for the electrocatalytic oxidation of ethanol

Direct ethanol fuel cell (DEFC) is a kind of energy conversion device with potential application prospect. The development of non-precious metal-based catalysts with high activity and stability is of great necessary for ethanol oxidation reaction (EOR). Here, the laminated composites with hollow structure were synthesized by a simple strategy, which consists of NiO nanocrystals anchored on pitaya peel-derived carbon (PPC). The electrochemical tests show that the optimal electrocatalyst (NiO@PPC-600) exhibits excellent catalytic activity for EOR with the current density (j) of 231.8 mA cm-2 (1.6 V vs. RHE) under alkaline conditions. Furthermore, the j retention rate (83.0%) of NiO@PPC-600 exceeds that (16.4%) of Pt/C in the long-term 12 h EOR test. The superior properties of the NiO@PPC-600 are mainly ascribed to its mesoporous structure that facilitates electrolyte and electron transfer and the PPC substrate that avoids the shedding of NiO nanocrystals, it has moderate lattice defects and graphitization, minimal contact resistance and Tafel slope. The work provides a simple route to prepare a high-efficient electrocatalyst for EOR, and the reuse of biomass pitaya peel (PP) is realized.