Performance For Ethanol Electro-oxidation Research Articles

Additive-free Electrodeposition of SnCoNi Trimetallic Catalysts for Ethanol Electrooxidation

SnCoNi catalysts were synthesized via electrodeposition, with and without citric acid, to assess their ethanol electrooxidation performance. The additive-free catalyst exhibited superior properties, including lower charge transfer resistance and a smaller Tafel slope compared to the citric acid-modified catalyst. Chronoamperometry testing further revealed better electrochemical stability for the additive-free catalyst, with less current loss over time. Cyclic voltammetry confirmed the enhanced ethanol oxidation activity with a relatively high current density. The improved performance is attributed to better mass transport, active site exposure, and the synergistic effects of Sn, Co, and Ni in the additive-free catalyst, making it more efficient for ethanol electrooxidation. These findings suggest that the additive-free catalyst exhibits more favorable properties for ethanol electrooxidation compared to its citric acid-modified counterpart.

Tuning electronic structure of Pt to enhance ethanol electrooxidation performance of SnO2 patched ultrathin PtRhNi nanowires

Tuning electronic structure of Pt to enhance ethanol electrooxidation performance of SnO2 patched ultrathin PtRhNi nanowires

Enhancing ethanol electrooxidation stability catalyzed by Pt with SnO2 modified graphene as support

Developing catalysts for the stable electrooxidation of ethanol have been a goal pursued by scientists. The present work reports a facile synthesis of catalysts with a double junction structure of Pt and SnO2 on graphene (Pt/SnO2GN) through sol–gel combined with glycol hydrothermal reduction method. The physicochemical analyses show that the reduced Pt uniformly dispersed on GN is located adjacent to SnO2 and has electronic interaction with the composite carrier. The electrochemical results exhibit that Pt/SnO2GN has better catalytic performance for ethanol electrooxidation than PtSnO2/GN and PtSn/GN. The ethanol oxidation peak current density on Pt/SnO2GN, after 1500 cycles of voltammetric testing, can still maintain 99.2% of the highest. The excellent catalytic stability of Pt/SnO2GN is ascribed to the double junction structure and the appropriate interaction between Pt and SnO2 on GN, which enlarge the ECSA of Pt, improve the structural integrity, accelerate the charge transfer kinetics and increase the CO tolerance.

PtAu Nanoparticle as a Catalyst for Ethanol Electrooxidation

In this work, PtAu nanoparticles were successfully synthesized using the electrodeposition technique. The nanoparticles obtained were irregularly spherical in shape and in the size range of 20-200 nm. X-ray diffraction (XRD) confirmed that the formed PtAu nanoparticles were alloys, because they showed a peak of 2θ in the region between Pt and Au metals, namely at 2θ 39.15˚ and 45.53˚. The cyclic voltammetry (CV) test showed that the PtAu catalyst has an ethanol electrooxidation activity of 22.9 mA/cm2, 11 times higher than the Pt catalyst previously synthesized using the same technique and conditions. In addition, at 300–1000 cycles the ethanol electrooxidation performance is fairly constant, indicating that this catalyst is quite stable. Interestingly alloying Pt with Au also increases the poisoning resistance of the catalyst from CO or other intermediate species. Thus, the use of PtAu catalysts can effectively increase catalytic activity, maintain stability of the catalyst, and reduce the possibility of poisoning by intermediate species.

Pt Atomic Layers with Tensile Strain and Rich Defects Boost Ethanol Electrooxidation.

Surface and strain engineering are two effective strategies to improve performance; however, synergetic controls of surface and strain effects remains a grand challenge. Herein, we report a highly efficient and stable electrocatalyst with defect-rich Pt atomic layers coating an ordered Pt3Sn intermetallic core. Pt atomic layers enable the generation of 4.4% tensile strain along the [001] direction. Benefiting from synergetic controls of surface and strain engineering, Pt atomic-layer catalyst (Ptatomic-layer) achieves a remarkable enhancement on ethanol electrooxidation performance with excellent specific activity of 5.83 mA cm-2 and mass activity of 1166.6 mA mg Pt-1, which is 10.6 and 3.6 times higher than the commercial Pt/C, respectively. Moreover, the intermetallic core endows Ptatomic-layer with outstanding durability. In situ infrared reflection-absorption spectroscopy as well as density functional theory calculations reveal that tensile strain and rich defects of Ptatomci-layer facilitate to break C-C bond for complete ethanol oxidation for enhanced performance.

Engineering three-dimensional superstructure of Pd aerogel with enhanced performance for ethanol electrooxidation

• Pd aerogel illustrates great electrocatalytic activity and durability toward ethanol oxidation reaction. • Pd aerogel was prepared through drying Pd hydrogel by supercritical CO 2. • One-pot and eco-friendly synthesis method for the generation of Pd aerogel assembled by nanochaines. A new, straightforward, and one-step method to synthesize self-supported three-dimensional (3D) Pd aerogel utilizing formaldehyde as a reducing agent in an alkaline medium was introduced for the first time in this research. The physicochemical properties investigation of Pd aerogel was conducted using x-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM) analyses. The electrocatalytic activity of prepared self-assembled nanoarchitecture toward ethanol electrooxidation was examined utilizing cyclic voltammetry (CV) and chronoamperometry (CA). The Pd aerogel on account of the unique morphology and numerous open interconnected pores revealed superior electrocatalytic activity (1016 mAmg -1 pd ) and enhanced durability toward ethanol electrooxidation in comparison to Pd/C nanocatalyst (281 mAmg -1 pd ). The larger electrochemical active surface area of the Pd aerogel catalyst (79.14 m 2 g −1 ) led to a boost in current density in the electrooxidation of ethanol in comparison to the Pd/C catalyst (12.34 m 2 g −1 ). We believe that our unique method can be used as a fast and powerful method for the synthesis of used catalysts in various energy-related systems.

Synthesis of Pt-CuO/RuO2 composites by dealloying from metallic glass and their ethanol electrooxidation performance

Synthesis of the noble metal-based catalyst with a multi-composite system, unique structure, and special morphology is very important for boosting the catalytic performance while reducing the noble metal use. Here, attractive island/nanosheet structural Pt-CuO/RuO2 composites were constructed on the surface of Cu-Al-Ce-based metallic glass ribbons containing a small amount of Pt and Ru by dealloying. The surface morphology of these binder-free, self-supported flexible hybrid electrocatalysts can be facilely regulated in a controllable way. Electrochemical measurements revealed the islands-nanosheets/glassy hybrid electrocatalysts obtained from Cu60Al10Ce26Pt3Ru1 MG ribbon exhibit superior electrocatalytic performance toward ethanol oxidation with a high current density of ∼215 mA⋅cm−2 and better stability, outperforming commercial Pt/C and other dealloyed products. This can be attributed to the enlarged surface area, the abundant Pt-rich active sites, and the synergistic effects of Pt, Ru/RuO2, and CuO in the removal of poisoning intermediates. This work provides a new perspective for the design of high-active binder-free composite catalysts based on multicomponent metallic glass with low noble metal usage.

Hierarchical AgAu alloy nanostructures for highly efficient electrocatalytic ethanol oxidation

The ethanol oxidation reaction is a significant anodic reaction for direct alcohol fuel cells. The most commonly used catalysts for this reaction are Pt-based materials; however, Pt-based electrocatalysts cause carbon monoxide poisoning with intermediates before the complete transformation of alcohol to CO2. Herein, we present hierarchical AgAu bimetallic nanoarchitectures for ethanol electrooxidation, which were fabricated via a partial galvanic reduction reaction between Ag and HAuCl4. The ethanol electrooxidation performance of the optimal AgAu nanohybrid was increased to 1834 mA mg−1, which is almost 10 times higher than that of the pristine Au catalyst (190 mA mg−1) in alkaline solutions. This was achieved by introducing Ag into the Au catalyst and controlling the time of the replacement reaction. The heterostructure also presents a higher current density than that of commercial Pt/C (1574 mA mg−1). Density functional theory calculations revealed that the enhanced activity and stability may stem from unavoidable defects on the surface of the integrated AgAu nanoarchitectures. Ethanol oxidation reactions over these defects are more energetically favorable, which facilitates the oxidative removal of carbonaceous poison and boosts the combination with radicals on adjacent Au active sites.

Synthesis of Free‐Standing Alloyed PdSn Nanoparticles with Enhanced Catalytic Performance for Ethanol Electrooxidation

AbstractAlloyed Pd‐based nanostructured materials have been demonstrated as highly active fuel cell anode electrocatalysts for the alcohol oxidation reaction. Challenges remain in the controlled synthesis of freestanding PdM alloys catalysts through optimization of their interfacial and surface structures, which can prevent degradation and poor durability. Herein, we present an oil‐bath‐based approach to synthesize PdxSny nanoparticles (NPs) with L‐ascorbic acid (AA) as a reducing agent and cetyltrimethylammonium bromide as a structure‐directing agent. PdxSny NPs (x/y=0.66, 0.83, and 1.11) show a particular freestanding shape. Among the three alloys, Pd20Sn24 (x/y=0.83) NPs have the best electrocatalytic activity (2018 mA mg−1) toward the ethanol oxidation reaction (EOR). The enhanced performance of PdxSny NPs might be attributed to i) a change in the electron structure of Pd, ii) varied interatomic distance within a unit cell, and iii) weak adsorption of in‐situ generated oxygen‐containing (e. g. *OH and Pd−O) or carbon‐containing (e. g. *CH3CHOH, *CH3CHO, and *CH3CO) intermediate species. Experimental data proposed that higher catalytic temperature, higher pH values, and higher ethanol concentration should accelerate each step of electrooxidation of the EOR.

One-Pot Synthesis of Ternary Alloy Hollow Nanostructures with Controlled Morphologies for Electrocatalysis.

The rational design and synthesis of multimetallic hollow nanostructures (HNSs) have been attracting great attention due to their structural and compositional advantages for application in electrocatalysis. Herein, the one-pot synthesis of Pd-Pt-Ag ternary alloy HNSs with controllable morphologies through a self-templating approach without any pre-synthesized templates is reported. Simultaneous reduction of multiple metal precursors by ascorbic acid in the presence of cetyltrimethylammonium chloride (CTAC) yielded initially metastable Pd-Ag nanocrystals, which can act as a self-template, and subsequent galvanic replacement and reduction led to the formation of final Pd-Pt-Ag HNSs. The size and hollowness (the ratio of inner cavity diameter to outer diameter) of the HNSs could be tuned through control over the concentration of CTAC. This can be attributed to the manipulated reduction kinetics of multiple metal precursors with the change in the CTAC concentration. The prepared Pd-Pt-Ag HNSs exhibited improved catalytic performance for ethanol electro-oxidation due to their large active surface areas and ternary alloy composition.

Bimetallic PtIr nanoalloy on TiO2-based solid solution oxide with enhanced oxygen reduction and ethanol electro-oxidation performance in direct ethanol fuel cells

Elevating the electrocatalytic performance of both cathode and anode catalysts is critical to the advancement and widespread utilization of low-temperature fuel cells.

Ethylene glycol assisted solvo-hydrothermal synthesis of NGr-Co3O4 nanostructures for ethanol electrooxidation

Different morphologies of Co3O4 nanostructures grown on nanographitic flakes have been synthesized based on the decomposition of cobalt acetate precursor in water, ethylene glycol and water (50%)-ethylene (50%) solution at 180 °C for 18 h via a solvo-hydrothermal process. A subsequent electrophoretic deposition process is used to form composite layers on stainless steel plates. The composite layer fabricated in the water (50%)-ethylene (50%) solution is found to have the best electrocatalytic performance for ethanol electrooxidation due to the hierarchical nanoporous microstructures of Co3O4 exhibiting the lowest onset voltage for ethanol electrooxidation (around −0.3 V vs. Ag/AgCl) among the fabricated electrocatalyst layers. Moreover, the ethanol electrooxidation current for the electrode fabricated in the water (50%)-ethylene glycol (50%) reaches roughly 6.6 mA/cm2, while it is about 3.3 mA/cm2 at 0.5 V (vs. Ag/AgCl) for the electrode fabricated in pure ethylene glycol (values obtained after 1-h stability tests). The electrode fabricated in pure water is confirmed to not exhibit significant ethanol electrooxidation.

Graphene-nickel nitride hybrids supporting palladium nanoparticles for enhanced ethanol electrooxidation

The AG-Ni 3 N hybrid was designed for anchoring Pd nanoparticles which exhibits outstanding performance for ethanol electrooxidation. In addition, the AG-Ni 3 N support promotes the adsorption of OH and then facilitates the oxidation removal of CO intermediates. Electrocatalysts for ethanol oxidation reaction (EOR) are generally limited by their poor durability because of the catalyst poisoning induced by the reaction intermediate carbon monoxide (CO). Therefore, the rapid oxidation removal of CO intermediates is crucial to the durability of EOR-based catalysts. Herein, in order to effectively avoiding the catalyst CO poisoning and improve the durability, the graphene-nickel nitride hybrids (AG-Ni 3 N) were designed for supporting palladium nanoparticles (Pd/AG-Ni 3 N) and then used for ethanol electrooxidation. The density functional theory (DFT) calculations demonstrated the introduction of AG-Ni 3 N depresses the CO absorption and simultaneously promotes the adsorption of OH species for CO oxidation removal. The fabricated Pd/AG-Ni 3 N catalyst distinctively exhibits excellent electroactivity with the mass catalytic activity of 3499.5 mA mg −1 on EOR in alkaline media, which is around 5.24 times higher than Pd/C (commercial catalyst). Notably, the Pd/AG-Ni 3 N hybrids display excellent stability and durability after chronoamperometric measurements with a total operation time of 150,000 s.

CoP/RGO-Pd Hybrids with Heterointerfaces as Highly Active Catalysts for Ethanol Electrooxidation.

The ethanol oxidation reaction is of critical importance to the commercial viability of direct ethanol fuel cell technology. However, owing to the poor C-C bond cleavage capability, almost all ethanol oxidation is incomplete and suffers from low selectivity toward the C1 pathway. Herein, under the support of theoretical calculations that the heterointerfaces between CoP and Pd can reduce the energy barrier of C-C bond cleavage, rich heterointerfaces in CoP/RGO-Pd hybrids were designed to improve ethanol electrooxidation performance through enhancing the selectivity toward the C1 pathway. The experimental results show that the faradaic efficiency of the C1 pathway of CoP/RGO-Pd hybrids is as high as 27.6%, surpassing most reported catalysts in the literature. As a result of this enhancement, CoP/RGO-Pd10 exhibits mass activity as high as 4597 mA·mgPd-1 and specific activity as high as 10 mA·cm-2, which are much higher than those of other Pd-based electrocatalysts.

Facile synthesis of PdAg nanocatalysts on CeO2/C composite supports as high-performance catalysts toward alkaline ethanol electro-oxidation

PdAg nanocatalysts on CeO2/C supports were prepared using a facile, environment-friendly method and exhibited superior performance for ethanol electro-oxidation.

Ir3Pb alloy nanodendrites with high performance for ethanol electrooxidation and their enhanced durability by alloying trace Au

Porous Ir3Pb nanodendrites exhibit excellent activity and superior CO2 selectivity for the EOR under acidic conditions, and their durability can be enhanced dramatically by alloying trace Au.

Carbon supported PdSn nanocatalysts with enhanced performance for ethanol electrooxidation in alkaline medium

In this work, simple chemical reduction method is used to prepare Pd–Sn nanocatalysts supported on carbon for ethanol electro-oxidation in alkaline environment using ethylene glycol as reductant. The composition, structure and morphologies of PdSn/f-C catalysts are investigated by X-ray diffraction, X-ray photoelectron spectroscopy, energy dispersive X-ray and transmission electron microscopy. The electro-chemical activity and durability of as-obtained PdSn/f-C nanocatalysts are investigated and determined by cyclic voltammetry and Chronoamperometric measurements. The obtained results demonstrate that as prepared PdSn/f-C nanocatalysts have uniform dispersion and small particle size. In addition to, the as prepared PdSn/f-C nanocatalysts have higher electro-chemical activity and better stability toward EOR in alkaline environment than those of Pd/f-C and commercial Pd/C (JM) nanocatalysts. Specifically, the electro-catalytic activity of Pd1.5Sn/f-C nanocatalyst (3413.3mAmgPd−1) is almost 8.6 times higher than Pd/C (JM) nanocatalyst (355.2 mAmgPd−1), which has competitive power among reported Pd–Sn catalysts. These results indicate that the uniform carbon supported PdSn nanostructure are promising electrocatalysts for direct ethanol fuel cells.

Single-crystalline ultrathin nanofilms of Ni aerogel with Ni(OH)2 hybrid nanoparticles towards enhanced catalytic performance for ethanol electro-oxidation

Abstract In this study, we reported a novel and facile synthesis of self-supported three-dimensional (3D) Ni aerogel using cellulose hydrogel as template followed by removing the template under a moderate condition. The as-prepared Ni aerogel composed of Ni(OH)2 ultrathin nanofilms and Ni(OH)2 hybrid nanoparticles had hierarchical porous structure with a considerable specific surface area of 100 m2 g−1, which was beneficial to the enhanced catalytic activity towards ethanol electro-oxidation. Additionally, the self-supported 3D structure of Ni aerogel with free-carbon supports showed a positive effect on the stability of the catalysts. Electrochemical measurements revealed that a high peak current density for Ni aerogel achieved about 27.6 mA cm−2 in an electrolyte of 1.0 M KOH with 0.1 M ethanol, which was 5 times higher than that on alone Ni nanoparticles. Meanwhile, the Rct of Ni aerogel catalyst was only 0.88 Ω cm−2 after the CA measurements for 1800s, which was much smaller than commercial Ni nanoparticles and other similar catalysts reported. The enhanced electrocatalytic performance for ethanol electro-oxidation can be ascribed to the high surface area and predominant properties of above-mentioned special materials structure. This novel Ni aerogel and its excellent properties have great prospects in the application of electro-oxidation catalyst.

When ternary PdCuP alloys meet ultrathin nanowires: Synergic boosting of catalytic performance in ethanol electrooxidation

Noble metal-phosphorus (NMP) alloys have received special attention in the electrocatalysis. Despite a few efforts, the fabrication of anisotropic multicomponent NMPs is largely unsuccessful. Here we develop a facile yet general surfactant-directed aqueous synthesis for one-dimensional (1D) ternary PdCuP alloy nanowires (NWs), and demonstrate their structural and compositional synergy in promoting catalytic performance towards ethanol electrooxidation. Anisotropic PdCuP NWs with an ultrathin diameter of 2.5 nm and ultralong length of hundreds of nanometers are synthesized via in-the-columnar epitaxial growth of crystalline alloys along columnar assemblies of amphiphilic dioctadecyldimethylammonium chloride (DODAC) by NaH2PO2 as the reducing agent and P source simultaneously. This protocol is also synthetically universal, enables the controllability in tuning the P contents and elemental compositions of multicomponent NMP NWs (for example, binary PdP, ternary PdAgP and PdPtP NWs). With synergistically structural and compositional merits, ultrathin PdCuP NWs display dramatically enhanced ethanol electrooxidation performance with a superior mass activity of 6.7 A mgPd−1, which is 9.4 fold higher than commercial Pd nanoparticle catalyst and also surpasses previously reported nanocatalysts. This approach will provide a new access for rational design of anisotropic non-metal-alloyed multicomponent noble metal-based nanocatalysts with desirable functions and synergies for a wide range of (electro)catalytic applications.

Efficient Ni(OH)2 Supported Ultra-Low Content of Pt Electrocatalyst for Ethanol Oxidation in Alkaline Solution

Background: Direct ethanol fuel cells have gained considerable attention as promising sustainable green power sources for portable electronic devices and automotive propulsion systems. The electrocatalyst is one of the key parameters in DEFCs. However, the current electrocatalyst still suffers from high price due to a relatively large amount of noble metal used, or relatively low activity if non-noble metal was employed. Therefore, the design and fabrication of high-efficient electrocatalyst with low-content of noble metal is still of interest. Methods: Methods: Ni(OH)2 nanoflakes supported ultra-low content of Pt (Pt/Ni(OH)2) electrocatalyst was obtained via microemulsion, impregnation and chemical reduction processes. The Pt/Ni(OH)2 electrocatalyst was characterized by SEM, TEM, XRD and FTIR, and its performance for ethanol electro- oxidation was evaluated by cyclic voltammetry, Tafel and current-time curves. Results: TEM result showed that Pt NPs with sizes of ca. 4-6 nm were highly dispersed on the Ni(OH)2 nanoflakes, indicative of the successful preparation of Pt/Ni(OH)2. No peaks related to Pt NPs were observed in the XRD pattern of Pt/Ni(OH)2, revealing a low content and/or high dispersion of Pt NPs. The electrochemical investigation showed that the Pt/Ni(OH)2 electrode presented a superior catalytic performance and stability for ethanol electro-oxidation in alkaline solution. Conclusion: The Pt/Ni(OH)2 electrode with nominal 0.62 wt.% of Pt was successfully synthesized and showed an excellent catalytic activity and stability toward ethanol electro-oxidation mainly due to its porous structure, high dispersion of Pt and formation of NiOOH facilitating oxidation of ethanol. The acetate species was the major product during ethanol electro-oxidation.