Catalysts For Ethanol Oxidation Reaction Research Articles

Bio-extract mediated green synthesis of bi-functional ammonium cobalt phosphate nanoflakes electrode/catalyst for supercapattery and ethanol oxidation

The present study proposes a low-cost, green technique to the synthesis of bi-functional ammonium cobalt phosphate for energy storage and conversion applications. The comprehensive physiochemical investigations are carried out using various spectral-analytical techniques. The results of phase and surface morphology confirm the formation of an orthorhombic crystal structure with flakes-like microstructure. With a maximal specific capacity of 448.3 mAhg−1 at 2 mAcm−2, bio-solvent driven NH4CoPO4·H2O with graphene oxide (GO) nanoflakes demonstrates exceptional battery-type energy storage capabilities. As constructed supercapattery device exhibits a high specific energy of 85.4 Wh kg−1 at power output of 1283 W kg−1 and 81 % stability after 5000 cycles. Further exploration as a non-precious metal-based catalyst for ethanol oxidation reaction (EOR), NH4CoPO4·H2O /GO showed a high peak current density of 83.4 mAcm−2 at 20 mVs−1. Coupled oxygen/hydrogen evolution processes are investigated in 1 M KOH in order to acquire a better understanding of the catalyst's EOR activity. The NH4CoPO4·H2O/GO sample exhibited the lowest overpotentials of |ηOER@10| = 420 mV, and |ηHER@10| = 112 mV, with Tafel slopes of 169.8 mV dec−1 for OER and 132.8 mV dec-1 for HER, respectively. This is due to the catalyst's slow OH adsorption during OER and the limited H*recombination during HER. Therefore, this approach provides a green and cost-effective method to synthesis efficient bi-functional electrode/catalysts for supercapattery and alkaline fuel cells.

B doped cobalt-nickel bimetallic phosphide as bifunctional catalyst for ethanol oxidation reaction and hydrogen evolution reaction

The ethanol oxidation reaction (EOR) is an ideal alternative to the oxygen evolution reaction (OER) towards energy efficient hydrogen production. Here, the chrysanthemum-shaped B doped cobalt-nickel bimetallic phosphide with heterogeneous structure grown on nickel foam (B-Ni2P/CoP/NF) are synthesized and can act as a high activity bifunctional electrocatalysts for both the hydrogen evolution reaction (HER) and EOR. In 1.0 M KOH, the obtained catalyst shows good activity and excellent long-term stability (no decay after 108 h) for HER, with an overpotential of only 33 mV (vs. RHE) to reach a current density of 10 mA cm−2. The calculation of turnover frequency (TOF) and transfer coefficient (β) prove that the catalyst has good intrinsic catalytic activity, For EOR, in 1.0 M KOH+1.0 M C2H5OH solution, the B-Ni2P/CoP/NF catalyst requires only 1.45 V (vs. RHE) oxidation potential to reach the current density of 50 mA cm−2, which is 270 mV less than OER. Using B-Ni2P/CoP/NF as a bifunctional catalyst, the current density of 20 mA cm−2 can be achieved with only 1.48 V cell voltage in 1.0 M KOH+ 1.0 M C2H5OH solution, which is remarkably lower than the required cell voltage of water electrolysis (1.63 V) to achieve the same current density. This study demonstrates an efficient bimetallic phosphide as earth-abundant bifunctional electrocatalysts for green hydrogen production coupled with electrolysis of ethanol.

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.

Electrocatalytic ethanol-to-CO2 selectivity on the Ir electrode: A quasi-quantitative electrochemical infrared absorption spectroscopic investigation

Ir has long been regarded as an alternative ethanol-to-CO2 electrocatalyst, but little is known about the ethanol oxidation reaction (EOR) mechanism on Ir, especially the C1 pathway selectivity. Thereby, in situ quasi-quantitative electrochemical infrared absorption spectroscopy (QEIAS), consisting of total-reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS), infrared absorption spectroscopy (IRAS), and transmission infrared absorption spectroscopy (TIAS) with a thin-layer flow cell, is established to probe it. Initially, the well-accepted EOR dual-pathway mechanism is confirmed via ATR-SEIRAS and IRAS. Ir-Had species (ca. 2040 cm−1), originating from the ethanol dissociation at low potentials, are observed for the first time to replenish the reaction process. Based on it, the apparent Faradaic efficiency of the C1 pathway (FEC1) is readily estimated to be as high as 76.4% (0.7 V) in acidic media. The quantitative analysis of reaction residual verifies these FEC1 results through high-performance liquid chromatography (HPLC), and a relative error of only 2–9% exists between the two methods. Thus, Ir might be more efficient for ethanol complete oxidation than other Pt-group metallic catalysts, especially in acidic media. This work could be necessary for the rational design of Ir-based EOR catalysts with high C1 pathway selectivity and low over-potential for direct ethanol fuel cells.

Composition engineering of carbon nanotubes supported PtxRhRu ultrafine nanocatalysts for ethanol electro-oxidation: Elucidating the role of trimetallic sites

The practice of direct ethanol fuel cells (DEFCs) is hindered by insufficient activity of anode Pt-based catalyst for ethanol oxidation reaction (EOR), while alloying Rh and Ru to Pt is hopeful to solve the problem by simultaneously enhancing CC cleavage and decreasing poisoning; and Ru owning better stability and activity than usually doped Sn in alkaline electrolyte. Nevertheless, Pt-Rh-Ru catalysts were rarely reported. In this work, to avoid random trials, the “composition engineering” strategy was applied to design PtxRhRu catalysts. The optimal x range was predicted by DFT. Then, carbon nanotubes supported PtxRhRu ultrafine nanoparticles (PtxRhRu/CNTs) were synthesized and characterized. The synthetic mechanism was also studied. EOR tests show that, in line with the forecast, Pt4RhRu/CNTs (∼1.9 nm) exhibit the highest activity (5.85 mA·cm−2), 6.97 times of commercial Pt/C, and higher than most reports. The selectivity, stability and durability are also excellent. DFT analysis reveals the role of Pt-Rh-Ru site for the first time, that the optimal route on PtxRhRu is changed. New route clearly enhances complete ethanol oxidation and reduces poisoning. Bifunctional mechanism on Pt-Rh-Ru site was also confirmed. This study may provide new perspective for material design; the products are also promotive for DEFCs into practice.

Electrodeposition-Assisted Crystal Growth Regulation of PdBi Clusters on Carbon Cloths for Ethanol Oxidation.

Carbon-supported Pd-based clusters are one of the most promising anodic catalysts for ethanol oxidation reaction (EOR) due to their encouraging activity and practical applications. However, unclear growth mechanism of Pd-based clusters on the carbon-based materials has hindered their extensive applications. Herein, we first introduce multi-void spherical PdBi cluster/carbon cloth (PdBi/CC) composites by an electrodeposition routine. The growth mechanism of PdBi clusters on the CC supports has been systemically investigated by evaluating the selected samples and tuning their compositions, which involve the big difference in standard redox potential between Pd2+/Pd and Bi3+/Bi and easy adsorption of Bi3+ on the surface of Pd-rich seeds. Benefitting from the ensembles of many nanocrystal subunits, multi-void spherical PdBi clusters can present collective properties and novel functionalities. In addition, the outstanding characteristics of CC supports enable PdBi clusters with stable nanostructures. Thanks to the unique structure, Pd20Bi/CC catalysts manifest higher EOR activity and better stability compared to Pd/CC. Systematic characterizations and a series of CO poisoning tests further confirm that the dramatically enhanced EOR activity and stability can be attributed to the incorporation of Bi species and the strong coupling of the structure between PdBi clusters and CC supports.

Surface Ligand Modification on Ultrathin Ni(OH)2 Nanosheets Enabling Enhanced Alkaline Ethanol Oxidation Kinetics.

The ethanol oxidation reaction (EOR) is an economical pathway in many electrochemical systems for clean energy, such as ethanol fuel cells and the anodic reaction in hydrogen generation. Noble metals, such as platinum, are benchmark catalysts for EOR owing to their superb electrochemical capability. To improve sustainability and product selectivity, nickel (Ni)-based electrocatalysts are considered promising alternatives to noble-metal EOR. Although Ni-based electrocatalysts are relieved from intermediate poisoning, their performances are largely limited by their relatively high onset potential. Therefore, the EOR usually competes with the oxygen evolution reaction (OER) at working potentials, resulting in a low EOR efficiency. Here, we demonstrate a strategy to modify the surface ligands on ultrathin Ni(OH)2 nanosheets, which substantially improved their catalytic properties for the alkaline EOR. Chemisorbed octadecylamine ligands could create an alcoholophilic layer at the nanosheet surface to promote alcohol diffusion and adsorption, resulting in outstanding EOR activity and selectivity over the OER at higher potential. These non-noble-metal-based 2D electrocatalysts and surface ligand engineering showcase a promising strategy for achieving high-efficiency electrocatalysis of EOR in many practical electrochemical processes.

Effective ethanol-to-CO2 electrocatalysis at iridium-bismuth oxide featuring the impressive negative shifting of the working potential

Since low overpotential for the anodic ethanol oxidation reaction (EOR) can favor the higher output voltage and power of direct ethanol fuel cells (DEFCs), it is critical to design new EOR catalysts with efficient ethanol-to-CO2 activity at low applied potentials. Thereby, carbon-supported Ir-Bi2O3 (Ir-Bi2O3/C) catalysts with highly dispersive bismuth oxide on the iridium surface are designed and prepared, which can merit splitting the ethanol C–C bond and promoting the oxidation of C1 intermediates at the bifunctional interfaces. The as-obtained Ir-Bi2O3/C catalysts show superior EOR mass activity of up to ca. 2250 mA mg−1Ir. Moreover, they exhibit the record lowest onset oxidation potentials (0.17–0.22 V vs. RHE) and the peak potential (ca. 0.58 V vs. RHE), being 130–300 mV lower than the previous landmark noble metallic catalysts. Furthermore, an apparent C1 pathway faraday efficiency (FEC1) of 28% ± 5.9% at 0.5 V vs. RHE can be obtained at Ir-Bi2O3/C. This work might provide new insights into the new anodic EOR catalysts for increasing the power of DEFCs.

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.

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.

Rhombohedral Pd–Sb Nanoplates with Pd‐Terminated Surface: An Efficient Bifunctional Fuel‐Cell Catalyst

Developing high-performance electrocatalysts for both ethanol oxidation reaction (EOR) and oxygen reduction reaction (ORR) is essential for the commercialization of direct ethanol fuel cells (DEFCs), but it is still formidable challenging. Herein, for the first time we have successfully prepared a novel Pd-Sb hexagonal nanoplate for boosting both cathodic and anodic fuel cell reactions. Detailed structural characterizations reveal that the nanoplates have ordered rhombohedral phase of Pd8 Sb3 (denoted as Pd8 Sb3 HPs) with Pd-terminated surface. Significantly, the unique Pd8 Sb3 HPs can exhibit much enhanced activity towards the oxidation of various alcohols in alkaline media. In particular, Pd8 Sb3 HPs/C displays superior specific and mass activities of 29.3mA cm-2 and 4.5 A mgPd -1 towards EOR, which are 7.0 and 11.3 times higher than those of commercial Pd/C, and 9.8 and 3.8 times higher than those of commercial Pt/C, respectively, representing one of the best EOR catalysts reported to date. In-situ electrochemical ATR-SEIRAS measurements reveal that Pd8 Sb3 HPs/C can effectively promote the C2 pathway of EOR, which is the key to the improved activity. As further disclosed by the density functional theory calculations, the higher EOR intrinsic catalytic activity of Pd8 Sb3 HPs can be ascribed to the reduced energy barrier of ethanol dehydrogenation. In addition, Pd8 Sb3 HPs/C can also show superior performance to both commercial Pd/C and Pt/C in cathodic ORR. This work advances the controllable synthesis of Pd-Sb nanostructure, which give huge impetus to the design of high-efficiency bifunctional electrocatalysts for energy conversion and beyond. This article is protected by copyright. All rights reserved.

Preparation of Co/N-CNT@poly(3,4-ethylenedioxythiophene)–NH2/Pt as an efficient catalyst for ethanol oxidation reaction

Direct ethanol fuel cell (DEFC) is one of the most advanced technologies for energy applications. A new Pt-based electrocatalyst for DEFC is developed through reasonable strategies to assist the commercialization of ethanol oxidation reaction (EOR). We obtain the composite material (Co/N-CNT@PEDOT-NH2) formed by Co, N co-doped carbon nanotubes (Co/N-CNT) and functional group (–NH2) grafted poly(3,4-ethylenedioxythiophene) (PEDOT-NH2) in ionic liquid (IL) by in-situ oxidation method as the catalyst support of Pt nanoparticles (Pt NPs). It is worth noting that the obtained composite material is entangled with each other to form a network structure with the help of IL, so that Pt NPs is uniformly loaded on the surface of the composite to promote the electron transmission. Meanwhile, the unique structure can form π-π* conjugation and hydrogen bonding, and help to anchor Pt NPs. The characteristics of the composite are measured by structure characterization (TEM, SEM, FT-IR, Raman, XRD, XPS) and a series of electrochemical tests. The results show that the mass activity (MA) of Co/N-CNT@PEDOT-NH2/Pt (1669.1 mA mg−1Pt) and Co/N-CNT/Pt (732.7 mA mg−1Pt) are higher than commercial Pt/C (279.6 mA mg−1Pt), indicating that Co/N-CNT@PEDOT-NH2/Pt is a promising EOR electrocatalyst.

Facile Synthesis of Pd@PtM (M = Rh, Ni, Pd, Cu) Multimetallic Nanorings as Efficient Catalysts for Ethanol Oxidation Reaction.

Pt-based multimetallic nanorings with a hollow structure are attractive as advanced catalysts due to their fantastic structure feature. However, the general method for the synthesis of such unique nanostructures is still lack. Here we report the synthesis of Pd@PtM (M = Rh, Ni, Pd, Cu) multimetallic nanorings by selective epitaxial growth of Pt alloyed shells on the periphery of Pd nanoplates in combination with oxidative etching of partial Pd in the interior. In situ generation of CO and benzoic acid arising from interfacial catalytic reactions between Pd nanoplates and benzaldehyde are critical to achieve high-quality Pt-based multimetallic nanorings. Specifically, the in-situ generated CO promotes the formation of Pt alloyed shells and their epitaxial growth on Pd nanoplates. In addition, the as-formed benzoic acid and residual oxygen are responsible for selective oxidative etching of partial Pd in the interior. When evaluated as electrocatalysts, the Pd@PtRh nanorings exhibit remarkably enhanced activity and stability for ethanol oxidation reaction (EOR) compared to the Pd@PtRh nanoplates and commercial Pt/C due to their hollow nanostructures.

Oxygen-rich PdSnCu nanocrystals with particle connection features as enhanced catalysts for ethanol oxidation reaction

Most electrocatalysts show a high mass and special activity during the ethanol oxidation reaction, but those still suffer from limited stability, finite renewable capability and poor anti-poisoning durability. Furthermore, the reliable structure and appropriate composition of catalysts are fairly associated with the electrocatalysis performance. Herein, we report the development of trimetallic Pd61Sn34Cu5 nanocrystals (NCs) whose rough surfaces are rich in step atoms and coupled with abundant of SnOx and CuO, which may effectively boost reaction activity and rapidly remove carbonaceous intermediate, respectively. Under the tuning on the composition, the defect rich Pd61Sn34Cu5 NCs exhibit elevated electrocatalysis activity and durability for ethanol oxidation reaction with an optimized mass activity (1.26 A ) and specific activity (10.6 mA cm−2), which is about 2.21 and 2.58 times greater than that of the commercial Pd/C catalyst (0.57 A and 4.1 mA cm−2).

Engineering of Amorphous PtOx Interface on Pt/WO3 Nanosheets for Ethanol Oxidation Electrocatalysis

AbstractDirect and complete electro‐oxidation of ethanol to CO2 is highly desirable for the commercialization of the direct ethanol fuel cells but is challenging. Current electrocatalysts (mainly Pt, Pd) for ethanol oxidation reaction (EOR), unfortunately, still suffer from low CO2 selectivity and rapid performance deterioration. In this study, a new Pt/α‐PtOx/WO3 electrocatalyst containing amorphous PtOx structures is successfully synthesized via a facile hydrothermal reaction following Ar atmosphere annealing. The migration of lattice oxygens in the WO3 during the annealing process is confirmed as the mechanism for the formation and manipulation of amorphous interfaces containing PtOx species in the Pt/α‐PtOx/WO3 electrocatalyst. The obtained Pt/α‐PtOx/WO3 with tunable amorphous PtOx interfaces favors the desorption of poisoning EOR intermediates (such as CO) and high CO2 selectivity. Therefore, the state‐of‐art of the Pt/α‐PtOx/WO3 exhibits excellent EOR activity (2.76 A mg–1), stability (47.99% of the initial activity preserved after 3600 s), and particularly high CO2 selectivity (reached 21.9%, higher than most reported values for Pt or other noble metals based EOR catalysts). This study may provide a new strategy to improve the EOR performance of metal‐based catalysts and to rationally design and prepare other high‐performing electrocatalysts via engineering the amorphous interfaces.

Unexpected electocatalytic activity of a micron-sized carbon sphere-graphene (MS-GR) supported palladium composite catalyst for ethanol oxidation reaction (EOR)

For the first time, a hybrid carbon material consisting of micron-sized carbon spheres and graphene (denoted as MS-GR) was prepared via a hydrothermal method. In this work, micron-sized carbon spheres were prepared using glucose and 1-butyl-3-methylimidazolium tetrafluoroborate as the starting materials through a hydrothermal method, and graphene was employed as purchased. One-pot and two-step hydrothermal methods were respectively employed to prepare MS-GR, and in each preparation method, three different amounts of graphene were added in the preparation system while maintaining the added amounts of other reagents identical for each prepared catalyst. As a result, six kinds of hybrid carbon materials were fabricated in this work. Next, MS-GR supported palladium composite catalysts were fabricated through a hydrothermal method using PdO·H2O as the palladium source. Metallic Pd particles, metallic Pd particles along with PdO were indicated by XRD patterns to be the main substances of the one-pot and two-step hydrothermally prepared MS-GR supported catalysts, respectively. As presented by the SEM images, micron-sized carbon spheres and individual graphene sheets as well as the small particles were exhibited clearly in all prepared catalysts, suggesting that all the resultant catalysts were a composite material. Most importantly, as indicated by the CV and CA curves, all synthesized catalysts showed obvious electrocatalytic activities for EOR. In particular, the peak current density of peak f for EOR in the CV curves on catalyst t-4 was as high as 29.1 mA cm-2, significantly larger than the previously reported values. And the current density of EOR measured by CA test on catalyst t-4 was retained as high as 2.83 mA cm-2 after 600 s, showing an excellent electrocatalytic durability. In this work, a carbon material constructed by micron-sized carbon spheres and graphene as well as a novel MS-GR supported Pd catalyst was developed for the first time, which was very helpful to the final commercialization of a Pd-based EOR electrocatalyst due to the greatly reduced the preparation cost and the facile preparation procedure.

A Phosphorus-Doped Ag@Pd Catalyst for Enhanced CC Bond Cleavage during Ethanol Electrooxidation.

Ethanol is preferred to be oxidized into CO2 for the construction of a high-performance direct ethanol fuel cell since this complete ethanol oxidation reaction (EOR) transfers 12 electrons. However, this EOR is sluggish and has the low activity as well as poor selectivity. To promote such a favorable EOR, more exactly the cleavage selectivity of CC bonds in ethanol, phosphorus-doped silver-core-and-Pd-shell catalysts (denoted as Ag@PdP) are designed and synthesized. In the alkaline media, a Ag@Pd2 P0.2 catalyst is superior toward EOR into CO2 . It exhibits seven times higher mass activity and six times higher selectivity than the benchmark Pd/C catalyst. As confirmed by means of density functional theory calculation and in situ Fourier-transform infrared spectroscopy, such high performance stems from an increased adsorption energy of OH radicals on the Pd active sites. Meanwhile, the tensile strain effect of a core-shell structure of this Ag@Pd2 P0.2 catalyst favors the formation of adsorbed CH3 CO intermediate, the key species for the enhanced C-C cleavage into CO2 , instead of acetate. The proposed way to design and synthesize such high-performance EOR catalysts will explore the practical applications of direct alkaline ethanol fuel cells.

MOF-Derived 2D/3D Hierarchical N-Doped Graphene as Support for Advanced Pt Utilization in Ethanol Fuel Cell.

Development of bifunctional catalysts with low platinum (Pt) content for the ethanol oxidation reaction (EOR) and the oxygen reduction reaction (ORR) is highly desirable, yet challenging. Herein, we present structural engineering of a series of two-dimensional/three-dimensional (2D/3D) hierarchical N-doped graphene-supported nanosized Pt3Co alloys and Co clusters (PtCo@N-GNSs) via a hydrolysis-pyrolysis route. For the ORR, the optimal PtCo@N-GNS exhibits a high mass activity of 3.01 A mgPt-1, which is comparable to the best Pt-based catalyst obtained through sophisticated synthesis. It also possesses excellent stability with minor decay after 50 000 cyclic voltammograms (CV) cycles in acidic medium. For the EOR, PtCo@N-GNS achieves the highest mass-specific and area-specific activities of 1.96 A mgPt-1 and 5.75 mA cm-2, respectively, among all of the reported EOR catalysts to date. The unique 2D/3D hierarchy, high Pt utilization, and valid encapsulation of nanosized Pt3Co/Co synergistically contribute to the robust ORR and EOR activities of the present PtCo@N-GNS. A direct ethanol fuel cell based on PtCo@N-GNS delivers a high open-circuit potential of 0.9 V, a stable power density of 10.5 mW cm-2, and an excellent rate performance, implying the feasibility of the bifunctional PtCo@N-GNS. This work offers a new strategy for designing an ultralow Pt loading yet highly active and durable catalyst for ethanol fuel cell application.

Comparative study of catalyst effect on ethanol electrooxidation in alkaline medium: Pt- and Pd-based catalysts containing Sn and Ru

The ethanol oxidation reaction (EOR) on Pd:M- and Pt:M-based nanocatalysts (M = Sn or Ru) was investigated by using electrochemical and chromatographic methods. These carbon-supported materials were prepared by the microwave-assisted method. The experimental bulk compositions of the Pt-based catalysts were very close to the nominal composition, and all the catalysts displayed the Pt or Pd fcc crystalline structure with crystallite sizes ranging from 1.6 to 6.8 nm. The Pd-based catalysts presented much higher catalytic activity and stability than the Pt-based ones. Electrolysis (HPLC) showed that the Pd:M catalysts are good materials for C2 (acetaldehyde and acetic acid) by-product production and improve the yields of ethanol consumption as compared to the poor activity of the Pt:M catalyst in basic medium. In alkaline medium, the co-catalyst did not lead to the huge differences observed in acidic medium. Pd:Ru/C proved to be the best catalyst for EOR in basic medium, surpassing the activity of Sn, which is known as the most active catalyst for this reaction in acidic medium.

Anode Catalytic Activity of Palladium‐Nickel Alloy Nanoparticles for Ethanol Oxidation in Alkali

AbstractTo fabricate cost‐effective anode catalysts for direct ethanol fuel cells (DEFC), Pd and a series of bimetallic PdxNi100‐x alloy nano catalyst has been synthesized by adhering toclassical wet chemical synthetic procedure. External capping agents have not been employed for stabilization of the nanoparticles. Several physicochemical characterizations reveal the generation of uniformly dispersed PdxNi100‐x catalysts with average crystallite size 6 nm. The catalytic capability of the PdxNi100‐x/C catalysts for ethanol oxidation reaction (EOR) has been verified by cyclic voltammetry (CV) and chronoamperometry (CA) study. It has been revealed that the peak current density is about 1.2 times higher for ethanol oxidation on Pd80Ni20/C catalyst than similarly synthesized Pd/C catalyst. Moreover, the catalytic proficiency of the bimetallic nano catalysts have been strongly dependent on the Pd : Ni ratio. The poisoning protected ability of the PdxNi100‐x/Ccatalysts leads to show stable performance after several cycles of continuous operation. Cyclic voltammetric and ex‐situ FTIR study of probable intermediates of EOR like acetaldehyde, sodium acetate reveal that Ni facilitate the generation of acetate in comparison to carbonate enlightening the reasonable mechanism of the ethanol oxidation reaction on PdNi surface.