Catalytic Activity For Ethanol Oxidation Research Articles

N-doped carbon-stabilized PdNiCu nanoparticles derived from PdNi@Cu-ZIF-8 as highly active and durable electrocatalyst for boosting ethanol oxidation

Controlling the component, tailoring the size and designing the carbon supporting materials are three promising strategies to improve electrocatalytic activity. Herein, a monatomic Cu carrier (CuCN) with larger specific surface area was used to anchor PdNi alloy nanoparticles by a facile one-step reduction method. Physical characterization revealed that the PdNi nanoparticles in the synthesized material possess good dispersion, which is mainly attributed to the high specific surface area of CuCN-900.Electrochemicalresults revealed that CuCN supported PdNi nanoparticles (Pd1Ni1/CuCN-900) nanohybrids had superior durability and catalytic activity for ethanoloxidation (EOR) compared with that of other PdxNiy/CuCN and commercial Pd/C. Rotating disk electrode (RDE) results further demonstrated that Pd1Ni1/CuCN-900 has a faster kinetic process of EOR than commercial Pd/C. DFT calculation implies that OH adsorption is preferentially near the Ni atom, the OH species on Ni1Pd1 surface play an important role in the process of EOR. This is of great research implications for finding new carbon carriers and regulating catalyst components to improve the catalytic efficiency of PdNi catalysts.

The Role of a Sn Promoter on an Anodic Pt Electrocatalyst Prepared over H2 O2 -Functionalized Carbon Supports for Direct Ethanol Fuel Cell (DEFC) Applications.

Multiwalled carbon nanotubes and Vulcan carbon were functionalized with a 30 %v/v hydrogen peroxide solution and employed as supports for Pt and PtSn catalysts prepared by the polyol method. PtSn catalysts with a Pt loading of 20 wt.% and a Pt : Sn atomic ratio equal to 3 : 1 were evaluated in the ethanol electrooxidation reaction. The effects of the oxidizing treatment on the surface area and the surface chemical nature were analyzed through N2 adsorption, isoelectric point, and temperature-programmed desorption measurements. Results showed that the H2 O2 treatment affects the surface area of the carbons to a great extent. Characterization results indicated that the performance of the electrocatalysts strongly depends both on the presence of Sn and on the support functionalization. PtSn/CNT-H2 O2 electrocatalyst displays a high electrochemical surface area and enhanced catalytic activity for ethanol oxidation in comparison to other catalysts in the present study.

Improving the catalytic activity of Pt-Rh/C towards ethanol oxidation through the addition of Pb

This paper describes the effect of composition on the catalytic activity of carbon-supported Pt-Pb, Pt-Rh, and Pt-Rh-Pb catalysts towards ethanol oxidation in acid media. The catalysts were synthesised by a polyol reduction method and characterised using several experimental techniques, including X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray absorption near edge structure, and X-ray energy dispersive spectroscopy. The catalytic activity towards ethanol oxidation was evaluated by cyclic voltammetry, chronoamperometry, and in situ Fourier transform infrared spectroscopy (FTIR) experiments. XRD data indicate the presence of Pb in both alloyed and oxide forms. TEM images reveal nanoparticles well-dispersed on the carbon support, with spherical shapes and particle sizes around 2.0–6.5 nm. The Pt3RhPb/C catalyst showed the highest catalytic activity for ethanol oxidation, reaching current densities 6.0 times higher than the commercial Pt/C catalyst. The trimetallic catalyst showed the highest CO2 and acetic acid formation, explaining the higher current densities presented during cyclic voltammetry and chronoamperometry. Additionally, since the oxidation appears to follow a non-selective path, the role of Pb in the trimetallic catalyst is not related to driving the reaction towards the production of CO2. The improvement in catalytic activity occurred due to the synergy between the metals.

Biosynthesis of ZnO Nanosheets Decorated with Pd Nanoparticles and Their Application for Electrochemical Investigation of Ethanol

Hierarchical ZnO microflowers with sheet thickness of ≈ 23 nm were prepared in the presence of Cystoceira baccata algae extract. Pd nanoparticles with an average size of 4.9 nm were embedded on the surface of these nanosheets in the presence of Cystoceira baccata algae extract. The structure of ZnO@Pd was characterized by XRD, FESEM, high-resolution transmission electron microscopy, and energy-dispersive X-ray spectroscopy methods. To investigate the possible application of the synthesized nanoparticles, the electrooxidation of ethanol on the surface of ZnO@Pd modified carbon paste electrode in alkaline media was studied using cyclic voltammetry. The electrode showed high catalytic activity for ethanol oxidation. It also showed high selectivity toward ethanol in comparison to other alcohols. Chronoamperometric measurements showed that this electrode could be used as a probe for determination of ethanol in a relatively wide linear range (180–500 mM) with a low detection limit (60 μM).

Metal and Metal Oxide Interaction in Hollow CuO/Pd Catalyst Boosting Ethanol Electrooxidation

A low Pd-loaded lychee-nut-like catalysts of CuO/Pd with hollow nanostructure are prepared by electrochemical displacement reaction, in which a Cu2O mesoporous sphere is as a sacrificial template in the presence of triblock copolymers Pluronic P123 (EO20PO70EO20). Furthermore, the feeding molar ratio of Cu2O and Na2PdCl4 is found to be critical factor for preparing well-defined hollow lychee-nut-like (HLN) CuO/Pd. Morphology, composition and crystal structure of the optimal HLN CuO/Pd catalysts are sufficiently characterized by transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy. The as-synthesized HLN CuO/Pd catalysts show high catalytic activity for ethanol oxidation in alkaline medium and the catalytic mass activity of the HLN CuO/Pd is 5.9-fold of commercial Pd/C and 10.8-fold of Pd black. In turn, HLN CuO/Pd catalysts possess outstanding stability and superior tolerance to CO species. The remarkably electrochemical catalysis performance of HLN CuO/Pd catalysts is attributed to the unique lychee-nut–like open nanostructures and the mutual interaction between Pd and CuO support, which optimizing the electronic structure.

Zn–Ni–P Nanoparticles Decorated g-C3N4 Nanosheets Applicated as Photoanode in Photovoltaic Fuel Cells

A novel ternary hybrid catalyst with high-efficient photoelectrocatalytic property, namely composite photocatalyst of Zn–Ni–P@C3N4, was successfully designed and prepared for ethanol oxidation in alkaline media. A new electrode material for photoactivated fuel cells (PFC) was proposed. The Zn–Ni–P@C3N4 photoanode was used to generate electricity by catalytic oxidation of ethanol which was used as a direct fuel. The catalyst with ternary hybrid structure exhibiteds superior catalytic activity for ethanol oxidation. Compared to the nanostructures of Zn–P@C3N4 and Ni–P@C3N4 respectively, it possessed a more negative onset potential, higher oxidation peak current, a greater peak current density and minimum mass transfer resistance. These unique properties above were proved by a series of characterizations which include Cyclic Voltammetry (CV), Linear Scan Voltammetry (LSV), Current–time curves and Electrochemical Impedance Spectroscopy (EIS) etc. The excellent electrocatalytic and photoelectrocatalytic performance could be ascribed to the maximum interfacial contact of Ni2P, ZnP2 and g-C3N4, which decreases the agglomeration of nanostructures and effectively suppresses the recombination of photogenerated electron-hole. This work provides a strategy for the synthesis of superior semiconductor which can be used as an efficient visible-light-driven catalyst for photochemical synthesis and energy conversion.

Effect of pore size in mesoporous MnO2 prepared by KIT-6 aged at different temperatures on ethanol catalytic oxidation

KIT-6 mesoporous silica aged at 40, 100, and 150 °C were used as hard templates to prepare different mesoporous MnO2 catalysts, marked as Mn-40, Mn-100, and Mn-150, respectively. The catalytic activities of these catalysts and the effect of pore sizes on ethanol catalytic oxidation were investigated. Mn-40, Mn-100, and Mn-150 have triple, double, and single pore systems, respectively. On decreasing the aging temperature of KIT-6, the pore sizes of KIT-6 decrease and that of mesoporous MnO2 catalysts increase. The pore sizes and catalytic activities increase in the order: Mn-40 >Mn-100 > Mn-150. Mn-40 catalyst has a higher TOF (0.11 s−1 at 120 °C) and the best catalytic activity for ethanol oxidation because of a bigger pore size with three pore systems with maximum distribution at 1.9, 3.4, and 6.6 nm, decrease in symmetry and degree of order, more surface lattice oxygen species, oxygen vacancies resulting from more Mn3+ ions, and better low-temperature reducibility.

Enhanced Electrocatalytic Activity of Pt-M (M= Co, Fe) Chitosan Supported Catalysts for Ethanol Electrooxidation in Fuel Cells

Here, metal nanoparticles were synthesized by chemical reduction of the corresponding metal salts in the presence of chitosan polymer. Binary and ternary metallic-chitosan Pt-Fe-CH, Pt-Co-CH and Pt-Fe-Co-CH nanocomposites were prepared. Transmission electron microscopy images and UV–Vis spectra of the nanocomposites confirmed the presence of the metal nanoparticles. The electrocatalytic activity of the nanocomposites for ethanol oxidation was tested by cyclic voltammetry, Liner Sweep Voltammetry, amperometric i-t curve and electrochemical impedance spectroscopy techniques. The effect of some experimental factors on ethanol oxidation was investigated. CO stripping was used to determine the CO tolerance of the catalysts for ethanol oxidation. Incorporation of small amounts of Co and Fe nanoparticles in the Pt-CH catalyst caused the higher activity of the catalyst for ethanol electrooxidation. The activation energy of Pt-Co-Fe-CH catalyst obtained from the Arrhenius equation was lower than other studied catalysts. These results showed that Pt-Fe-Co-CH catalyst has better catalytic activity for ethanol oxidation among all prepared catalysts.

Development and Characterization of Fuel Cell Sensor for Potential Transdermal Ethanol Sensing

Existing fuel cell alcohol sensors suffer from humidity interference and signal instability which renders them useless for transdermal ethanol detection in a non-ideal environment. To address these insufficiencies in fuel cell sensors, various electrode designs, along with the catalysts that would best improve response, were explored in this work. The designs include both two and three electrode setups with Nafion as the proton exchanging membrane. The three-electrode setup provided a more stable signal compared to the two-electrode setup. Considering the development of a potential transdermal ethanol sensor, the ethanol exposed area of the working electrode was optimized to be 1cm2. Catalysts such as Cu, stainless steel, and Ni were studied in these experiments and it was determined that Ni demonstrated the best catalytic activity for ethanol oxidation and oxygen reduction; providing 300 times greater current response than Fe and 3 times greater than Cu. The lower detection limit of the sensor is 1 part per million (ppm) and the sensitivity of the fuel cell sensor using the Ni catalyst was found to be 0.02 nAppm-1 in this study.

Ethanol Oxidation on Rh/Pd(poly) in Alkaline Solution

Bimetallic electrodes prepared by Rh nanoislands spontaneously deposited on polycrystalline palladium, Pd(poly), at submonolayer coverage were explored for ethanol oxidation in alkaline media. Characterization of obtained Rh/Pd(poly) nanostructures was performed ex situ by AFM imaging and by X-ray photoelectron spectroscopy. In situ characterization of the obtained electrodes and subsequent ethanol oxidation measurements were performed by cyclic voltammetry in 0.1M KOH. Palladium surface with 50% Rh coverage exhibited the highest catalytic activity for ethanol oxidation in alkaline media. The origin of the enhanced catalysis of Rh/Pd(poly) surfaces with respect to bare Pd was explained by the electronic effect. Possible reaction pathways for ethanol oxidation were discussed taking into account the activity of obtained bimetallic electrodes for the oxidation of CO and acetaldehyde, as the most probable reaction intermediates.

Development and Characterization of Fuel Cell Sensor for Potential Transdermal Ethanol Sensing

The existing fuel cell alcohol sensors [1-3] suffer severely with humidity interference and signal instability. This interference and instability renders the existing sensors useless for transdermal ethanol detection in non-ideal environment. To address these issues of the fuel cell alcohol sensor, various electrode designs along with the catalysts were explored in this work. The design includes both two and three electrode setups with the Nafion as proton exchange membrane, where the three electrode setup provided stable signal compared to two electrode setup. Considering the development of a potential transdermal ethanol sensor, the ethanol exposed area of the working electrode was optimized to 1cm2and reference and counter electrode were placed on the other side of the Nafion membrane. For the ethanol measurements in the three electrode system, a fixed potential was applied between working and reference electrode and the change in current due to ethanol concentration was measured between working and counter electrode. To eliminate the interference due to humidity the applied potential for measurement was same as that of the open circuit potential (OCP) of the fuel cell in presence of humidity. Catalysts such as Ni, Cu, Fe and Au were studied, where Ni has better catalytic activity for ethanol oxidation and oxygen reduction [4] providing almost 600, 300 and 3 times greater current response than Au, Fe and Cu respectively (Figure 1). The sensitivity for the sensor was found 0.062 nA/ppm in vapor phase for this Ni catalyst. Figure 1: Amperometric responses of fuel cell sensor for ethanol (a) Fe, (b) Au, (c) Ni and (d) Cu catalysts. Acknowledgements: This work is funded by the ASSIST NSF ERC and NSF I-Corps Teams.

Preparation and characterization of porous sponge-like Pd@Pt nanotubes with high catalytic activity for ethanol oxidation

Porous sponge-like Pd@Pt bimetallic nanotubes (PS Pd@Pt NTs) were prepared by a two-step method for the first time. The as-prepared PS Pd@Pt have an outer diameter of ~45nm and a thickness of ~5nm, numerous Pt nanoparticles distribute discontinuously around the surface of Pd NTs. The electro-catalytic behavior of the PS Pd@Pt NTs for ethanol oxidation was studied by using cyclic voltammetry and chronoamperometry. The results indicated that PS Pd@Pt NTs exhibit higher catalytic activity and better stability than Pt nanowires and Pt on Pd nanotubes.

Ethanol electro-oxidation on partially alloyed Pt-Sn-Rh/C catalysts

Ternary Pt-Sn-Rh/C catalysts of Pt:Sn:Rh=1:0.8:0.2 and 1:1:0.33 atomic ratios were synthesized using the formic acid method and their electrochemical activities were compared for ethanol oxidation with that of binary Pt-Sn/C (1:1) and Pt-Rh/C (1:0.11) catalysts. XRD analysis indicated the presence of Sn in both alloyed and oxide form and suggested the formation of a ternary Pt-Sn-Rh alloy in both catalysts. The particle size by TEM was around 3.5nm for all catalysts. The efficiency for Pt utilization increased with Rh content. Pt-Sn-Rh/C catalysts exhibited higher catalytic activity for ethanol oxidation than Pt-Rh/C, but lower than Pt-Sn/C. Among ternary catalysts, Pt-Sn-Rh/C (1:0.8:0.2) was the most active. In situ IRRAS showed Rh plays a dual counteracting role during ethanol electro-oxidation on Pt-Sn-Rh/C catalysts, once it promotes C-C bond breaking, thus favouring CO2 formation, but hinders adsorption of ethanol, decreasing the production of acetic acid.

Surface modification of Pt/C catalyst with Ag for electrooxidation of ethanol

The surface modification of Pt/C catalyst with Ag and the electrocatalytic oxidation of ethanol on the Ag–modified Pt/C catalysts are investigated. The Ag–modified Pt/C catalysts are prepared by means of the potentiostatic deposition of Ag on the Pt nanoparticles loaded on carbon black and coated on glassy carbon (GC) electrodes. Instrumental analysis and electrochemical analysis show that the metal nanoparticles are well distributed on carbon black and the surface of the Pt nanoparticles is partially covered by Ag. Cyclic voltammetric (CV) results display that the deposition of Ag leads to a significant improvement in the activity of Pt/C for ethanol oxidation in alkaline solution. In a wide range of Ag loadings, the Ag–modified Pt/C catalysts show more negative onset oxidation potential and much higher peak current density than the Pt/C catalyst, though Ag has no catalytic activity for ethanol oxidation.

Carbon-supported PdSn–SnO2 catalyst for ethanol electro-oxidation in alkaline media

Carbon-supported PdSn–SnO2 with high electrical catalytic activity for ethanol oxidation in alkaline solution was synthesized using an impregnation reduction method. XRD analysis of the as-prepared PdSn–SnO2/C revealed that the Pd diffraction peaks shifted to lower 2θ values with respect to the corresponding peaks of the Pd/C catalyst, indicating that Sn doping could shrink the Pd crystalline lattice. XPS measurements confirmed the existence of Sn and SnO2 in the PdSn–SnO2/C catalysts. The prepared PdSn–SnO2/C catalysts presented a remarkably higher electrocatalytic activity than that of the Pd–Sn/C and Pd/C catalysts. This was mainly because the easy adsorption-dissociation of OHads over the SnO2 surface changed the electronic effect and accelerated the adsorption of ethanol on the surface of Pd, thus enhancing the overall ethanol oxidation kinetics and contributing to a significant improvement in the catalytic activity.

Enhancing Alkaline Ethanol Oxidation on Ordered Intermetallic Pt3pb-Ptpb Core-Shell Nanoparticles Prepared by Converting Nanocrystalline Metals to Ordered Intermetallic Compounds

1. Introduction Recently, interest in direct fuel cells (DFCs) has increased in the field of polymer electrolyte membrane (PEM) fuel cells in which small organic molecule (SOM) liquid fuels, such as methanol (MeOH), ethanol (EtOH), and formic acid (FA), were used as fuels.1 Ethanol is a particularly attractive fuel because it has a lower toxicity, it is biogenerated, and it does not release carbon that was previously sequestered underground as coal, petroleum, or natural gas into the atmosphere.2 However, the full potential of DFCs has not been realised due to the slow kinetics in the anode reactions.3 Literature reports have described much faster oxidation kinetics for organic fuels in alkaline media than in acidic media.4 One of the research and development challenges for alkaline-type polymer electrolyte fuel cells (PEFCs) using SOMs is the design of better alternatives to the Pt, Pd, and Pt-Ru alloys currently used as the anode catalysts.5 To improve the electrocatalytic activity, Pt- and Pd-based alloy electrocatalysts have been investigated in alkaline media.6 Although the aforementioned alloys are promising materials, problems are associated with the use of disordered alloys (and alloys in general) as catalysts for fuel cell applications, including the low utilisation of the surface for electrocatalysis, the surface segregation of metal atoms, and the partial poisoning by CO due to insufficient quantities of the bimetallic elements on the surface. A new approach that prevents the problems inherent in disordered alloy catalysts has been proposed for highly active electrocatalysts for fuel cell applications.7 In contrast with a disordered alloy, intermetallic compounds with definite compositions and structures, such as PtPb and PtBi, exhibit excellent electrocatalytic performance for oxidising FA in acidic solutions in their onset potential for oxidation and current density.8,9 Abruña and co-workers have examined the FA, MeOH and EtOH oxidation activities for a wide range of intermetallic compounds in acidic media and found a significant number of the compounds, such as PtPb, PtBi and Pt3Ti, exhibit enhanced catalytic activities compared with pure Pt.8, 9 Our previous study indicated that the PtPb and PtBi ordered intermetallic compounds exhibited higher electrocatalytic activity for MeOH and EtOH oxidation in alkaline aqueous solutions than other Pt, Pt-Ru alloy and Pt-based ordered intermetallic compounds.10 In this paper, to enhance the electrocatalytic activity of PtPb ordered intermetallic compounds toward MeOH and EtOH in alkaline aqueous solutions, carbon black (CB)-supported Pt3Pb-PtPb intermetallic compound core-shell NPs were prepared via a two-step synthesis in which Pt3Pb-PtPb intermetallic compound core-shell NPs were formed on the CB through the reaction of the CB-supported Pt NPs and a Pb precursor in the presence of a reducing agent under microwave irradiation (Fig.1). The possibility of developing high-performance DFCs using Pt3Pb-PtPb intermetallic compound core-shell NPs as anode catalysts for alkaline EtOH oxidation is demonstrated. 2 . Results and Discussion We have successfully synthesised Pt3Pb-PtPb intermetallic compound core-shell NPs through a two-step synthesis in ethylene glycol under microwave irradiation. The pXRD, HX-PES and TEM/STEM characterisations demonstrated that pure PtPb NPs and Pt3Pb-PtPb intermetallic compound core-shell NPs could be prepared using one- and two-step syntheses, respectively, without requiring annealing. The Pt3Pb-PtPb intermetallic compound core-shell NPs exhibited higher catalytic activity for ethanol oxidation in alkaline aqueous solutions, enhanced tolerance for CO-poisoning and improved stability compared with commercial Pt NPs or pure PtPb NPs. 3 .

Improved performance using tungsten carbide/carbon nanofiber based anode catalysts for alkaline direct ethanol fuel cells

Tungsten carbides (WC) nanoparticles on platelet type-carbon nanofibers (p-CNFs) catalysts have been synthesized for alkaline direct ethanol fuel cells (ADEFC). Physical properties of WC/CNFs samples with various WC contents are analyzed by transmission electron microscope (TEM), thermal gravimetric analysis (TGA) and nitrogen isotherm (BET). The WC/CNFs catalysts showed an improved kinetics for the ethanol oxidation than p-CNFs did. It indicates that the significant increase in the catalytic activity for ethanol oxidation on WC/CNFs than p-CNFs did due to the synergistic structural effect between WC nanoparticles and the p-CNFs supports. WC/CNFs also showed good performances in ADEFC single cells. The maximum current density of P4W3 and P4W4 was 9.0 and 4.4 mA cm−2, respectively. These catalysts can be used as the ethanol oxidation in direct ethanol fuel cells in alkaline media.

Gas-liquid interface-mediated room-temperature synthesis of "clean" PdNiP alloy nanoparticle networks with high catalytic activity for ethanol oxidation.

PdNiP alloy nanoparticle networks (PdNiP NN) were prepared by simultaneous reduction of PdCl2, NiCl2 and NaH2PO2 with NaBH4via a gas-liquid interface reaction at room temperature using N2 bubbles. PdNiP NN had markedly higher activity and durability for ethanol oxidation than PdNi nanoparticle networks and PdNiP grain aggregates.

Bi-modified Pd/C catalyst via irreversible adsorption and its catalytic activity for ethanol oxidation in alkaline medium

A facile approach to promote ethanol electro-oxidation on Pd-based catalysts is presented by the modification of Bi on Pd/C catalyst via irreversible adsorption. X-ray diffraction (XRD), transmission electron microscope (TEM) and X-ray photoelectron spectroscopy (XPS) measurements show that the modification of Bi has no significant effect on the Pd morphology and particle size distribution. Bi(III) and Pd(0) are the dominant forms in Pd-Bi/C catalyst. Electrochemical tests show that the modification of the appropriate amount of Bi on Pd/C catalyst can remarkably enhance activity toward ethanol oxidation reaction (EOR) up to about 2.4 times higher compared to Pd/C catalyst. The Pd-Bi/C (20:1) catalyst exhibits excellent stability and enhances CO tolerance. The enhanced electrochemical performance of Pd-Bi/C catalyst is attributed to the electronic effect and the bifunctional mechanism. The high exchange current density and the low apparent activation energy on Pd-Bi/C (20:1) catalyst reveal its faster kinetics and higher intrinsic activity compared to Pd/C catalyst.

Newly‐Designed Complex Ternary Pt/PdCu Nanoboxes Anchored on Three‐Dimensional Graphene Framework for Highly Efficient Ethanol Oxidation

Newly-designed ternary Pt/PdCu nanoboxes on three-dimensional graphene framework (Pt/PdCu/3DGF) have been fabricated via a dual solvothermal strategy. This structurally well-defined Pt/PdCu/3DGF system possesses an approximately 4-fold improvement in catalytic activity for ethanol oxidation in alkaline media over the commercial 20% Pt/C catalyst as normalized by the total mass of active metals, showing the great potential for direct fuel cell applications.