Electrocatalysts For Ethanol Oxidation Research Articles

Pd nanoparticles supported on silver, zinc, and reduced graphene oxide as a highly active electrocatalyst for ethanol oxidation

In this manuscript, we present a facile approach to synthesize a highly active catalyst for the electro-oxidation of ethanol using Pd nanoparticles supported on a Ag–Zn alloy on reduced graphene oxide. This nanocomposite material was fabricated via a two-step process of incineration followed by sol-gel synthesis. The physical properties of the catalyst were evaluated using X-ray diffraction, X-ray photoelectron spectroscopy, and scanning and transmission electron microscopies. To understand the catalyst's activity for ethanol oxidation, we performed a series of cyclic voltammetry and electrochemical impedance spectroscopy experiments in alkaline medium. The catalyst exhibited good catalytic activity with a current density of 13.01 mA cm−2, a value seven times higher than the commercial standard Pd/C catalyst and higher than any other previously reported Pd-based catalyst. The results were attributed synergistic effects between the Pd and alloy support along with the large electrochemically active surface area of the material. Taken together, these results suggest that ethanol electrocatalysts based on nanocomposites of Pd, Ag, and Zn is promising candidates for future ethanol fuel cells.

PdSnW Ternary Alloy Nanoparticle with Excellent CO Anti‐Poisoning Activity for Boosting Alkaline Ethanol Oxidation Reaction

AbstractEfficient ethanol oxidation reaction (EOR) catalysts with anti‐poisoning ability and high selectivity are in high demand for the widespread application of direct ethanol fuel cells (DEFCs). Here, the PdSnW ternary alloy nanoparticles are synthesized by a facile solvothermal method and exhibit an enhanced EOR catalytic performance. CO stripping experiment, X‐ray photoelectron spectroscopy and in situ Fourier transform infrared are employed to study the correlation between catalyst structure and EOR catalytic performance. The oxyphilic Sn and W not only provide dangling O−H bond, accelerating the subsequent oxidation of adsorbed intermediate CO species, but also moderate the electron state of Pd, enhancing the adsorption of CH3CH2OH, thus resulting in the promotion of C−C bond cleavage and an increased C1 selectivity. As a consequence, PdSnW alloy nanoparticle catalyst exhibit a better stability and a higher mass activity than those of Pd/C, PdSn and PdW, respectively. This work not only offers novel insights to strategically design highly efficient electrocatalysts for ethanol oxidation, but also further clarifies the inherent structure‐activity relationship.

Titanium Oxycarbide as Platinum-Free Electrocatalyst for Ethanol Oxidation.

The compound material titanium oxycarbide (TiOC) is found to be an effective electrocatalyst for the electrochemical oxidation of ethanol to CO2. The complete course of this reaction is one of the main challenges in direct ethanol fuel cells (DEFCs). While TiOC has previously been investigated as catalyst support material only, in this study we show that TiOC alone is able to oxidize ethanol to acetaldehyde without the need of expensive noble metal catalysts like Pt. It is suggested that this behavior is attributed to the presence of both undercoordinated sites, which allow ethanol to adsorb, and oxygenated sites, which facilitate the activation of water. This is a milestone in DEFC research and development and opens up innovative possibilities for the design of catalyst materials for intermediate temperature fuel cells.

NiO coupled with CeO2 as an efficient electrocatalysts for ethanol oxidation in hybrid water splitting

Replacing oxygen evolution reaction (OER) by ethanol oxidation reaction (EOR) is an effective strategy to reduce energy consumption in water splitting. Thus, a heterostructure composed of NiO nanosheets and CeO2 nanorods (NRs) (NiO@CeO2) are preapred by hydrothermal method as an efficient electrocatalyst for EOR. Characterization and electrochemical results suggest that NiO@CeO2 shows enhanced EOR performance due to the synergistic effect, which deliver current density (j) of 10 mA cm-2 at only 1.37 V, much smaller than that of NiO and CeO2. So, NiO@CeO2-based electrode shows a low cell voltage (1.39 V@ 10 mA cm-2) for overall water splitting (OWS).

Synthesis of Pt-Au nanoparticles supported on reduced graphene oxide as a highly active and durability catalyst for electro-oxidation of ethanol

Design of advanced electrocatalyst, with high active and stability in electro-oxidation reactions for Direct Alcohol Fuel Cells system is urgent scientific need in the context of electrochemical energy application. Herein, Pt-Au nanoparticles supported on reduced graphene oxide, with low content of metals (With the theoretical content of 1.87% (Au) and 4.67% (Pt)), as a highly active and durability catalyst for electro-oxidation of ethanol is successfully synthesized. The current density (mass specific activity) of the PtAu/rGO catalyst for electro-oxidation ethanol, in alkaline media, was 13195 mAmgPt-1, which is 1.26 times higher than that of the Pt/rGO catalyst. After 4000s, the current density of PtAu/rGO catalyst reached 317 mAmgPt-1, is higher than that of Pt/rGO catalyst, reaching 172 mAmgPt-1. The high catalytic activity and stability of the bimetallic PtAu/rGO catalyst in the electrochemical oxidation of ethanol in alkaline medium are attributed to the synergistic effect of Au, Pt and rGO, among which, Au not only plays the role of enhancing the dispersion of Pt, but also has the effect of preventing the agglomeration of Pt nanoparticles during the reaction. This research could open up the potential to develop advanced bimetallic PtAu materials that can be used as electrochemical catalysts for various reactions.

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.

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.

MoO3/C-supported Pd nanoparticles as an efficient bifunctional electrocatalyst for ethanol oxidation and oxygen reduction reactions

MoO3/C-supported Pd nanoparticles as an efficient bifunctional electrocatalyst for ethanol oxidation and oxygen reduction reactions

Design and Synthesis of Palladium/Black Phosphorus–Graphene Hybrids as High-Performance Catalysts for Ethanol Electrooxidation in Alkaline Media

In this study, a series of Pd-supported black phosphorus–graphene (Pd/BP-G) catalysts are prepared to explore their electrocatalytic performances in the electrooxidation of ethanol in alkaline media. The characterization results show that BP is combined with activated graphene to form a P–C bond and a P–O–C bond heterojunction. Pd nanoparticles equally anchor on the BP-G hybrid, and Pd/BP-G exhibited enhanced electrocatalytic activity for the ethanol oxidation reaction in alkaline media. The electrochemically active surface area and mass activity for the Pd/BP-G catalyst reached 210.4 m2·gPd–1 and 3960.0 mA·mgPd–1, which are 9.54 and 5.86 times higher than those of commercial Pd/C, respectively. Further studies show that Pd/BP-G catalysts have reliable stabilities and faster reaction kinetics. These results indicate that the prepared Pd/BP-G catalysts have great application potentials in direct ethanol fuel cells.

Biosynthesize of Zinc Oxide Nanoparticles and Their Promoter Actions in the Application of Pd/ZnO Catalyst for Electro-Oxidation of Ethanol

Biosynthesize of Zinc Oxide Nanoparticles and Their Promoter Actions in the Application of Pd/ZnO Catalyst for Electro-Oxidation of Ethanol

Synthesis, Characterization and Electrochemical Performance of GO-PANIPpPDA/ Pd-Ni Nanocomposite as a Novel Catalyst for Ethanol Electrooxidation

Synthesis, Characterization and Electrochemical Performance of GO-PANIPpPDA/ Pd-Ni Nanocomposite as a Novel Catalyst for Ethanol Electrooxidation

Recent progress in the development of Platinum-based electrocatalysts for the oxidation of ethanol in fuel cells

Humans have an ever-increasing and ever-insatiable need for energy. The world's energy demands are currently being met by burning nonrenewable fossil fuels. Recurring challenges for civilization include developing dynamic energy cradles for a prosperous society to lessen fossil fuel depletion and environmental issues. The energy gap in the modern era can only be closed by the discovery of vast quantities of non-conventional resources. In place of dirty and inefficient fossil fuels, fuel cells provide a powerful and environmentally friendly alternative. In the realm of fuel cells, the direct ethanol fuel cell (DEFC) has garnered a lot of attention because it is a renewable fuel, easy to handle, and safe to use. High catalytic capabilities and durability make Pt-based electrocatalysts very promising. However, widespread commercial use has been hampered by their expensive price, poor stability, and Pt shortage. The keys to DEFC's practical uses are increasing the activity and durability of Pt-based electrocatalysts while decreasing the Pt content. This article will provide a summary of the most recent results about the development of Pt-based alloy electrocatalysts for ethanol oxidation. In addition, the most significant technological challenges are recognized, as well as prospective future study fields to solve these difficulties in order to pave the way for more research and development leading to practical implementation.

Large Au@Pd/PdOx core–porous shell nanoparticles as efficient ethanol oxidation electrocatalysts

An ultrathin layer of PdOx on the surface of large Au@Pd core–porous shell nanoparticles with diameters of between 20 and 60 nm plays a significant role in electrochemical ethanol oxidation.

Length-tunable Pd2Sn@Pt core-shell nanorods for enhanced ethanol electrooxidation with concurrent hydrogen production.

The electrooxidation of ethanol as an alternative to the oxygen evolution reaction presents a promising approach for low-cost hydrogen production. However, the design and synthesis of efficient ethanol oxidation electrocatalysts remain key challenges. Here, a colloidal procedure is developed to prepare Pd2Sn@Pt core-shell nanorods with an expanded Pt lattice and tunable length. The obtained Pd2Sn@Pt catalysts exhibit superior activity and stability for ethanol electrooxidation compared to Pd2Sn and commercial Pt/C catalysts. By tuning the length of the Pd2Sn@Pt nanorods, remarkable mass activity of up to 4.75 A mgPd+Pt-1 and specific activity of 20.14 mA cm-2 are achieved for the short nanorods owing to their large specific surface area. A hybrid electrolysis system for ethanol oxidation and hydrogen evolution is constructed using Pd2Sn@Pt as the anodic catalyst and Pt mesh as the cathode. The system requires a low cell voltage of 0.59 V for the simultaneous production of acetic acid and hydrogen at a current density of 10 mA cm-2. Density functional theory calculations further reveal that the strained Pt shell reduces energy barriers in the ethanol electrooxidation pathway, facilitating the conversion of ethanol to acetic acid. This work provides valuable guidance for developing highly efficient ethanol electrooxidation catalysts for integrated hydrogen production systems.

Performance study of palladium modified platinum anode in direct ethanol fuel cells: A green power source

The direct ethanol fuel cell is a green and renewable power source alternative to fossil fuels and produces less emissions compared to a combustion engine. Ethanol can be generated in great quantity from renewable resources like biomass through a fermentation process. Bio-generated ethanol is thus attractive fuel since growing crops for biofuels absorbs much of the carbon dioxide emitted into the atmosphere from the oxidation of ethanol. The platinum and palladium were co-deposited on graphite substrate by the galvanostatic technique and employed as anode catalyst for ethanol electrooxidation. The information on surface morphology, structural characteristics and bulk composition of the catalyst was obtained using scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive X-ray (EDX) spectroscopy. The cyclic voltammetry (CV) were used for the estimation of the electrochemically active surface area (ECSA) of the synthesized catalysts in alkaline medium. The CVs for ethanol oxidation revealed superior catalytic activity of Pt–Pd/C compared to Pd/C and Pt/C. The effect of OH− on ethanol oxidation at Pt–Pd/C catalyst was studied using cyclic voltammetry, quasisteady-state polarization, chronoamperometry, and electrochemical impedance spectroscopy (EIS). The Pt–Pd/C catalyst shows good stability and enhanced electrocatalytic activity is ascribed to the synergistic effect of higher electrochemical surface area, preferred OH− adsorption on the surface and palladium ad-atom contribution on the alloyed surface.

High-selective and effective carbon nanotubes supported ultrasmall PtPdRh electrocatalysts for ethanol oxidation

Pt as the most effective ethanol oxidation reaction (EOR) catalyst confronts the problems of insufficient activity, unsatisfactory selectivity and poisoning by intermediates. It hindered the practical use of direct ethanol fuel cells (DEFCs). Therefore, in this work, carbon nanotubes (CNTs) supported ultrasmall PtPdRh nanoparticles (PtPdRh/CNTs, ∼2.3 nm) were synthesized with polyallylamine hydrochloride and hexadecyl trimethyl ammonium bromide for EOR. Pd as the core may reduce the cost, and Rh is helpful to cleave C−C bond. The introduction of Pd and Rh further brings about synergetic effect and adjustment of electronic structures. Moreover, partially oxidized PtPdRh nanoparticles is favorable to generate *OH species in alkaline media to accelerate intermediates removal. Benefit from the nanostructures, the mass and specific activities of PtPdRh/CNTs (1345.16 mA·mg−1 and 1.37 mA·cm−2) are higher than both commercial Pt/C and corresponding mono-/bi-metal catalysts. PtPdRh/CNTs also exhibit excellent selectivity and anti-poisoning ability, with jf/jb as high as 6.17, larger than most up-to-date reports. Besides, PtPdRh/CNTs own excellent stability and durability. This study adopting a rational design strategy to fabricate high-selective and effective EOR catalysts is conducive to the practical application of DEFCs.

Electro-Design of Bimetallic PdTe Electrocatalyst for Ethanol Oxidation: Combined Experimental Approach and Ab Initio Density Functional Theory (DFT)-Based Study.

An alternative electrosynthesis of PdTe, using the electrochemical atomic layer deposition (E-ALD) method, is reported. The cyclic voltammetry technique was used to analyze Au substrate in copper (Cu2+), and a tellurous (Te4+) solution was used to identify UPDs and set the E-ALD cycle program. Results obtained using atomic force microscopy (AFM) and scanning electron microscopy (SEM) techniques reveal the nanometer-sized flat morphology of the systems, indicating the epitaxial characteristics of Pd and PdTe nanofilms. The effect of the Pd:Te ratio on the crystalline structure, electronic properties, and magnetic properties was investigated using a combination of density functional theory (DFT) and X-ray diffraction techniques. Te-containing electrocatalysts showed improved peak current response and negative onset potential toward ethanol oxidation (5 mA; −0.49 V) than Pd (2.0 mA; −0.3 V). Moreover, DFT ab initio calculation results obtained when the effect of Te content on oxygen adsorption was studied revealed that the d-band center shifted relative to the Fermi level: −1.83 eV, −1.98 eV, and −2.14 eV for Pd, Pd3Te, and Pd3Te2, respectively. The results signify the weakening of the CO-like species and the improvement in the PdTe catalytic activity. Thus, the electronic and geometric effects are the descriptors of Pd3Te2 activity. The results suggest that Pd2Te2 is a potential candidate electrocatalyst that can be used for the fabrication of ethanol fuel cells.

Interfacial engineering Pb skin-layer at Rh surface to promote ethanol electrooxidation into CO2 in alkaline media

Rh is recently regarded as the promising electrocatalyst for ethanol oxidation into CO2 due to its high activity of splitting C–C bond, whereas the further oxidation of as-generated C1 species (CO and CHx) is pretty sluggish at Rh surface. To solve this, here the oxophile Pb skin-layer is inhabited at Rh nanoparticles to obtain the Pb@Rh core-shell structure with controllable Pb coverage (θPb), expecting to tune the surface reactivity of ethanol oxidation reaction (EOR) according to the Langmuir-Hinshelwood Mechanism as well as the strain effect. Fortunately, the as-obtained Pb@Rh/C catalysts indeed significantly enhance the catalysis performance of EOR, the optimal mass activity is ca. 1450 mA mg-1 metal when θPb is ca. 0.53 (Pb0.53@Rh), being ca. 13 times higher than pristine Rh catalyst. Meanwhile, as much as ca. 57% of the initial EOR current remains even after a 20,000-s durability measurement. And the apparent C1 pathway faraday efficiency (CO2 selectivity) is also estimated to be ca. 21% at Pb0.53@Rh surface. This work can provide a simple and promising protocol to tune the surface reactivity by interfacial engineering manipulation.

Enhancing Ethanol Electrooxidation Stability over PtIr/GN Catalysts by In Situ Formation of IrO2 at Adjacent Sites

PtIr alloy is considered as one of the most promising catalysts for ethanol electrooxidation due to its excellent C–C bond breaking and dehydrogenation abilities. However, a small amount of intermediate species produced by ethanol oxidation can still poison Pt, thereby affecting the stability of ethanol oxidation. Here, graphene supported PtIr nanoparticles (PtIr/GN) with a Pt: Ir atomic ratio of 3:1 is synthesized by a simple hydrothermal reduction and thermal annealing. The physicochemical analyses show that IrO2 is formed in situ in PtIr/GNs (O) during annealing and located adjacent to PtIr alloys. IrO2 and PtIr are evenly dispersed on GNs. The electrochemical results indicate that PtIr/GNs (O) has higher catalytic activity and stability for ethanol electrooxidation than PtIr/GNs. After 1000 voltammetric cycles, the peak current density for PtIr/GNs (O) is 2.5 times higher than that for PtIr/GNs. The outstanding electrochemical performance of PtIr/GNs (O) is derived from PtIr alloy that promotes the cleavage of the C–C bond and weakens the adsorption of Pt to intermediate species, IrO2 that improves the tolerance of Pt to CO-like species and enhances the structural stability of Pt, and PtIr alloy and IrO2 in adjacent positions that synergistically improve the stability of catalytic ethanol oxidation.